Phase I/II randomized trial of dendritic cell vaccination with or without cyclophosphamide for consolidation therapy of advanced ovarian cancer in first or second remission

Abstract

Purpose: In spite of increased rates of complete response to initial chemotherapy, most patients with advanced ovarian cancer relapse and succumb to progressive disease. Immunotherapy may have potential for consolidation therapy.

Experimental design: This randomized open-label phase I/II trial evaluated responses of patients with advanced ovarian cancer in remission for vaccination with monocyte-derived dendritic cells (DC) loaded with Her2/neu, hTERT, and PADRE peptides, with or without low-dose intravenous cyclophosphamide. All patients also received pneumococcal vaccine and were randomized to cyclophosphamide 2 days prior to first vaccination. Blood samples were analyzed by ELISPOT and flow cytometry.

Results: Of 11 patients, 2 recurred during vaccination. Nine received all 4 doses: 3 patients recurred at 6, 17, and 26 months, respectively, and 6 have no evidence of disease at 36 months. No grade 3/4 vaccine-related toxicities were noted. The 3-year overall survival was 90%. Patients receiving cyclophosphamide showed a non-significant improvement in survival over controls. Patients receiving cyclophosphamide had a transient reduction in neutrophils, but no change in total lymphocytes or regulatory T cells. Modest T-cell responses to Her2/neu and hTERT were seen post-vaccine by IFN-γ ELISPOT. Patients demonstrated below normal responses to the diphtheria conjugate protein CRM197, a component of the pneumococcal vaccine.

Conclusions: In this setting, peptide-loaded DC vaccination elicits modest immune responses, but survival is promising. Pneumococcal vaccination revealed substantial immune suppression, even in patients in remission. Rational design of consolidative strategies for ovarian cancer will need to overcome tolerance and immunosuppression.

Fig. 1

Kaplan–Meier survival plots. Progression-free survival (a) and overall survival (b) of vaccinated patients receiving no cyclophosphamide IDD-6 (Arm 1) or cyclophosphamide (Arm 2). There is no difference in PFS (exact P = 0.17) or OS (exact P = 1.00); 0 indicates censored

Fig. 2

ELISPOT analysis was performed using PBMCs obtained at the indicated time points post-vaccination against hTERT 988Y, her2/neu 369V2V9, 689, and PADRE for patients on Arm 1 (a), and Arm 2 or a single low dose of cyclophosphamide prior to IDD-6 (b). Responses to PMA and ionomycin from 5 × 103 cells are also shown; note scale difference. Longitudinal analysis was performed at baseline (−4 weeks) and post-vaccination. Composite plots for each peptide are also depicted with median values denoted by times symbol at each time point (c)

Fig. 2

ELISPOT analysis was performed using PBMCs obtained at the indicated time points post-vaccination against hTERT 988Y, her2/neu 369V2V9, 689, and PADRE for patients on Arm 1 (a), and Arm 2 or a single low dose of cyclophosphamide prior to IDD-6 (b). Responses to PMA and ionomycin from 5 × 103 cells are also shown; note scale difference. Longitudinal analysis was performed at baseline (−4 weeks) and post-vaccination. Composite plots for each peptide are also depicted with median values denoted by times symbol at each time point (c)

Fig. 3

(a) Absolute neutrophil count (ANC), (b) absolute lymphocyte count (ALC), and (c) Treg count in peripheral blood for Arm 1 and Arm 2 patients at baseline and at days 21–60. The ANC and ALC were determined from CBC measurements. The Tregs were determined by flow cytometry performed on PBMC to quantify CD3+CD4+CD25+FoxP3+ cells. The first value post-treatment in the time window of day +21 to +60 is plotted

Fig. 4

Longitudinal analysis of (a) absolute neutrophil count (ANC), (b) absolute lymphocyte count (ALC), (c) Treg count in peripheral blood for Arm 1 and Arm 2 patients, and (d) longitudinal plots of individual Treg levels plotted as change from baseline in Arm 1 and Arm 2 patients. The individual patients are plotted as well as the mean values