Active Immunotherapy With Mitumprotimut-T (Favid (R), Id-Klh) Following Rituximab Induction In Patients (Pts) With, Follicular B-Cell Lymphoma (Fl): Progression Free Survival (Pfs) At 4-Year Follow Up

Abstract Background: We report here PFS with a 4-year follow-up of previously reported results from a Ph 2 trial in which both treatment-naïve (TN) and relapsed/refractory (R/R) pts with FL with stable disease (SD) or a clinical response (PR or CR/CRu) following 4 weekly doses of rituximab received mitumprotimut-T active immunotherapy (Koc et al, Blood, 2006; 108: #691). Treatment: Pts received rituximab (375 mg/m2 i.v. weekly × 4) and those with stable or responding disease assessed at Week 11 received mitumprotimut-T (1 mg sq monthly × 6) starting on Week 12 along with Leukine® (sargramostim, GM-CSF, 250 mcg, sq) on days 1-4. Pts continued to receive booster injections on a reduced schedule (every 2 months (mos) × 6, then quarterly) until disease progression. Radiological scans were performed every 3 mos for the first 2 years on study, then every 6 mos thereafter and reviewed centrally. Objective response and disease progression were assessed using modified IWG criteria. Results: 89 pts had ≥SD following rituximab and received mitumprotimut-T + Leukine, 54 R/R and 35 TN. There were 2 CRs and 40 PRs following rituximab for a pre mitumprotimut-T objective response rate (ORR) of 47%. The overall response for the combined treatment was 63% (18 CR, 38 PR). During the mitumprotimut-T treatment phase, 16 pts (9 TN, 7 RR) converted to CR/CRu. The following table presents PFS for all pts and patient subsets. Conclusion: These data show that 43% of all rituximab responders and 51% of TN rituximab responders remain in remission with 42 mos follow up. These results appear favorable when compared to published results of single-agent rituximab studies in pts with TN FL, where the reported 3-yr PFS are ∼20%, and suggest a clinical benefit to adding mitumprotimut-T to rituximab therapy. This hypothesis is being tested in an ongoing Ph 3 study of rituximab single agent vs. rituximab followed by mitumprotimut-T + GM-CSF. A total of 349 pts have been randomized and 78% are TN. An interim blinded analysis of response in the first 226 randomized pts showed an ORR of 70% with 47% of pts in CR/CRu (Freedman et al, Blood2006; 108:#2756). Subjects Progression-Free at: Group n 12 mos 24 mos 36 mos 42 mos All Efficacy-Evaluable Subjects 89 61% 38% 31% 29% Relapsed/Refractory Subjects 54 57% 31% 22% 19% Treatment-Naive Subjects 35 67% 48% 44% 44% All rituximab Responders 43 70% 50% 43% 43% Relapsed/Refractory Responders 19 63% 41% 33% 33% Treatment-Naive Responders 24 75% 57% 51% 51%