Ublituximab + TGR-1202 Demonstrates Activity and a Favorable Safety Profile in Relapsed/Refractory B-Cell NHL and High-Risk CLL: Phase I Results

Introduction: Ublituximab (UTX) is a novel anti-CD20 mAb that has been glycoengineered for enhanced ADCC.  TGR-1202 is a novel once daily oral PI3Kδ inhibitor with clinical activity in B-cell lymphoma and a notably differentiated tolerability profile compared to similar agents.  The combination of UTX + TGR-1202 showed strong synergistic activity in-vitro(Lugano 2013).  Herein we report the results from the Phase 1 (dose-escalation) and updated results from the Phase Ib (dose-expansion) evaluating the safety and efficacy of the combination of UTX + TGR-1202 in patients (pts) with heavily pre-treated rel/ref NHL and CLL. 

Methods:  A 3+3 design was utilized with rel/ref NHL and CLL pts accruing independently and no limit on the number or type of prior therapies.  Patients refractory to prior PI3K or BTK inhibitors were eligible.  UTX was administered D1, 8, 15 of Cyc 1 & 2, followed by D1 of Cyc 4, 6, 9 & 12.  TGR-1202 was administered orally once-daily starting on D1 of Cyc 1.  Primary endpoints: Safety and dose limiting toxicities (DLT).  Secondary endpoints: Efficacy (ORR, CR rate). 

Results: 56 patients have been enrolled to date and are evaluable for safety: 16 CLL/SLL, 16 FL, 16 DLBCL, 5 MZL, 2 MCL and 1 Richter’s transformation.  Med age 64 yo (range 29-86); 37 M/19 F; median # prior treatment regimens = 3 (range 1-9).  Day 1 infusion reactions (2% G 3/4), neutropenia (23% G 3/4), diarrhea (2% G 3/4), and nausea (0% G 3/4) were the most commonly reported adverse events considered at least possibly related to either study drug.  One patient (CLL cohort 1) with baseline Gr 3 neutropenia at study entry worsened to Gr 4 resulting in a dose delay which necessitated enrollment of an additional 3 pts at that dose level.  Dose escalation continued into all planned subsequent NHL and CLL cohorts (up to 1200 mg).  No MTD was observed in the Phase I portion and subtype specific expansion cohorts (Phase Ib) with 800 and 1200 mg dose of micronized TGR-1202 followed.   Activity was observed at all dose levels; however a possible dose-response relationship was observed with TGR-1202 at higher doses compared to the lower doses.  Of the 37 evaluable pts treated at the higher doses of TGR-1202 (1200 mg original formulation or > 600 mg micronized), overall response was as follows:  CLL/SLL (5/7); FL/MZL (10/15); DLBCL (5/12); MCL (0/2) and Richter’s (1/1).  No CLL pts progressed at the first efficacy assessment, despite 4/5 having high-risk cytogenetics.  Two CLL pts with SD include a 17p del, ibrutinib refractory patient who eventually progressed on treatment and the other remains on study awaiting future assessments.  Of interest, 7 of the DLBCL pts were GCB subtype of which 71% were rituximab refractory, with 3/7 achieving an objective response, 2 remaining in stable disease (4+ and 5+ mos each), and 2 having progressed to date (avg time on study 7 mos, range 2 – 16+ mos).

Conclusions: The combination of UTX + TGR-1202 is active and well tolerated in pts with both indolent and aggressive rel/ref NHL and CLL.  The Phase I portion is complete and enrollment remains open in expansion cohorts for CLL, FL/MZL and DLBCL pts evaluating TGR-1202 micronized doses at 800 to 1200 mg in combination with UTX.  Given the favorable safety profile and clinical activity observed, Phase 3 programs are planned with UTX + TGR-1202.