Active Immunotherapy with Mitumprotimut-T (FavId®, Id-KLH) Following Rituximab Induction in Patients (pts) with Follicular B-Cell Lymphoma (FL): Progression Free Survival (PFS) at 4-Year Follow Up

Background: We report here PFS with a 4-year follow-up of previously reported results from a Ph 2 trial in which both treatment-naive (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, Blood 2006; 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%