Conference Coverage

Vaccine maintenance improves relapse-free survival in BRCA wild-type ovarian cancer



The autologous tumor cell vaccine gemogenovatucel-T (Vigil Ovarian) is well tolerated as maintenance therapy in stage III-IV ovarian cancer patients and may improve relapse-free survival, particularly in BRCA wild-type disease, according to findings from the ongoing VITAL study.

Dr. Rodney P. Rocconi, interim cancer center director and professor of gynecologic oncology at the Mitchell Cancer Institute, University of South Alabama, Mobile

Dr. Rodney P. Rocconi

In patients with and without BRCA1/2 mutations, the median relapse-free survival was longer with gemogenovatucel-T maintenance than with placebo, but the difference did not reach statistical significance (P = .065).

However, among patients with wild-type BRCA, the median relapse-free survival was significantly longer with gemogenovatucel-T (P = .0007).

Rodney P. Rocconi, MD, of the Mitchell Cancer Institute at University of South Alabama, Mobile, reported these results in an abstract that was slated for presentation at the Society of Gynecologic Oncology’s Annual Meeting on Women’s Cancers. The meeting was canceled because of the COVID-19 pandemic. Some data have been updated from the abstract.

Study rationale

Gemogenovatucel-T (formerly called FANG) is an autologous tumor cell vaccine transfected with a plasmid encoding granulocyte-macrophage colony–stimulating factor and a novel bifunctional short hairpin interfering RNA targeting furin convertase.

“In the era of personalized, targeted medicine, I think this is about as personalized as you can get, this type of vaccine,” Dr. Rocconi said. “Essentially, we harvest patients’ own cancer cells and create a vaccine that is targeted to the antigens on their cells so that it recognizes only that patient’s cancer.”

The vaccine also helps recruit immune cells to the area and has a very limited off-target effect, Dr. Rocconi added.

He noted that gemogenovatucel-T previously demonstrated promising efficacy and limited side effects in a phase 1 study that included patients with advanced ovarian cancer (Mol Ther. 2012 Mar;20[3]:679-86).

“So we thought that, in ovarian cancer, as a maintenance therapy, it made a lot of sense,” Dr. Rocconi said, noting that the overall prognosis for advanced epithelial ovarian cancer remains limited.

Treatment and toxicity

Dr. Rocconi and colleagues reported data on 91 patients in the VITAL study. The patients had achieved a complete response after frontline surgery and chemotherapy, and they were randomized to maintenance with gemogenovatucel-T or placebo.

Patients had a median time from surgery to randomization of 208.5 days in the gemogenovatucel-T group and 200 days in the control group. The patients were treated with 1 x 107 cells/mL of gemogenovatucel-T or placebo intradermally once a month for up to 12 doses.

Gemogenovatucel-T was well tolerated. No added overall toxicity was noted in the gemogenovatucel-T group versus the control group, and no grade 4/5 toxicities were observed, Dr. Rocconi said. Grade 2/3 toxic events were observed in 8% of patients in the gemogenovatucel-T group, compared with 18% in the control group. The most common events were nausea and musculoskeletal pain in the gemogenovatucel-T group, and were bone pain and fatigue in the control group.

Relapse-free and overall survival

In the entire cohort, the median relapse-free survival was longer with gemogenovatucel-T maintenance – 12.6 months versus 8.4 months with placebo (hazard ratio, 0.69) – but the difference did not reach statistical significance (P = .065).

However, in the 67 patients with wild-type BRCA, the median relapse-free survival was 19.4 months with gemogenovatucel-T and 14.8 months with placebo, a statistically significant difference (HR, 0.459; P = .0007).

The median overall survival was not reached in the BRCA wild-type patients treated with gemogenovatucel-T, and it was 41.4 months from the time of randomization in those who received placebo (HR, 0.417; P = .02).

No benefit was seen with gemogenovatucel-T in patients with known BRCA1/2 mutations, Dr. Rocconi said.

‘Encouraging’ results

The overall improvement in the gemogenovatucel-T group was encouraging, particularly in a maintenance-type trial, Dr. Rocconi said. He noted that prior treatments for maintenance have received approval based on shorter survival gains, and the finding of particular benefit in BRCA wild-type disease could have important implications for a population that usually has lesser benefit from treatments, compared with patients who have BRCA mutations.

“So this result is very unique,” Dr. Rocconi said, explaining that about 85% of ovarian cancer patients have BRCA wild-type disease; with this treatment, patients with wild-type BRCA may achieve similar survival rates as those seen in BRCA-mutant disease.

“I think, in general, immunotherapy has been somewhat disappointing in ovarian cancer, so to have a targeted vaccine work in ovarian cancer, just broadly ... is pretty noteworthy,” he said. “We’re really excited, obviously, about the overall success we’ve seen for all patients, but most importantly in those with BRCA wild type. This is a pretty marked significance in recurrence-free intervals and overall survival, and we’re definitely pleased with that.”

Next steps

The findings from this trial have been submitted for publication, and efforts are underway to determine next steps through communication with the Food and Drug Administration, Dr. Rocconi said.

Additionally, other studies are underway to assess gemogenovatucel-T in patients who fall in “the middle ground” – that is, patients who have BRCA wild-type disease but have “some homologous recombination deficiency where the tumor itself might be BRCA deficient or have some other type of deficiency,” Dr. Rocconi explained.

“So we’re trying to tease out specifically what is going on across all the different variations of ovarian cancer patients, and also looking for potential biomarkers for predicting response,” he said. “What we would like to see is a companion test where we’re able to predict which patients can really respond and do best with this technology, and, that way, we know how to stratify patients most appropriately.”

The current trial was sponsored by Gradalis. Dr. Rocconi disclosed relationships with Gradalis, Genentech, Clovis, and Johnson & Johnson.

SOURCE: Rocconi RP et al. SGO 2020, Abstract LBA7.

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