Abstract
This investigator-initiated, open-label phase 1/2 clinical trial evaluates maveropepimut-S, a survivin-targeting vaccine, combined with pembrolizumab and low-dose cyclophosphamide in patients with recurrent epithelial ovarian cancer (ClinicalTrials.gov identifier: NCT03029403). The primary endpoints are safety and clinical efficacy measured by overall response rate and disease control rate. Secondary endpoints include recommended phase 2 dose, progression-free survival, overall survival, and survivin-specific immune response. Forty-seven patients are enrolled and forty-four are evaluable. Most treatment-related adverse events are grade 1 or 2, most commonly injection site reactions. The recommended phase 2 dose is 0.25 milliliters. The overall response rate is 23% and the disease control rate is 67%, with greater activity in platinum-sensitive disease. Median progression-free survival is 6.3 months in platinum-sensitive disease and 1.2 months in platinum-resistant disease. Survivin-specific immune responses occur in 62.5% of tested patients and correlate with clinical benefit. The combination demonstrates tolerability and sustained clinical activity.
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Acknowledgements
We thank the patients and their families for participating in this study. The sponsor of the study was Princess Margaret Cancer Centre, University Health Network. We would like to thank Princess Margaret Cancer Foundation, Ontario Institute of Cancer Research, BioVaxys (prior Immunovaccine), and Terry Fox Research Institute for funding this study. This study was also supported in part by a research grant from Investigator-Initiated Studies Program of Merck Canada Inc. The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck Canada Inc or BioVaxys. Data collection was performed at the Drug Development Program-Phase II at Princess Margaret Cancer Centre. No medical writer was used for the study manuscript.
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A.C.V.: Honoraria from AstraZeneca and Merck Sharp & Dhome; Consultancy/advisor role from Merck Sharp & Dhome outside the submitted work. S.L.: Institutional funding for clinical trials as PI from AstraZeneca, Merck Sharp & Dhome, Repare Therapeutics, Seagen, Schrodinger, GSK and Roche. Consultancy/advisor role from AstraZeneca, GlaxoSmithKline, Merck Sharp & Dhome, AbbVie, Eisai, Zai Lab, Gilead, outside the submitted work. I.C.: declares institutional funding for clinical trials as PI from AstraZeneca, Merck Sharp & Dhome, Vivesto, Tolremo, Orion, Bayer, lncyte; consultancy/advisor role from AstraZeneca, GlaxoSmithKline, Merck Sharp & Dhome, AbbVie, Biontech, lncyte, outside the submitted work. A.M.: Honoraria from AstraZeneca, AbbVie, Daichii Sankyo, Eisai, GSK, MSD, Lilly and Pharma. A.M.O.: PI and Steering Committees with AstraZeneca, GSK. Advisory to Abbvie, CEO in Ozmosis Research. The remaining authors declare no competing interests.
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Veneziani, A.C., Lheureux, S., Millar, D.G. et al. Maveropepimut-S, pembrolizumab and low dose cyclophosphamide in metastatic ovarian cancer: phase 1/2 PESCO trial. Nat Commun (2026). https://doi.org/10.1038/s41467-026-72125-0
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DOI: https://doi.org/10.1038/s41467-026-72125-0
