Final follow up survey of the randomized Pbo-controlled study of oregovomab (Ov) as a consolidation treatment for advanced ovarian cancer (OC): Insights into surveillance approaches

5079 Background: Ov is a monoclonal antibody specific for CA125 currently in two phase III studies as a consolidation immunotherapy for OC. A five year outcome follow up for patients participating in the prior randomized phase II study used to design the current pivotal trials has been completed. An assessment of survival post relapse (SPR) as a function of identifiable risk factors, and implications for long term survival survey methodology were reviewed. Methods: OC patients with no evaluable disease post front-line chemotherapy were randomized to IV infusions of OV or Pbo Q4 wks × 3, then Q12 wks. At relapse, therapy was stopped and second-line Rx was initiated without restriction. All patients were surveyed quarterly for long term outcomes for a pre-specified 5 years from initial randomization. A Kaplan-Meier (KM) analysis of overall survival and Cox multivariate analysis of SPR was completed. Results: 145 randomized participants were followed, including 67 designated as the successful front-line (SFLT) subpopulation identified to have characteristics favorable for intervention with immunotherapy (basis of ongoing phase III program). At five years, 47% of Ov (n = 73) and 37% of Pbo (n = 72) patients were alive overall, and 56% of Ov (n = 34) and 32% of Pbo (n = 33) were alive in the SFLT population. KM estimates of median survival are 57.5 mo [44.5-non-estimable (ne)] for Ov and 48.6 mo [30.9-ne] for Pbo in the overall population and ne mo [50.5-ne] for Ov and 48.6 mo [24-ne] for Pbo (p = 0.11) in the subpopulation. For relapsed patients, improved survival post relapse was most associated (Cox regression p < 0.10) with lower CA125 velocity at relapse, treatment (Ov), and longer time to relapse. Conclusions: Survival data was consistent with previously reported time to relapse data in this study. For the SFLT, the 5 yr duration of survival survey and sample size were insufficient for a definitive outcome. However, results support the hypothesis that treatment with OvaRex may provide clinical benefit. The ongoing phase III studies will include a 10 year survival survey of 354 patients to definitively assess the impact of this treatment on long term survival. [Table: see text]