Survival rates among patients vaccinated following resection of colorectal cancer metastases in a phase II randomized study compared with contemporary controls.
3557 Background: Patients with completely resected metastases from colorectal cancer (CRC) remain at high risk of recurrence and death despite adjuvant chemotherapy. Recently, survival of prostate cancer patients was enhanced by antigen-presenting cell therapy. We investigated whether administration of an antigen-presenting cell vaccine based on dendritic cells (DC) after metastasectomy would reduce the risk of recurrence and increase survival.Patients (n=74) with no evidence of disease after resection of CRC metastases and completion of their physician-determined peri-operative chemotherapy were randomized 1:1 to four immunizations with: DC modified with the PANVAC-VF poxvectors encoding CEA, MUC1, CD54, CD58, and CD80 or the PANVAC-VF poxvectors along with GM-CSF at the injection site. We report recurrence-free survival (RFS) at 2 years and overall survival (OS). CEA specific T cell responses were measured by ELISPOT. Data from a prospectively registered, comparable, contemporary control group of patients who had undergone metastasectomy for CRC were also available.The arms of the study and contemporary controls were well balanced. The majority of the toxicities for the DC and PANVAC arms respectively were grade 1, 2 injection site reactions (63% versus 64%), low grade fevers (17% vs 31%), myalgia (11% vs 11%), and fatigue (26% vs 34%). The two year RFS was similar in all groups (50, 56 and 55% for the DC arm, the PANVAC arm and the contemporary control group, respectively). However, there was a trend for improved RFS among patients with CEA-specific T cell responses (log rank p = 0.10). At a median follow-up of 40 months, 2 of 37 patients treated with DC and 5 of 37 treated with PANVAC alone have died, with a combined survival rate exceeding that of the unvaccinated control patients.Patients vaccinated after metastasectomy experienced a longer survival relative to contemporary controls. A phase III study of OS comparing patients vaccinated after resection with the DC vaccine and observation is warranted.
Morse, M; Niedzwiecki, D; Marshall, J; Garrett, CR; Chang, DZ; Aklilu, M; Crocenzi, TS; Cole, DJ; Dessureault, S; Hobeika, A; Osada, T; Clary, BM; Hsu, SD; Devi, G; Bulusu, A; Annechiarico, R; Chadaram, V; Clay, TM; Lyerly, HK
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