Immunotherapy Provides Durable Responses in Pretreated Ovarian Cancer

Patients with platinum-resistant or refractory ovarian cancer experienced responses and survival benefits from intraperitoneal Olvi-Vec (olvimulogene nanivacirepvec) and platinum-based chemotherapy with or without Avastin (bevacizumab), according to a new study.

The findings, published by the journal JAMA Oncology, showed a 54% overall response rate (patients whose disease partially or entirely responded to treatment) with a 7.6-month duration of response. In addition, these patients had a disease control rate (patients whose disease stabilized, shrunk or disappeared) of 88%. When assessed via cancer antigen 125 (CA-125, a marker measured in the blood to indicate treatment response), the overall response rate was 85%.

The phase 2 VIRO-15 clinical trial included 27 pretreated patients with ovarian cancer that was either platinum-resistant (14 patients) or platinum-refractory (13 patients). The patients, at a median age of 62, received Olvi-Vec through a temporary intraperitoneal dialysis catheter (within the area that contains abdominal organs) as two consecutive, daily doses, then platinum-doublet chemotherapy with or without Avastin.

“The results from the phase 2 trial suggest potential survival benefits of this novel immunochemotherapy approach for women with recurrent platinum-resistant or -refractory disease,” Dr. Robert W. Holloway, the lead investigator and medical director of the gynecologic oncology program at AdventHealth Cancer Institute in Orlando, said in a press release from Genelux, the manufacturer of Olvi-Vec. “This patient population represents a considerable unmet medical need in gynecologic oncology. The data also demonstrated modification of the tumor immune microenvironment with oncolytic virus Olvi-Vec in ways that reverse platinum resistance, and in addition induce tumor specific T-cell response. We believe the currently enrolling Phase 3 OnPrime/GOG-3076 clinical trial will hopefully provide more evidence that we can produce a life changing therapy."

With a median follow-up duration of 47 months, the median progression-free survival (the time during and after treatment that the patient lives without the disease worsening) was 11 months, and the six-month progression-free survival rate was 77%, according to the study. Findings from the study also demonstrated a median overall survival (the time that a patient lives after treatment) of 15.7 months (18.5 months in the platinum-resistant group, 14.7 months in the platinum-refractory group).

Side effects related to treatment included fever and abdominal pain, with no reported discontinuations or deaths related to treatment.

The study authors described the overall response rate and progression-free survival findings as “promising,” said the study’s “hypothesis-generating results warrant further evaluation in a confirmatory phase 3 trial.”

In the release, Genelux explained that Olvi-Vec is “a proprietary, oncolytic vaccinia virus, modified to increase its safety, tumor selectivity and therapeutic potential.” Of note, the vaccinia virus is typically used as part of a smallpox vaccine. When oncolysis is mediated by a virus, it may result in cell death and immune system activation, both of which lead to long-term immunotherapy, according to the release.

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