- Email: [email protected]
Infectious Optimism following the 10th International Oncolytic Virus Meeting
Meeting Report
Infectious Optimism following the 10th International Oncolytic Virus Meeting Matthew J. Atherton,1 Laura Evgin,2 Brian A. Keller,3 Mira M. Shenouda,4 Kyle B. Stephenson,5 Richard G. Vile,2 John C. Bell,3,5 David H. Evans,4 and Brian D. Lichty1,5 The 10th International Conference on Replicating Oncolytic Virus Therapeutics was held in Vancouver, Canada from October 1–4, 2016. The agenda for the meeting comprised lectures from several streams within the field of oncolytic viral therapeutics. Exploring the strengthening relationship among oncolytic viruses, cancer immunology, and immunotherapy; gaining an understanding for effective therapeutic delivery routes; and learning of exciting results from translational studies all featured prominently among areas discussed. As the field matures, commercialization and patientcentered research have become important avenues for growth; however, an abundance of high quality laboratory-based science continues to be performed in order to optimize future therapeutic approaches. Here, we summarize the latest innovations presented at this meeting. Keynote talks from Cassian Yee (MD Anderson Cancer Center) and Yonghong Wan (McMaster University) set the scene for the meeting and focused on recent developments in cancer immunotherapy and oncolytic viruses (OVs). Dr. Yee has been at the forefront of utilizing adoptive cellular therapies (ACTs) for treating patients with advanced malignancies. Dramatic and curative responses have been achieved following ACT using the patient’s endogenous T cells; however, challenges still exist in manufacturing processes alongside their widespread availability.1 A significant part of Dr. Yee’s research aimed to address these issues. Subsequently, Dr. Wan presented a combinatorial approach whereby oncolytic MG1 Maraba, encoding a mutant ERK neoantigen, was able to boost a population of adoptively
12
transferred T cells specific to the same antigen with curative results in an aggressive pre-clinical sarcoma model harboring the neoantigen. Dr. Wan explained how oncolytic rhabdoviruses, such as MG1 Maraba, were able to dramatically boost antigen-specific T cells due to their ability to engage central memory T cells (TCMs) in immunoprivileged splenic sites.2 As OVs engage the immune system in numerous ways, including in situ vaccination and modification of immunosuppressive tumor microenvironments, they are being recognized as bona fide anti-cancer immunotherapuetics.3 Integrating OVs into the oncologist’s growing arsenal of treatment modalities will be one of the keys to the ongoing success of these versatile agents over the coming years. Viral Engineering and Replication
Robust and cancer-specific replication is a desired therapeutic property in the OV field. This session focused on pre-clinical efforts dedicated to viral engineering and treatment strategies to enhance downstream therapeutic utility. William Jia (University of British Columbia) began by presenting combination therapies using the PKR-inhibitor C16 or the antibiotic nifuroxazide in conjunction with an oncolytic herpes simplex virus (oHSV) in glioma models. Chemically targeting STAT1/3 with these agents increased cancer cell permissiveness to oHSV. Karen Mossman (McMaster University) introduced the concept of immunogenic cell death (ICD) and its induction through various herpes virus platforms.4 The utility of a combinatorial approach was demonstrated when the non-ICD-inducing chemotherapeutic mitomycin C improved the efficacy of an oHSV-1 platform. These examples demon-
Molecular Therapy: Oncolytics Vol. 7 December 2017
strate that, when combined with rationally selected therapeutics, replication and efficacy of OVs can be further enhanced. Interrogating the role of viral genetics featured strongly for the remainder of this section. Korneel Grauwet (Harvard University) investigated the relationship of viral immune evasion genes with an oHSV-1 platform. Important observations were gleaned using a mouse glioblastoma model, implicating natural killer (NK) cells as being critical for the clearance of HSV-1 infection and potentially decreasing oHSV’s therapeutic efficacy. Larissa Pikor (Ottawa Hospital Research Institute [OHRI]) discussed a CRISPR/Cas9-mediated approach to better understand OV resistance genes. Stable Cas9 nuclease-expressing cells and a lentiviral guide RNA (gRNA) library facilitated a negative selection screen in cell lines resistant to OVs; harvesting surviving cells for sequencing and comparing to mock infected cells identified genes that confer OV sensitivity. Amelia Aitken (OHRI) presented data about the “viral suppressor of RNA interference (RNAi)-1 (VSR-1)” and the improvement in efficacy that was observed when VSR-1 was encoded in the vesicular stomatitis OV, VSVD51, suppressing antiviral RNA interference (RNAi)- enhanced tumor cell specificity and oncolysis. The final two presenters discussed approaches to engineer oncolytically superior Vaccinia virus (VacV). Andrea McCart (University of Toronto) used a single gene deletion approach. Specifically deleting K1L, A46R, and A52R creates OVs that demonstrate superior replication, cytotoxicity, and spread, respectively. Similarly, Brian Keller (OHRI) has isolated an 89-virus library that consists of clonal 1
McMaster Immunology Research Centre, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55905, USA; 3Centre for Innovative Cancer Therapeutics, Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada; 4 Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2E1, Canada; 5Turnstone Biologics, Ottawa, ON K1S 3V5, Canada 2
Correspondence: Brian D. Lichty, McMaster Immunology Research Centre, McMaster University, Hamilton, ON L8S 4K1, Canada. E-mail: [email protected]
www.moleculartherapy.org
Meeting Report stocks of unique VacVs with insertion of an mCherry-expressing transposable element. This library has been characterized in terms of OV-relevant properties, and interesting phenotypes have been observed, especially in 3 highlighted clones with unique insertion sites in the same gene. Such engineering projects facilitate the generation of improved OV candidates while furthering our understanding of OV biology. Immunity
Cancer immunotherapy is continuing to gain momentum in the clinic and, as such, featured heavily during the conference. Steve Thorne (University of Pittsburgh) opened the session by presenting different approaches to activate the immune system as well as combating tumor-associated immunosuppression. Deglycosylation of the VacV particle is able to skew the immunity toward a beneficial cell-mediated response as opposed to generating neutralizing antiviral antibodies. Dr. Thorne also presented another engineering approach enabling Vaccinia to degrade the immunosuppressive factor, PGE2, thus enhancing anti-tumor immunity. Clinical data following the intrapleural administration of oncolytic HSV to mesothelioma patients were presented by Joe Conner (Virttu Biologics). Analysis of pleural fluid following treatment revealed an induction of pro-inflammatory cytokines and underlined the promise of oHSV as an immunotherapeutic in this setting. The significant potential of OVs to act as a vaccine against specific tumor-associated antigens (TAAs) was highlighted by Brian Lichty (McMaster University). MG1 Maraba virus acts as a versatile boosting agent as well as potent oncolytic, and this was demonstrated in preclinical HPV, prostate, and sarcoma models making use of viral, differentiation, and mutated antigens. Data from the first human clinical trial utilizing MG1 Maraba expressing the MAGE-A3 TAA were greatly anticipated. Siri Tähtinen (University of Helsinki) presented proof-of-principal data for an immunologic approach of coating an adenovirus with TAAs; mice bearing B16Ova melanoma tumors were successfully treated with this strategy. Induction of antitumor immunity is of fundamental importance for the success of OVs.
Engineering and combinatorial approaches were also demonstrated in the context of immunity. By manufacturing a VSV-measles virus (VSV-MV) hybrid, Christopher Richardson and colleagues (Dalhousie University) were able to exploit the abundant neoplastic expression of nectin-4, which acts as a receptor for MV, and treatment of immuno-competent mice with VSV-MV resulted in anti-tumor activity. Nino Chiocca (Harvard University) presented data utilizing a replication deficient adenovirus armed with the HSV TK gene, and, following treatment with this virus, an increased intratumoral expression of the immune checkpoint PDL-1 was observed. Combination treatments using this viral approach alongside PD-1 blockade for malignant glioma are undergoing clinical evaluation. In a similar vein, Marie-Claude BourgeoisDaigneault (OHRI) combined MG1 Maraba with a checkpoint inhibitor (CI) in a preclinical breast cancer model and found that such multi-modal therapy conferred a survival benefit to tumor-bearing mice. Alan Melcher (The Institute of Cancer Research, London [ICR]) described how systemically administered oncolytic reovirus was able to cross the blood-brain barrier to access brain tumors, despite the presence of neutralizing antibodies—delivery through protective cell carriage by leukocytes, as previously described, is thought likely.5 Reovirus upregulated PD-1 and PD-L1 in the tumor and, when given alongside anti-PD-1 therapy, was effective in immuno-competent orthotopic murine models. Ruta Veinalde (Nationales Centrum für Tumorerkrankungen [NCT]) described oncolytic MVs encoding interleukin-12 (IL-12) and a-PDL-1. Treatment with MV IL-12 and MV a-PDL-1 cured 60% and 90% of mice bearing MC38 CEA tumors, respectively, as well as conferring protective immunity upon rechallenge.6 As such, combining OVs with checkpoint blockade has great potential. Combining CIs with OVs is not, however, a universal recipe for success. Richard Vile’s lab (Mayo Clinic) mapped the expression of inhibitory checkpoints following adoptive cell therapy and oncolytic virotherapy in a murine melanoma model. Multiple doses of VSV expressing hgp100 activated Pmel
T cells, with low expression of PD-1 and TIM-3 observed. The expansion of endogenous CD44hi CD62Llo effector T cells was also documented with elevated expression of PD-1 and TIM-3. However, neither PD-1 nor TIM-3 blockade enhanced therapy.7 Hiroshi Nakashima (Harvard University) presented a murine glioma model of T cell exhaustion. Using Clone 13 lymphocytic choriomeningitis (LCMV), chronic viral infection induced anti-viral T cells with an exhausted phenotype in mice and lack of rejection of glioma tumors expressing the viral protein gp33; this exhaustion was reversed using anti-PD-1 antibodies. These studies highlight the importance of using experimental models in which genuine anti-tumor T cell exhaustion and dysfunction exist to meaningfully investigate the combination of OVs, ACTs, and CIs. The interplay of OVs with differing immune cell populations was also discussed. Elizabeth Ilett (University of Leeds) provided mechanistic details of reovirus interaction with circulating monocytes. This was predominantly immunoglobulin G (IgG) dependent, and, while viral replication was not induced, monocytes were activated. Furthermore, granulocyte-macrophage colony-stimulating factor (GMCSF) preconditioning mobilized a population of monocytes that delivered intravenously (i.v.) administered reovirus to tumors.8 Melanoma cells endogenously expressing NY-ESO-1 can present antigen via the class II pathway to CD4+ T cells,9 and Tiphaine Delaunay (Institut national de la santé et de la recherche médicale [INSERM]) explored whether this T cell stimulation is enhanced by MV or VacV. Interferon gamma (IFNg) production from NY-ESO1-specific CD4+ T cells was substantially increased in co-cultures when NY-ESO-1+ melanoma cells were previously infected with MV or VV compared to uninfected controls. Shaun Xiaoliu Zhang (University of Houston) described an engineered HSV-2- FusOn-H2 virus, secreting a chimeric HER2-specific affibody and protein L molecule, bringing macrophages and NK cells into contact with tumor cells. HSV-2FusOn-H2 significantly improved efficacy in a moderately permissive murine tumor model relative to the parental strain.
Molecular Therapy: Oncolytics Vol. 7 December 2017
13
www.moleculartherapy.org
Meeting Report Almohanad Alkayyal (OHRI) presented an infected cell vaccine platform generated using oncolytic MG1-expressing IL-12 (MG1 IL-12 ICV). MG1 IL-12 ICV induced robust NK cell activation and recruitment as well as primed peritoneal T cells in a peritoneal carcinomatosis model. Addition of PD-1 blockade enhanced MG1 IL-12 ICV therapy.10 The innovative research presented here brings optimism to future clinical trials of OVs as cancer immunotherapeutics. Combination Therapies
Ideally, combination therapies provide synergistic effects, and two sessions were dedicated to augmenting the effects of OV therapy. Kah Whye Peng (Mayo Clinic) described the combination of VSV mIFNb with anti-PDL1 checkpoint blockade in a murine model of acute myeloid leukemia, resulting in increased survival and induction of tumor-specific T cell responses.11 Ji Yong Yoo (Ohio State) revealed that b1 integrin blockade decreased intratumoral (IT) type I IFN and led to increased HSV replication and prolonged survival in breast cancer xenografts. Jean-Simon Diallo (OHRI) introduced the combination of vanadate with VSV and VacV. Positive effects were noted in T cell, NK cell, and macrophage populations, with prolonged survival documented in both immuno-deficient and syngeneic models. Leslee Sprague (Ohio State University) presented the use of HSV1716 in combination with alisertib (an Aurora A kinase inhibitor) against neuroblastoma xenografts. Synergy was demonstrated in this model, with in vivo effects of alisertib attributed to decreased myeloid-derived suppressor cells (MDSCs) and decreased NK cell infiltration, with the latter thought to delay HSV clearance. Ji Young Yoo (Ohio State University) also described how tumor necrosis factor-a (TNF-a) inhibits the replication of oHSV within tumor cells via the induction of apoptosis, thereby acting as a potential barrier to this oncolytic. Trametinib (a potent MAP/ERK kinase [MEK] inhibitor) was able to decrease TNF-a secretion from microglia and macrophages. When combined with oHSV, a significant increase in replication was observed, resulting in prolonged survival in a murine glioma model. Systematic preclinical screening of compounds to
14
enhance OV therapy is of obvious translational value. Another area of investigation is to combine OV therapy with adoptive cell therapy. Nori Kasahara (University of Miami) showed how novel antigens could be introduced to tumor cells, which are subsequently targeted by adoptively transferred T cells. As a proof of concept, a replicating retroviral vector (RRV) expressing the gp33 antigen was combined with the transfer of P14 T cells. In order to increase the infiltration and efficacy of adoptively transferred T cells, Mikko Siurala (TILT Biotherapeutics) engineered an adenovirus secreting IL-2 and TNF-a for IT administration.12 Boris Simovic (McMaster University), showed that TCMs used as ACTs in combination with a rhabdoviral OV vaccine was curative when targeting a neoepitope in a murine sarcoma model. Interestingly, this combinatory effect was dependent on in vivo expansion of endogenous T cells. Oncolytic viral therapy and adoptive cell transfer have been widely investigated and show promising results; excitement surrounds combining these to further enhance the profiles of both immunotherapeutic approaches.
ease (GVHD) in allogeneic bone marrow transplants in a BALB/c model of multiple myeloma (MM). Dr. McFadden’s approach is to infect the donor-derived bone marrow ex vivo with MYXV prior to transplantation, which is efficacious in this model. Aladar Szalay, (StemImmune) presented a different approach for the delivery of VacV in a murine glioblastoma model. Dr. Szalay’s team is using fatty tissue-derived stem cells to deliver VacV via magnetic resonance imaging (MRI)-guided IT injections. Julia Davydova (University of Minnesota) spoke to the need to optimize model selection in OV studies. Dr. Davydova’s group is currently investigating the oncolytic potential, toxicity, and bio-distribution of the oncolytic adenovirus Ad5/Ad3-DE3-ADP-Luc in immuno-competent pigs. Takafumi Nakamura (Tottori University) spoke about the improved selective oncolytic potential of a doubledeleted mutant of VacV–DVGF (C11R)/DO1L. O1L deletion-targeted viral replication in MAPK-activated tumor cells, resulting in diminished toxicity in a severe combined immunodeficiency (SCID) mouse model. Early-phase clinical trials will be expedited by decreasing OV related toxicity. Debate
The addition of OVs to preexisting clinical treatments is also being investigated. Jeffrey Bryant (Duke University) provided an update on an ongoing clinical trial using the poliovirus rhinovirus hybrid, PVSRIPO for glioblastoma: 20%–25% response rates have been observed in 42 patients. Combinations with corticosteroids and alkylators are currently under investigation. Karsten Geletneky (Klinikum Darmstadt) presented a case series of three glioblastoma patients treated with oncolytic parvovirus H-1 (H1-PV) in combination with bevacizumab and an anti-PD1 CI. All three patients had rapid tumor clearance within 2 weeks with no major side effects. Such clinical data are key for informing future multi-modal approaches. Delivery, Imaging, and Toxicology
Understanding viral delivery and toxicology is also critical for the success of future clinical studies. Grant McFadden (University of Florida) uses myxoma virus (MYXV) to overcome graft-versus-host dis-
Molecular Therapy: Oncolytics Vol. 7 December 2017
Delegates of the 2016 meeting partook in the inaugural OV debate session. Kerry Fisher was the eloquent protagonist for the statement that “This house believes that i.v. administration is the most realistic approach by which OV therapy will enter routine clinical practice,” and Rob Coffin, who was in favor of IT delivery, ably opposed him. Imlygic, the first OV to pass muster in phase III trials for advanced stage melanoma, is administered via the IT route, thereby demonstrating that IT delivery works, and, thus, the suggestion “if it ain’t broke why fix it”? was made.13 Further logical arguments for IT delivery included the lack of a viral dilution that would occur as a result of i.v. delivery; clinical experience revealed that IT delivery was not technically difficult and was readily achievable. On the flip side, it was argued that, clinically, an i.v. infusion was much more convenient and, in fact, IT dosing, especially with regards to visceral lesions, was not straightforward and required a multi-disciplinary team. The possibility of
www.moleculartherapy.org
Meeting Report delivering the entire IT dose to non-vital tumor tissue was raised due to the intrinsically heterogeneous nature of tumors.14 Increased interstitial pressure within a neoplasm also poses the concern of the IT dose not remaining within the tumor. Intravenous dosing would therefore be easier to plan and deliver as well as having the advantage of reaching multiple lesions with a single injection. Perhaps in the age of precision-based medicine, trying to find a “one size fits all” delivery technique risks losing efficacy across this diverse group of therapeutics, and each candidate OV will need to be evaluated based on its own merit. Tumor Microenvironment
Responses to cancer therapy are greatly influenced by the heterogeneous tumor microenvironment. Carolina Ilkow (OHRI) focused on the interaction of cancer-associated fibroblasts (CAFs) and OVs. Evidence that CAFs are sensitive to OV infection by virtue of reduced anti-viral defenses was presented.15 Subsequently, the role of the artificial miRNAs was discussed; one such molecule (amiRNA6) increased OV killing and was able to mediate its effects through intercellular exome transfer. Joshua Freedman (University of Oxford) presented his work on the use of bi-specific T cell engagers (BiTEs) binding fibroblast-associated protein (FAP), which is highly expressed by CAFs. Enadenotucirev (EnAd) expressing the FAP specific BiTE (EnAd-BiTE) combines direct adenoviral oncolytic killing with the ability to target CAFs for T cellmediated destruction. Targeting CAFs is another emerging mechanism by which OVs can exert anti-cancer activity. Understanding the interactions of OVs and the tumor microenvironment is crucial for safety and efficacy. Wouter van den Bossche (Erasmus MC) presented his work on the effects of the oncolytic adenovirus Delta24RGD. By culturing human macrophages with Delta24-RGD-infected glioblastomalike stem cells, macrophages were skewed toward an M1 phenotype. Moreover, glioblastoma patients receiving Delta24-RGD had increased infiltration of M1-like macrophages in resected tumors compared to untreated patients. Robert Andtbacka (Uni-
versity of Utah) presented the CALM extension study on behalf of Darren Shafren (Viralytics). In a phase II trial, 57 patients received 10 IT injections of coxsackievirus A21 (CAVATAK) in late stage melanoma. 39% had a 6-month progression-free survival and 75.4% were alive at 1 year. Tumors from patients with controlled disease had elevated immune cell infiltration and increased immune checkpoint expression. Preliminary data from a current phase 1b clinical trial of CAVATAK combined with ipilimumab revealed durable responses. Amber Miller (Mayo Clinic) presented the potential use of a genomic screen to predict the efficacy and spread of OV therapy. In a phase I clinical trial, involving 12 patients treated with VSV-IFNb, pre-treatment tumor and healthy tissue samples were collected and subjected to RNA sequencing and compared to clinical response data, enabling identification of genes involved in viral control. Gaining insight into the changes induced by OVs in the tumor microenvironment will inform strategies to enhance therapeutic precision while minimizing adverse effects. Clinical Trials
As the OV field progresses, clinical trial data will continually become available. Keri Streby (Nationwide Children’s Hospital) reported on a phase I trial evaluating the safety and tolerability of IT Seprehvir for pediatric recurrent solid non-central nervous system (CNS) tumors. While no dose-limiting toxicities were recorded, significant tumor regressions were not observed. Steven Russell (Mayo Clinic) provided an overview of numerous trials with measles in the context of MM and ovarian cancer. Of note, one MM patient who had a complete response to MV therapy had an exceptionally high mutational burden, potentially rendering such tumors susceptible to immunotherapies. Jean Rommelaere (Heidelberg) discussed a phase I/IIa trial using the H-1 parvovirus (ParvOryx01) for glioblastoma. Patients received either IT or i.v. virus followed by resection. No dose-limiting toxicity was observed, and viral replication as well as induction of tumor specific immunity was demonstrated. The OV field waits with intrigue as more trial results are presented.
Combinatorial clinical strategies were also discussed. Robert Andtbacka updated results from MASTERKEY-265, investigating the combination therapy of Imlygic and pembrolizumab for advanced melanoma. In 21 treated patients, a 57% response rate was observed, with 23% exhibiting a complete response. This study preceded the ongoing phase III KEYNOTE-034 evaluating Imlygic plus pembrolizumab. Dr. Andtbacka also presented results from a phase II trial to evaluate the safety and efficacy of HF10 (a spontaneously occurring attenuated HSV) in combination with ipilimumab for advanced melanoma on behalf of Takara Bio, Inc. Interim analysis revealed a 65% disease control rate and an 80% 1-year overall survival in a 46-patient study. Doug Jolly (Tocagen) provided a synopsis of a phase I study for high grade glioma using the “conditionally oncolytic” Toca 511 to deliver the cytosine deaminase gene in conjunction with 5-fluorocytosine.16 Overall survival was 13.6 months and significantly longer compared to an external control group. An international phase II/III potential registration trial with 170 patients with recurrent aggressive CNS neoplasia using Toca 511 is ongoing. Hardev Pandha (University of Surrey) described the phase I/II CANON study using CAVATAK, a bio-selected ICAM-1targeted Coxsackievirus 21, for non-muscle invasive bladder cancer in combination with mitomycin C. Synergistic viral replication and cytotoxicity was recorded alongside evidence of ICD, increased IFN, and induction of checkpoint genes; this therapy was well tolerated. Translation of preclinical combination experiments has resulted in objective tumor responses and genuine cause for optimism. Conclusions
Two awards were bestowed at the 2016 meeting. Joshua Freedman (University of Oxford) was the selected trainee abstract winner of the inaugural Charles Conrad Memorial Travel Award, sponsored by DNAtrix and presented by Frank Tufaro (DNAtrix). Stephen Russell (Mayo Clinic) was recognized for his life-long contributions to the field of OVs and was named as the 2016 recipient of the Golden Virus Award, as selected by the conference organizing
Molecular Therapy: Oncolytics Vol. 7 December 2017
15
www.moleculartherapy.org
Meeting Report committee. The diversity of viral platforms, engineering strategies, and pre-clinical therapeutic approaches make it clear that a great deal of intriguing research is ongoing in the OV field. Clinical data presented here built upon that which was presented at the 9th International Conference in June of 2015,17 with interest from industry partners blossoming. Significant strides are being taken to consolidate the role of OVs in the clinic, and this is being driven forward by innovative laboratory research. The level of interaction and quality of science presented in Vancouver reflects the great excitement surrounding the future of viral oncolytics.
AUTHOR CONTRIBUTIONS M.J.A. – writing the original draft and reviewing and editing; L.E., B.A.K., and M.M.S. – writing the original draft; K.B.S. – reviewing and editing; R.G.V., J.C.B., and D.H.E. - supervision; B.D.L. – reviewing and editing and supervision.
CONFLICTS OF INTEREST B.D.L. and J.C.B. are named as inventors on patents covering Maraba virus as an oncolytic vaccine.
REFERENCES 1. Yee, C. (2014). The use of endogenous T cells for adoptive transfer. Immunol. Rev. 257, 250–263. 2. Bridle, B.W., Nguyen, A., Salem, O., Zhang, L., Koshy, S., Clouthier, D., Chen, L., Pol, J., Swift, S.L., Bowdish, D.M., et al. (2016). Privileged Antigen Presentation in Splenic B Cell Follicles Maximizes T Cell Responses
16
in Prime-Boost Vaccination. J. Immunol. 196, 4587–4595.
Expressing Maraba Virus Cellular Vaccine. Cancer Immunol. Res. 5, 211–221.
3. Lichty, B.D., Breitbach, C.J., Stojdl, D.F., and Bell, J.C. (2014). Going viral with cancer immunotherapy. Nat. Rev. Cancer 14, 559–567.
11. Shen, W., Patnaik, M.M., Ruiz, A., Russell, S.J., and Peng, K.-W. (2016). Immunovirotherapy with vesicular stomatitis virus and PD-L1 blockade enhances therapeutic outcome in murine acute myeloid leukemia. Blood 127, 1449–1458.
4. Cuddington, B.P., and Mossman, K.L. (2015). Oncolytic bovine herpesvirus type 1 as a broad spectrum cancer therapeutic. Curr. Opin. Virol. 13, 11–16. 5. Adair, R.A., Roulstone, V., Scott, K.J., Morgan, R., Nuovo, G.J., Fuller, M., Beirne, D., West, E.J., Jennings, V.A., Rose, A., et al. (2012). Cell carriage, delivery, and selective replication of an oncolytic virus in tumor in patients. Sci. Transl. Med. 4, 138ra77. 6. Veinalde, R., Grossardt, C., Hartmann, L., BourgeoisDaigneault, M.-C., Bell, J.C., Jäger, D., von Kalle, C., Ungerechts, G., and Engeland, C.E. (2017). Oncolytic measles virus encoding interleukin-12 mediates potent antitumor effects through T cell activation. OncoImmunology 6, e1285992. 7. Shim, K.G., Zaidi, S., Thompson, J., Kottke, T., Evgin, L., Rajani, K.R., Schuelke, M., Driscoll, C.B., Huff, A., Pulido, J.S., and Vile, R.G. (2017). Inhibitory Receptors Induced by VSV Viroimmunotherapy Are Not Necessarily Targets for Improving Treatment Efficacy. Mol. Ther. 25, 962–975.
12. Siurala, M., Havunen, R., Saha, D., Lumen, D., Airaksinen, A.J., Tähtinen, S., Cervera-Carrascon, V., Bramante, S., Parviainen, S., Vähä-Koskela, M., et al. (2016). Adenoviral Delivery of Tumor Necrosis Factor-a and Interleukin-2 Enables Successful Adoptive Cell Therapy of Immunosuppressive Melanoma. Mol. Ther. 24, 1435–1443. 13. Andtbacka, R.H.I., Collichio, F.A., Amatruda, T., Senzer, N.N., Chesney, J., Delman, K.A., Spitler, L.E., Puzanov, I., Doleman, S., Ye, Y., et al. (2013). OPTiM: A randomized phase III trial of talimogene laherparepvec (T-VEC) versus subcutaneous (SC) granulocyte-macrophage colony-stimulating factor (GM-CSF) for the treatment (tx) of unresected stage IIIB/C and IV melanoma. http://meetinglibrary. asco.org/content/117592-132. 14. Hanahan, D., and Weinberg, R.A. (2011). Hallmarks of cancer: the next generation. Cell 144, 646–674.
8. Ilett, E., Kottke, T., Donnelly, O., Thompson, J., Willmon, C., Diaz, R., Zaidi, S., Coffey, M., Selby, P., Harrington, K., et al. (2014). Cytokine conditioning enhances systemic delivery and therapy of an oncolytic virus. Mol. Ther. 22, 1851–1863.
15. Ilkow, C.S., Marguerie, M., Batenchuk, C., Mayer, J., Ben Neriah, D., Cousineau, S., Falls, T., Jennings, V.A., Boileau, M., Bellamy, D., et al. (2015). Reciprocal cellular cross-talk within the tumor microenvironment promotes oncolytic virus activity. Nat. Med. 21, 530–536.
9. Fonteneau, J.F., Brilot, F., Münz, C., and Gannagé, M. (2016). The Tumor Antigen NY-ESO-1 Mediates Direct Recognition of Melanoma Cells by CD4+ T Cells after Intercellular Antigen Transfer. J. Immunol. 196, 64–71.
16. Cloughesy, T.F., Landolfi, J., Hogan, D.J., Bloomfield, S., Carter, B., Chen, C.C., Elder, J.B., Kalkanis, S.N., Kesari, S., Lai, A., et al. (2016). Phase 1 trial of vocimagene amiretrorepvec and 5-fluorocytosine for recurrent high-grade glioma. Sci. Transl. Med. 8, 341ra75.
10. Alkayyal, A.A., Tai, L.-H., Kennedy, M.A., de Souza, C.T., Zhang, J., Lefebvre, C., Sahi, S., Ananth, A.A., Mahmoud, A.B., Makrigiannis, A.P., et al. (2017). NK-Cell Recruitment Is Necessary for Eradication of Peritoneal Carcinomatosis with an IL12-
17. Peters, C., Nigim, F., Chiocca, E.A., and Rabkin, S.D. (2016). Oncolytic viruses on the cusp of success?: proceedings of the 9th International Conference on Oncolytic Virus Therapeutics. Mol. Ther. Oncolytics 3, 16016.
Molecular Therapy: Oncolytics Vol. 7 December 2017
Infectious Optimism following the 10th International Oncolytic Virus Meeting Matthew J. Atherton,1 Laura Evgin,2 Brian A. Keller,3 Mira M. Shenouda,4 Kyle B. Stephenson,5 Richard G. Vile,2 John C. Bell,3,5 David H. Evans,4 and Brian D. Lichty1,5 The 10th International Conference on Replicating Oncolytic Virus Therapeutics was held in Vancouver, Canada from October 1–4, 2016. The agenda for the meeting comprised lectures from several streams within the field of oncolytic viral therapeutics. Exploring the strengthening relationship among oncolytic viruses, cancer immunology, and immunotherapy; gaining an understanding for effective therapeutic delivery routes; and learning of exciting results from translational studies all featured prominently among areas discussed. As the field matures, commercialization and patientcentered research have become important avenues for growth; however, an abundance of high quality laboratory-based science continues to be performed in order to optimize future therapeutic approaches. Here, we summarize the latest innovations presented at this meeting. Keynote talks from Cassian Yee (MD Anderson Cancer Center) and Yonghong Wan (McMaster University) set the scene for the meeting and focused on recent developments in cancer immunotherapy and oncolytic viruses (OVs). Dr. Yee has been at the forefront of utilizing adoptive cellular therapies (ACTs) for treating patients with advanced malignancies. Dramatic and curative responses have been achieved following ACT using the patient’s endogenous T cells; however, challenges still exist in manufacturing processes alongside their widespread availability.1 A significant part of Dr. Yee’s research aimed to address these issues. Subsequently, Dr. Wan presented a combinatorial approach whereby oncolytic MG1 Maraba, encoding a mutant ERK neoantigen, was able to boost a population of adoptively
12
transferred T cells specific to the same antigen with curative results in an aggressive pre-clinical sarcoma model harboring the neoantigen. Dr. Wan explained how oncolytic rhabdoviruses, such as MG1 Maraba, were able to dramatically boost antigen-specific T cells due to their ability to engage central memory T cells (TCMs) in immunoprivileged splenic sites.2 As OVs engage the immune system in numerous ways, including in situ vaccination and modification of immunosuppressive tumor microenvironments, they are being recognized as bona fide anti-cancer immunotherapuetics.3 Integrating OVs into the oncologist’s growing arsenal of treatment modalities will be one of the keys to the ongoing success of these versatile agents over the coming years. Viral Engineering and Replication
Robust and cancer-specific replication is a desired therapeutic property in the OV field. This session focused on pre-clinical efforts dedicated to viral engineering and treatment strategies to enhance downstream therapeutic utility. William Jia (University of British Columbia) began by presenting combination therapies using the PKR-inhibitor C16 or the antibiotic nifuroxazide in conjunction with an oncolytic herpes simplex virus (oHSV) in glioma models. Chemically targeting STAT1/3 with these agents increased cancer cell permissiveness to oHSV. Karen Mossman (McMaster University) introduced the concept of immunogenic cell death (ICD) and its induction through various herpes virus platforms.4 The utility of a combinatorial approach was demonstrated when the non-ICD-inducing chemotherapeutic mitomycin C improved the efficacy of an oHSV-1 platform. These examples demon-
Molecular Therapy: Oncolytics Vol. 7 December 2017
strate that, when combined with rationally selected therapeutics, replication and efficacy of OVs can be further enhanced. Interrogating the role of viral genetics featured strongly for the remainder of this section. Korneel Grauwet (Harvard University) investigated the relationship of viral immune evasion genes with an oHSV-1 platform. Important observations were gleaned using a mouse glioblastoma model, implicating natural killer (NK) cells as being critical for the clearance of HSV-1 infection and potentially decreasing oHSV’s therapeutic efficacy. Larissa Pikor (Ottawa Hospital Research Institute [OHRI]) discussed a CRISPR/Cas9-mediated approach to better understand OV resistance genes. Stable Cas9 nuclease-expressing cells and a lentiviral guide RNA (gRNA) library facilitated a negative selection screen in cell lines resistant to OVs; harvesting surviving cells for sequencing and comparing to mock infected cells identified genes that confer OV sensitivity. Amelia Aitken (OHRI) presented data about the “viral suppressor of RNA interference (RNAi)-1 (VSR-1)” and the improvement in efficacy that was observed when VSR-1 was encoded in the vesicular stomatitis OV, VSVD51, suppressing antiviral RNA interference (RNAi)- enhanced tumor cell specificity and oncolysis. The final two presenters discussed approaches to engineer oncolytically superior Vaccinia virus (VacV). Andrea McCart (University of Toronto) used a single gene deletion approach. Specifically deleting K1L, A46R, and A52R creates OVs that demonstrate superior replication, cytotoxicity, and spread, respectively. Similarly, Brian Keller (OHRI) has isolated an 89-virus library that consists of clonal 1
McMaster Immunology Research Centre, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55905, USA; 3Centre for Innovative Cancer Therapeutics, Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada; 4 Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2E1, Canada; 5Turnstone Biologics, Ottawa, ON K1S 3V5, Canada 2
Correspondence: Brian D. Lichty, McMaster Immunology Research Centre, McMaster University, Hamilton, ON L8S 4K1, Canada. E-mail: [email protected]
www.moleculartherapy.org
Meeting Report stocks of unique VacVs with insertion of an mCherry-expressing transposable element. This library has been characterized in terms of OV-relevant properties, and interesting phenotypes have been observed, especially in 3 highlighted clones with unique insertion sites in the same gene. Such engineering projects facilitate the generation of improved OV candidates while furthering our understanding of OV biology. Immunity
Cancer immunotherapy is continuing to gain momentum in the clinic and, as such, featured heavily during the conference. Steve Thorne (University of Pittsburgh) opened the session by presenting different approaches to activate the immune system as well as combating tumor-associated immunosuppression. Deglycosylation of the VacV particle is able to skew the immunity toward a beneficial cell-mediated response as opposed to generating neutralizing antiviral antibodies. Dr. Thorne also presented another engineering approach enabling Vaccinia to degrade the immunosuppressive factor, PGE2, thus enhancing anti-tumor immunity. Clinical data following the intrapleural administration of oncolytic HSV to mesothelioma patients were presented by Joe Conner (Virttu Biologics). Analysis of pleural fluid following treatment revealed an induction of pro-inflammatory cytokines and underlined the promise of oHSV as an immunotherapeutic in this setting. The significant potential of OVs to act as a vaccine against specific tumor-associated antigens (TAAs) was highlighted by Brian Lichty (McMaster University). MG1 Maraba virus acts as a versatile boosting agent as well as potent oncolytic, and this was demonstrated in preclinical HPV, prostate, and sarcoma models making use of viral, differentiation, and mutated antigens. Data from the first human clinical trial utilizing MG1 Maraba expressing the MAGE-A3 TAA were greatly anticipated. Siri Tähtinen (University of Helsinki) presented proof-of-principal data for an immunologic approach of coating an adenovirus with TAAs; mice bearing B16Ova melanoma tumors were successfully treated with this strategy. Induction of antitumor immunity is of fundamental importance for the success of OVs.
Engineering and combinatorial approaches were also demonstrated in the context of immunity. By manufacturing a VSV-measles virus (VSV-MV) hybrid, Christopher Richardson and colleagues (Dalhousie University) were able to exploit the abundant neoplastic expression of nectin-4, which acts as a receptor for MV, and treatment of immuno-competent mice with VSV-MV resulted in anti-tumor activity. Nino Chiocca (Harvard University) presented data utilizing a replication deficient adenovirus armed with the HSV TK gene, and, following treatment with this virus, an increased intratumoral expression of the immune checkpoint PDL-1 was observed. Combination treatments using this viral approach alongside PD-1 blockade for malignant glioma are undergoing clinical evaluation. In a similar vein, Marie-Claude BourgeoisDaigneault (OHRI) combined MG1 Maraba with a checkpoint inhibitor (CI) in a preclinical breast cancer model and found that such multi-modal therapy conferred a survival benefit to tumor-bearing mice. Alan Melcher (The Institute of Cancer Research, London [ICR]) described how systemically administered oncolytic reovirus was able to cross the blood-brain barrier to access brain tumors, despite the presence of neutralizing antibodies—delivery through protective cell carriage by leukocytes, as previously described, is thought likely.5 Reovirus upregulated PD-1 and PD-L1 in the tumor and, when given alongside anti-PD-1 therapy, was effective in immuno-competent orthotopic murine models. Ruta Veinalde (Nationales Centrum für Tumorerkrankungen [NCT]) described oncolytic MVs encoding interleukin-12 (IL-12) and a-PDL-1. Treatment with MV IL-12 and MV a-PDL-1 cured 60% and 90% of mice bearing MC38 CEA tumors, respectively, as well as conferring protective immunity upon rechallenge.6 As such, combining OVs with checkpoint blockade has great potential. Combining CIs with OVs is not, however, a universal recipe for success. Richard Vile’s lab (Mayo Clinic) mapped the expression of inhibitory checkpoints following adoptive cell therapy and oncolytic virotherapy in a murine melanoma model. Multiple doses of VSV expressing hgp100 activated Pmel
T cells, with low expression of PD-1 and TIM-3 observed. The expansion of endogenous CD44hi CD62Llo effector T cells was also documented with elevated expression of PD-1 and TIM-3. However, neither PD-1 nor TIM-3 blockade enhanced therapy.7 Hiroshi Nakashima (Harvard University) presented a murine glioma model of T cell exhaustion. Using Clone 13 lymphocytic choriomeningitis (LCMV), chronic viral infection induced anti-viral T cells with an exhausted phenotype in mice and lack of rejection of glioma tumors expressing the viral protein gp33; this exhaustion was reversed using anti-PD-1 antibodies. These studies highlight the importance of using experimental models in which genuine anti-tumor T cell exhaustion and dysfunction exist to meaningfully investigate the combination of OVs, ACTs, and CIs. The interplay of OVs with differing immune cell populations was also discussed. Elizabeth Ilett (University of Leeds) provided mechanistic details of reovirus interaction with circulating monocytes. This was predominantly immunoglobulin G (IgG) dependent, and, while viral replication was not induced, monocytes were activated. Furthermore, granulocyte-macrophage colony-stimulating factor (GMCSF) preconditioning mobilized a population of monocytes that delivered intravenously (i.v.) administered reovirus to tumors.8 Melanoma cells endogenously expressing NY-ESO-1 can present antigen via the class II pathway to CD4+ T cells,9 and Tiphaine Delaunay (Institut national de la santé et de la recherche médicale [INSERM]) explored whether this T cell stimulation is enhanced by MV or VacV. Interferon gamma (IFNg) production from NY-ESO1-specific CD4+ T cells was substantially increased in co-cultures when NY-ESO-1+ melanoma cells were previously infected with MV or VV compared to uninfected controls. Shaun Xiaoliu Zhang (University of Houston) described an engineered HSV-2- FusOn-H2 virus, secreting a chimeric HER2-specific affibody and protein L molecule, bringing macrophages and NK cells into contact with tumor cells. HSV-2FusOn-H2 significantly improved efficacy in a moderately permissive murine tumor model relative to the parental strain.
Molecular Therapy: Oncolytics Vol. 7 December 2017
13
www.moleculartherapy.org
Meeting Report Almohanad Alkayyal (OHRI) presented an infected cell vaccine platform generated using oncolytic MG1-expressing IL-12 (MG1 IL-12 ICV). MG1 IL-12 ICV induced robust NK cell activation and recruitment as well as primed peritoneal T cells in a peritoneal carcinomatosis model. Addition of PD-1 blockade enhanced MG1 IL-12 ICV therapy.10 The innovative research presented here brings optimism to future clinical trials of OVs as cancer immunotherapeutics. Combination Therapies
Ideally, combination therapies provide synergistic effects, and two sessions were dedicated to augmenting the effects of OV therapy. Kah Whye Peng (Mayo Clinic) described the combination of VSV mIFNb with anti-PDL1 checkpoint blockade in a murine model of acute myeloid leukemia, resulting in increased survival and induction of tumor-specific T cell responses.11 Ji Yong Yoo (Ohio State) revealed that b1 integrin blockade decreased intratumoral (IT) type I IFN and led to increased HSV replication and prolonged survival in breast cancer xenografts. Jean-Simon Diallo (OHRI) introduced the combination of vanadate with VSV and VacV. Positive effects were noted in T cell, NK cell, and macrophage populations, with prolonged survival documented in both immuno-deficient and syngeneic models. Leslee Sprague (Ohio State University) presented the use of HSV1716 in combination with alisertib (an Aurora A kinase inhibitor) against neuroblastoma xenografts. Synergy was demonstrated in this model, with in vivo effects of alisertib attributed to decreased myeloid-derived suppressor cells (MDSCs) and decreased NK cell infiltration, with the latter thought to delay HSV clearance. Ji Young Yoo (Ohio State University) also described how tumor necrosis factor-a (TNF-a) inhibits the replication of oHSV within tumor cells via the induction of apoptosis, thereby acting as a potential barrier to this oncolytic. Trametinib (a potent MAP/ERK kinase [MEK] inhibitor) was able to decrease TNF-a secretion from microglia and macrophages. When combined with oHSV, a significant increase in replication was observed, resulting in prolonged survival in a murine glioma model. Systematic preclinical screening of compounds to
14
enhance OV therapy is of obvious translational value. Another area of investigation is to combine OV therapy with adoptive cell therapy. Nori Kasahara (University of Miami) showed how novel antigens could be introduced to tumor cells, which are subsequently targeted by adoptively transferred T cells. As a proof of concept, a replicating retroviral vector (RRV) expressing the gp33 antigen was combined with the transfer of P14 T cells. In order to increase the infiltration and efficacy of adoptively transferred T cells, Mikko Siurala (TILT Biotherapeutics) engineered an adenovirus secreting IL-2 and TNF-a for IT administration.12 Boris Simovic (McMaster University), showed that TCMs used as ACTs in combination with a rhabdoviral OV vaccine was curative when targeting a neoepitope in a murine sarcoma model. Interestingly, this combinatory effect was dependent on in vivo expansion of endogenous T cells. Oncolytic viral therapy and adoptive cell transfer have been widely investigated and show promising results; excitement surrounds combining these to further enhance the profiles of both immunotherapeutic approaches.
ease (GVHD) in allogeneic bone marrow transplants in a BALB/c model of multiple myeloma (MM). Dr. McFadden’s approach is to infect the donor-derived bone marrow ex vivo with MYXV prior to transplantation, which is efficacious in this model. Aladar Szalay, (StemImmune) presented a different approach for the delivery of VacV in a murine glioblastoma model. Dr. Szalay’s team is using fatty tissue-derived stem cells to deliver VacV via magnetic resonance imaging (MRI)-guided IT injections. Julia Davydova (University of Minnesota) spoke to the need to optimize model selection in OV studies. Dr. Davydova’s group is currently investigating the oncolytic potential, toxicity, and bio-distribution of the oncolytic adenovirus Ad5/Ad3-DE3-ADP-Luc in immuno-competent pigs. Takafumi Nakamura (Tottori University) spoke about the improved selective oncolytic potential of a doubledeleted mutant of VacV–DVGF (C11R)/DO1L. O1L deletion-targeted viral replication in MAPK-activated tumor cells, resulting in diminished toxicity in a severe combined immunodeficiency (SCID) mouse model. Early-phase clinical trials will be expedited by decreasing OV related toxicity. Debate
The addition of OVs to preexisting clinical treatments is also being investigated. Jeffrey Bryant (Duke University) provided an update on an ongoing clinical trial using the poliovirus rhinovirus hybrid, PVSRIPO for glioblastoma: 20%–25% response rates have been observed in 42 patients. Combinations with corticosteroids and alkylators are currently under investigation. Karsten Geletneky (Klinikum Darmstadt) presented a case series of three glioblastoma patients treated with oncolytic parvovirus H-1 (H1-PV) in combination with bevacizumab and an anti-PD1 CI. All three patients had rapid tumor clearance within 2 weeks with no major side effects. Such clinical data are key for informing future multi-modal approaches. Delivery, Imaging, and Toxicology
Understanding viral delivery and toxicology is also critical for the success of future clinical studies. Grant McFadden (University of Florida) uses myxoma virus (MYXV) to overcome graft-versus-host dis-
Molecular Therapy: Oncolytics Vol. 7 December 2017
Delegates of the 2016 meeting partook in the inaugural OV debate session. Kerry Fisher was the eloquent protagonist for the statement that “This house believes that i.v. administration is the most realistic approach by which OV therapy will enter routine clinical practice,” and Rob Coffin, who was in favor of IT delivery, ably opposed him. Imlygic, the first OV to pass muster in phase III trials for advanced stage melanoma, is administered via the IT route, thereby demonstrating that IT delivery works, and, thus, the suggestion “if it ain’t broke why fix it”? was made.13 Further logical arguments for IT delivery included the lack of a viral dilution that would occur as a result of i.v. delivery; clinical experience revealed that IT delivery was not technically difficult and was readily achievable. On the flip side, it was argued that, clinically, an i.v. infusion was much more convenient and, in fact, IT dosing, especially with regards to visceral lesions, was not straightforward and required a multi-disciplinary team. The possibility of
www.moleculartherapy.org
Meeting Report delivering the entire IT dose to non-vital tumor tissue was raised due to the intrinsically heterogeneous nature of tumors.14 Increased interstitial pressure within a neoplasm also poses the concern of the IT dose not remaining within the tumor. Intravenous dosing would therefore be easier to plan and deliver as well as having the advantage of reaching multiple lesions with a single injection. Perhaps in the age of precision-based medicine, trying to find a “one size fits all” delivery technique risks losing efficacy across this diverse group of therapeutics, and each candidate OV will need to be evaluated based on its own merit. Tumor Microenvironment
Responses to cancer therapy are greatly influenced by the heterogeneous tumor microenvironment. Carolina Ilkow (OHRI) focused on the interaction of cancer-associated fibroblasts (CAFs) and OVs. Evidence that CAFs are sensitive to OV infection by virtue of reduced anti-viral defenses was presented.15 Subsequently, the role of the artificial miRNAs was discussed; one such molecule (amiRNA6) increased OV killing and was able to mediate its effects through intercellular exome transfer. Joshua Freedman (University of Oxford) presented his work on the use of bi-specific T cell engagers (BiTEs) binding fibroblast-associated protein (FAP), which is highly expressed by CAFs. Enadenotucirev (EnAd) expressing the FAP specific BiTE (EnAd-BiTE) combines direct adenoviral oncolytic killing with the ability to target CAFs for T cellmediated destruction. Targeting CAFs is another emerging mechanism by which OVs can exert anti-cancer activity. Understanding the interactions of OVs and the tumor microenvironment is crucial for safety and efficacy. Wouter van den Bossche (Erasmus MC) presented his work on the effects of the oncolytic adenovirus Delta24RGD. By culturing human macrophages with Delta24-RGD-infected glioblastomalike stem cells, macrophages were skewed toward an M1 phenotype. Moreover, glioblastoma patients receiving Delta24-RGD had increased infiltration of M1-like macrophages in resected tumors compared to untreated patients. Robert Andtbacka (Uni-
versity of Utah) presented the CALM extension study on behalf of Darren Shafren (Viralytics). In a phase II trial, 57 patients received 10 IT injections of coxsackievirus A21 (CAVATAK) in late stage melanoma. 39% had a 6-month progression-free survival and 75.4% were alive at 1 year. Tumors from patients with controlled disease had elevated immune cell infiltration and increased immune checkpoint expression. Preliminary data from a current phase 1b clinical trial of CAVATAK combined with ipilimumab revealed durable responses. Amber Miller (Mayo Clinic) presented the potential use of a genomic screen to predict the efficacy and spread of OV therapy. In a phase I clinical trial, involving 12 patients treated with VSV-IFNb, pre-treatment tumor and healthy tissue samples were collected and subjected to RNA sequencing and compared to clinical response data, enabling identification of genes involved in viral control. Gaining insight into the changes induced by OVs in the tumor microenvironment will inform strategies to enhance therapeutic precision while minimizing adverse effects. Clinical Trials
As the OV field progresses, clinical trial data will continually become available. Keri Streby (Nationwide Children’s Hospital) reported on a phase I trial evaluating the safety and tolerability of IT Seprehvir for pediatric recurrent solid non-central nervous system (CNS) tumors. While no dose-limiting toxicities were recorded, significant tumor regressions were not observed. Steven Russell (Mayo Clinic) provided an overview of numerous trials with measles in the context of MM and ovarian cancer. Of note, one MM patient who had a complete response to MV therapy had an exceptionally high mutational burden, potentially rendering such tumors susceptible to immunotherapies. Jean Rommelaere (Heidelberg) discussed a phase I/IIa trial using the H-1 parvovirus (ParvOryx01) for glioblastoma. Patients received either IT or i.v. virus followed by resection. No dose-limiting toxicity was observed, and viral replication as well as induction of tumor specific immunity was demonstrated. The OV field waits with intrigue as more trial results are presented.
Combinatorial clinical strategies were also discussed. Robert Andtbacka updated results from MASTERKEY-265, investigating the combination therapy of Imlygic and pembrolizumab for advanced melanoma. In 21 treated patients, a 57% response rate was observed, with 23% exhibiting a complete response. This study preceded the ongoing phase III KEYNOTE-034 evaluating Imlygic plus pembrolizumab. Dr. Andtbacka also presented results from a phase II trial to evaluate the safety and efficacy of HF10 (a spontaneously occurring attenuated HSV) in combination with ipilimumab for advanced melanoma on behalf of Takara Bio, Inc. Interim analysis revealed a 65% disease control rate and an 80% 1-year overall survival in a 46-patient study. Doug Jolly (Tocagen) provided a synopsis of a phase I study for high grade glioma using the “conditionally oncolytic” Toca 511 to deliver the cytosine deaminase gene in conjunction with 5-fluorocytosine.16 Overall survival was 13.6 months and significantly longer compared to an external control group. An international phase II/III potential registration trial with 170 patients with recurrent aggressive CNS neoplasia using Toca 511 is ongoing. Hardev Pandha (University of Surrey) described the phase I/II CANON study using CAVATAK, a bio-selected ICAM-1targeted Coxsackievirus 21, for non-muscle invasive bladder cancer in combination with mitomycin C. Synergistic viral replication and cytotoxicity was recorded alongside evidence of ICD, increased IFN, and induction of checkpoint genes; this therapy was well tolerated. Translation of preclinical combination experiments has resulted in objective tumor responses and genuine cause for optimism. Conclusions
Two awards were bestowed at the 2016 meeting. Joshua Freedman (University of Oxford) was the selected trainee abstract winner of the inaugural Charles Conrad Memorial Travel Award, sponsored by DNAtrix and presented by Frank Tufaro (DNAtrix). Stephen Russell (Mayo Clinic) was recognized for his life-long contributions to the field of OVs and was named as the 2016 recipient of the Golden Virus Award, as selected by the conference organizing
Molecular Therapy: Oncolytics Vol. 7 December 2017
15
www.moleculartherapy.org
Meeting Report committee. The diversity of viral platforms, engineering strategies, and pre-clinical therapeutic approaches make it clear that a great deal of intriguing research is ongoing in the OV field. Clinical data presented here built upon that which was presented at the 9th International Conference in June of 2015,17 with interest from industry partners blossoming. Significant strides are being taken to consolidate the role of OVs in the clinic, and this is being driven forward by innovative laboratory research. The level of interaction and quality of science presented in Vancouver reflects the great excitement surrounding the future of viral oncolytics.
AUTHOR CONTRIBUTIONS M.J.A. – writing the original draft and reviewing and editing; L.E., B.A.K., and M.M.S. – writing the original draft; K.B.S. – reviewing and editing; R.G.V., J.C.B., and D.H.E. - supervision; B.D.L. – reviewing and editing and supervision.
CONFLICTS OF INTEREST B.D.L. and J.C.B. are named as inventors on patents covering Maraba virus as an oncolytic vaccine.
REFERENCES 1. Yee, C. (2014). The use of endogenous T cells for adoptive transfer. Immunol. Rev. 257, 250–263. 2. Bridle, B.W., Nguyen, A., Salem, O., Zhang, L., Koshy, S., Clouthier, D., Chen, L., Pol, J., Swift, S.L., Bowdish, D.M., et al. (2016). Privileged Antigen Presentation in Splenic B Cell Follicles Maximizes T Cell Responses
16
in Prime-Boost Vaccination. J. Immunol. 196, 4587–4595.
Expressing Maraba Virus Cellular Vaccine. Cancer Immunol. Res. 5, 211–221.
3. Lichty, B.D., Breitbach, C.J., Stojdl, D.F., and Bell, J.C. (2014). Going viral with cancer immunotherapy. Nat. Rev. Cancer 14, 559–567.
11. Shen, W., Patnaik, M.M., Ruiz, A., Russell, S.J., and Peng, K.-W. (2016). Immunovirotherapy with vesicular stomatitis virus and PD-L1 blockade enhances therapeutic outcome in murine acute myeloid leukemia. Blood 127, 1449–1458.
4. Cuddington, B.P., and Mossman, K.L. (2015). Oncolytic bovine herpesvirus type 1 as a broad spectrum cancer therapeutic. Curr. Opin. Virol. 13, 11–16. 5. Adair, R.A., Roulstone, V., Scott, K.J., Morgan, R., Nuovo, G.J., Fuller, M., Beirne, D., West, E.J., Jennings, V.A., Rose, A., et al. (2012). Cell carriage, delivery, and selective replication of an oncolytic virus in tumor in patients. Sci. Transl. Med. 4, 138ra77. 6. Veinalde, R., Grossardt, C., Hartmann, L., BourgeoisDaigneault, M.-C., Bell, J.C., Jäger, D., von Kalle, C., Ungerechts, G., and Engeland, C.E. (2017). Oncolytic measles virus encoding interleukin-12 mediates potent antitumor effects through T cell activation. OncoImmunology 6, e1285992. 7. Shim, K.G., Zaidi, S., Thompson, J., Kottke, T., Evgin, L., Rajani, K.R., Schuelke, M., Driscoll, C.B., Huff, A., Pulido, J.S., and Vile, R.G. (2017). Inhibitory Receptors Induced by VSV Viroimmunotherapy Are Not Necessarily Targets for Improving Treatment Efficacy. Mol. Ther. 25, 962–975.
12. Siurala, M., Havunen, R., Saha, D., Lumen, D., Airaksinen, A.J., Tähtinen, S., Cervera-Carrascon, V., Bramante, S., Parviainen, S., Vähä-Koskela, M., et al. (2016). Adenoviral Delivery of Tumor Necrosis Factor-a and Interleukin-2 Enables Successful Adoptive Cell Therapy of Immunosuppressive Melanoma. Mol. Ther. 24, 1435–1443. 13. Andtbacka, R.H.I., Collichio, F.A., Amatruda, T., Senzer, N.N., Chesney, J., Delman, K.A., Spitler, L.E., Puzanov, I., Doleman, S., Ye, Y., et al. (2013). OPTiM: A randomized phase III trial of talimogene laherparepvec (T-VEC) versus subcutaneous (SC) granulocyte-macrophage colony-stimulating factor (GM-CSF) for the treatment (tx) of unresected stage IIIB/C and IV melanoma. http://meetinglibrary. asco.org/content/117592-132. 14. Hanahan, D., and Weinberg, R.A. (2011). Hallmarks of cancer: the next generation. Cell 144, 646–674.
8. Ilett, E., Kottke, T., Donnelly, O., Thompson, J., Willmon, C., Diaz, R., Zaidi, S., Coffey, M., Selby, P., Harrington, K., et al. (2014). Cytokine conditioning enhances systemic delivery and therapy of an oncolytic virus. Mol. Ther. 22, 1851–1863.
15. Ilkow, C.S., Marguerie, M., Batenchuk, C., Mayer, J., Ben Neriah, D., Cousineau, S., Falls, T., Jennings, V.A., Boileau, M., Bellamy, D., et al. (2015). Reciprocal cellular cross-talk within the tumor microenvironment promotes oncolytic virus activity. Nat. Med. 21, 530–536.
9. Fonteneau, J.F., Brilot, F., Münz, C., and Gannagé, M. (2016). The Tumor Antigen NY-ESO-1 Mediates Direct Recognition of Melanoma Cells by CD4+ T Cells after Intercellular Antigen Transfer. J. Immunol. 196, 64–71.
16. Cloughesy, T.F., Landolfi, J., Hogan, D.J., Bloomfield, S., Carter, B., Chen, C.C., Elder, J.B., Kalkanis, S.N., Kesari, S., Lai, A., et al. (2016). Phase 1 trial of vocimagene amiretrorepvec and 5-fluorocytosine for recurrent high-grade glioma. Sci. Transl. Med. 8, 341ra75.
10. Alkayyal, A.A., Tai, L.-H., Kennedy, M.A., de Souza, C.T., Zhang, J., Lefebvre, C., Sahi, S., Ananth, A.A., Mahmoud, A.B., Makrigiannis, A.P., et al. (2017). NK-Cell Recruitment Is Necessary for Eradication of Peritoneal Carcinomatosis with an IL12-
17. Peters, C., Nigim, F., Chiocca, E.A., and Rabkin, S.D. (2016). Oncolytic viruses on the cusp of success?: proceedings of the 9th International Conference on Oncolytic Virus Therapeutics. Mol. Ther. Oncolytics 3, 16016.
Molecular Therapy: Oncolytics Vol. 7 December 2017