Id/KLH Vaccine (FavId™) Following Treatment with Rituximab: An Analysis of Response Rate Improvement (RRI) and Time-to-Progression (TTP) in Follicular Lymphoma (FL).

Abstract

Abstract Background: Id/KLH vaccine (FavId) administered as a single agent has been associated with tumor regressions in patients with relapsed/refractory (RR) FL. B-cell depletion has been demonstrated to augment the T-cell immune response to subsequent vaccine administration in mice (Qin 1998 Nat Med 4:627). Objective: To evaluate the efficacy and safety of Id-KLH administered during the period of rituximab induced B-cell depletion. Eligibility: FL pts who were: treatment naïve (TN); RR following chemotherapy; or relapsed following rituximab. Treatment: Following rituximab (375mg/m2 i.v. weekly x 4) pts received Id-KLH (1 mg s.q. monthly x 6) starting on week 12. GM-CSF, 250 mcg, was administered s.q. at the Id-KLH injection site on days 1–4. Pts could continue Id-KLH until progression. Results: 103 pts received rituximab. Response to rituximab at month 3 was 35% (3-CR; 33-PR). Eleven (11) pts were PD following rituximab (11%). Id/KLH could not be made for 4 pts (4%). Eighty-eight (88) pts were begun on Id-KLH. Among the 45 RR pts, 32 (72%) have not progressed at a median follow-up of 12 months compared with 40% of historical control pts treated with rituximab alone (Witzig 2002 JCO 20:2453). Among the 43 TN pts, 82% have not progressed after a median follow-up of 9 months. RRI (SD to PR, PR to CR after month 3) was observed in 21 pts (12-SD to PR; 9-PR to CR). Robust T-cell responses to both Id and KLH were observed (3 of 3 pts tested). Anti-KLH antibody responses were generally not seen until B-cell recovery. The most frequent adverse event was an injection site reaction. A flu-like syndrome was also observed consistent with GM-CSF administration. Conclusion: Id/KLH vaccine (FavId), administered to pts with FL during a period of B-cell depletion induced by rituximab, can result in an anti-Id T-cell response, and appears to result in an RRI and an increased TTP compared to historical controls. A randomized, double-blind, placebo-controlled, Phase 3 trial of rituximab + FavId has been initiated.