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Phase 2 trial: Dendritic cell vaccine maintenance prolongs PFS in EOC



A dendritic cell vaccine improved progression-free survival when administered sequentially after chemotherapy in patients with epithelial ovarian carcinoma who have undergone primary debulking surgery, according to interim findings from a randomized, phase 2, open-label trial.

Of 99 patients enrolled in the international, multicenter trial between November 2013 and March 2016, 92 received at least one dose of therapy and had a postbaseline endpoint assessment (the modified intention-to-treat population). Median progression-free survival was 18.3 months in the 31 patients who received autologous dendritic cell vaccine (DCVAC) given concomitantly with chemotherapy (group A), 24.3 months in the 30 patients who received DCVAC given sequentially as maintenance therapy after chemotherapy (group B), and 18.6 months in the 31 controls who received chemotherapy alone (group C), Lukas Rob, MD, reported at the annual meeting of the American Society of Clinical Oncology.

“When DCVAC was administered as maintenance [therapy] after the chemotherapy, the time to disease progression was prolonged by almost 6 months. Based on the hazard ratio, there was a 57% decrease in the hazard of progression in favor of arm B,” said Dr. Rob, of University Hospital Kralovske Vinohrady, Prague.

Compared with group C, progression-free survival hazard ratios were 0.64 and 0.43 in the modified intention-to-treat population in groups A and B, respectively, he said.

“These results are statistically significant and the clinical benefit is even more significant in patients who received more doses of DCVAC,” he added, explaining that the hazard ratios for patients in groups A and B who received at least eight doses of DCVAC and/or three cycles of chemotherapy (the per protocol population, including 87 patients) were 1.01 and 0.32, respectively.

Although the overall survival data in this study is immature, there is “a strong trend in favor of DCVAC in the maintenance treatment arm,” he said.

Study participants had FIGO stage III epithelial ovarian cancer (EOC) and a performance status score of 0-2. All had undergone primary debulking surgery and had less than 1 cm maximal residuum and no prior systemic therapy. Patients were randomized up to 6 weeks after surgery. Chemotherapy in all three groups included six cycles of carboplatin and paclitaxel, and DCVAC was given at doses of 1 x 107 dendritic cells per dose for a planned 10 doses.

Most patients with EOC – about 70% of those with stage III/IV disease – relapse after optimal debulking surgery and chemotherapy.

“There is no doubt that we need a new treatment modality,” he said. Because autologous DCVAC can present tumor antigens to elicit a durable immune response, he and his colleagues hypothesized that adding DCVAC to chemotherapy could improve outcomes – either when used concomitantly to target tumor-induced immune suppression and allowing for partial recovery of the immune system after each cycle, or when used sequentially as maintenance therapy, as minimal tumor burden after chemotherapy would provide optimal conditions for immune stimulation and the immune system would be fully recovered after completing cytotoxic therapy.

The treatments in this study were well tolerated; no grade 3 or greater adverse events were related solely to DCVAC, and the vaccine did not worsen the side effects of chemotherapy, Dr. Rob said.

The findings suggested that sequential DCVAC after chemotherapy in patients with EOC is a promising maintenance treatment option that can delay disease progression, he concluded, noting that “due to the excellent result in the maintenance arm we decided ... to enroll more patients in arms B and C to increase the power of this study.”

Additionally, a phase 3 trial is planned and enrollment should begin in early 2019, he said.

Dr. Rob reported having no disclosures.

SOURCE: Rob L et al. ASCO 2018, Abstract 5509.

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