Novel Vaccine Combo Shows Responses in Recurrent Epithelial Ovarian Cancer

The combination of maveropepimut-S (MVP-S), pembrolizumab (Keytruda), and intermittent low-dose cyclophosphamide demonstrated clinical activity and a favorable safety profile in patients with recurrent epithelial ovarian cancer (EOC), according to a press release from the developer, BioVaxys Technology Corp.¹

Supporting results for the triplet regimen come from the phase 1b/2 PESCO trial (NCT03029403), an investigator-initiated study conducted at the Princess Margaret Cancer Centre. The final analysis included 47 patients, with 16 patients enrolled in the phase 1 dose-escalation portion and 31 patients in the phase 2 expansion.

Per the developer, MVP-S is a formulation based on DPX made of 5 peptides derived from survivin, a T helper peptide, and an innate immune stimulant. It is designed to elicit a robust and persistent immune response through instruction to the immune system.

“The combination of MVP-S, pembrolizumab, and low-dose cyclophosphamide in endothelial ovarian cancer demonstrated promising and sustained clinical activity with good tolerability,” said Kenneth Kovan, president and chief operating officer of Biovaxys.¹ “Other studies suggest that anti–PD-1 [therapy] enhances the robust antigen-specific, cytotoxic immune response already induced by MVP-S. These findings reinforce survivin as a viable target for immunotherapy in ovarian cancer, together with checkpoint inhibitors such as anti–PD-1.”

PESCO Trial Efficacy Data

Among evaluable patients with high-grade endometrial cancer, the objective response rate (ORR) was 24.0%, and the disease control rate (DCR) was 82.0%. The median duration of response (DOR) for responders was 5.5 months.

Clinical benefit was more pronounced in the platinum-sensitive population (Cohort A), which achieved an ORR of 40.0% and a DCR of 90.0%. In the platinum-resistant cohort (Cohort B), the ORR was 16.0%, and the DCR was 54.0%. These results in the platinum-resistant setting compare favorably to historical data for single-agent chemotherapy, which typically yields an ORR of approximately 11.8%.²

The study also evaluated the induction of survivin-specific T-cell responses, a hallmark of the MVP-S mechanism of action. Survivin-specific immune responses occurred in 62.0% of tested patients and correlated with disease control in 93.0% of those responders. Notably, the longest detected immune response in the trial lasted 195 weeks, with 1 patient in Cohort A remaining in complete response (CR) for more than 3 years.

Trial Breakdown

The PESCO trial was an open-label, non-randomized study with 2 distinct phases. In the dose-escalation phase, investigators evaluated 2 dose levels of MVP-S to determine the recommended phase 2 dose (RP2D).³

Following the dose-escalation period, additional patients were enrolled into the dose-expansion period to further evaluate the treatment. Patients received 1 priming dose of MVP-S via injection under the skin of the upper thigh at 0.25 mL on cycle 1, day 1. After approximately 6 weeks, they received an additional boosting dose of 0.25 or 0.5 mL of MVP-S. Pembrolizumab was given intravenously at 200 mg on day 1 of every 21-day cycle, and cyclophosphamide was given orally at 50 mg twice daily, starting 7 days before cycle 1, day 1, then continuing for 7 days on, 7 days off.

Eligible patients were 18 years or older with histologically or cytologically confirmed advanced epithelial ovarian, fallopian tube, or primary peritoneal cancer, as well as documented disease progression from their prior line of therapy and receipt of a front-line platinum-based regimen following primary or interval debulking surgery with documented disease recurrence. Additional enrollment criteria included measurable disease per RECIST v1.1 guidelines, an ECOG performance status of 0 or 1, and adequate organ function.

The primary end points included safety, the determination of the RP2D, and clinical efficacy based on the ORR and DCR. Secondary endpoints included efficacy in the platinum-sensitive and platinum-resistant cohorts, progression-free survival, and overall survival. For 2 years after treatment vaccination, all patients were followed; those with prior immunotherapy were excluded from the study.

References

1. BioVaxys reports positive clinical study results from Phase 1b/2 PESCO trial of MVP-S with pembrolizumab (Keytruda™) and low-dose cyclophosphamide for patients with recurrent epithelial ovarian cancer (EOC). News release. BioVaxys Technology Corp. January 20, 2026. Accessed January 21, 2026. https://tinyurl.com/vtjdfx9v
2. Pujade-Lauraine E, Hilpert F, Weber B, et al. Bevacizumab combined with chemotherapy for platinum-resistant recurrent ovarian cancer: The AURELIA open-label randomized phase III trial. J Clin Oncol. 2014;32(13):1302-1308. doi:10.1200/JCO.2013.51.4489
3. Phase 2 study of pembrolizumab, DPX-Survivac vaccine and cyclophosphamide in advanced ovarian, primary peritoneal or fallopian tube cancer. ClinicalTrials.gov. Updated September 19, 2025. Accessed January 21, 2026. https://tinyurl.com/ns6jheyw