A Randomized, Double-Blind, Placebo-Controlled Study of DCVAC Maintenance Therapy in Patients with FIGO Stage III-IV Ovarian Cancer After First-Line Chemotherapy
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Study Design: This study is a randomized, double-blind, placebo-controlled phase II trial that included patients with FIGO stage III-IV ovarian cancer. The participants were randomly assigned to the dendritic cell vaccine (DCVAC) group or the placebo group at a 2:1 ratio. Patients with no disease progression after postoperative chemotherapy were administered the study drug for a maximum of 15 doses. Follow-up was conducted every three months.Objective: The safety and efficacy of a DCVAC as maintenance therapy after first-line chemotherapy in patients with ovarian and fallopian tube cancer were assessed. The immunogenicity of the DCVAC for maintenance therapy was also preliminarily assessed.Results: A total of 21 patients, all with high-grade serous carcinoma in terms of pathological histological type, entered the study drug treatment phase. Among them, 14 patients were assigned to the DCVAC drug infusion group, and 7 patients were assigned to the control group. There were no significant differences between the two groups in terms of age, tumour stage, type of surgery, surgical satisfaction, chemotherapy efficacy, number of doses, or BRCA status. (1) Safety : The main adverse reactions, including abdominal pain, leukopenia, and elevated TSH, were graded as 1–2 according to the Common Terminology Criteria for Adverse Events (CTCAE), version 5.0. (2) Efficacy : Three months after the last patient completed treatment, the median progression-free survival (PFS) in the treatment group was 22.6 months, whereas the median PFS in the control group was not yet reached. The interim analysis revealed no significant difference in PFS between the treatment and control groups (p = 0.64), and no improvement in PFS has been observed so far. Long-term follow-up is needed to further clarify the treatment outcomes. For the three patients with ovarian cancer who did not achieve a complete response (CR) after first-line treatment, the progression-free intervals (PFIs) after DCVAC treatment were 11.8, 24.2, and 29.8 months, respectively. One patient with enlarged retroperitoneal fused lymph nodes that could not be surgically removed had stable lymph node lesions during DC treatment, with a PFI of 24.2 months. (3) Immune reactivity : After DCVAC treatment, there was a trend towards increased numbers of antitumour immune cells, such as T cells, B cells, natural killer (NK) cells, and conventional dendritic cells (cDCs) in the peripheral blood of patients, whereas the number of plasmacytoid dendric cells (pDCs) tended to decrease. Patients with a high proportion of CD8 + PD-1 + T cells (> 40.47%) in the peripheral blood before treatment had a significantly longer PFI than those with a low proportion of these cells, whereas those with a high proportion of senescent CD8 + T cells (> 40.46%) had a significantly shorter PFI than those with a low proportion of these cells. These findings suggest that the baseline proportions of CD8 + PD-1 + T cells and senescent CD8 + T cells in the peripheral blood may be potential biomarkers for selecting individuals who are likely to respond well to the vaccine.Conclusion: Maintenance therapy with DCVAC after first-line chemotherapy in patients with FIGO stage III-IV ovarian cancer is safe and induces an immune response. With respect to efficacy, the interim analysis of PFS revealed no significant differences, so further follow-up and final analysis are needed.