Patients seropositive for cytomegalovirus (CMV) and undergoing allogeneic haemopoietic stem-cell transplantation (HCT) are at risk for CMV reactivation. Stimulating viral immunity by vaccination ...might achieve CMV viraemia control without the need for antiviral agents. CMVPepVax is a chimeric peptide composed of a cytotoxic CD8 T-cell epitope from CMV pp65 and a tetanus T-helper epitope. It is formulated with the adjuvant PF03512676, a Toll-like receptor 9 agonist, which augments cellular immunity. We aimed to assess safety, immunogenicity, and possible clinical benefit of the CMVPepVax vaccine in patients undergoing HCT.
We did a randomised, open-label, phase 1b trial at one transplant centre in the USA. Eligible patients were CMV-seropositive, positive for HLA-A*0201, aged 18-75 years, and undergoing HCT from a matched-related or matched-unrelated donor. Patients were reassessed for eligibility on day 28 after HCT. We randomly allocated patients to either the CMVPepVax vaccine or observation, in blocks stratified by CMV donor serostatus. CMVPepVax was administered subcutaneously on days 28 and 56. The primary outcome was safety, which consisted of secondary graft failure, grade III-IV acute GVHD, non-relapse mortality by day 100, serious adverse events related to the vaccine (judged by the data and safety monitoring committee DSMC) grade 3-4 adverse events related to the vaccine (judged by the DSMC) within 2 weeks of vaccination, and development of double-strand (ds) DNA autoantibodies. Statistical analyses included all randomised patients and were done per-protocol. This study is registered with ClinicalTrials.gov, number NCT01588015. This trial is closed to accrual and the final analysis is presented in this report.
Between Oct 31, 2012, and Nov 5, 2014, 36 eligible patients were allocated to either CMVPepVax (n=18) or observation (n=18), with no adverse effect on HCT (no secondary graft failures in either group) or cases of acute GVHD (seven patients assigned vaccine and six under observation had acute GVHD of grade 2 or less), and no unexpected adverse events. Compared with observation, better relapse-free survival was recorded in patients allocated the vaccine (seven vs one; hazard ratio HR 0·12, 95% CI 0·01-0·94; p=0·015). No patients had non-relapse mortality by day 100. One serious adverse event (grade 1 fever) was attributed to CMVPepVax but resolved within 48 h. Four patients assigned the vaccine had a serious adverse event, which was unrelated to the vaccine (grade 3 thrombocytopenia, grade 3 device-related infection, grade 2 nausea, and grade 1 fever), compared with nine patients under observation (grade 4 maculopapular rash, grade 3 nausea, grade 3 infection, grade 3 thrombotic thrombocytopenic purpurea, grade 2 nausea, grade 2 generalised muscle weakness, grade 2 infection, grade 1 fever, and grade 1 fatigue; p=0·16). 54 grade 3-4 adverse events were reported in patients assigned the vaccine compared with 91 in patients who were under observation (p=0·2). No patients had grade III-IV acute GVHD or developed dsDNA autoantibodies.
The results show safety and immunogenicity of the CMVPepVax vaccine. The prospect of substantial clinical benefits warrant testing in a phase 2 trial.
National Cancer Institute.
Hematopoietic cell transplantation (HCT) and chimeric antigen receptor (CAR)-T cell patients are immunocompromised, remain at high risk following SARS-CoV-2 infection, and are less likely than ...immunocompetent individuals to respond to vaccination. As part of the safety lead-in portion of a phase 2 clinical trial in patients post HCT/CAR-T for hematological malignancies (HM), we tested the immunogenicity of the synthetic modified vaccinia Ankara-based COVID-19 vaccine COH04S1 co-expressing spike (S) and nucleocapsid (N) antigens. Thirteen patients were vaccinated 3–12 months post HCT/CAR-T with two to four doses of COH04S1. SARS-CoV-2 antigen-specific humoral and cellular immune responses, including neutralizing antibodies to ancestral virus and variants of concern (VOC), were measured up to six months post vaccination and compared to immune responses in historical cohorts of naïve healthy volunteers (HV) vaccinated with COH04S1 and naïve healthcare workers (HCW) vaccinated with the FDA-approved mRNA vaccine Comirnaty® (Pfizer, New York, NY, USA). After one or two COH04S1 vaccine doses, HCT/CAR-T recipients showed a significant increase in S- and N-specific binding antibody titers and neutralizing antibodies with potent activity against SARS-CoV-2 ancestral virus and VOC, including the highly immune evasive Omicron XBB.1.5 variant. Furthermore, vaccination with COH04S1 resulted in a significant increase in S- and N-specific T cells, predominantly CD4+ T lymphocytes. Elevated S- and N-specific immune responses continued to persist at six months post vaccination. Furthermore, both humoral and cellular immune responses in COH04S1-vaccinated HCT/CAR-T patients were superior or comparable to those measured in COH04S1-vaccinated HV or Comirnaty®-vaccinated HCW. These results demonstrate robust stimulation of SARS-CoV-2 S- and N-specific immune responses including cross-reactive neutralizing antibodies by COH04S1 in HM patients post HCT/CAR-T, supporting further testing of COH04S1 in immunocompromised populations.
Cytomegalovirus (CMV) infection remains a major cause of morbidity/mortality after allogeneic hematopoietic cell transplantation (HCT). Preemptive antiviral therapy is associated with drug-induced ...toxicities, and prophylactic therapy with letermovir is associated with late reactivations and delayed antiviral immune reconstitution. Therefore, substituting antivirals with a vaccine that harnesses the native immune response to CMV may improve outcomes for HCT recipients. Our group has developed a peptide vaccine, CMVPepvax, composed of an HLA-A*0201 restricted pp65 495-503 CD8 T cell epitope, covalently linked to a universal tetanus T helper epitope and co-administered with PF-03512676 adjuvant. CMV PepVax was safe and immunogenic in a healthy volunteer study (La Rosa et al. PMID: 22402037;) and a phase Ib HCT recipient trial (Nakamura, et al. PMID: 26853648) with the latter demonstrating a promising sign of efficacy in reducing CMV viremia.
In this double blind, placebo-controlled, randomized phase 2 trial (NCT02396134), HCT recipients were enrolled at four USA transplant centers. Eligible patients were CMV seropositive, HLA A*0201-positive, 18-75 years, receiving HCT from a matched related/unrelated donor. T-cell depleting agents (i.e. ATG) or recipients of ex-vivo T-cell-depleted grafts were excluded. Prophylactic antiviral therapy was not allowed. Patients were enrolled prior to day 0 of HCT and reassessed on day +28 for eligibility and randomization to the vaccine (VA) or placebo arm (PA), stratified by donor CMV serostatus. PepVax was administered subcutaneously on days +28 and +56 post-HCT. The primary endpoint of the trial was CMV viremia ≥1250 IU/m or CMV disease through 100 days post-HCT. A total of 96 patients were planned to be randomized at 1:1 ratio, providing 90% power to detect a reduction of viremia from 40% to 15%. CMVpp65-specific immune reconstitution was monitored by measuring levels of CD8 T cells binding to MHC class I pp65 495-503 and HIVgag 77-85 (as control) multimers (Immudex Dextramers), as well as CD28 and CD45 memory markers (BD Biosciences). The intensity of the fluorescent labels was measured using a Gallios flow cytometer with Kaluza software (Beckman Coulter).
Enrollment started in June 2015 but was stopped in November 2017 when a planned interim analysis suggested futility for the primary efficacy endpoint. By that time, 76 subjects had been consented, of whom 61 met the day 28 eligibility criteria and were randomized to the VA (n=32) or PA (n=29). The unblinded data were released when the planned one-year follow up was completed for these 61 subjects. The two groups were overall balanced in their demographics and HCT characteristics. There was no difference in the primary endpoint of CMV reactivation/disease between VA (25.1%) and PA (13.8%, p=0.15). The incidence of preemptive therapy was similar between the two arms. PepVax was well tolerated with no increase in adverse events. Transplant outcomes were also similar between the two groups with regards to 1-year overall survival, relapse-free survival, non-relapse mortality, relapse, and acute GVHD. In subjects in VA who reached the primary endpoint (n=8), CMV viremia occurred at a median of 20 days (interquartile range: 15-23 days; range, 0-48) after the first vaccine, suggesting that there was insufficient time for the vaccine-induced T cell expansion.
Significantly higher levels of long lasting pp65-specific T cells with effector memory phenotype were measured in non viremic participants in the VA compared to those in the PA; this effect was driven by differences observed late after vaccination (p = 0.004 by GEE analysis; Figure, panel A). In patients who controlled viremia, robust expansion of functional pp65-specific CD8 T cells was observed following PepVax injections (Figure, panels B-C).
Our results confirm safety and immunogenicity of PepVax in CMV seropositive HCT recipients. However, the trial failed to demonstrate a clinical efficacy of PepVax in reducing CMV viremia/disease despite favorable CD8 T cell responses. Early CMV reactivation/disease detected before receipt of the second vaccine may have reduced the ability of PepVax to elicit a protective T cell response. Transfer of vaccine-induced immunity through donor CMV immunization combined with recipient booster immunization may overcome this issue and lead to faster immune reconstitution post-HCT.
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Hill: Amplyx: Consultancy; OptumHealth: Consultancy; CRISPR therapeutics: Consultancy; Gilead: Consultancy, Research Funding; Allogene therapeutics: Consultancy; Octapharma: Consultancy; Allovir: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; CLS Behring: Consultancy; Karius: Research Funding. Al Malki: Hansa Biopharma: Consultancy; Jazz Pharmaceuticals, Inc.: Consultancy; Neximmune: Consultancy; Rigel Pharma: Consultancy; CareDx: Consultancy. Pullarkat: Amgen, Dova, and Novartis: Consultancy, Honoraria; AbbVie, Amgen, Genentech, Jazz Pharmaceuticals, Novartis, Pfizer, and Servier: Membership on an entity's Board of Directors or advisory committees. Aribi: Seagen: Consultancy. Devine: Tmunity: Current Employment, Research Funding; Magenta Therapeutics: Current Employment, Research Funding; Sanofi: Consultancy, Research Funding; Johnsonand Johnson: Consultancy, Research Funding; Orca Bio: Consultancy, Research Funding; Be the Match: Current Employment; Vor Bio: Research Funding; Kiadis: Consultancy, Research Funding. Verneris: Novartis: Other: advisory board; jazz: Other: advisory board; Fate Therapeutics: Consultancy. Miller: Fate Therapeutics, Inc: Consultancy, Patents & Royalties, Research Funding; GT Biopharma: Consultancy, Patents & Royalties, Research Funding; Vycellix: Consultancy; ONK Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Magenta: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Wugen: Membership on an entity's Board of Directors or advisory committees. Forman: Allogene: Consultancy; Lixte Biotechnology: Consultancy, Current holder of individual stocks in a privately-held company; Mustang Bio: Consultancy, Current holder of individual stocks in a privately-held company. Diamond: Pfizer Inc: Other; Helocyte Inc: Membership on an entity's Board of Directors or advisory committees, Other, Patents & Royalties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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Background: Cytomegalovirus (CMV) infection causes significant complications in recipients of hematopoietic cell transplant (HCT). Preemptive anti-viral therapy limits CMV viremia and disease, ...though its use is associated with toxicity, delayed immune reconstitution, and risk of late-onset CMV disease. We developed a novel CMV vaccine (CMVPepVax) based on the HLA-A*0201 pp65495-503 CD8+T-cell epitope (NLVPMVATV) fused with the Tetanus toxin P2 epitope (tt830-843:QYIKANSKFIGITE). The vaccine was formulated with PF03512676 (1.0 mg), a synthetic single-stranded phosphorothioate DNA containing CpG motifs provided by Pfizer Inc. In a Phase 1b healthy volunteer trial, CMVPepVax was found to be safe and immunogenic LaRosa et al. 2012. We report on clinical results demonstrating reliable safety, reduced CMV reactivation and chronic (c)GVHD in HCT recipients injected with CMVPepVax compared to randomized observational HCT recipients.
Objectives: The primary study objective was safety, with secondary objectives including immunologic responses of HCT recipients to CMVPepVax measured by pentamer assay, prevention of CMV reactivation, and clinical outcome.
Patients and methods: Eligible recipients (R+) wereCMV seropositive, HLA-A*0201, between 18-75 years (y) receiving allogeneic T-replete HCT for hematologic malignancy from matched-related (MRD) or 8/8 and 7/8 matched unrelated donors (MUD), excluding those with acute leukemia not in remission. Patients were reassessed on day (d)28 for eligibility and randomized unless they failed to engraft, experienced pre-d28 CMV reactivation or grade 3-4 acute (a)GVHD, received prednisone >1mg/kg/day within 7d of immunization, or had ongoing non-hematologic toxicity (CTCAE >=grade 3). Randomization was stratified by donor (D) CMV serostatus D- vs D+. Patients randomized to the vaccine arm (VA) received CMVPepVax on d28 and d56. Patients randomized to the observation arm (OA) were followed as per standard of care. All patients were monitored for safety/toxicity, CMV-related events, and immune recovery.
Results: As of July 2014, of 36 planned patients, 30 patients were enrolled and followed for at least 100d. The median age was 50y (range: 20-76y), with balanced gender accrual. All patients received peripheral blood stem cell grafts, while hematologic diagnosis, pre-HCT conditioning regimens, and GVHD prophylaxis were similar in the VA vs OA. Vaccinations were well tolerated in all 14 patients, and no patient met the safety stopping rule per-protocol. Of three VA patients who developed serious adverse events (SAE), 2 were unrelated and only one was probable (Grade 1 fever), while 8 patients experienced SAE in the OA. The frequency and severity of unrelated AE was similar between arms across all organ systems. None of 6 monitored vaccine recipients developed anti-dsDNA antibodies. In 9 VA patients who reached d180 without reactivation, increases in CMVpp65 pentamer levels after 1st and 2ndinjections were compared to 10 OA patients, using generalized estimating equations. The model indicates an average 6.5fold positive vaccine effect (p=0.02). While this pilot trial was not powered to detect reduced CMV reactivation, we observed a ~5-fold lower rate of CMV reactivation in the VA (1/14 =7%) compared to the OA (6/16=37%, p=0.09) by d100. aGVHD occurred post-randomization in 6/16 (grade II; 5, III: 1) subjects on the OA, and in 2/14 subjects (grade II: 2) on the VA (p = 0.2). An unexpected and striking finding was differing rates of cGVHD in patients who reached d180 in the VA (1/11) vs. OA (7/12, p=0.03). Noteworthy is that the vaccine formulation is more likely to stimulate TH1 responses, yet TH2 immunity is mechanistically associated with cGVHD. An interesting, but unexplained difference in relapse was observed in the OA (3/16) vs VA (0/14) patients, though the observation period is short. Recent observations relating CMV reactivation and reduced relapse have driven strong interest in a mechanistic understanding of the phenomena observed in this trial related to CMV vaccine or the adjuvant, PF03512676.
Conclusions: Trial results indicate safety of injecting CMVPepVax in HCT recipients on d28 and d56, no increase in aGVHD, and reduced CMV reactivation associated with vaccine-stimulated immunity. Compelling observations of reduced cGVHD and relapse will be further tested in a recently NIH-funded multi-institution expanded accrual phase 2 trial.
Merson:Pfizer Inc.: Employment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract 528
Allogeneic Stem Cell transplantation remains the only curative treatment modality for hematologic malignancies such as AML, ALL, and MDS. Reduced intensity regimens were designed which ...replaced the alkylating agent cyclophosphamide with the purine nucleoside antimetabolite, fludarabine, a potent immunosuppressive with a substantially milder toxicity profile. Clofarabine is a purine nucleoside analogue designed to exploit a double halogen strategy which confers resistance to adenosine deaminase, increases stability and bioavailability and makes the drug more efficient than fludarabine at inhibiting ribonucleotide reductase (RNR) and disrupting mitochondrial function, leading to apoptosis. Clofarabine is potentially a superior antileukemic agent as compared with fludarabine, thus enhancing the activity of the conditioning regimen.
To evaluate a novel clofarabine containing regimen as conditioning for adult fully matched allogeneic stem cell transplant.
phase I dose escalation: clofarabine (dose level 1 = 30 mg/m2, dose level 2 and 3 =40 mg/m2) IV daily days –7 to day –3 infused over 30 minutes IV, plus Melphalan (dose level 1 and 2, 100mg/m2, dose level 3, 140 mg/m2) administered over 30 minutes IV on day –2. Related or unrelated allogeneic stem cells were infused on day 0. GVHD prophylaxis: initially cyclosporine plus mycophenolate, then tacrolimus plus sirolimus was adopted as per City of Hope standard of care. Patients (pts) age ≥ 18 years with AML, ALL, MDS in either CR1, CR2 or in relapse (up to 50% marrow blasts), not deemed eligible for standard transplant regimens by the attending physician, or at high risk for relapse, are eligible.
16 eligible pts, all with AML, have been treated thus far, 7,males, 9 females, with a median age of 63 years (30 – 66). Seven pts were in CR1, 2 pts were in CR2, 4 pts where induction failures, and 3 pts were in first relapse. Grade 3 non-hematologic toxicities included elevation of transaminases, diarrhea, and hyponatremia. No dose limiting toxicities (DLT) were seen in the 3 pts treated at dose level 1. One patient in dose level 2 died prior to engraftment due to hepatic, renal, and infectious toxicities; that dose level has been expanded to 12 patients and no further DLTs were seen. The first patient treated at dose level 3 developed multiorgan failure and died prior to engraftment. Given the excellent results seen in the two previous cohorts we opted not to dose escalate any further patients beyond clofarabine 40 mg/m2 and melphalan 100 mg/m2. Three patients with primary induction failure received an unrelated donor graft and had complete engraftment and obtained remission. The median time to ANC recovery is 14 days and to platelet recovery is 16 days (see table). Mild acute skin graft versus host disease (GvHD) was seen in five patients, mild chronic GvHD in four patients, one patient developed severe chronic GVHD of the liver and died at day 201 from CNS bleed due to tacrolimus-sirolimus related TTP-HUS. Of the 14 patients that successfully completed transplant (no DLT or engraftment difficulty), only one patient has relapsed, with median follow-up of 10.5 months (range 4–24).
The combination of clofarabine and melphalan is a well tolerated reduced intensity conditioning regimen with enhanced anti-leukemia activity leading to complete engraftment of related and unrelated fully matched allogeneic stem cells. Complete engraftment with prolonged disease free survival was seen at both dose levels 1 and 2.
Off Label Use: clofarabine as a component of the conditioning regimen for allogeneic transplant.
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