A Phase Ib/II Study of Ibrutinib in Combination with Obinutuzumab-Gazyva As First-Line Treatment for Patients with Chronic Lymphocytic Leukemia > 65 Years Old or with Coexisting Conditions

Standard treatment for patients with chronic lymphocytic leukemia (CLL) is rapidly evolving and gradually has incorporated the combined use of monoclonal antibodies (mAbs) and targeted therapy with small molecules. Single agent Ibrutinib (Ibr), a first-in-class BTK inhibitor, is effective in previously untreated patients including those that are older than 65 or considered unfit to receive chemotherapy-based combinations. The complete response rate in patients receiving single agent Ibr is relatively low (overall response rate of 86% and complete response of 4% based on 2008 iwCLL criteria), though most patients have durable remissions. The combination of Ibr with mAbs like Obinutuzumab-Gazyva (G), a third-generation anti-CD20 mAb, can ameliorate the Ibr-induced lymphocytosis and increase the overall and complete response rates. Accordingly, we initiated an open-label phase Ib/II clinical study of Ibr in combination with G for first-line therapy of previous untreated pts with CLL. The study completed enrollment of 32 previously untreated patients with CLL. Patients received G administered based on FDA dosing recommendations for 6 cycles (28 days/cycle) and Ibr 420mg po (1-3 hours before starting G infusion), and daily for up to 3 years. All patients received prophylactic medications. Patients were assessed for response by 2008 iwCLL criteria two months after completion of G, as the primary efficacy endpoint. The median age of the patients was 65 (range: 46-78) years. 84% of the patients had a CIRS >6, 45% had a Rai stage III-IV and 19% had an ECOG performance ≤2. The median baseline absolute lymphocyte count (ALC) was 79x103/mm3(range: 1.4-412.4). Patients showed the following FISH/cytogenetic abnormalities: del(13q) in 55%, trisomy 12 in 23% and del(11q) in 19%. Only 2 (6%) of these patients showed del(17p). From the patients with IGVH mutational status available (n=17), 11 (65%) were unmutated (>98% homology). Most adverse events (AEs) were grade 1-2 (74%). Six patients (19%) had grade 1-2 G-infusion-related reaction (IRR) and only one patient (3%) showed grade 3 IRR (without the need for G discontinuation). We observed neutropenia (all grades: 52%, grade 3-4: 23%), thrombocytopenia (all grades: 71%, grade 3-4: 19%) and anemia (all grades: 26%). There were no cases of febrile neutropenia. Two patients (6%) had grade 1 bleeding (one patient with asymptomatic lower gastrointestinal bleeding and the second patient with epistaxis) that resolved spontaneously