- Email: [email protected]
Eradication of disseminated adenovirus infection in a pediatric hematopoietic stem cell transplantation recipient using the novel antiviral agent CMX001
Journal of Clinical Virology 50 (2011) 167–170
Contents lists available at ScienceDirect
Journal of Clinical Virology journal homepage: www.elsevier.com/locate/jcv
Case Report
Eradication of disseminated adenovirus infection in a pediatric hematopoietic stem cell transplantation recipient using the novel antiviral agent CMX001 Kris Paolino a , Jane Sande b , Evelio Perez b , Brett Loechelt b , Barbara Jantausch c , Wendy Painter d , Margaret Anderson d , Tim Tippin d , E. Randall Lanier d , Terry Fry b , Roberta L. DeBiasi c,e,∗ a
Department of Infectious Diseases, Walter Reed Army Medical Center, Washington, DC, United States Division of Blood and Marrow Transplantation, Children’s National Medical Center, Washington, DC, United States Division of Infectious Diseases, Children’s National Medical Center, Washington, DC, United States d Chimerix, Inc., Durham, NC, United States e Department of Pediatrics, George Washington University School of Medicine, Washington, DC, United States b c
a r t i c l e
i n f o
Article history: Received 22 July 2010 Received in revised form 14 October 2010 Accepted 14 October 2010 Keywords: Adenovirus Stem-cell transplantation Antiviral therapy
a b s t r a c t Adenovirus infection is a serious and often fatal complication in hematopoietic stem cell transplant patients. There are currently no FDA-approved therapies for adenovirus infection, with only anecdotal, off-label uses described for a variety of anti-viral agents or immune therapies. We report the first case of successful eradication of disseminated adenovirus infection by the novel antiviral agent CMX001 in a severely immunocompromised pediatric stem cell transplant recipient following failure to respond to intravenous cidofovir. Complete clinical and virologic response was documented; virologic and pharmacokinetic data are reported. CMX001 is a promising new oral antiviral agent under development for the prophylaxis and treatment of severe infections caused by double-stranded DNA viruses including adenovirus in immunocompromised patients. © 2010 Elsevier B.V. All rights reserved.
1. Why this case is important We report the first case of successful eradication of disseminated adenovirus infection by the novel antiviral agent CMX001 in a severely immunocompromised pediatric stem cell transplant recipient following failure to respond to intravenous cidofovir. Infections are a major cause of morbidity and mortality following hematopoietic stem cell transplantation (HSCT). Due to the expansion of available agents to treat bacterial and fungal infection as well as changes in the approach to HSCT such as the use of lymphocyte-targeted conditioning,1 umbilical cord blood as a stem cell source2 and T cell depleted allografts, viral infections have emerged as one of the major challenges in the field. Management of cytomegalovirus (CMV) reactivation using high-sensitivity monitoring with PCR and prophylactic use of effective antiviral agents has reduced the incidence of CMV disease.3 However, other viral pathogens such as adenovirus remain a major cause of morbidity and mortality, in part, due to lack of effective agents.4 Although
Abbreviations: AdV, adenovirus; CMV, cytomegalovirus; HSCT, hematopoietic stem cell transplantation; GvHD, graft-versus-host disease. ∗ Corresponding author at: George Washington University School of Medicine, Children’s National Medical Center, 111 Michigan Avenue NW, WW 3.5, Washington, DC 20010, United States. Tel.: +1 202 476 5052; fax: +1 202 476 3850; mobile: +1 202 329 9629. E-mail address: [email protected] (R.L. DeBiasi). 1386-6532/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jcv.2010.10.016
intravenous cidofovir is used to treat adenovirus infection, it has limited clinical utility due to its potential to cause nephrotoxicity. CMX001 (manufactured by Chimerix, Inc.) is an orally bioavailable lipid-conjugate of the nucleotide analog, cidofovir.5 The lipid conjugate allows oral administration and enables rapid uptake of CMX001 into cells where it is cleaved and the resulting cidofovir is phosphorylated to the active antiviral agent. CMX001 has a broad spectrum of activity, effective against all 5 families of double-stranded DNA viruses including orthopoxviruses (variola, monkeypox, vaccinia, cowpox, and ectromelia viruses), herpesviruses (cytomegalovirus, herpes simplex-1 and -2 viruses, varicella zoster virus, Epstein-Barr virus, and human herpes-6 and -8 viruses), adenoviruses (AdV), polyomaviruses (BK and JC virus), and papilloma viruses. The antiviral activity of CMX001 against adenovirus has been characterized in vitro in cell culture systems and in vivo in animal models. In vitro studies demonstrated that CMX001 is effective against multiple serotypes of adenovirus (AdV types 3, 5, 7, 8, and 31).6 The median EC50 was 0.02 M (range < 0.009–0.28 M) for CMX001 compared to 1.3 M (range 0.50–2.0 M) for cidofovir, a 65-fold increase in potency for CMX001 as compared to cidofovir for the median isolate (AdV 7).6 The patient described herein had an AdV 2 infection determined by hexon gene sequencing; the patient’s AdV 2 isolate EC50 was <0.03 M for CMX001. In vivo, CMX001 was highly effective against adenovirus in an immunocompromised, AdV 5 Syrian Hamster model characterized by severe systemic disease with hep-
168
K. Paolino et al. / Journal of Clinical Virology 50 (2011) 167–170
atic necrosis.7 CMX001 (2.5 mg/kg/d) prevented mortality in AdV 5-infected hamsters when administered two days post-infection. Infectious AdV 5 titers in liver were reduced 6 log10 to nearly undetectable levels in most animals by seven days post infection. 1.1. Case description A 12-year old girl with severe aplastic anemia received a 9/10 HLA matched (allele mismatch at B) allogeneic bone marrow transplantation following alemtuzumab/fludarabine/melphalan conditioning. Despite prophylaxis with cyclosporine A, methotrexate and anti-thymocyte globulin she developed grade 4 graft-versus-host disease (GvHD) of the intestine and skin that was refractory to high-dose steroids and monoclonal antibodies. She subsequently received mesenchymal stem cells on a compassionate use experimental protocol with gradual improvement, such that she tolerated enteral feeding. She developed recurrent diarrhea in association with rising quantitative plasma adenovirus DNA PCR (first detected day +89 post-transplant). Quantitative PCR (Viracor) was performed using a validated multiplex quantitative real-time PCR assay and Taqman chemistry with an Applied Biosystems 7500 Fast machine. Colonic biopsies and stool cultures confirmed adenovirus enteritis, with pulmonary specimens also culture positive later in the disease course. Despite taper of immunosuppression (tacrolimus, mycophenolate, and prednisone) and treatment with IV cidofovir 1 mg/kg 3 times weekly (days +92 to +131 post-transplant), plasma adenoviremia increased to 680 million copies/ml. Her clinical condition deteriorated with severe gastrointestinal (GI) bleeding, hepatitis and, eventually respiratory failure (day +132 post-transplant) despite increasing cidofovir to 5 mg/kg once weekly (day +132 post-transplant) and administration of intravenous immune globulin (day +129 post-transplant). Her renal function deteriorated while receiving intravenous cidofovir, eventually necessitating veno-venous hemodialysis. Given the extremely poor prognosis for disseminated adenovirus infection in this setting, CMX001 was administered (beginning day +133 post-transplant) under an FDA-approved Emergency Investigational New Drug Application following IRB approval and appropriate informed consent by the parent. At the time of treatment with CMX001, the patient was intubated and sedated, had metabolic acidosis, and renal insufficiency with creatinine levels between 1.6 and 1.9. The patient had unremitting gastrointestinal bleeding requiring daily transfusions of packed RBCs and platelets. CMX001 was started at a dose of 2 mg/kg twice weekly with a prompt and continued reduction in plasma adenovirus load noted following initiation of therapy (Fig. 1). Within the first 5 weeks of CMX001 therapy, transfusion requirements dramatically decreased, renal function and hepatic function improved and the patient was extubated (day +175 post-transplant), with an undetectable viral load (day +159 post-transplant). Within 8 weeks, hemodialysis was discontinued; the patient was transferred from the ICU with resolution of GI bleeding and renal impairment. The patient had persistent absolute lymphocyte counts (ALC) less than 300 throughout the treatment course. Serial analysis of viral load demonstrated consistent marked reductions while on therapy (Fig. 1), despite the fact that the ALC remained well below normal limits. There was subsequent recovery of ALC after the viral load had decreased to near undetectable. Following resolution of AdV viremia and clinical signs and symptoms of disease, the patient was maintained on CMX001 at a dose of 3 mg/kg weekly. CMX001 was well tolerated and no drug-related serious adverse events were observed. 1.2. CMX001 administration and pharmacokinetics The patient initially required continuous nasogastric (NG) suctioning due to severe GI bleeding, thus CMX001 was administered
Fig. 1. Plasma adenovirus levels prior to (day +132 post-transplant) and during (day +133) treatment with CMX001. Adenovirus was first detected day +89 post-transplant, with continued rise in adenovirus load despite administration of intravenous cidofovir days +92 to +132 post-transplant and IVIG (day +129 posttransplant). Treatment with CMX001 was initiated on day +133 post-transplant at 2 mg/kg administered twice weekly increasing to 3 mg/kg after the 6th dose. After the virus became undetectable (<102 ) (day +159 post-transplant), administration of CMX001 continued at 3 mg/kg but the schedule was reduced to once weekly for maintenance. The inset shows patient’s dose normalized maximum plasma concentrations, [Cmax , ng/mL/dose (mg/kg)] and systemic exposure [AUC0inf, h*ng/mL/dose (mg/kg)] of CMX001 after the 1st, 10th and 20th doses (first three bars) in comparison to adult healthy volunteers (HVT) administered a single dose (fourth bar). Arrows indicate timing of 1st, 10th and 20th CMX001 doses.
via NG tube with interruption of suctioning for as long as tolerated (generally 1–3 h). Plasma samples were obtained at regular intervals throughout her treatment course for analysis of CMX001 and cidofovir concentrations using a validated analytical method (LC/MS/MS). AdV viremia resolved despite lower than predicted plasma exposure to CMX001 during the first 5 weeks of treatment (through approximately the 10th dose) (Fig. 1, inset). For example, after the 1st CMX001 administration (2 mg/kg), the CMX001 plasma Cmax was 49 ng/mL (dose normalized Cmax 24.5, depicted in Fig. 1, inset), and the area under the plasma concentration versus time curve (AUC0-inf) was 1469 h*ng/mL (dose normalized AUC0-inf 734.5, depicted in Fig. 1, inset). The potential impact of the patients GI bleeding and use of NG suctioning on absorption, and ultimately systemic exposure to CMX001 are uncertain but likely decreased exposure, because as the patient’s GI bleeding resolved, higher systemic exposures to CMX001 were observed. For example, after the 20th CMX001 administration (3 mg/kg), the CMX001 plasma Cmax was 180 ng/mL (dose normalized Cmax 60, depicted in Fig. 1, inset), and AUC0-inf was 5022 h*ng/mL (dose normalized AUC0-inf 1674, depicted in Fig. 1, inset). The CMX001 parameters measured in this patient compare to a mean plasma Cmax of 350 ng/mL (dose normalized Cmax 175, depicted in Fig. 1, inset), and an AUC0-inf of 2650 h*ng/mL (dose normalized AUC0-inf 1325, depicted in Fig. 1, inset) observed in healthy adult volunteers receiving CMX001 (2 mg/kg). As expected, the cidofovir plasma concentrations following oral administration of CMX001 were much lower compared to CMX001, except after the first administration of CMX001, which closely followed the last administration of intravenous cidofovir (5 mg/kg, administered the day prior to initiation of CMX001 treatment). For
K. Paolino et al. / Journal of Clinical Virology 50 (2011) 167–170
example, cidofovir Cmax observed in this patient following the 1st and 20th administration of CMX001 were 163 ng/mL (T = 0, prior to CMX001 administration), and 57 ng/mL, respectively. These values compare to a mean cidofovir Cmax of 31 ng/mL measured in healthy adult volunteers receiving 2 mg/kg CMX001. 2. Discussion Disseminated adenovirus is a serious and often fatal complication of HSCT. Clinical manifestations include respiratory disease, hepatitis, nephritis, cystitis, gastrointestinal disease including hemorrhagic colitis and enteritis, encephalitis, and multiorgan failure. Risk factors for disease include young age, allogeneic transplantation, T cell depleting conditioning regimens, unrelated or HLA-mismatched grafts, lymphocytopenia, and GvHD.8,9 The expected mortality rate in patients with disseminated adenovirus disease is up to 80% depending on the organ system involved.8 There are currently no FDA-approved therapies for adenovirus infection, with only anecdotal, off-label uses described for a variety of anti-viral agents or immune therapies such as IVIG or donorlymphocyte infusion. While intravenous cidofovir is often used in this setting,10,11 efficacy has not been well established due to virulence of the virus, variable pharmacokinetics/dynamics, and unavoidable toxicities of prolonged cidofovir therapy. Thus, new agents to treat adenovirus following HSCT are clearly needed. Furthermore, the availability of high-sensitivity PCR-based monitoring offers the opportunity to monitor and potentially prevent disseminated adenovirus infection utilizing pre-emptive therapeutic approaches. As is the case with CMV infection in this patient population, pre-emptive therapy is likely to be more practical as less toxic, more effective, orally administered agents are identified.12,13 Our extremely high-risk patient exhibited complete response to treatment with CMX001, in combination with mesenchymal stem cell infusion, despite continued immunosuppression. Oral administration of CMX001 was achieved despite the presence of severe GI dysfunction due to graft-versus-host disease and biopsy proven viral infection of the colon. Plasma analysis demonstrated, initially, lower than expected concentrations of CMX001 presumably due to extensive GI disease, however, a complete virologic and clinical response was observed and plasma concentrations increased as the GI disease resolved. Concentrations of CMX001 achieved in plasma (e.g., an actual Cmax of 96 ng/ml or 0.17 M after the 10th dose) substantially exceeded the EC50 of the patient’s isolate (<0.03 M). However, calculation of inhibitory quotients, often expressed as plasma exposure over viral susceptibility, is inherently misleading for drugs in which the drug in plasma is an inactive precursor to an active intracellular drug. In the case of CMX001, the plasma species (CMX001) is relatively short-lived while the active intracellular antiviral (CDV-PP) has a half life of approximately a week.14 Also notable in this patient was an improvement in renal function while receiving treatment with CMX001, consistent with animal and human data that have revealed no evidence of nephrotoxicity.5 This is likely due to lower peak plasma concentrations of cidofovir observed following administration of CMX001 compared with intravenous cidofovir and that CMX001 per se is not a substrate for the human organic anion transporters which actively secrete cidofovir into the kidneys.15 In this patient, peak plasma cidofovir concentrations (using CMX001) were more than 100-fold lower than those reported for administration of 5 mg/kg intravenous cidofovir. CMX001 was designed to deliver cidofovir to the intracellular compartment where viral replication occurs, not to the plasma from where cidofovir is actively secreted into the renal proximal tubule cells, leading to kidney toxicity. Hence low plasma concentrations of cidofovir are a desirable trait of CMX001 that reduces the potential for nephrotoxicity with no relevance to efficacy.
169
In summary, CMX001 is a promising new oral antiviral agent under development for the prophylaxis and treatment of a number of severe infections caused by double-stranded DNA viruses, including adenovirus in immunocompromised patients including HSCT recipients. Although we present a single case report, further studies are warranted to evaluate the use of CMX001 in this patient population from the perspectives of potential improved efficacy, increased oral bioavailability, and decreased toxicity compared to current antiviral therapy. Conflict of interest None. Funding None. Ethical approval Not required. Acknowledgements CMX001 pharmacokinetic/virologic analyses were provided by Chimerix, Inc., Durham, NC. Chimerix assisted in protocol development/conduct, and manuscript preparation. W. Painter, M. Anderson, T. Tippin and R. Lanier are employed by Chimerix, Inc. References 1. Myers GD, Krance RA, Weiss H, Kuehnle I, Demmler G, Heslop HE, et al. Adenovirus infection rates in pediatric recipients of alternate donor allogeneic bone marrow transplants receiving either antithymocyte globulin (ATG) or alemtuzumab (Campath). Bone Marrow Transplant 2005;36: 1001–8. 2. Vandenbosch K, Ovetchkine P, Champagne MA, Haddad E, Alexandrov L, Duval M. Varicella-zoster virus disease is more frequent after cord blood than after bone marrow transplantation. Biol Blood Marrow Transplant 2008;14: 867–71. 3. Boeckh M, Ljungman P. How we treat cytomegalovirus in hematopoietic cell transplant recipients. Blood 2009;113:5711–9. 4. Zaia J, Baden L, Boeckh MJ, Chakrabarti S, Einsele H, Ljungman P, et al. Viral disease prevention after hematopoietic cell transplantation. Bone Marrow Transplant 2009;44:471–82. 5. Painter GR, Trost LC, Lampert BM, Almond MR, Buller M, Kern E, et al. CMX001. Anti-smallpox agent, anti-cytomegalovirus agent, viral polymerase inhibitor. Drugs Fut 2008;33:655. 6. Hartline CB, Gustin KM, Wan WB, Ciesla SL, Beadle JR, Hostetler KY, et al. Ether lipid–ester prodrugs of acyclic nucleoside phosphonates: activity against adenovirus replication in vitro. JID 2005;191:396–9. 7. Toth K, Spencer JF, Dhar D, Sagartz JE, Buller RM, Painter GR, et al. Hexadecyloxypropyl-cidofovir, CMX001, prevents adenovirus-induced mortality in a permissive, immunosuppressed animal model. Proc Natl Acad Sci USA 2008;105:7293–7. 8. La Rosa AM, Champlin RE, Mirza N, Gajewski J, Giralt S, Rolston KV, et al. Adenovirus infections in adult recipients of blood and marrow transplants. Clin Infect Dis 2001;32:871–6. 9. Williams KM, Agwu AL, Dabb AA, Higman MA, Loeb DM, Valsamakis A, et al. A clinical algorithm identifies high risk pediatric oncology and bone marrow transplant patients likely to benefit from treatment of adenoviral infection. J Pediatr Hematol Oncol 2009;31:825–31. 10. Neofytos D, Ojha A, Mookerjee B, Wagner J, Filicko J, Ferber A, et al. Treatment of adenovirus disease in stem cell transplant recipients with cidofovir. Biol Blood Marrow Transplant 2007;13:74–81. 11. Bordigoni P, Carret AS, Venard V, Witz F, Le Faou A. Treatment of adenovirus infections in patients undergoing allogeneic hematopoietic stem cell transplantation. Clin Infect Dis 2001;32:1290–7. 12. Paczesny S, Salmon A, Clement L, Venard V, Bordigoni P. Prompt versus preemptive intervention with cidofovir for adenovirus diseases after allogeneic stem cell transplantation: impact on survival in a single center experience of 25 patients. J Pediatr Hematol Oncol 2005;27:457. 13. Kampmann B, Cubitt D, Walls T, Naik P, Depala M, Samarasinghe S, et al. Improved outcome for children with disseminated adenoviral infection following allogeneic stem cell transplantation. Br J Haematol 2005;130: 595–603.
170
K. Paolino et al. / Journal of Clinical Virology 50 (2011) 167–170
14. Aldern KA, Ciesla SL, Winegarden KL, Hostetler KY. Increased antiviral activity of 1-O-hexadecyloxypropyl-[2-(14)C]cidofovir in MRC-5 human lung fibroblasts is explained by unique cellular uptake and metabolism. Mol Pharmacol 2003;63:678–81.
15. Tippin TK, Lampert BM, Painter GR, Lanier ER. Lipid conjugates of cidofovir and tenofovir, CMX001 and CMX157, are not substrates of human organic anion transporters OAT1 and OAT3. In: The American Association of Pharmaceutical Scientists Annual Meeting. 2010.
Contents lists available at ScienceDirect
Journal of Clinical Virology journal homepage: www.elsevier.com/locate/jcv
Case Report
Eradication of disseminated adenovirus infection in a pediatric hematopoietic stem cell transplantation recipient using the novel antiviral agent CMX001 Kris Paolino a , Jane Sande b , Evelio Perez b , Brett Loechelt b , Barbara Jantausch c , Wendy Painter d , Margaret Anderson d , Tim Tippin d , E. Randall Lanier d , Terry Fry b , Roberta L. DeBiasi c,e,∗ a
Department of Infectious Diseases, Walter Reed Army Medical Center, Washington, DC, United States Division of Blood and Marrow Transplantation, Children’s National Medical Center, Washington, DC, United States Division of Infectious Diseases, Children’s National Medical Center, Washington, DC, United States d Chimerix, Inc., Durham, NC, United States e Department of Pediatrics, George Washington University School of Medicine, Washington, DC, United States b c
a r t i c l e
i n f o
Article history: Received 22 July 2010 Received in revised form 14 October 2010 Accepted 14 October 2010 Keywords: Adenovirus Stem-cell transplantation Antiviral therapy
a b s t r a c t Adenovirus infection is a serious and often fatal complication in hematopoietic stem cell transplant patients. There are currently no FDA-approved therapies for adenovirus infection, with only anecdotal, off-label uses described for a variety of anti-viral agents or immune therapies. We report the first case of successful eradication of disseminated adenovirus infection by the novel antiviral agent CMX001 in a severely immunocompromised pediatric stem cell transplant recipient following failure to respond to intravenous cidofovir. Complete clinical and virologic response was documented; virologic and pharmacokinetic data are reported. CMX001 is a promising new oral antiviral agent under development for the prophylaxis and treatment of severe infections caused by double-stranded DNA viruses including adenovirus in immunocompromised patients. © 2010 Elsevier B.V. All rights reserved.
1. Why this case is important We report the first case of successful eradication of disseminated adenovirus infection by the novel antiviral agent CMX001 in a severely immunocompromised pediatric stem cell transplant recipient following failure to respond to intravenous cidofovir. Infections are a major cause of morbidity and mortality following hematopoietic stem cell transplantation (HSCT). Due to the expansion of available agents to treat bacterial and fungal infection as well as changes in the approach to HSCT such as the use of lymphocyte-targeted conditioning,1 umbilical cord blood as a stem cell source2 and T cell depleted allografts, viral infections have emerged as one of the major challenges in the field. Management of cytomegalovirus (CMV) reactivation using high-sensitivity monitoring with PCR and prophylactic use of effective antiviral agents has reduced the incidence of CMV disease.3 However, other viral pathogens such as adenovirus remain a major cause of morbidity and mortality, in part, due to lack of effective agents.4 Although
Abbreviations: AdV, adenovirus; CMV, cytomegalovirus; HSCT, hematopoietic stem cell transplantation; GvHD, graft-versus-host disease. ∗ Corresponding author at: George Washington University School of Medicine, Children’s National Medical Center, 111 Michigan Avenue NW, WW 3.5, Washington, DC 20010, United States. Tel.: +1 202 476 5052; fax: +1 202 476 3850; mobile: +1 202 329 9629. E-mail address: [email protected] (R.L. DeBiasi). 1386-6532/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jcv.2010.10.016
intravenous cidofovir is used to treat adenovirus infection, it has limited clinical utility due to its potential to cause nephrotoxicity. CMX001 (manufactured by Chimerix, Inc.) is an orally bioavailable lipid-conjugate of the nucleotide analog, cidofovir.5 The lipid conjugate allows oral administration and enables rapid uptake of CMX001 into cells where it is cleaved and the resulting cidofovir is phosphorylated to the active antiviral agent. CMX001 has a broad spectrum of activity, effective against all 5 families of double-stranded DNA viruses including orthopoxviruses (variola, monkeypox, vaccinia, cowpox, and ectromelia viruses), herpesviruses (cytomegalovirus, herpes simplex-1 and -2 viruses, varicella zoster virus, Epstein-Barr virus, and human herpes-6 and -8 viruses), adenoviruses (AdV), polyomaviruses (BK and JC virus), and papilloma viruses. The antiviral activity of CMX001 against adenovirus has been characterized in vitro in cell culture systems and in vivo in animal models. In vitro studies demonstrated that CMX001 is effective against multiple serotypes of adenovirus (AdV types 3, 5, 7, 8, and 31).6 The median EC50 was 0.02 M (range < 0.009–0.28 M) for CMX001 compared to 1.3 M (range 0.50–2.0 M) for cidofovir, a 65-fold increase in potency for CMX001 as compared to cidofovir for the median isolate (AdV 7).6 The patient described herein had an AdV 2 infection determined by hexon gene sequencing; the patient’s AdV 2 isolate EC50 was <0.03 M for CMX001. In vivo, CMX001 was highly effective against adenovirus in an immunocompromised, AdV 5 Syrian Hamster model characterized by severe systemic disease with hep-
168
K. Paolino et al. / Journal of Clinical Virology 50 (2011) 167–170
atic necrosis.7 CMX001 (2.5 mg/kg/d) prevented mortality in AdV 5-infected hamsters when administered two days post-infection. Infectious AdV 5 titers in liver were reduced 6 log10 to nearly undetectable levels in most animals by seven days post infection. 1.1. Case description A 12-year old girl with severe aplastic anemia received a 9/10 HLA matched (allele mismatch at B) allogeneic bone marrow transplantation following alemtuzumab/fludarabine/melphalan conditioning. Despite prophylaxis with cyclosporine A, methotrexate and anti-thymocyte globulin she developed grade 4 graft-versus-host disease (GvHD) of the intestine and skin that was refractory to high-dose steroids and monoclonal antibodies. She subsequently received mesenchymal stem cells on a compassionate use experimental protocol with gradual improvement, such that she tolerated enteral feeding. She developed recurrent diarrhea in association with rising quantitative plasma adenovirus DNA PCR (first detected day +89 post-transplant). Quantitative PCR (Viracor) was performed using a validated multiplex quantitative real-time PCR assay and Taqman chemistry with an Applied Biosystems 7500 Fast machine. Colonic biopsies and stool cultures confirmed adenovirus enteritis, with pulmonary specimens also culture positive later in the disease course. Despite taper of immunosuppression (tacrolimus, mycophenolate, and prednisone) and treatment with IV cidofovir 1 mg/kg 3 times weekly (days +92 to +131 post-transplant), plasma adenoviremia increased to 680 million copies/ml. Her clinical condition deteriorated with severe gastrointestinal (GI) bleeding, hepatitis and, eventually respiratory failure (day +132 post-transplant) despite increasing cidofovir to 5 mg/kg once weekly (day +132 post-transplant) and administration of intravenous immune globulin (day +129 post-transplant). Her renal function deteriorated while receiving intravenous cidofovir, eventually necessitating veno-venous hemodialysis. Given the extremely poor prognosis for disseminated adenovirus infection in this setting, CMX001 was administered (beginning day +133 post-transplant) under an FDA-approved Emergency Investigational New Drug Application following IRB approval and appropriate informed consent by the parent. At the time of treatment with CMX001, the patient was intubated and sedated, had metabolic acidosis, and renal insufficiency with creatinine levels between 1.6 and 1.9. The patient had unremitting gastrointestinal bleeding requiring daily transfusions of packed RBCs and platelets. CMX001 was started at a dose of 2 mg/kg twice weekly with a prompt and continued reduction in plasma adenovirus load noted following initiation of therapy (Fig. 1). Within the first 5 weeks of CMX001 therapy, transfusion requirements dramatically decreased, renal function and hepatic function improved and the patient was extubated (day +175 post-transplant), with an undetectable viral load (day +159 post-transplant). Within 8 weeks, hemodialysis was discontinued; the patient was transferred from the ICU with resolution of GI bleeding and renal impairment. The patient had persistent absolute lymphocyte counts (ALC) less than 300 throughout the treatment course. Serial analysis of viral load demonstrated consistent marked reductions while on therapy (Fig. 1), despite the fact that the ALC remained well below normal limits. There was subsequent recovery of ALC after the viral load had decreased to near undetectable. Following resolution of AdV viremia and clinical signs and symptoms of disease, the patient was maintained on CMX001 at a dose of 3 mg/kg weekly. CMX001 was well tolerated and no drug-related serious adverse events were observed. 1.2. CMX001 administration and pharmacokinetics The patient initially required continuous nasogastric (NG) suctioning due to severe GI bleeding, thus CMX001 was administered
Fig. 1. Plasma adenovirus levels prior to (day +132 post-transplant) and during (day +133) treatment with CMX001. Adenovirus was first detected day +89 post-transplant, with continued rise in adenovirus load despite administration of intravenous cidofovir days +92 to +132 post-transplant and IVIG (day +129 posttransplant). Treatment with CMX001 was initiated on day +133 post-transplant at 2 mg/kg administered twice weekly increasing to 3 mg/kg after the 6th dose. After the virus became undetectable (<102 ) (day +159 post-transplant), administration of CMX001 continued at 3 mg/kg but the schedule was reduced to once weekly for maintenance. The inset shows patient’s dose normalized maximum plasma concentrations, [Cmax , ng/mL/dose (mg/kg)] and systemic exposure [AUC0inf, h*ng/mL/dose (mg/kg)] of CMX001 after the 1st, 10th and 20th doses (first three bars) in comparison to adult healthy volunteers (HVT) administered a single dose (fourth bar). Arrows indicate timing of 1st, 10th and 20th CMX001 doses.
via NG tube with interruption of suctioning for as long as tolerated (generally 1–3 h). Plasma samples were obtained at regular intervals throughout her treatment course for analysis of CMX001 and cidofovir concentrations using a validated analytical method (LC/MS/MS). AdV viremia resolved despite lower than predicted plasma exposure to CMX001 during the first 5 weeks of treatment (through approximately the 10th dose) (Fig. 1, inset). For example, after the 1st CMX001 administration (2 mg/kg), the CMX001 plasma Cmax was 49 ng/mL (dose normalized Cmax 24.5, depicted in Fig. 1, inset), and the area under the plasma concentration versus time curve (AUC0-inf) was 1469 h*ng/mL (dose normalized AUC0-inf 734.5, depicted in Fig. 1, inset). The potential impact of the patients GI bleeding and use of NG suctioning on absorption, and ultimately systemic exposure to CMX001 are uncertain but likely decreased exposure, because as the patient’s GI bleeding resolved, higher systemic exposures to CMX001 were observed. For example, after the 20th CMX001 administration (3 mg/kg), the CMX001 plasma Cmax was 180 ng/mL (dose normalized Cmax 60, depicted in Fig. 1, inset), and AUC0-inf was 5022 h*ng/mL (dose normalized AUC0-inf 1674, depicted in Fig. 1, inset). The CMX001 parameters measured in this patient compare to a mean plasma Cmax of 350 ng/mL (dose normalized Cmax 175, depicted in Fig. 1, inset), and an AUC0-inf of 2650 h*ng/mL (dose normalized AUC0-inf 1325, depicted in Fig. 1, inset) observed in healthy adult volunteers receiving CMX001 (2 mg/kg). As expected, the cidofovir plasma concentrations following oral administration of CMX001 were much lower compared to CMX001, except after the first administration of CMX001, which closely followed the last administration of intravenous cidofovir (5 mg/kg, administered the day prior to initiation of CMX001 treatment). For
K. Paolino et al. / Journal of Clinical Virology 50 (2011) 167–170
example, cidofovir Cmax observed in this patient following the 1st and 20th administration of CMX001 were 163 ng/mL (T = 0, prior to CMX001 administration), and 57 ng/mL, respectively. These values compare to a mean cidofovir Cmax of 31 ng/mL measured in healthy adult volunteers receiving 2 mg/kg CMX001. 2. Discussion Disseminated adenovirus is a serious and often fatal complication of HSCT. Clinical manifestations include respiratory disease, hepatitis, nephritis, cystitis, gastrointestinal disease including hemorrhagic colitis and enteritis, encephalitis, and multiorgan failure. Risk factors for disease include young age, allogeneic transplantation, T cell depleting conditioning regimens, unrelated or HLA-mismatched grafts, lymphocytopenia, and GvHD.8,9 The expected mortality rate in patients with disseminated adenovirus disease is up to 80% depending on the organ system involved.8 There are currently no FDA-approved therapies for adenovirus infection, with only anecdotal, off-label uses described for a variety of anti-viral agents or immune therapies such as IVIG or donorlymphocyte infusion. While intravenous cidofovir is often used in this setting,10,11 efficacy has not been well established due to virulence of the virus, variable pharmacokinetics/dynamics, and unavoidable toxicities of prolonged cidofovir therapy. Thus, new agents to treat adenovirus following HSCT are clearly needed. Furthermore, the availability of high-sensitivity PCR-based monitoring offers the opportunity to monitor and potentially prevent disseminated adenovirus infection utilizing pre-emptive therapeutic approaches. As is the case with CMV infection in this patient population, pre-emptive therapy is likely to be more practical as less toxic, more effective, orally administered agents are identified.12,13 Our extremely high-risk patient exhibited complete response to treatment with CMX001, in combination with mesenchymal stem cell infusion, despite continued immunosuppression. Oral administration of CMX001 was achieved despite the presence of severe GI dysfunction due to graft-versus-host disease and biopsy proven viral infection of the colon. Plasma analysis demonstrated, initially, lower than expected concentrations of CMX001 presumably due to extensive GI disease, however, a complete virologic and clinical response was observed and plasma concentrations increased as the GI disease resolved. Concentrations of CMX001 achieved in plasma (e.g., an actual Cmax of 96 ng/ml or 0.17 M after the 10th dose) substantially exceeded the EC50 of the patient’s isolate (<0.03 M). However, calculation of inhibitory quotients, often expressed as plasma exposure over viral susceptibility, is inherently misleading for drugs in which the drug in plasma is an inactive precursor to an active intracellular drug. In the case of CMX001, the plasma species (CMX001) is relatively short-lived while the active intracellular antiviral (CDV-PP) has a half life of approximately a week.14 Also notable in this patient was an improvement in renal function while receiving treatment with CMX001, consistent with animal and human data that have revealed no evidence of nephrotoxicity.5 This is likely due to lower peak plasma concentrations of cidofovir observed following administration of CMX001 compared with intravenous cidofovir and that CMX001 per se is not a substrate for the human organic anion transporters which actively secrete cidofovir into the kidneys.15 In this patient, peak plasma cidofovir concentrations (using CMX001) were more than 100-fold lower than those reported for administration of 5 mg/kg intravenous cidofovir. CMX001 was designed to deliver cidofovir to the intracellular compartment where viral replication occurs, not to the plasma from where cidofovir is actively secreted into the renal proximal tubule cells, leading to kidney toxicity. Hence low plasma concentrations of cidofovir are a desirable trait of CMX001 that reduces the potential for nephrotoxicity with no relevance to efficacy.
169
In summary, CMX001 is a promising new oral antiviral agent under development for the prophylaxis and treatment of a number of severe infections caused by double-stranded DNA viruses, including adenovirus in immunocompromised patients including HSCT recipients. Although we present a single case report, further studies are warranted to evaluate the use of CMX001 in this patient population from the perspectives of potential improved efficacy, increased oral bioavailability, and decreased toxicity compared to current antiviral therapy. Conflict of interest None. Funding None. Ethical approval Not required. Acknowledgements CMX001 pharmacokinetic/virologic analyses were provided by Chimerix, Inc., Durham, NC. Chimerix assisted in protocol development/conduct, and manuscript preparation. W. Painter, M. Anderson, T. Tippin and R. Lanier are employed by Chimerix, Inc. References 1. Myers GD, Krance RA, Weiss H, Kuehnle I, Demmler G, Heslop HE, et al. Adenovirus infection rates in pediatric recipients of alternate donor allogeneic bone marrow transplants receiving either antithymocyte globulin (ATG) or alemtuzumab (Campath). Bone Marrow Transplant 2005;36: 1001–8. 2. Vandenbosch K, Ovetchkine P, Champagne MA, Haddad E, Alexandrov L, Duval M. Varicella-zoster virus disease is more frequent after cord blood than after bone marrow transplantation. Biol Blood Marrow Transplant 2008;14: 867–71. 3. Boeckh M, Ljungman P. How we treat cytomegalovirus in hematopoietic cell transplant recipients. Blood 2009;113:5711–9. 4. Zaia J, Baden L, Boeckh MJ, Chakrabarti S, Einsele H, Ljungman P, et al. Viral disease prevention after hematopoietic cell transplantation. Bone Marrow Transplant 2009;44:471–82. 5. Painter GR, Trost LC, Lampert BM, Almond MR, Buller M, Kern E, et al. CMX001. Anti-smallpox agent, anti-cytomegalovirus agent, viral polymerase inhibitor. Drugs Fut 2008;33:655. 6. Hartline CB, Gustin KM, Wan WB, Ciesla SL, Beadle JR, Hostetler KY, et al. Ether lipid–ester prodrugs of acyclic nucleoside phosphonates: activity against adenovirus replication in vitro. JID 2005;191:396–9. 7. Toth K, Spencer JF, Dhar D, Sagartz JE, Buller RM, Painter GR, et al. Hexadecyloxypropyl-cidofovir, CMX001, prevents adenovirus-induced mortality in a permissive, immunosuppressed animal model. Proc Natl Acad Sci USA 2008;105:7293–7. 8. La Rosa AM, Champlin RE, Mirza N, Gajewski J, Giralt S, Rolston KV, et al. Adenovirus infections in adult recipients of blood and marrow transplants. Clin Infect Dis 2001;32:871–6. 9. Williams KM, Agwu AL, Dabb AA, Higman MA, Loeb DM, Valsamakis A, et al. A clinical algorithm identifies high risk pediatric oncology and bone marrow transplant patients likely to benefit from treatment of adenoviral infection. J Pediatr Hematol Oncol 2009;31:825–31. 10. Neofytos D, Ojha A, Mookerjee B, Wagner J, Filicko J, Ferber A, et al. Treatment of adenovirus disease in stem cell transplant recipients with cidofovir. Biol Blood Marrow Transplant 2007;13:74–81. 11. Bordigoni P, Carret AS, Venard V, Witz F, Le Faou A. Treatment of adenovirus infections in patients undergoing allogeneic hematopoietic stem cell transplantation. Clin Infect Dis 2001;32:1290–7. 12. Paczesny S, Salmon A, Clement L, Venard V, Bordigoni P. Prompt versus preemptive intervention with cidofovir for adenovirus diseases after allogeneic stem cell transplantation: impact on survival in a single center experience of 25 patients. J Pediatr Hematol Oncol 2005;27:457. 13. Kampmann B, Cubitt D, Walls T, Naik P, Depala M, Samarasinghe S, et al. Improved outcome for children with disseminated adenoviral infection following allogeneic stem cell transplantation. Br J Haematol 2005;130: 595–603.
170
K. Paolino et al. / Journal of Clinical Virology 50 (2011) 167–170
14. Aldern KA, Ciesla SL, Winegarden KL, Hostetler KY. Increased antiviral activity of 1-O-hexadecyloxypropyl-[2-(14)C]cidofovir in MRC-5 human lung fibroblasts is explained by unique cellular uptake and metabolism. Mol Pharmacol 2003;63:678–81.
15. Tippin TK, Lampert BM, Painter GR, Lanier ER. Lipid conjugates of cidofovir and tenofovir, CMX001 and CMX157, are not substrates of human organic anion transporters OAT1 and OAT3. In: The American Association of Pharmaceutical Scientists Annual Meeting. 2010.