Cytokine adjuvants for vaccine therapy of neoplastic and infectious disease

Cytokine & Growth Factor Reviews 22 (2011) 177–187

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Cytokine & Growth Factor Reviews journal homepage: www.elsevier.com/locate/cytogfr

Perspective

Cytokine adjuvants for vaccine therapy of neoplastic and infectious disease William K. Decker a,*, Amar Safdar b,** a b

Department of Pathology & Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA Department of Medicine, Division of Immunology and Infectious Disease, New York University Langone Medical Center, 550 First Ave., New York, NY 10016, USA

A R T I C L E I N F O

A B S T R A C T

Article history: Available online 20 August 2011

Vaccination, the revolutionary prophylactic immunotherapy developed in the eighteenth century, has become the most successful and cost-effective of medical remedies available to modern society. Due to the remarkable accomplishments of the past century, the number of diseases and pathogens for which a traditional vaccine approach might reasonably be employed has dwindled to unprecedented levels. While this happy scenario bodes well for the future of public health, modern immunologists and vaccinologists face significant challenges if we are to address the scourge of recalcitrant pathogens like HIV and HCV and well as the significant obstacles to immunotherapy imposed by neoplastic self. Here, the authors review the clinical and preclinical literature to highlight the manner by which the host immune system can be successfully manipulated by cytokine adjuvants, thereby significantly enhancing the efficacy of a wide variety of vaccination platforms. ß 2011 Elsevier Ltd. All rights reserved.

Keywords: Therapeutic vaccination Adjuvantation Cytokines Immunotherapy Historical perspective

1. A brief history of vaccination Few innovations have had a more meaningful impact upon modern medicine than the development of vaccination [1], a revolutionary achievement accomplished in piecemeal fashion over the course of the eighteenth and nineteenth centuries. Though purposeful inoculation of naı¨ve populations with smallpox virus may have had origins as ancient as China’s Han or even Qin dynasty [2], it is clear that the Ottoman Turks were commonly employing the practice of variolation by 1718, when the wife of the British ambassador to Istanbul, Lady Mary Wortley Montague, observed the local custom and popularized it upon her return to England [3]. Variolation consisted of the controlled inoculation of healthy individuals with infectious material derived from those with mild smallpox infections (now known to be caused by the strain Variola minor). While the course of disease following variolation was often milder than that of naturally acquired epidemic or endemic smallpox (Variola major), disease might still be relatively severe with a case fatality rate of 1–3%, about 1/10th that of fulminant smallpox. Nevertheless, survivors of variolation acquired durable immunity against Variola major and were typically spared the worst of its horrors [4]. Some years after the entrenchment of variolation among the eighteenth century European medical establishment, reports

* Corresponding author. Tel.: +1 713 798 5580; fax: +1 713 798 3033. ** Corresponding author. Tel.: +1 212 263 6400; fax: +1 212 263 3206. E-mail addresses: [email protected] (W.K. Decker), [email protected] (A. Safdar). 1359-6101/$ – see front matter ß 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.cytogfr.2011.07.001

regarding the possible protective efficacy of cowpox infection began to appear in the literature, a slow acknowledgement by the ivory tower of a fact long-recognized by the commoners: milkmaids almost never contracted smallpox. The earliest known such report may be credited to a British physician known only as Dr. Fewster whose paper, ‘‘Cowpox and its Ability to Prevent Smallpox’’, was read to the London Medical Society in 1765. Subsequent cowpox inoculations of healthy individuals were reported by academicians such as Jobst Bose in 1769 and Peter Plett in 1791, but the majority of known contemporaneous inoculators appear to have been farmers and milkmaids such as Sevel (1772), Jesty (1774), Rendell (1782), and Jensen (1791), all seeking to confer protective immunity upon their children. Few of these early pioneers had the means or ambition to publicize their discoveries and none also had the standing of a Fellow of the Royal Society as did Edward Jenner (Fig. 1A), the British physician who received full credit for the invention of smallpox vaccination in 1796. This is not to suggest that Jenner is undeserving of the credit that he received. Unlike his predecessors, Jenner demonstrated that protective immunity could be passed between vaccinees (i.e. not just from bovine host to human recipient), and most importantly, Jenner demonstrated that 23 inoculated individuals had genuinely developed immunity to smallpox by subsequently performing variolation and documenting the failure of these individuals to develop symptoms of disease. Indeed, until Jenner’s careful and elegant documentation, unproven anecdotal reports were universally met with skepticism and scorn or, to Peter Plett’s profound frustration, wholly ignored [5]. Following Jenner’s revolutionary discovery, nearly a century would elapse before the development of another vaccine. Jenner,

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Fig. 1. Giants of vaccinology and immunotherapy. (A) Edward Jenner, 1749–1823. (B) Agostino Bassi, 1773–1856. (C) Louis Pasteur, 1822–1895. (D) Joseph Lister, 1827–1912. (E) Robert Koch, 1843–1910. (F) William B. Coley, 1862–1936. Panels A–E released to the public domain through wikimedia commons. Panel F reprinted with permission from Nature Publishing Group.

a man truly ahead of his time, had been extraordinarily lucky. Nature had provided him with a pre-attenuated pathogen, a vaccine strain as perfect as any generated by years of serial passage in a laboratory. Future vaccinologists would need to wait for Antonio Bassi (Fig. 1B) to formally propose the germ theory of disease in 1844 [6], for Louis Pasteur (Fig. 1C) [7] and Joseph Lister (Fig. 1D) [8] to supply practical evidence in support of Bassi’s revolutionary theory, and finally, for Robert Koch (Fig. 1E) to develop and publicize his postulates between the years 1884 and 1890 [9]. In the century that separated Jenner and Koch, medical science proved that pathogens were the causative agents of disease and became aware that weakened or killed pathogens could often provoke protective immunity in inoculated hosts. Not coincidentally, this highly conducive scientific environment led to the development of a broad array of human vaccines in the late 19th and early 20th centuries. Beginning with the successful testing of the Pasteur/Roux rabies vaccine in 1885, eight important vaccines were introduced, providing protective immunity against plague (1897), cholera

(1917), typhoid (1917), diphtheria (1923), pertussis (1926), tuberculosis (1927), and tetanus (1927). Efforts continued throughout the war years and into the 1960s with the development of vaccines against virally transmitted diseases including yellow fever (1935), influenza (1945), polio (1955), measles (1963), mumps (1967), and rubella (1969). In the 1980s, advances in immunology, molecular biology, and medicinal chemistry led to the generation of multivalent cell-free polysaccharide vaccines for the prevention of meningococcal meningitis (Menomune, 1981) and pneumococcal pneumonia (PneumoVax, 1983). In late 1981, the first vaccine based upon a single purified surface antigen (HBsAg) became available for the prevention of hepatitis B (HBV) [10]. In addition to its unique composition, the original HBV vaccine was derived from a unique source: the plasma of four infected human hosts. While such a source seemed perfectly acceptable during the vaccine’s pre-HIV developmental phase, the burgeoning AIDS epidemic induced the manufacturers to develop a recombinant system of antigen production in yeast [11]. By the mid 1980s, the ability of medical science to manipulate the human immune system appeared to be unparalleled, and several contemporaneous discoveries engendered a significant degree of optimism regarding the use of immune-mediated therapies to treat or even cure cancer [12]. Though the idea of using the immune system to fight neoplastic disease was fairly novel in the 1980s, its practice was not. William B. Coley (Fig. 1F), a 19th century surgeon at the Hospital for the Ruptured and Crippled (now the Hospital for Special Surgery), developed the first immunotherapeutic treatment for cancer in 1893. Using a cocktail of heat-killed gram-positive and gram-negative bacteria, Coley treated his sickest patients by repetitive regimens of intratumoral injection, achieving extraordinary results that remain unrivaled to this day. Yet neither Coley nor any of his contemporaries recognized the treatment as an immunotherapy, i.e. that its mechanism of action had anything to do with the human immune system. Coley’s treatment never caught on with the broader medical community, supplanted in favor of contemporaneous developments in radiotherapy and chemotherapy. By the time the medical establishment was ready to embrace the idea of vaccine immunotherapy for the treatment of cancer, Coley and his ‘‘toxin’’ therapy had both been dead for over 50 years [13]. If there is a lesson to be learned from Coley’s experience, it is that the successful development of new vaccine therapies might be significantly enhanced by focus upon the adjuvant manipulation of the host immune system. This paradigm might be particularly true in the case of cancer, a disease which almost always provides a broad array of unique antigens, yet few danger signals to trigger TLR (Toll-like receptor) or other PRR (pattern recognition receptor) ligation and alert the host of its presence; but such a paradigm is also relevant with regard to recalcitrant infectious diseases that heretofore have defied the medical community’s erstwhile attempts at vaccine production. As Coley’s work clearly implies, the underlying receptivity of the vaccinee’s immune system might be at least as important as the antigenic composition of any vaccine. Indeed, ‘‘Coley’s Mixed Toxins’’ as the therapy was known, provided no tumor antigens of its own, relying instead upon (apparently) enhanced recognition of native antigens unique to neoplastic self as well as (likely) a robust stimulation of innate immunity. Accordingly, we report here recent advances in the use of cytokine adjuvants to alter the immunological landscape of the host in an effort to facilitate durable, antigen-specific immunity in response to vaccination. In many cases, the results demonstrate that inflammatory cytokine adjuvants offer the opportunity to boost specific immunity against important disease antigens for which immunostimulatory properties are suboptimal, inadequate, or absent.

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2. Type I interferons (IFN-a/b/v) Type I interferons (i.e. IFN-a), the most powerful natural adjuvants of the mammalian immune system, are secreted in response to infection by viral pathogens and should be considered as very effective vaccine adjuvants if it is a Th-1 type/cellular immune response that is the desired result of vaccination. In vivo, dendritic cells (DC) that express lymphoid-specific lineage markers, the plasmacytoid DC subset, serve as accessory cells that aid in the immune response by secretion of IFN-a in response to viral infection and other types of inflammation. Consistent with a role in viral defense, plasmacytoid DCs express intracellular Tolllike receptors (TLR)-7 and -9, which are important in the recognition of microbial nucleic acids, but do not express other TLRs, such as TLR-1, -2, -3, -4, -5, or -8. In response to activation by TLR ligation and/or inflammatory chemokines, plasmacytoid DCs migrate to sites of inflammation where they secrete robust quantities (up to 10 pg/cell) of IFN in situ [14–18]. IFN-a exerts distinct and profound immunologic effects upon target somatic cell populations, cells of the innate immune system, and cells of the adaptive immune system via modulation of professional antigen presenting cells (APCs), principally myeloid dendritic cells. Several groups have demonstrated that IFN-a treatment significantly elevates serum TNF-a and IL-12 levels in vivo; upregulates dendritic cell MHC class I, MHC class II, and CD86; increases the levels of circulating CD40+ APC and CD8+ T-cells; and enhances NK cell cytotoxic activity [19–21]. Most significantly, application of IFN-a induces global alterations to the manner by which antigens are processed and presented following ubiquitination and proteolytic digestion. In the presence of IFN-a, constitutively expressed catalytic subunits b1, b2, and b5 of the 26S proteasome are replaced by inducible catalytic subunits LMP2, LMP7, and MECL1, generating the so-called ‘‘immunoproteasome’’. Upregulation of processing/presentation components TAP1, TAP2, calnexin, calreticulin, and tapasin is also observed in both professional APC and somatic cell types [20–23]; and there is a growing body of evidence that modulation of target cells by IFN-a comprises an important aspect of Th-1 mediated immunity. 2.1. Neoplasia There are four recent reports (Table 1) in which adjuvant IFN-a was administered in conjunction with a cancer vaccine in an attempt to modulate host immunity and enhance tumor-specific immune responses [24–27]. Most prominently, Bocchia et al. reported a CR rate of 47% in an internally controlled vaccine trial targeting CML patients with the b3a2 fusion breakpoint of p210 BCR-ABL. The study enrolled refractory patients who had already undergone monotherapy with imatinib or IFN-a without exhibiting a complete cytogenetic remission. Though the authors reported that all 15 evaluable patients exhibited improved cytogenetic responses following vaccination, only 47% (7/15) met the clinical criteria for CCR. The authors also reported that 11 of 16 evaluable patients developed peptide-specific DTH responses and that 13 of 14 exhibited peptide-specific CD4+ cell proliferation. In three other reported trials for which IFN-a was utilized as a vaccine adjuvant, Melan-A/MART-1/gp100 peptides, tumor-derived peptide/gp96

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complexes (Oncophage), and allogeneic tumor cell lysates (Melacine) were used to vaccinate patients against metastatic melanoma. Nearly all clinical activity observed in these trials was limited to transient disease stabilization; however, 4 of 39 evaluable patients in the Melacine trial (10.4%) exhibited either a CR or PR, and all of these survived at least twice as long (>2 years) as the average study participant (14 months). There also exist promising preclinical experimental data indicating enhanced efficacy of poxvirus vaccines when administered in conjunction with IFN-a for treatment of colorectal and pancreatic adenocarcinomas [28]. The TRICOM poxvirus vector itself is a powerful adjuvant capable of significantly enhancing antigen-specific immune responses in a manner partially dependent upon its ability to elicit IFN-a production. In addition to the tumor vaccine antigen, the vector expresses B7-1, intercellular adhesion molecule-1, and LFA-3, three T-cell costimulatory molecules capable of imparting APC-like immunostimulatory properties to transduced somatic cell types [29]. Recent work has demonstrated that antigen-specific responses are enhanced by recognition of the fowlpox vector by TLRs 7 and 9, a mechanism clearly dependent upon IFN-a secretion from the pDC subset; however, only the MyD88 adaptor protein was shown to be absolutely required for the generation of antigen-specific immunity. The authors concluded that the development of vectormediated adaptive immunity was independent of MyD88s role in TLR signaling and was promulgated primarily by T-cell specific IL18 receptor signaling [30]. In a phase I clinical trial, vaccination of patients with advanced CEA+ neoplasms using TRICOM fowlpox and vacciniavirus vectors expressing CEA resulted in prolonged stabilization of disease (>6 months) in 14 of 58 enrollees. A single patient exhibited a complete pathologic response [31]. In another phase I trial, ten patients with advanced pancreatic cancer were vaccinated with vectors expressing both CEA and MUC-1. Overall survival was greatly enhanced among those who developed antiCEA and anti-MUC-1 immune responses (15.1 months) in comparison to those who did not (3.9 months) [32]. 2.2. Infectious disease Type I IFNs enhance antigen presentation and promote the expansion, survival, and effector function of cytotoxic T cells during respiratory viral infections such as influenza. IFNs are pleiotropic innate cytokines that have also been shown to augment T-cell responses following exposure to related viral antigens to combat infection. IFN-a modifies memory T-cell responses when exposed to related antigens, and this immune modulatory capacity may be important for the augmentation of vaccine-mediated immune induction [33]. In mice, IFN-a signaling enhances secretory IgA antibodies and boosts mucosal immunity in nasal passages and the lower respiratory tract when given in conjunction with influenza vaccine [34]; however, this intervention in healthy human volunteers failed to show a significant benefit in serum or mucosal immune protection despite IFN-a doses of up to 10 million units, though high dose IFN-a along with influenza vaccine was well-tolerated [35]. IFN-a has successfully been shown to improve the protective immunity of peptide and vector-based vaccines. These experimental vaccines may be developed in the

Table 1 Recent tumor vaccine trials utilizing adjuvant interferon alpha. Disease indication

Vaccine type

Immunological response

Clinical response

Reference

Melanoma Melanoma CML Melanoma

Peptide Hsp/tumor peptide complex Peptide Allogeneic lysate

71% (5/7) 29% (5/17) 69% (11/16) N/A

29% 22% 47% 10%

[24] [25] [26] [27]

(2/7) (4/18) (7/15) (4/39)

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future to afford protection against serious life-threatening infections such as Venezuelan equine encephalitis virus and other causes of viral encephalitis [36]. The role of adjuvant interferon in niche populations of immunosuppressed patients such as those with leukemia and lymphoma remains uncertain. The use of adjuvants capable of improving the deficient immune response to hepatitis B virus (HBV) vaccine in immunosuppressed populations has been explored. In patients dependent upon prolonged renal replacement therapy, responses to conventional HBV vaccine alone have been suboptimal. Administration of recombinant INF-a2b plus HBV vaccine in unvaccinated hemodialysis patients achieved earlier and higher seroprotection rates and a transient improvement in Th1-dependent immune responses. Mild to moderate fever, asthenia, and arthromyalgia were the most common adverse events noted [37]. Histamine alters the cytokine profiles of maturing monocytederived DC so that the resulting T-cells are increasingly Th-2 polarized in function. Human plasmacytoid DC, activated by viral infection, also respond to histamine through H2 receptors, resulting in marked down-regulation of IFN-a and TNF-a as well as a moderate switch in their capacity to polarize naive T-cells. This observation is intriguing as patients with atopic conditions and other high histamine states may attenuate plasmacytoid DC APC function via reduced IFN-a and ineffective generation of adaptive cellular immune responses following vaccination [38]. Further studies are needed to assess the feasibility of intervention with exogenous interferons in order to boost antigen-specific cellular immunity, enhance endogenous cytokine production, and elicit better vaccine responses. It is also of interest to explore nonbiologics that can enhance innate immune responses. Levamisole up-regulates the expressions of TLR-7 and 8, MyD88, IRF7 and levels of downstream pro-inflammatory cytokines (e.g. IFN-a, TNF-a) which promote DC activation. In mice, levamisole plus recombinant rHBsAG induced robust cell-mediated responses including high IgG2a/IgG1 ratios, T-cell proliferation, and antigenspecific, IFN-g secreting CTL [39]. 2.3. IFN-a mediators: CpG ODN, imiquimod, resiquimod The application of certain small molecule compounds can produce clinical effects similar or identical to that of IFN-a administration due to the ability of these agonists to engage TLR-7 or 9 on the in situ plasmacytoid DC (pDC) subfraction, thereby eliciting IFN-a secretion either locally or systemically. The most clinically relevant of these compounds in the context of vaccination are detailed below. 2.3.1. TLR-9 agonism (CpG ODN) In mammalian DNA, CpG islands (dinucleotide motifs comprised of cytosine and guanine in succession) are frequently modified in an epigenetic fashion by methylation of the cytosine residue. In contrast, prokaryotic and viral DNA are typically unmodified, providing the mammalian immune system with a powerful innate pattern for the recognition of microbial pathogens. TLR-9, localized in the intracellular endosomes of the pDC subset, does just that, inducing pDC to secrete IFN-a, to acquire a more myeloid-like phenotype that upregulates surface costimulatory molecules and presents antigens, or in some cases, both. The pDC response to CpG ODN depends upon the endosomal compartment to which the CpG molecule tends to localize, a characteristic itself dependent upon the secondary or tertiary structure of the molecule. CpG type A molecules (CpG-A) localize to early endosomes and mediate IFNa secretion, whereas CpG type B (CpG-B) molecules localize to late endolysosomes and mediate maturation. A third type of CpG ODN, CpG type C, can localize to both compartments and produce both outcomes. Interestingly, TLR-9 signal transduction proceeds

through different signaling mediators depending upon the compartment in which ligation occurs. In early endosomes, TLR-9 signals through MyD88 and IRF-7 while TLR-9 ligation in the late endolysosome potentiates signaling through IRF-5 and NFkB [16,40,41]. TLR-9 is also expressed in B-cells, a site at which the application of CpG ODN will result in proliferation, enhanced antibody and cytokine secretion, and the differentiation of memory B-cells into plasma cells [42,43]. CpG ODN are currently being used to adjuvant a variety of conventional and experimental vaccines in healthy adults including prophylactic approaches for anthrax [44], malaria [45,46], and influenza [47], as well as to boost vaccine responses in HIV-infected individuals [48,49]. Several small trials have also utilized CpG as an adjuvant in therapeutic vaccination of (predominantly) melanoma patients, and while some enhanced immune responses were noted, significant clinical benefit was not reported [50–52]. 2.3.2. TLR-7 Agonism (Imiquimod) and TLR-7/8 Agonism (Resiquimod) Engagement of toll-like receptors serve to link innate immune responses with adaptive immunity and can be exploited as powerful vaccine adjuvants for eliciting both primary and anamnestic immune responses. Imidazoquinolines like R837 and stimulatory ssRNA oligonucleotides polyUs21 both trigger TLR7mediated immune activation. In immunization studies, only polyUs21 led to robust priming of type 1 T helper cells and cytotoxic T lymphocytes, and it has been a powerful promoter of antitumor inducible immunity than imidazoquinolines [53,54]. Topical application of imiquimod (AldaraTM) is already standard of care treatment for some basal cell carcinomas and can be used as monotherapy to treat other cutaneous malignancies like melanoma [55]; however its potential role as a vaccine adjuvant for therapy of malignant disease has only recently begun to be reported in the clinical literature [56,57]. Imiquimod is poorly soluble in aqueous solution, heretofore limiting its use primarily to local, topical application. Resiquimod is a second generation analogue of imiquimod that targets not only pDC TLR-7 but also TLR-8 expressed in conventional myeloid DC. Resiquimod is reported to be in phase I clinical trials in conjunction with a vaccine approach for the treatment of invasive bladder cancer [58]. 3. Fms-like Tyrosine Kinase 3 Ligand (Flt3-L) Hematopoietic growth factor Fms-like Tyrosine Kinase 3 Ligand (Flt3-L) is a type I transmembrane protein that can also be cleaved and released as a soluble homodimeric cytokine. It is expressed both by stromal fibroblasts in the hematopoietic niche and by Tlymphocytes whereas expression of the Flt3 receptor is limited specifically to early progenitors of both the myeloid and lymphoid lineages as well as on fully differentiated myeloid and plasmacytoid dendritic cells; expression is downregulated or abrogated by commitment to alternative cell fate on megakaryocytic and erythroid precursors as well as pro-B and T cells. While targeted genomic disruptions of both Flt3 and Flt3-L indicate that this ligand receptor combination plays an important role in early hematopoietic development, exogenous administration of Flt-3L to the mature organism results in a dramatic increase of dendritic cell content in marrow, spleen, and thymus as well as peripheral blood and peripheral lymphoid organs [59–63]. Indeed, it is this dramatic increase in dendritic cell populations that underpins the rationale for the use of Flt-3L as a vaccine adjuvant. 3.1. Neoplasia The literature describes three recent trials in which Flt3-L was administered systemically in conjunction with cancer vaccination.

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The pervasive theme that emerges from these trials is that the excess numbers of DCs produced by treatment with Flt-3L cannot be translated into enhanced antigen-specific immunity in the absence of appropriate maturation, inflammatory, or activating factors. Two early trials report the use of adjuvant Flt3-L administered in conjunction with peptide vaccines for HER-2/ neu-expressing neoplasms, either breast/ovarian [64] or prostate [65]. Predictably, neither study was able to demonstrate enhanced peptide-specific immune responses despite significant increases in circulating DC. In a subsequent Flt3-L adjuvanted vaccine trial for immunotherapy of melanoma, the study authors preconditioned the vaccination site with the TLR-7 agonist imiquimod [66], a potent stimulator of the plasmacytoid DC subset, the activation of which induces copious IFN-a secretion. In this effective immunostimulatory environment, the authors reported that 5 of 8 patients treated with imiquimod developed specific responses to the Melan-A, tyrosinase, and NY-ESO-1 vaccine peptides whereas only 2 of 8 untreated patients developed such responses. One of twelve evaluable patients exhibited a clinical response to the vaccination protocol, though the authors did not mention the treatment group (imiquimod vs. no imiquimod) to which the responder had been randomized. 3.2. Infectious disease Injected soluble proteins that lack endogenous TLR ligands are often poorly immunogenic and may elicit antigen-specific tolerance due to inadequate stimulation of APCs. Adjuvants that promote the release of proinflammatory cytokines like TNF-a and IL-1b activate professional APC, thereby eliciting immunity. Flt3 ligand has been shown to induce expansion of dendritic cells (DCs) in vivo, dramatically enhancing the sensitivity of antigen-specific B and T-cell responses to systemic injection of soluble proteins via a CD40/CD40L-dependent signaling mechanism [67]. In non-human primates, soluble Flt3-L induced an increase in circulating DCs that peaked approximately 4 days after the last of 7 consecutive days of treatment [68]. Mycobacterium tuberculosis is the leading cause of infections worldwide, and current strategies for infection prevention in the developing world are fraught with inefficacies. The host immune resistance to active M. tuberculosis disease is dependent upon the activation and maintenance of pathogen-reactive T-cells. Dendritic cells (DCs) are the major antigen-presenting cells initiating antimycobacterial T-cell responses in vivo. The potential of in vivo targeting of DCs to improve antimycobacterial vaccine efficacy by means of nucleic acid vaccination was demonstrated using a DNA fusion of Flt3L and M. tuberculosis antigen 85B genes in mice. This strategy elicited enhanced IFN-g release from T-cells and better protection against virulent M. tuberculosis than DNAs encoding single vaccine components. Similarly, vaccination with the recombinant Mycobacterium bovis BCG strain secreting Flt3L (BCG:Flt3L) resulted in early expansion of DCs compared to immunization with BCG alone as well as the generation of target-specific IFN-gsecreting T cells. Importantly, the BCG:Flt3L construct was less virulent in immunosuppressed mice when compared to conventional BCG vaccination [69]. Another potential antimycobacterial vaccine candidate is early secretory antigenic target 6 (ESAT-6), shown to induce protective T cells response in animals. Mice immunized with a recombinant DNA vaccine encoding ESAT-6 and Flt3-L generated an effective T-cell-mediated immunity against M. tuberculosis that included elevated levels of lymphocyte proliferation, enhanced production of Th-1 cytokines (IFN-gamma and IL-2) by spleen cells, and increased specific antibody in sera, all in conjunction with lower levels of Th-2 cytokines (IL-4 and IL-10) [70]. Flt3-L has also been explored in conjunction with experimental HCV vaccination. In mice, co-vaccination of DNA encoding GM-CSF,

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Flt3-L, and the HCV NS5 protein induced increased antibody responses and specific CD4+ T-cell proliferation. Importantly, in these experiments no increase in splenic DCs or NK cell content was observed, in contrast with the dramatic increase of these cell types that were seen following administration of recombinant Flt3-L. This result somewhat mitigates hypothetical concerns for autoimmune disorders, splenic fibrosis, or hematopoietic malignancy that might occur following the use of recombinant forms of GM-CSF and Flt3-L [71]. Promotion of mucosal immunity via topical administration of vaccine alone has been difficult. In mice sublingual DNA vector encoding Flt3-L plus OMP of bacteria associated with chronic periodontitis elicited a protective immune response that included significant serum IgG (IgG1 and IgG2a) and salivary IgA, as well as a marked increase in Flt3-L in saliva and serum and an increased frequency of activated (CD80, CD86 and CD40 upregulated) dendritic cells in submandibular lymph nodes and spleen. This method may present another potential route for generating mucosal immunity against a host of primary infections [72]. 4. Interleukin 12 (IL-12) IL-12 is a critical regulator of Th-1 type or cell-mediated immunity. It is a heterodimeric cytokine comprised of covalently bound p35 and p40 subunits and secreted predominantly by myeloid APC such as dendritic cells, macrophages, and monocytes, though it can also be secreted by B-lymphocytes under some circumstances. IL-12 is an important component of the complex network of signaling molecules that regulate CD4+ Th-1, Th-2, Th17, and T regulatory responses. A wide variety of signals can induce IL-12 secretion including various TLR agonists, IFN-a, and other complex signals indicating the presence of intracellular infection [73]. In addition to promoting Th-1 type, CD8-mediated cellular immunity, the secretion of IL-12 also tends to suppress IL-4 mediated Th-2 responses, IL-23 mediated Th-17 responses, and IL10 mediated T-regulatory responses. While it was once thought that IL-12 was able to drive a Th-1 cell fate in naı¨ve, nonpolarized, CD4+ cells, recent work has established that an earlier, differentiative step generates a Th-1 precursor for which IL-12 is a survival, growth and differentiation factor. The revised model suggests that IFN-g secreted by cells of the innate immune system (i.e. NK cells) signals non polarized CD4+ cells through STAT1 causing the expression of the T-bet transcription factor. T-bet appears to be a negative regulator of transcription and is known to suppress expression of GATA-3, the major transcriptional regulator of Th-2 differentiation [74,75]. 4.1. Neoplasia Given the consensus that a cellular immune response is a prerequisite for the induction of durable, tumor-specific immunity, a significant number of recent vaccine trials have sought to use IL12 alone or in combination with other adjuvants in an attempt to generate a Th-1 polarized response (Table 2). Many of these trials also compared the use of additional adjuvants in combination with IL-12 to the use of IL-12 alone. Hansson et al. demonstrated idiotype-specific T-cell responses in 33% (5/15) of patients treated with idiotype vaccine and IL-12 yet were able to demonstrate specific responses in 85% (11/13) of patients treated with IL-12 and GM-CSF in tandem; however, the only two patients on study who demonstrated a clinical response were in the IL-12 only group [76]. Likewise, Hamid et al. demonstrated peptide specific T-cell responses in 87% (34/39) of patients receiving IL-12 + alum adjuvant whereas specific responses were documented in only 19% (4/21) of patients receiving IL-12 + GM-CSF. Among patients who did not relapse, 76% exhibited an immune response, while

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Table 2 Recent tumor vaccine trials utilizing adjuvant IL-12. Disease indication

Vaccine type

Additional adjuvant

Immunological response

Clinical response

Reference

Myeloma Melanoma Glioma Melanoma Melanoma Melanoma Melanoma

Idiotype Peptide DC/tumor fusion Peptide Peptide Peptide Peptide-pulsed PBMCs

GM-CSF Alum/GM-CSF None None None IFA None

57% 63% 20% 12% N/A 85% 53%

7% (2/28) 46% (17/37)a 33% (5/15) 8% (2/24) 35% (7/20) N/A 40% (6/15)

[76] [77] [78] [79] [80] [81] [82]

a

(16/28) (38/60) (3/15) (3/25) (32/40) (8/15)

Estimated.

specific immune responses were exhibited by only 39% of those who did relapse [77]. Kikuchi et al. reported clinical responses (reduction of tumor mass greater than 50%) in 33% (5/15) of patients following vaccination of malignant glioma patients with a DC/tumor cell fusion vaccine + rhIL-12; however durable response was limited to only 2 of the original 5 responders [78]. Two peptide vaccine + IL-12 trials for the treatment of melanoma reported modest clinical activity [79,80]; a third such trial that utilized both IL-12 and IFA (incomplete Freund’s adjuvant) reported an excellent immunological response rate of 85% (32/40) but made no mention of clinical responses [81]. Gajewski et al. reported clinical responses in 40% (6/15) of melanoma patients vaccinated with peptide-pulsed total PBMCs. Three of the six responders demonstrated mixed responses, and the study authors were able to demonstrate loss of the vaccine antigen in at least 2 of these 3 individuals. Of the three responders with true responses, 100% (3/ 3) were alive 17 months post-vaccination whereas only 17% (2/12) of patients without true responses were still alive [82]. 4.2. Infectious disease IL-12 is also an attractive candidate for improving protein vaccine responses [83]. Co-administration of DNA encoding IL-12 and GM-CSF with DNA encoding influenza A and La Crosse viral antigens demonstrated adjuvant effects upon protective immunity and a survival benefit following lethal viral challenge [84]. Animal studies using live attenuated conditionally replicating HSV modified to express IL-12 or GM-CSF showed IL-12 expressing virus conferred greater protection at a lower dose than GM-CSF expressing virus [85]. In intranasal influenza vaccination, IL-12 was shown to be important in promoting transferable adaptive humoral and cellular immune responses exhibited by elevated levels of lung and splenic IFN-g and IL-10 mRNA. IgG2a anti-H1N1 antibody levels in serum were significantly elevated, as were total, IgG1, IgG2a, and secretory IgA antibody levels in bronchoalveolar lavage fluids in comparison to animals given vaccine alone. Similarly, survival benefit favored co-administration of IL-12 with influenza vaccine [86]. The administration IL-12 along with influenza subunit vaccines was also shown to reverse the neonatal immune bias towards Th-2 skewing and conferred protection and Th1-like responses in newborn mice [87]. In other experiments, IL12 has been used to promote Th1/Th17-type responses, especially in gene gun delivery of DNA vaccines that, in the absence of IL-12, typically drive a strong Th-2 response. It was interested to note that co-delivery of IL-23 did not alter the type of immune response though the longevity of antibody responses following vaccination was increased in mice given IL-23 along with vaccine [88]. Virus-like particles (VLPs) using recombinant baculovirus infected cells have been use to express single or polyantigenic influenza structural proteins such as hemagglutinin (HA), neuraminidase (NA), matrix 1 (M1) and 2 (M2). In a recent publication, VLP formed by M1 and HA was given to mice both with and without concomitant IL-12 administration. All VLP-vaccinated and influenza-immunized control mice demonstrated high antibody

titers to the HA protein. Antibody responses were enhanced when VLP vaccine was formulated with IL-12 as an adjuvant although protection against lethal influenza virus challenge was unaltered by the addition of IL-12 [89]. Experiments performed using plasmid encoded IL-12 along with HIV and influenza virus DNA have shown that IL-12 promotes longevity of antibody responses and generation and maintenance of antigen-specific T-cells by augmented early post-vaccine response in a manner proportional to the number of Ag-specific cells primed during vaccination [90]. The response to the attenuated strain of Mycobacterium bovis Calmette Guerin (BCG) has led to marginal protection in adults living in tuberculosis endemic regions worldwide. Lactoferrin, an iron-binding protein found in mucosal secretions and neutrophil granules enhances endogenous IL-12 production from macrophages infected with BCG. Lactoferrin admixed to BCG vaccine resulted in increased host protection against virulent M. tuberculosis infection. Animals given Lactoferrin along with BCG demonstrated a lower bacterial burden and reduced structural damage to the lungs when challenged with virulent M. tuberculosis. This strategy for improved BCG response and modification of post vaccination disease requires further evaluation, and durability of protection will be a key determinant for adults in tuberculosis endemic regions who received childhood BCG vaccination [91]. 5. Granulocyte/macrophage-colony stimulating factor (GM-CSF) GM-CSF has long been recognized as an efficacious vaccine adjuvant, and the literature describes literally hundreds of vaccine trials that have utilized GM-CSF for immunomodulation of the host immune system. As its name implies, GM-CSF enhances both innate and adaptive immunity by means of its role as a growth and differentiation factor, chemokine, and phagocytotic regulator of neutrophils, macrophages and dendritic cells [92–97]. Importantly, GM-CSF clearly enhances phagocytic function and ADCC (antibody-dependent cell-mediated cytotoxicity), mostly likely via the inducible upregulation of the FcaRI scavenger receptor on neutrophils and macrophages [94,98–100]. GM-CSF is also reported to upregulate MHC class II expression on cells of monocytic lineage as well as adhesion molecules such as Mo1 and LeuM5 in the granulocytic subfraction [94]. 5.1. Neoplasia Given the sheer number of tumor vaccine trials that have employed GM-CSF, a competent review must necessarily focus upon those trials that have provided meaningful information affirmatively establishing its positive adjuvant affects. Table 3 outlines eleven such trials published between 1998 and 2006 [101–111]. By 2006, adjuvant efficacy of GM-CSF in the cancer vaccine setting appears to have been sufficiently well-established that subsequent studies no longer questioned such efficacy. Nevertheless, it is instructive to note that GM-CSF does not function as a blanket adjuvant that can enhance antigen-specific

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Table 3 Recent landmark tumor vaccine trials utilizing adjuvant GM-CSF. Disease indication

Vaccine type

Benefit with GM-CSF

Comments

Reference

Colon Melanoma Prostate CEA+ tumors N/A

Recombinant protein Autologous tumor/BCG Peptide-loaded DC Canarypox vector Recombinant protein

Yes Yes No No No

[101] [102] [103] [104] [105]

Melanoma Melanoma Any Colon Colon Melanoma

Peptide/IFA Peptide/KLH Autologous tumor Recombinant protein Recombinant protein/MPL Allogeneic tumor/BCG

Yes Yes No Yes Yes Yes

100% (9/9) vs. 33% (3/9) Ag-specific proliferative responses 20% (4/20) vs. 0% (0/15) clinical response rate 20% (9/44) vs. 37% (19/51) clinical response rate 44% (11/25) vs. 27% (6/22) post-vaccination SD Ag-specific Ab titers and other responses statistically lower in GM-CSF treated healthy volunteers GM-CSF vaccines exhibited 2-fold increase in peptide specific IFN-g release 56% (5/9) vs. 0% (0/28) Ag-specific IFN-g secretion at 2 wks post-vaccination NSD between vaccine + GM-CSF or vaccine + IFN-g 100% (12/12) vs. 75% (9/12) Ag-specific T-cell response rate 50% (3/6) vs. 0% (0/5) post-vaccination SD 100% (4/4) vs. 50% (2/4) alive post-vaccination (600 mg cohort vs. placebo)

immunity under any and all circumstances, and these cited studies are useful in establishing a number of take home messages regarding the appropriate use of adjuvant GM-CSF. In accordance with its role in enhancing phagocytosis, GM-CSF appears to adjuvant effectively when used in conjunction with soluble recombinant proteins. The data also suggest that GM-CSF can play an adjuvant role in conjunction with peptide vaccination. Of the four trials that were unable to demonstrate successful adjuvant activity, three utilized cell-based or vector based platforms including peptide-loaded autologous DC [103], irradiated, autologous tumor cells [108], and a viral vector encoding a tumor-specific antigen [104]. With the benefit of hindsight, it is relatively easy to surmise that adjuvant GM-CSF might indeed interfere with the antigenic specificity of pre-loaded DCs via the activation of resident DCs that did not have access to antigen. The reasons for which GM-CSF failed to adjuvant the other vaccine platforms are a matter of greater conjecture but could conceivably be related to the relative inefficiency of in vivo transduction (canarypox vector) and/or the absence of danger signals associated with autologous tumor. Additionally, these trials were also helpful in establishing that GM-CSF adjuvant activity can effectively synergize with other adjuvants including BCG (Bacille CalmetteGue´rin) [102], IFA (incomplete Freund’s adjuvant) [106], MPL (monophosphoryl lipid A) [110], aluminum hydroxide [77], and other cytokine adjuvants [25,76,108]. 5.2. Infectious disease In patients with immunosuppressive disease like hematological malignancy, protective immune responses to vaccines are often impaired. GM-CSF has been unsuccessfully used to promote conventional vaccine responses against influenza virus and Streptococcus pneumonia in stem cell transplant recipients and patients with B cell malignancies. In a randomized trial, multiple doses of GM-CSF given before or following conventional polysaccharide pneumococcal vaccine failed to improve the dismal response in patents with chronic lymphocytic leukemia [112]. Similarly, in 94 patients with hematologic malignancy, GM-CSF coadministered with HBV vaccine or vaccine alone resulted in a modest (9%) improvement in seroconversion. The higher median anti-HBs titers in patients given GM-CSF adjuvant did not achieve statistical significance [113]. Recombinant GM-CSF given systemically as an adjuvant also did not improve the antibody titer or the development of protective immunity to HBV vaccination in HIV coinfected patients receiving an accelerated vaccine schedule [114]. As well, a similar lack of improved response was noted in a weakly immunogenic peptide-based HIV vaccine trial in which recipients received recombinant GM-CSF as a co-adjuvant [115]. Hence, novel methods to target delivery of GM-CSF to DCs/APCs are being considered.

[106] [107] [108] [109] [110] [111]

Mice vaccinated with BCG secreting murine GM-CSF showed an approximately 10-fold increase in protection against disseminated M. tuberculosis infection in comparison to mice vaccinated with conventional BCG. This protection was conferred via a measurable increase in APC number and higher mycobacterial-specific IFNgamma-secreting T-cells generated after BCG:GM-CSF vaccination; furthermore, this adaptive antimycobacterial cellular immune response was sustained for more than four months [116]. Other groups have shown similar results with a BCG-prime followed by a boost with a DNA vaccine co-expressing GM-CSF. An increase in antigen-specific IFN-g producing CTLs induced mice to generate efficient immune protection against M. tuberculosis challenge. This strategy appears promising and needs further clinical evaluation [117,118]. GM-CSF also provides a means to enhance host defense against intracellular infection via modulation of dendritic cells. Coexpression or co-delivery of a GM-CSF gene transfer vector with an antimicrobial vaccine enhances microbial antigen-specific Tcell responses and immune protection. Transduction of DCs with a vector-based tuberculosis vaccine may be a powerful way to activate T-cells in susceptible individuals. Such genetically modified DC vaccines can be administered either parenterally or mucosally via the respiratory tract [119]. Plasmid DNA encoding a T cell epitope and adjuvant GM-CSF was shown to induce both cellmediated and humoral immune responses and demonstrated partial protection against S. japonicum infection [120]. The protective efficacy of a multi-component DNA-prime/proteinboost vaccine was comprised of selected Trypanosoma antigenic candidates and GM-CSF expression plasmids. These mice showed undetectable tissue parasitism, inflammation, and fibrosis in heart and skeletal muscle [121]. The GM-CSF component of such vaccines appears to be an important direction for future research, especially for immunosuppressed patients like those with hematologic malignancies, allogeneic hematopoietic or organ transplantation, or when dealing with vaccines containing hypoimmunogenic epitopes (i.e. HIV antigens). 6. Other potential adjuvant candidates The glycolipid a-Galactosylceramide (a-GalCer), a synthetic antigen for NKT cells, is an adjuvant for protein antigens which can induce protective immunity against cancer and viral diseases, and has been proven to be safe and immune stimulatory in human cancer and patients with viral hepatitis. a-GalCer and its more potent analogues exhibit a superior adjuvant effect on HIV and malaria vaccines in animals. These glycolipids bind with CD1d molecules to activate invariant natural killer T cells, and subsequently induce activation of various immune-competent cells, including dendritic cells. This provides another potentially effective adjuvant for cancer and infectious disease vaccines [122].

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a-GalCer adjuvanted animals showed reduced morbidity and mortality after challenge with wild type influenza virus following vaccination. The adjuvant also increased the amount of virusspecific total IgG, IgG1, and IgG2a antibodies as well as IFN-g secreting CD8+ T-cells [123]. Mucosal delivery of vaccines against sexually transmitted pathogens such as HIV are highly desirable, however, inherent mucosal tolerance poses a serious impediment in eliciting protective immune responses following locally administered vaccines. By inhibition of mucosal NK T-cells, aGalCer may mitigate immune tolerance and stimulate immune responsiveness to foreign antigens. Co-administration of a-GalCer along with a CTL-inducing HIV envelope peptide via oral or intranasal routes was more efficient in priming broader antigenspecific immune responses [124]. One issue with the use of aGalCer pertains to its ability to induce NKT cell anergy due to nonselective presentation of a-GalCer by B-cell CD1d. Recently, a novel nanoparticle formulation of a-GalCer was shown to be selectively presented by DCs and macrophages but not B- cells, thus avoiding the issue of NKT cell anergy. Hence, this formulation appears to be a potentially attractive immunomodulator for future vaccine development [125]. Engagement of CD40 with CD40L induces DC maturation and activation. A study of chimeric CD40L with virus-like particles may enhance presentation of SIV gag and HIV env proteins by directly activating DCs. Mice immunized with this vaccine construct exhibited higher levels of env-specific antibodies and elevated levels of multifunctional IFN-g, IL-2 and TNF-a CD4+ Th-1 cells. The addition of chimeric CD40L along with viral proteins induced DC activation and enhanced the magnitude of humoral and cellular immune responses [126]. Clinically, an elegant permutation of this strategy has shown promise in the treatment of hormonerefractory prostate cancer. Spencer and colleagues have transduced autologous DCs from prostate cancer patients with an inducible CD40 variant that can be activated with a high-affinity small molecule dimerizer. When administered, these transduced DC can be maintained in an activated state that allows circumvention of ectodomain-dependent negative feedback mechanisms. Preliminary phase I results indicated efficacy, and phase II studies are in early accrual [127,128]. Complex Cationic Liposomes and Non-coding DNA (CLDC) and MHC ligand analogues are other recently described potential vaccine adjuvants. Animals given CLDC-adjuvanted woodchuck hepatitis virus surface antigen vaccine showed rapid induction of humoral and cellular immune responses compared to conventional, alum-adjuvanted WHsAg vaccine. The adjuvant activity of CLDC needs further evaluation for improving vaccine responses among patients with underlying conditions that result in substandard responses to conventional vaccination [129]. Improving efficacy of conventional trivalent influenza vaccines is highly desirable, and MHC class II activation has been another target for immune enhancement and modulation that might improve vaccine responses. sLAG-3 (IMP321) has a naturally high affinity for MHC class II. Healthy volunteers randomized into five groups received flu vaccine plus 0, 3, 10, 30 or 100 mg IMP321. IMP321 in doses of 10, 30 or 100 mg resulted in the generation of higher levels of IFN-g, TNF-a, or IL-2 secreting flu-specific Th-1 CD4+ T-cells. The potential role of this and other non-specific MCH class II ligands awaits evaluation in a number of different settings including immunocompromised patients [130]. Interleukin-28 (IL-28B) belongs to the newly described IFN-l family of cytokines that have influence upon differential functions of innate immunity. Although type I IFNs (IFN-a/b/v) and type III IFNs (IFN-l) signal via distinct receptor complexes, they activate the same intracellular signaling pathway and have similar biological activities. IL-29, IL-28A, and IL-28B all appear to be potentially attractive candidates as vaccine adjuvants. Plasmid-

encoded IL-28B demonstrated the ability to boost immune responses against a multi-clade consensus HIV vaccine plasmid. Just like IL-12, IL-28B demonstrated the ability of robustly enhancing the adaptive immune response; however, unlike IL12, IL-28B adjuvantation promoted (a) a decline in regulatory Tcell populations, (b) an increase in the percentage of splenic CD8+ T-cells in vaccinated animals, and (c) a vaccine-specific CTL population that exhibited a higher degree of antigen-specific cytolytic degranulation. In addition, IL-28B administered in conjunction with influenza vaccine induced 100% protection from death after lethal influenza challenge [131]. 7. Concluding remarks When the data are viewed in their entirety, there are certain trends and themes that emerge. First and foremost, it is vitally important for investigators to fully understand the biology of any potential adjuvant or adjuvant system as well as the manner by which such adjuvants(s) might interact with the vaccine component of the therapeutic approach. All cytokines are not created equal and will not have equivalent effects upon any given vaccination strategy. Each cytokine adjuvant occupies its own unique place within the broader context of the complete immune response. For example, adjuvants like Flt-3L and GM-CSF can be extremely useful in the proper context; however, it is relatively ineffective to generate increased numbers of DC and to bring those DC to the site of vaccination if they do not receive additional and practical instruction upon their arrival. Adjuvant strategies should be designed around the type of T-helper polarization desired. In cancer immunotherapy, this is decidedly a Th-1 response, and investigators should consider those adjuvants that naturally predispose toward the near-term generation of IFN-a and perhaps the long-term generation of IL-12. The temporal and spatial considerations of adjuvantation must be considered as well. It might be relatively easy to administer IFN-a subcutaneously, but it might be much more effective to make use of physiologic type I interferon production via the ligation of TLR-7 and/or 9 on the pDC subset. It is these types of strategies that appear to be exhibiting the best results in current clinical practice. In experimental infectious disease vaccination, a Th-1 response is often not the desired response, again, depending upon the nature of the vaccine. Protein, subunit, single-antigen, and inactivated pathogen vaccines function via the stimulation of antibody responses, and, as previously, the investigator should carefully consider the type of response desired. If a Th-2 response is desired, IFN-a should be used with caution, and agents like IL-12 or CD40L should not be used at all. Non-cytokine adjuvants like Alhydrogel, a powerful inducer of Th-2 responses, might also be considered. The prophylactic rather than therapeutic nature of infectious disease vaccination necessitates that experimental strategies be both extremely safe and extremely effective, a distinction that tends to keep such strategies out of the clinic until they are genuinely efficacious. Above all, the investigator should spend as much time in preparing the host adjuvantation strategy as he or she spends on the design of an elegant vaccine. The right adjuvantation strategy can mean the difference between success and failure, and the takehome message should be that this aspect of the treatment regimen deserves a critical amount of contemplation. It should not be considered as an afterthought. Despite the fact that Western medicine has been practicing some form of vaccinology for almost 300 years, only over the course of the last century have physicians and researchers begun to understand the biologic mechanisms that govern this quasimagical, seemingly miraculous field of science. While Jenner accepted and documented that scarification with cowpox pus could impart an astonishing invulnerability to one of the most

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feared plagues of the eighteenth century, he had not the slightest notion as to the etiology of the disease nor the manner by which a trifle of epidermal detritus worked its preternatural charms. This state of affairs stands in marked contrast to the depth of knowledge available to the field at the end of the twentieth century, an era replete with staggering scientific breakthroughs offering breathtaking insight into the realm of human biology. Yet for all the advances of the 20th century, there remained then and still remain today more unknowns than knowns, and the confidence of vaccinology’s previous generations, in retrospect, is replete with some naı¨vete´ and even a little hubris. In no field is this more apparent than cancer immunotherapy, a field in which we still endeavor to duplicate or even adequately explain the century-old empirical accomplishments of William Coley. Despite this Carneadean position, significant progress, both from notable clinical failures and from the methodical advance of basic research, continues to peel away the layers of the onion that is the adaptive immune system. This progress has lead to the discovery of the biological signaling molecules – interferons, Flt3-L, IL-12, GM-CSF, and more – that mediate the immune potentiating effects of agents such as Coley’s bacterial extracts (containing unmethylated CpG, lipopolysaccharide, lipoteichoic acid, and certainly innumerable others) [13], ancient alum-based adjuvants (i.e. Alhydrogel), or modern, state of the art TLR agonists (i.e. imiquimod/resiquimod). As underlying signaling mechanisms come into clearer focus, future generations of researchers will also have the opportunity to perform feats of biological magic analogous to those of the field’s early pioneers, and it is the authors’ opinion that improved vaccines will one day induce the immune system to address the intractable problems of today as artfully and efficiently as the vaccines of Jenner, Pasteur, and Coley did centuries ago. Acknowledgements The authors are indebted to Simon N. Robinson, Ph.D. at the University of Texas M.D. Anderson Cancer Center for his gracious assistance in the preparation and editing of this manuscript. References [1] Roush SW, Murphy TV. Historical comparisons of morbidity and mortality for vaccine-preventable diseases in the United States. JAMA 2007;298(November 14 (18)):2155–63. [2] Lombard M, Pastoret PP, Moulin AM. A brief history of vaccines and vaccination. Rev Sci Tech 2007;26(April (1)):29–48. [3] Hopkins DR. Princes and peasants: smallpox in history. Chicago: University of Chicago Press; 1983. [4] Atkinson W, Hamborsky J, McIntyre L, Wolfe S. Epidemiology and prevention of vaccine-preventable diseases, 9th ed., Washington, DC: Public Health Foundation; 2005. [5] Hopkins DR. The greatest killer: smallpox in history. Chicago: University of Chicago Press; 2002. [6] Porter JR. Agostino Bassi bicentennial (1773–1973). Bacteriol Rev 1973;37(September (3)):284–8. [7] Ullmann A. Pasteur–Koch: distinctive ways of thinking about infectious diseases. Microbe 2007;2(8):383–7. [8] Herr HW. Ignorance is bliss: the Listerian revolution and education of American surgeons. J Urol 2007;177(February (2)):457–60. [9] Gradmann C. A matter of methods: the historicity of Koch’s postulates 1840– 2000. Medizinhist J 2008;43(2):121–48. [10] Mandell GL, Bennett JE, Dolin R. Principles and practice of infectious diseases, 6th ed., New York: Churchill Livngstone; 2004. [11] Beasley RP. Development of hepatitis B vaccine. JAMA 2009;302(July 15 (3)):322–4. [12] Parish CR. Cancer immunotherapy: the past, the present and the future. Immunol Cell Biol 2003;81(April (2)):106–13. [13] Decker WK, Safdar A. Bioimmunoadjuvants for the treatment of neoplastic and infectious disease: Coley’s legacy revisited. Cytokine Growth Factor Rev 2009;20(August (4)):271–81. [14] Colonna M, Trinchieri G, Liu YJ. Plasmacytoid dendritic cells in immunity. Nat Immunol 2004;5(December (12)):1219–26. [15] Decker WK, Xing D, Shpall EJ. Dendritic cell immunotherapy for the treatment of neoplastic disease. Biol Blood Marrow Transplant 2006;12(February (2)):113–25.

185

[16] Guiducci C, Ott G, Chan JH, et al. Properties regulating the nature of the plasmacytoid dendritic cell response to Toll-like receptor 9 activation. J Exp Med 2006;203(August 7 (8)):1999–2008. [17] McKenna K, Beignon AS, Bhardwaj N. Plasmacytoid dendritic cells: linking innate and adaptive immunity. J Virol 2005;79(January (1)):17–27. [18] Piccioli D, Sammicheli C, Tavarini S, et al. Human plasmacytoid dendritic cells are unresponsive to bacterial stimulation and require a novel type of cooperation with myeloid dendritic cells for maturation. Blood 2009;113(April 30 (18)):4232–9. [19] Barnes E, Salio M, Cerundolo V, et al. Impact of alpha interferon and ribavirin on the function of maturing dendritic cells. Antimicrob Agents Chemother 2004;48(September (9)):3382–9. [20] Schmidt J, Patrut EM, Ma J, et al. Immunomodulatory impact of interferonalpha in combination with chemoradiation of pancreatic adenocarcinoma (CapRI). Cancer Immunol Immunother 2006;55(November (11)):1396–405. [21] Schmidt J, Jager D, Hoffmann K, Buchler MW, Marten A. Impact of interferonalpha in combined chemoradioimmunotherapy for pancreatic adenocarcinoma (CapRI): first data from the immunomonitoring. J Immunother 2007;30(January (1)):108–15. [22] Hendil KB, Khan S, Tanaka K. Simultaneous binding of PA28 and PA700 activators to 20 S proteasomes. Biochem J 1998;332(June 15 (Pt 3)):749–54. [23] Tosello V, Zamarchi R, Merlo A, et al. Differential expression of constitutive and inducible proteasome subunits in human monocyte-derived DC differentiated in the presence of IFN-alpha or IL-4. Eur J Immunol 2009;39(January (1)): 56–66. [24] Di PT, Pilla L, Capone I, et al. Immunization of stage IV melanoma patients with Melan-A/MART-1 and gp100 peptides plus IFN-alpha results in the activation of specific CD8(+) T cells and monocyte/dendritic cell precursors. Cancer Res 2006;66(May 1 (9)):4943–51. [25] Pilla L, Patuzzo R, Rivoltini L, et al. A phase II trial of vaccination with autologous, tumor-derived heat-shock protein peptide complexes Gp96, in combination with GM-CSF and interferon-alpha in metastatic melanoma patients. Cancer Immunol Immunother 2006;55(August (8)):958–68. [26] Bocchia M, Gentili S, Abruzzese E, et al. Effect of a p210 multipeptide vaccine associated with imatinib or interferon in patients with chronic myeloid leukaemia and persistent residual disease: a multicentre observational trial. Lancet 2005;365(February 19 (9460)):657–62. [27] Vaishampayan U, Abrams J, Darrah D, Jones V, Mitchell MS. Active immunotherapy of metastatic melanoma with allogeneic melanoma lysates and interferon alpha. Clin Cancer Res 2002;8(December (12)):3696–701. [28] Hance KW, Rogers CJ, Zaharoff DA, Canter D, Schlom J, Greiner JW. The antitumor and immunoadjuvant effects of IFN-alpha in combination with recombinant poxvirus vaccines. Clin Cancer Res 2009;15(April 1 (7)): 2387–96. [29] Hodge JW, Sabzevari H, Yafal AG, Gritz L, Lorenz MG, Schlom J. A triad of costimulatory molecules synergize to amplify T-cell activation. Cancer Res 1999;59(November 15 (22)):5800–7. [30] Lousberg EL, Diener KR, Fraser CK, et al. Antigen-specific T-cell responses to a recombinant fowlpox virus are dependent on MyD88 and interleukin-18 and independent of Toll-like receptor 7 (TLR7)- and TLR9-mediated innate immune recognition. J Virol 2011;85(April (7)):3385–96. [31] Marshall JL, Gulley JL, Arlen PM, et al. Phase I study of sequential vaccinations with fowlpox-CEA(6D)-TRICOM alone and sequentially with vacciniaCEA(6D)-TRICOM, with and without granulocyte-macrophage colony-stimulating factor, in patients with carcinoembryonic antigen-expressing carcinomas. J Clin Oncol 2005;23(February 1 (4)):720–31. [32] Kaufman HL, Kim-Schulze S, Manson K, et al. Poxvirus-based vaccine therapy for patients with advanced pancreatic cancer. J Transl Med 2007;5:60. [33] Gallagher KM, Lauder S, Rees IW, Gallimore AM, Godkin AJ. Type I interferon (IFN alpha) acts directly on human memory CD4 + T cells altering their response to antigen. J Immunol 2009;183(September 1 (5)):2915–20. [34] Thompson JM, Whitmore AC, Staats HF, Johnston R. The contribution of type I interferon signaling to immunity induced by alphavirus replicon vaccines. Vaccine 2008;26(September 15 (39)):4998–5003. [35] Couch RB, Atmar RL, Cate TR, et al. Contrasting effects of type I interferon as a mucosal adjuvant for influenza vaccine in mice and humans. Vaccine 2009;27(August 27 (39)):5344–8. [36] O’Brien L, Perkins S, Williams A, et al. Alpha interferon as an adenovirusvectored vaccine adjuvant and antiviral in Venezuelan equine encephalitis virus infection. J Gen Virol 2009;90(April (4)):874–82. [37] Miquilena-Colina ME, Lozano-Rodriguez T, Garcia-Pozo L, et al. Recombinant interferon-alpha2b improves immune response to hepatitis B vaccination in haemodialysis patients: results of a randomised clinical trial. Vaccine 2009;27(September 18 (41)):5654–60. [38] Mazzoni A, Leifer CA, Mullen GE, Kennedy MN, Klinman DM, Segal DM. Cutting edge: histamine inhibits IFN-alpha release from plasmacytoid dendritic cells. J Immunol 2003;170(March 1 (5)):2269–73. [39] Zhang W, Du X, Zhao G, et al. Levamisole is a potential facilitator for the activation of Th1 responses of the subunit HBV vaccination. Vaccine 2009;27(August 6 (36)):4938–46. [40] Honda K, Ohba Y, Yanai H, et al. Spatiotemporal regulation of MyD88-IRF-7 signalling for robust type-I interferon induction. Nature 2005;434(April 21 (7036)):1035–40. [41] Honda K, Yanai H, Negishi H, et al. IRF-7 is the master regulator of type-I interferon-dependent immune responses. Nature 2005;434(April 7 (7034)): 772–7.

186

W.K. Decker, A. Safdar / Cytokine & Growth Factor Reviews 22 (2011) 177–187

[42] Jung J, Yi AK, Zhang X, Choe J, Li L, Choi YS. Distinct response of human B cell subpopulations in recognition of an innate immune signal CpG DNA. J Immunol 2002;169(September 1 (5)):2368–73. [43] Murad YM, Clay TM. CpG oligodeoxynucleotides as TLR9 agonists: therapeutic applications in cancer. BioDrugs 2009;23(6):361–75. [44] Rynkiewicz D, Rathkopf M, Sim I, et al. Marked enhancement of the immune response to BioThrax((R)) (anthrax vaccine adsorbed) by the TLR9 agonist CPG 7909 in healthy volunteers. Vaccine )2011;(May 30). [45] Crompton PD, Mircetic M, Weiss G, et al. The TLR9 ligand CpG promotes the acquisition of Plasmodium falciparum-specific memory B cells in malarianaive individuals. J Immunol 2009;182(March 1 (5)):3318–26. [46] Ellis RD, Martin LB, Shaffer D, et al. Phase 1 trial of the Plasmodium falciparum blood stage vaccine MSP1(42)-C1/Alhydrogel with and without CPG 7909 in malaria naive adults. PLoS One 2010;5(1):e8787. [47] Cooper CL, Davis HL, Morris ML, et al. Safety and immunogenicity of CPG 7909 injection as an adjuvant to Fluarix influenza vaccine. Vaccine 2004;22(August 13 (23–24)):3136–43. [48] Cooper CL, Angel JB, Seguin I, Davis HL, Cameron DW. CPG 7909 adjuvant plus hepatitis B virus vaccination in HIV-infected adults achieves long-term seroprotection for up to 5 years. Clin Infect Dis 2008;46(April 15 (8)): 1310–4. [49] Sogaard OS, Lohse N, Harboe ZB, et al. Improving the immunogenicity of pneumococcal conjugate vaccine in HIV-infected adults with a toll-like receptor 9 agonist adjuvant: a randomized, controlled trial. Clin Infect Dis 2010;51(July 1 (1)):42–50. [50] Speiser DE, Lienard D, Rufer N, et al. Rapid and strong human CD8 + T cell responses to vaccination with peptide IFA, and CpG oligodeoxynucleotide 7909. J Clin Invest 2005;115(March (3)):739–46. [51] Speiser DE, Schwarz K, Baumgaertner P, et al. Memory and effector CD8 T-cell responses after nanoparticle vaccination of melanoma patients. J Immunother 2010;33(October (8)):848–58. [52] Valmori D, Souleimanian NE, Tosello V, et al. Vaccination with NY-ESO-1 protein and CpG in Montanide induces integrated antibody/Th1 responses and CD8 T cells through cross-priming. Proc Natl Acad Sci U S A 2007;104(May 22 (21)):8947–52. [53] Shukla NM, Malladi SS, Mutz CA, Balakrishna R, David SA. Structure-activity relationships in human toll-like receptor 7-active imidazoquinoline analogues. J Med Chem 2010;53(June 10 (11)):4450–65. [54] Rajagopal D, Paturel C, Morel Y, Uematsu S, Akira S, Diebold SS. Plasmacytoid dendritic cell-derived type I interferon is crucial for the adjuvant activity of Toll-like receptor 7 agonists. Blood 2010;115(March 11 (10)):1949–57. [55] Tarhini AA, Agarwala SS. First international symposium on melanoma and other cutaneous malignancies. Expert Opin Biol Ther 2004;4(September (9)):1541–6. [56] Adams S, O’Neill DW, Nonaka D, et al. Immunization of malignant melanoma patients with full-length NY-ESO-1 protein using TLR7 agonist imiquimod as vaccine adjuvant. J Immunol 2008;181(July 1 (1)):776–84. [57] Daayana S, Elkord E, Winters U, et al. Phase II trial of imiquimod and HPV therapeutic vaccination in patients with vulval intraepithelial neoplasia. Br J Cancer 2010;102(March 30 (7)):1129–36. [58] Morse MA, Bradley DA, Keler T, et al. CDX-1307: a novel vaccine under study as treatment for muscle-invasive bladder cancer. Expert Rev Vaccines 2011;10(June (6)):733–42. [59] Drexler HG, Quentmeier H. FLT3: receptor and ligand. Growth Factors 2004;22(June (2)):71–3. [60] Lyman SD, Jacobsen SE. c-kit ligand and Flt3 ligand: stem/progenitor cell factors with overlapping yet distinct activities. Blood 1998;91(February 15 (4)):1101–34. [61] Maraskovsky E, Brasel K, Teepe M, et al. Dramatic increase in the numbers of functionally mature dendritic cells in Flt3 ligand-treated mice: multiple dendritic cell subpopulations identified. J Exp Med 1996;184(November 1 (5)):1953–62. [62] Onai N, Obata-Onai A, Schmid MA, Manz MG. Flt3 in regulation of type I interferon-producing cell and dendritic cell development. Ann N Y Acad Sci 2007;1106(June):253–61. [63] Stirewalt DL, Radich JP. The role of FLT3 in haematopoietic malignancies. Nat Rev Cancer 2003;3(September (9)):650–65. [64] Disis ML, Rinn K, Knutson KL, et al. Flt3 ligand as a vaccine adjuvant in association with HER-2/neu peptide-based vaccines in patients with HER-2/ neu-overexpressing cancers. Blood 2002;99(April 15 (8)):2845–50. [65] McNeel DG, Knutson KL, Schiffman K, Davis DR, Caron D, Disis ML. Pilot study of an HLA-A2 peptide vaccine using flt3 ligand as a systemic vaccine adjuvant. J Clin Immunol 2003;23(January (1)):62–72. [66] Shackleton M, Davis ID, Hopkins W, et al. The impact of imiquimod, a Toll-like receptor-7 ligand (TLR7L), on the immunogenicity of melanoma peptide vaccination with adjuvant Flt3 ligand. Cancer Immun 2004;4(September 23):9. [67] Pulendran B, Smith JL, Jenkins M, Schoenborn M, Maraskovsky E, Maliszewski CR. Prevention of peripheral tolerance by a dendritic cell growth factor: flt3 ligand as an adjuvant. J Exp Med 1998;188(December 7 (11)):2075–82. [68] Teleshova N, Jones J, Kenney J, et al. Short-term Flt3L treatment effectively mobilizes functional macaque dendritic cells. J Leukoc Biol 2004;75(June (6)):1102–10. [69] Triccas JA, Shklovskaya E, Spratt J, et al. Effects of DNA- and Mycobacterium bovis BCG-based delivery of the Flt3 ligand on protective immunity to Mycobacterium tuberculosis. Infect Immun 2007;75(November (11)):5368–75. [70] Xu J, Xu W, Chen X, Zhao D, Wang Y. Recombinant DNA vaccine of the early secreted antigen ESAT-6 by Mycobacterium tuberculosis and Flt3 ligand

[71]

[72]

[73]

[74] [75]

[76]

[77]

[78]

[79]

[80]

[81]

[82]

[83] [84]

[85]

[86]

[87]

[88]

[89]

[90]

[91]

[92]

[93]

[94]

[95]

enhanced the cell-mediated immunity in mice. Vaccine 2008;26(August 18 (35)):4519–25. Encke J, Bernardin J, Geib J, Barbakadze G, Bujdoso R, Stremmel W. Genetic vaccination with Flt3-L and GM-CSF as adjuvants: Enhancement of cellular and humoral immune responses that results in protective immunity in a murine model of hepatitis C virus infection. World J Gastroenterol 2006;12(November 28 (44)):7118–25. Zhang T, Hashizume T, Kurita-Ochiai T, Yamamoto M. Sublingual vaccination with outer membrane protein of Porphyromonas gingivalis and Flt3 ligand elicits protective immunity in the oral cavity. Biochem Biophys Res Commun 2009;390(December 18 (3)):937–41. Decker WK, Xing D, Li S, et al. Th-1 polarization is regulated by dendritic-cell comparison of MHC class I and class II antigens. Blood 2009;113(April 30 (18)):4213–23. Del VM, Bajetta E, Canova S, et al. Interleukin-12: biological properties and clinical application. Clin Cancer Res 2007;13(August 15 (16)):4677–85. Langrish CL, McKenzie BS, Wilson NJ, de Waal MR, Kastelein RA, Cua DJ. IL-12 and IL-23: master regulators of innate and adaptive immunity. Immunol Rev 2004;December (202):96–105. Hansson L, Abdalla AO, Moshfegh A, et al. Long-term idiotype vaccination combined with interleukin-12 (IL-12), or IL-12 and granulocyte macrophage colony-stimulating factor, in early-stage multiple myeloma patients. Clin Cancer Res 2007;13(March 1 (5)):1503–10. Hamid O, Solomon JC, Scotland R, et al. Alum with interleukin-12 augments immunity to a melanoma peptide vaccine: correlation with time to relapse in patients with resected high-risk disease. Clin Cancer Res 2007;13(January 1 (1)):215–22. Kikuchi T, Akasaki Y, Abe T, et al. Vaccination of glioma patients with fusions of dendritic and glioma cells and recombinant human interleukin 12. J Immunother 2004;27(November (6)):452–9. Cebon J, Jager E, Shackleton MJ, et al. Two phase I studies of low dose recombinant human IL-12 with Melan-A and influenza peptides in subjects with advanced malignant melanoma. Cancer Immun 2003;3(July 16 (7)). Peterson AC, Harlin H, Gajewski TF. Immunization with Melan-A peptidepulsed peripheral blood mononuclear cells plus recombinant human interleukin-12 induces clinical activity and T-cell responses in advanced melanoma. J Clin Oncol 2003;21(June 15 (12)):2342–8. Lee P, Wang F, Kuniyoshi J, et al. Effects of interleukin-12 on the immune response to a multipeptide vaccine for resected metastatic melanoma. J Clin Oncol 2001;19(September 15 (18)):3836–47. Gajewski TF, Fallarino F, Ashikari A, Sherman M. Immunization of HLAA2 + melanoma patients with MAGE-3 or MelanA peptide-pulsed autologous peripheral blood mononuclear cells plus recombinant human interleukin 12. Clin Cancer Res 2001;7(March (3 Suppl)):895s–901s. O’Toole M, Wooters J, Brown E, et al. Interleukin-12 as adjuvant in peptide vaccines. Ann N Y Acad Sci 1996;795(October 31):379–81. Operschall E, Schuh T, Heinzerling L, Pavlovic J, Moelling K. Enhanced protection against viral infection by co-administration of plasmid DNA coding for viral antigen and cytokines in mice. J Clin Virol 1999;13(June (1–2)):17–27. Parker JN, Pfister LA, Quenelle D, et al. Genetically engineered herpes simplex viruses that express IL-12 or GM-CSF as vaccine candidates. Vaccine 2006;24(March 6 (10)):1644–52. Arulanandam BP, O’Toole M, Metzger DW. Intranasal interleukin-12 is a powerful adjuvant for protective mucosal immunity. J Infect Dis 1999;180(October (4)):940–9. Arulanandam BP, Mittler JN, Lee WT, O’Toole M, Metzger DW. Neonatal administration of IL-12 enhances the protective efficacy of antiviral vaccines. J Immunol 2000;164(April 1 (7)):3698–704. Williman J, Lockhart E, Slobbe L, Buchan G, Baird M. The use of Th1 cytokines IL-12 and IL-23, to modulate the immune response raised to a DNA vaccine delivered by gene gun. Vaccine 2006;24(May 22 (21)):4471–4. Galarza JM, Latham T, Cupo A. Virus-like particle (VLP) vaccine conferred complete protection against a lethal influenza virus challenge. Viral Immunol 2005;18(1):244–51. Chattergoon MA, Saulino V, Shames JP, Stein J, Montaner LJ, Weiner DB. Coimmunization with plasmid IL-12 generates a strong T-cell memory response in mice. Vaccine 2004;22(April 16 (13–14)):1744–50. Hwang SA, Wilk KM, Budnicka M, et al. Lactoferrin enhanced efficacy of the BCG vaccine to generate host protective responses against challenge with virulent Mycobacterium tuberculosis. Vaccine 2007;25(September 17 (37–38)):6730–43. Gazitt Y, Shaughnessy P, Devore P. Mobilization of dendritic cells and NK cells in non-Hodgkin’s lymphoma patients mobilized with different growth factors. J Hematother Stem Cell Res 2001;10(February (1)):177–86. Robin G, Markovich S, Athamna A, Keisari Y. Human recombinant granulocyte-macrophage colony-stimulating factor augments viability and cytotoxic activities of human monocyte-derived macrophages in long-term cultures. Lymphokine Cytokine Res 1991;10(August (4)):257–63. Schuster SJ, Venugopal P, Kern JC, McLaughlin P. GM-CSF plus rituximab immunotherapy: translation of biologic mechanisms into therapy for indolent B-cell lymphomas. Leuk Lymphoma 2008;49(September (9)):1681–92. Shaughnessy PJ, Bachier C, Lemaistre CF, Akay C, Pollock BH, Gazitt Y. Granulocyte colony-stimulating factor mobilizes more dendritic cell subsets than granulocyte-macrophage colony-stimulating factor with no polarization of dendritic cell subsets in normal donors. Stem Cells 2006;24(July (7)):1789–97.

W.K. Decker, A. Safdar / Cytokine & Growth Factor Reviews 22 (2011) 177–187 [96] Steis RG, VanderMolen LA, Longo DL, et al. Recombinant human granulocytemacrophage colony-stimulating factor in patients with advanced malignancy: a phase Ib trial. J Natl Cancer Inst 1990;82(April 18 (8)):697–703. [97] Young DA, Lowe LD, Clark SC. Comparison of the effects of IL-3, granulocytemacrophage colony-stimulating factor, and macrophage colony-stimulating factor in supporting monocyte differentiation in culture Analysis of macrophage antibody-dependent cellular cytotoxicity. J Immunol 1990;145(July 15 (2)):607–15. [98] Charak BS, Agah R, Mazumder A. Granulocyte-macrophage colony-stimulating factor-induced antibody-dependent cellular cytotoxicity in bone marrow macrophages: application in bone marrow transplantation. Blood 1993;81(June 15 (12)):3474–9. [99] Connor RI, Shen L, Fanger MW. Evaluation of the antibody-dependent cytotoxic capabilities of individual human monocytes. Role of Fc gamma RI and Fc gamma RII and the effects of cytokines at the single cell level. J Immunol 1990;145(September 1 (5)):1483–9. [100] Keler T, Wallace PK, Vitale LA, et al. Differential effect of cytokine treatment on Fc alpha receptor I- and Fc gamma receptor I-mediated tumor cytotoxicity by monocyte-derived macrophages. J Immunol 2000;164(June 1 (11)):5746–52. [101] Samanci A, Yi Q, Fagerberg J, et al. Pharmacological administration of granulocyte/macrophage-colony-stimulating factor is of significant importance for the induction of a strong humoral and cellular response in patients immunized with recombinant carcinoembryonic antigen. Cancer Immunol Immunother 1998;47(November (3)):131–42. [102] Leong SP, Enders-Zohr P, Zhou YM, et al. Recombinant human granulocyte macrophage-colony stimulating factor (rhGM-CSF) and autologous melanoma vaccine mediate tumor regression in patients with metastatic melanoma. J Immunother 1999;22(March (2)):166–74. [103] Simmons SJ, Tjoa BA, Rogers M, et al. GM-CSF as a systemic adjuvant in a phase II prostate cancer vaccine trial. Prostate 1999;39(June 1 (4)):291–7. [104] von MM, Arlen P, Gulley J, et al. The influence of granulocyte macrophage colony-stimulating factor and prior chemotherapy on the immunological response to a vaccine (ALVAC-CEA B7.1) in patients with metastatic carcinoma. Clin Cancer Res 2001;7(May (5)):1181–91. [105] Somani J, Lonial S, Rosenthal H, Resnick S, Kakhniashvili I, Waller EK. A randomized, placebo-controlled trial of subcutaneous administration of GMCSF as a vaccine adjuvant: effect on cellular and humoral immune responses. Vaccine 2002;21(December 13 (3–4)):221–30. [106] Weber J, Sondak VK, Scotland R, et al. Granulocyte-macrophage-colonystimulating factor added to a multipeptide vaccine for resected Stage II melanoma. Cancer 2003;97(January 1 (1)):186–200. [107] Scheibenbogen C, Schadendorf D, Bechrakis NE, et al. Effects of granulocytemacrophage colony-stimulating factor and foreign helper protein as immunologic adjuvants on the T-cell response to vaccination with tyrosinase peptides. Int J Cancer 2003;104(March 20 (2)):188–94. [108] Dillman RO, Wiemann M, Nayak SK, DeLeon C, Hood K, DePriest C. Interferongamma or granulocyte-macrophage colony-stimulating factor administered as adjuvants with a vaccine of irradiated autologous tumor cells from shortterm cell line cultures: a randomized phase 2 trial of the cancer biotherapy research group. J Immunother 2003;26(July (4)):367–73. [109] Ullenhag GJ, Frodin JE, Jeddi-Tehrani M, et al. Durable carcinoembryonic antigen (CEA)-specific humoral and cellular immune responses in colorectal carcinoma patients vaccinated with recombinant CEA and granulocyte/macrophage colony-stimulating factor. Clin Cancer Res 2004;10(May 15 (10)):3273–81. [110] Neidhart J, Allen KO, Barlow DL, et al. Immunization of colorectal cancer patients with recombinant baculovirus-derived KSA (Ep-CAM) formulated with monophosphoryl lipid A in liposomal emulsion, with and without granulocyte-macrophage colony-stimulating factor. Vaccine 2004;22(January 26 (5–6)):773–80. [111] Barrio MM, de Motta PT, Kaplan J, et al. A phase I study of an allogeneic cell vaccine (VACCIMEL) with GM-CSF in melanoma patients. J Immunother 2006;29(July (4)):444–54. [112] Safdar A, Rodriguez GH, Rueda AM, et al. Multiple-dose granulocyte-macrophage-colony-stimulating factor plus 23-valent polysaccharide pneumococcal vaccine in patients with chronic lymphocytic leukemia: a prospective, randomized trial of safety and immunogenicity. Cancer 2008;113(July 15 (2)):383–7. [113] Yagci M, Acar K, Sucak GT, Yamac K, Haznedar R. Hepatitis B virus vaccine in lymphoproliferative disorders: a prospective randomized study evaluating the efficacy of granulocyte-macrophage colony stimulating factor as a vaccine adjuvant. Eur J Haematol 2007;79(October (4)):292–6. [114] Overton ET, Kang M, Peters MG, et al. Immune response to hepatitis B vaccine in HIV-infected subjects using granulocyte-macrophage colony-stimulating factor (GM-CSF) as a vaccine adjuvant: ACTG study 5220. Vaccine 2010;28(August 2 (34)):5597–604. [115] Spearman P, Kalams S, Elizaga M, et al. Safety and immunogenicity of a CTL multiepitope peptide vaccine for HIV with or without GM-CSF in a phase I trial. Vaccine 2009;27(January 7 (2)):243–9. [116] Ryan AA, Wozniak TM, Shklovskaya E, et al. Improved protection against disseminated tuberculosis by Mycobacterium bovis bacillus CalmetteGuerin secreting murine GM-CSF is associated with expansion and activation of APCs. J Immunol 2007;179(December 15 (12)):8418–24. [117] Dou J, Tang Q, Yu F, et al. Investigation of immunogenic effect of the BCG priming and Ag85A-GM-CSF boosting in Balb/c mice model. Immunobiology 2010;215(2):133–42.

187

[118] Nambiar JK, Ryan AA, Kong CU, Britton WJ, Triccas JA. Modulation of pulmonary DC function by vaccine-encoded GM-CSF enhances protective immunity against Mycobacterium tuberculosis infection. Eur J Immunol 2010;40(January (1)):153–61. [119] McCormick S, Santosuosso M, Zhang XZ, Xing Z. Manipulation of dendritic cells for host defence against intracellular infections. Biochem Soc Trans 2006;34(April (Pt 2)):283–6. [120] Zhang L, Yang Y, Yang X, et al. T cell epitope-based peptide-DNA dual vaccine induces protective immunity against Schistosoma japonicum infection in C57BL/6J mice. Microbes Infect 2008;10(March (3)):251–9. [121] Gupta S, Garg NJ. Prophylactic efficacy of TcVac2 against Trypanosoma cruzi in mice. PLoS Negl Trop Dis 2010;4(8):e797. [122] Li X, Fujio M, Imamura M, et al. Design of a potent CD1d-binding NKT cell ligand as a vaccine adjuvant. Proc Natl Acad Sci U S A 2010;107(July 20 (29)):13010–5. [123] Kopecky-Bromberg SA, Fraser KA, Pica N, et al. Alpha-C-galactosylceramide as an adjuvant for a live attenuated influenza virus vaccine. Vaccine 2009;27(June 8 (28)):3766–74. [124] Courtney AN, Nehete PN, Nehete BP, Thapa P, Zhou D, Sastry KJ. Alphagalactosylceramide is an effective mucosal adjuvant for repeated intranasal or oral delivery of HIV peptide antigens. Vaccine 2009;27(May 26 (25– 26)):3335–41. [125] Thapa P, Zhang G, Xia C, et al. Nanoparticle formulated alpha-galactosylceramide activates NKT cells without inducing anergy. Vaccine 2009;27(May 26 (25–26)):3484–8. [126] Zhang R, Zhang S, Li M, Chen C, Yao Q. Incorporation of CD40 ligand into SHIV virus-like particles (VLP) enhances SHIV-VLP-induced dendritic cell activation and boosts immune responses against HIV. Vaccine 2010;28(July 12 (31)):5114–27. [127] Hanks BA, Jiang J, Singh RA, et al. Re-engineered CD40 receptor enables potent pharmacological activation of dendritic-cell cancer vaccines in vivo. Nat Med 2005;11(February (2)):130–7. [128] Sonpavde G, Slawin KM, Spencer DM, Levitt JM. Emerging vaccine therapy approaches for prostate cancer. Rev Urol 2010;12(1):25–34. [129] Cote PJ, Butler SD, George AL, et al. Rapid immunity to vaccination with woodchuck hepatitis virus surface antigen using cationic liposome–DNA complexes as adjuvant. J Med Virol 2009;81(October (10)):1760–72. [130] Brignone C, Grygar C, Marcu M, Perrin G, Triebel F. IMP321 (sLAG-3) safety and T cell response potentiation using an influenza vaccine as a model antigen: a single-blind phase I study. Vaccine 2007;11–25(June (24)):4641–50. [131] Morrow MP, Pankhong P, Laddy DJ, et al. Comparative ability of IL-12 and IL28B to regulate Treg populations and enhance adaptive cellular immunity. Blood 2009;113(June 4 (23)):5868–77. William K. Decker is an Assistant Professor in the Department of Pathology & Immunology at Baylor College of Medicine in Houston, Texas. He received an undergraduate degree in Biology from Tufts University in Boston, Massachusetts and a PhD in Molecular and Human Genetics from Baylor College of Medicine. After further postdoctoral study at Baylor and a brief stint in industry, he returned to academia as a Senior Research Scientist in the Department of Stem Cell Transplantation and Cellular Therapy at the University of Texas MD Anderson Cancer Center, a position he held for seven years. His research has focused upon dendritic cell regulation of the Th-1 immune response, and his work has demonstrated that dendritic cells possess the ability to compare MHC class I and class II antigenic sequences via a novel regulatory complex involving tRNA molecules and their associated tRNA synthetases. He has also focused upon the soluble signaling mediators used by these so-called ‘‘Th-1’’ dendritic cells to mediate cellular immune responses. He is currently engaged in translating these basic discoveries into viable therapeutic regimens for the treatment of neoplastic disease. Amar Safdar is an Associate Professor and Director, Transplant Infectious Diseases in the Department of Medicine, Division of Immunology and Infectious Disease at the New York University Langone Medical Center in New York City. Previously, he was Director of the Immunology Research Program in the Department of Infectious Diseases, Infection Control, and Employee Health at the University of Texas MD Anderson Cancer Center in Houston, Texas. He received his MD degree from Dow Medical College in Karachi, Pakistan and completed his Internal Medicine training at New York Medical College and the New York Downtown Hospital, Cornell University Medical Center, New York, NY. He then received both clinical and research training in Infectious Diseases as a Fellow at the Memorial Sloan Kettering Cancer Center and Weill Medical College of Cornell University, New York, NY. His clinical research has focused upon vaccine preventable illnesses in immunocompromised cancer patients as well as the role that small molecule cytokine adjuvants may play in the perpetuation of adaptive immune responses. He is a Fellow of both the American College of Physicians and the Infectious Disease Society of America.