Survival update from a multicenter, randomized, phase III trial of vitespen versus observation as adjuvant therapy for renal cell carcinoma in patients at high risk of recurrence

Abstract

3009 Background: Vitespen (formerly HSPPC-96) is a novel, autologous, heat shock protein (gp96)-peptide complex vaccine. The survival registry is investigating long-term efficacy of vitespen in renal cell carcinoma (RCC) patients at high risk for recurrence postnephrectomy. Methods: Eligible patients were enrolled and active in Antigenics’ C-100–12 phase III protocol, with a last survival status of alive at study end. Patients randomized in C-100–12 (1:1, vitespen vs. observation) had AJCC stage I (T1b), II (≥5 cm; Fuhrman grade 3/4), stage III, or stage IV (M0) RCC, ≥25% clear cells, ECOG performance score 0/1 and ≥7 g viable tumor tissue for vaccine production. The registry's primary objective is to assess OS. Registry patients are contacted every 6 (no recurrence) or 3 (upon recurrence) m, for a total of 3 y from final C-100–12 data cutoff. Results: Upon C-100–12 termination, 513 of 728 patients were eligible for follow-up. Currently, 306/513 (60%) patients are in the registry database; 207 patients are being contacted. The cohort of 306 patients is well balanced by C-100–12 randomization arm: (59.8% vitespen, 59.5% observation). Formal statistical analyses are in process. Descriptively, updated OS data show a favorable trend in the vitespen arm vs. observation in all analysis sets, especially among patients with earlier-stage disease (stage I/II high grade; n = 118) or at intermediate risk for recurrence (stage I/II high grade, III T1, T2, T3a, low grade; n = 184 ), with 13/125 (10.4%) vs. 21/115 (18.3%), and 18/184 (9.8%) vs. 33/178 (18.5%) deaths reported in the vitespen and observation arms, respectively. Conclusions: The registry provides an opportunity to confirm whether the emerging survival advantage demonstrated at the data cutoff for the C-100–12 trial improves with prolonged follow-up. Formal statistical analyses are ongoing; data available to date show continuing signals of clinical benefit associated with vitespen treatment in patients with better prognostic factors. [Table: see text]