Effect of adding ublituximab to ibrutinib on PFS, ORR, and MRD negativity in previously treated high-risk chronic lymphocytic leukemia: Final results of the GENUINE phase III study.

Abstract

8022 Background: The BTK inhibitor ibrutinib (IB) has advanced the treatment for patients (pts) with CLL, however, among pts with high-risk CLL, disease control with IB is less durable. Ublituximab (UTX) is a glycoengineered mAb with enhanced ADCC. The GENUINE study evaluated the addition of UTX to IB vs. IB alone in high-risk rel/ref CLL. With a median follow up now 3.5+ yrs, we present the final results. Methods: Eligible pts having rel/ref CLL with centrally confirmed del17p, del11q, and/or a TP53 mutation, were randomized 1:1 to IB (420 mg QD) alone or with UTX (900 mg on D1, 8, 15 of Cy 1, D1 of Cy 2-6, and Q3 Cy thereafter). No limit on # of prior Tx; prior IB excluded. Primary endpoint was overall response rate (ORR) by iwCLL 2008 (excludes PR-L); secondary endpoints were CR rate, peripheral blood MRD negativity (analyzed centrally), PFS, and safety. Response was by blinded independent review. Results: 117 pts were treated (59 in UTX + IB arm; 58 in IB arm). Med age was 66 yrs and med # of prior Tx was 1 (range 1-5) for each arm. Baseline features were relatively balanced including ECOG, gender, and med time since diagnosis (6+ yrs). 17p del was greater in the IB arm (50% vs 44%); bulky disease was greater in UTX + IB arm (47% vs 28%); IGHV-unmut was 83% for both arms. At data-cutoff of Sep 1, 2019, AEs were comparable between the arms, except infusion reactions (UTX + IB: All G 53% / G 3/4 3%) and neutropenia (All G 36% vs 21%, G 3/4 19% vs. 12%) which were higher for UTX + IB. At a med follow up of 42 mos, all efficacy endpoints were in favor of UTX + IB (see Table). Conclusions: In contrast to prior studies adding rituximab to IB, GENUINE is the first randomized trial to demonstrate a PFS benefit with the addition of an anti-CD20 to IB. Increasing depth of response (CR rate, MRD-neg) post first year of Tx supports maintenance therapy with UTX. Clinical trial information: NCT02301156 . [Table: see text]