Maveropepimut-S, a DPX-Based Immune-Educating Therapy, Shows Promising and Durable Clinical Benefit in Patients with Recurrent Ovarian Cancer, a Phase II Trial

Purpose: Patients with platinum-resistant ovarian cancer respond poorly to existing therapies. Hence there is a need for more effective treatments.Patients and Methods: The DeCidE1 trial is a multicenter, randomized, open-label, single-arm phase II study to evaluate the safety and effectiveness of maveropepimut-S with cyclophospha-mide in patients with recurrent ovarian cancer. Median follow-up for evaluable subjects was 4.4 months. Data were collected from March 2019 to June 2021. Subjects receivedtwo injections of 0.25 mL maveropepimut-S 3 weeks apart, followed by one 0.1-mL doses, every 8 weeks up to progression. Oral cyclophosphamide, 50 mg twice daily, was administered in repeating weekly on and off cycles.Results: Twenty-two patients were enrolled. Median age was 58 years (38-78 years). Among the evaluable population, the objective response rate (ORR) was 21% [90% confidence interval (CI), 7.5%-41.9%], with a disease control rate (DCR) of 63% (90% CI, 41.8%-81.3%), including 4 (21%) patients with partial responses, 8 (42%) stable disease, and 7 (37%) progressive disease. The ORRs were consistent across subgroups based on platinum sensitivity, and DCR was higher in the platinum-resistant subpop-ulation. Four SD patients maintained clinical benefit up to 25 months. Most treatment-related adverse events (TRAE) were grade 1 and 2 (87% of unique events). Most common AEs were injection site reactions. Eight subjects reported grade 3 and no grade 4 AEs. Survivin-specific T-cell responses were observed in treated patients with clinical benefit.Conclusions: Maveropepimut-S with intermittent low-dose cyclophosphamide is well-tolerated, with clinical benefit for patients with recurrent ovarian cancer. Observed responses are irrespective of the platinum status.