Maintenance vigil immunotherapy in newly diagnosed advanced ovarian cancer: Efficacy assessment of homologous recombination proficient (HRP) patients in the phase IIb VITAL trial.

5502 Background: In the VITAL (NCT02346747) trial, maintenance therapy with Vigil, an autologous tumor cell vaccine transfected with a DNA plasmid encoding GMCSF and bi-shRNA-furin for TGFβ expression control, following frontline platinum-based chemotherapy led to a recurrence-free survival (RFS) benefit in patients with advanced high-grade ovarian cancer (HR=0.69, 90% CI 0.44–1.07, p=0.078) and significantly in BRCA-wt patients (HR=0.51, 90% CI 0.30-0.88, p=0.020) ( Rocconi et al. Lancet Oncol. 2020). Here we report post-hoc HR deficiency (HRD) subgroup analysis and identification of an additional molecular subgroup sensitive to Vigil therapy involving STRING analysis. Methods: This double-blind, placebo-controlled, Phase 2b study randomized 92 patients with newly diagnosed stage III/IV ovarian cancer with a complete clinical response (CR) to frontline surgery and chemotherapy. Patients received 1 x 10e7 cells/ml of Vigil or placebo intradermally once a month for up to 12 doses or disease progression. RFS was the primary endpoint assessed by blinded independent central review. HRD status was determined according to the Myriad Genetics myChoice CDx assay (HRD score < 42 for proficient). Using tumor annotated DNA polymorphism data, a protein-protein interaction network was constructed using the STRING database. Properties of this network including topological distance and the identification of hub genes were used to predict a target molecular population sensitive to Vigil. Results: In the per-protocol population (PP, n=91), 62 BRCA-wt patients were tested for HRD status. Forty-five patients were HR proficient (HRP) and 17 patients were HR deficient (HRD). No HRP patients in the Vigil group reported treatment related Grade 3 or higher adverse events. From the time of study randomization median RFS was improved with Vigil (n=25) in HRP patients compared to placebo (n=20) (Table 1). Similarly, overall survival (OS) benefit was observed in the Vigil group compared to placebo (Table 1). Improved RFS was demonstrated for a subset of patients with STRING predicted molecular profile. Conclusions: Vigil immunotherapy as frontline maintenance in Stage III/IV ovarian cancer is well tolerated and showed clinical benefit in both BRCA-wt and HRP molecular profile patients. Results suggest a unique molecular network that enhances sensitivity to Vigil therapy. Clinical trial information: NCT02346747. [Table: see text]

Engineering autologous tumor cell vaccine to locally mobilize antitumor immunity in tumor surgical bed

Autologous tumor cell–based vaccines (ATVs) are emerging as a transformable approach for personalized immunotherapy, but their therapeutic efficacy remains unsatisfying in patients with cancer. Here, we design a photodynamic therapy (PDT)–motivated ATV (P-ATV) in Fmoc-KCRGDK–phenylboronic acid (FK-PBA) hydrogel, which mobilizes local immune activation to inhibit relapse of postoperative tumors. The FK-PBA targeting overexpressed sialic acid on tumor cells can enable on-demand gelation in residue tumor areas and maintain continuous vaccination in surgical bed. Unlike neoantigen-based vaccine or adoptive cell therapy that takes several months to prepare, P-ATV can be easily manufactured within a few days and efficiently boost neoepitope-specific CD8+ T cells to activate personalized immunotherapy. This simple and powerful approach of engineered ATVs provides an alternative strategy for personalized immunotherapy and is readily transformable to various kinds of cell-based antigens to inhibit the relapse of postoperative tumors.

Survival by stage and tumor measurability in metastatic melanoma patients treated with autologous dendritic cell tumor cell vaccines.

2637 Background: Survival of cancer patients is greatly affected by stage and tumor burden. The purpose of this study was to determine survival for melanoma patients who were treated with patient specific vaccines in the context of prospective clinical trials, by cohorts defined by stage and tumor measurability. Methods: Metastatic melanoma patients were treated with autologous dendritic cells loaded with antigens from irradiated cells from short-term autologous tumor cell lines (DCV). All patients had a metastatic melanoma lesion surgically resected, from which a tumor cell line was established. Irradiated tumor cells (ITC) were incubated with autologous dendritic cells (DC) to produce the DCV, which were injected s.c. in 500 micrograms GM-CSF weekly x 3 weeks, then monthly for 5 months. Data was pooled for DCV-treated patients enrolled in either of two phase II trials: one single-arm (NCT00948480), one randomized (NCT00436930). Patients were assigned to one of three cohorts based on their most advanced stage of disease prior to treatment, and whether they had measurable disease at the time of treatment. Survival was determined per Kaplan and Meier. Results: The final therapeutic products consisted of autologous DC with non-phagocytosed ITC making up 0% to 20% of cells in the final product. There were 45 men and 27 women. Median age was 52 years (range 17 to 83). Tumor sources were 37-lymph node, 20-viscera, and 15-soft tissue. No patients were lost to follow up; all surviving patients were followed 5 years. Toxicity was minimal. Median overall survival (OS) for all 72 patients was 49.4 mos; 5-year OS 46%. There was no correlation between survival and the number of DC or ITC in the first three injections. Patients with recurrent stage 3 disease that had not recurred (n=18) had a 72% 5-year OS; patients with non-measurable stage 4 (n=30) had a 53% 5-year OS. Patients with measurable stage 4 (n=18) had received an average of four prior therapies. They had a median OS of 18.5 months, and 2-year OS of 46%. Conclusions: This patient-specific DCV was associated with encouraging survival in all three clinical subsets. Because of its mechanism of action and absence of toxicity, it should be evaluated further. Clinical trial information: NCT00948480, NCT00436930.

Randomized phase II trial of patient-specific dendritic cell vaccines loaded with autologous tumor antigens versus autologous monocytes in patients with primary advanced ovarian cancer.

TPS10 Background: With standard debulking surgery and combination chemotherapy (adjuvant ± neoadjuvant) the 5-year survival for women with newly diagnosed advanced epithelial ovarian cancer (stage III or IV) is less than 40%. After completion of primary therapy there is an opportunity to introduce an immunotherapy modality in an effort to improve long-term survival. In patients with metastatic melanoma, patient-specific vaccines consisting of autologous dendritic cells (DC) loaded with autologous tumor antigens (ATA) derived from a short-term autologous tumor cell line were associated with minimal toxicity and a 5-year survival of 50% in a single arm trial, and more than doubled median survival (43 vs. 20 months) in a randomized trial. Newly diagnosed patients with ovarian cancer might benefit from addition of such patient-specific therapeutic vaccines (DC-ATA) to standard therapy. Methods: This is a double-blind, 2:1 randomized trial comparing adjunctive treatment with DC-ATA to autologous monocytes (MC) in patients with newly diagnosed stage III or IV epithelial cancer of the ovary, fallopian tube, or peritoneum. Patients eligible for randomization are those who have completed or discontinued standard primary therapy, have a Karnofsky performance status ≥70, have an autologous tumor cell line, and have a monocyte product from which DC can be derived. The tumor cell line is derived from fresh tumor; MC are derived from leukapheresis, and MC are converted to DC by incubation with GM-CSF and IL-4. Patients are stratified by whether there is no evidence of disease at completion of primary therapy, and then are randomized, typically 6 to 7 months after tumor collection. Treatment can begin about 4 weeks from randomization. The trial has been open at a single site since mid-November 2017; the first tumor was collected in December. Appropriate tumor samples have been submitted from 11 patients and all 11 have resulted in cell lines. The first patient was randomized in May 2018. As of October 2018 four patients had been randomized and all four had started treatment. Additional clinical sites are being initiated. Clinical trial information: NCT02033616.