Chemotherapy-Free Combination of Obinutuzumab and Ibrutinib in First LINE Treatment of Follicular Lymphoma. the Alternative Study By the German Low Grade Lymphoma Study Group (GLSG)

Background: The clinical course of follicular lymphoma (FL) is characterized by a slow progression over years with continuous relapses despite good response to initial treatment. The median overall survival is 10 to more than 15 years. Standard therapy for patients requiring treatment consists of an anti-CD 20 antibody combined with chemotherapy followed by antibody maintenance. With this combination a 1-year-PFS of 93% was seen in the GLSG-2000 trial (Hiddemann et al, Blood 2005). Because of the substantial side effects of chemotherapy such as infections, secondary malignancies and impairment of the stem cell reserve novel “chemotherapy-free” treatment approaches could substantially improve the treatment tolerability in FL. The BTK-inhibitor ibrutinib has demonstrated promising activity in patients with iNHL, CLL and MCL. Anticipating the recent reports on a superior activity of obinutuzumab as compared to rituximab in the GALLIUM trial (Marcus et al., NEJM 2017), the GLSG initiated a phase II study combining ibrutinib and obinutuzumab to explore the efficacy and safety of this “chemotherapy-free” alternative. Methods: ALTERNATIVE is a prospective multicenter single-arm phase 2 study of the combination of ibrutinib and obinutuzumab in 98 patients with previously untreated FL and a high tumor burden (defined by modified GELF criteria) in need of treatment. Induction comprises 6 cycles of obinutuzumab at a dose of 1000 mg by intravenous infusion on days 1, 8, 15 of cycle 1 and on day 1 of cycles 2-6 to be given every 21 days. Ibrutinib is administered orally at a dose of 560 mg once daily throughout all 6 cycles. In patients with at least partial response (defined by Cheson Response Criteria 2007) after the end of induction, maintenance with obinutuzumab (1000mg every 8 weeks) plus ibrutinib (560mg daily) is given for an additional 24 months. In patients remaining MRD positive at 30 months ibrutinib is continued for another 12 months in an extended maintenance setting without obinutuzumab. The primary efficacy endpoint is the rate of investigator-assessed PFS one year after registration. Response rates at end of induction, after one year and after end of maintenance, duration of response, percentage of progression during induction and maintenance, time to treatment failure, overall survival, duration of molecular remission in MRD negative patients and safety are key secondary endpoints. Results: 98 patients with advanced stage FL were included, The median a