IBCL-203: Umbralisib, a PI3Kδ/CK1ε Dual Inhibitor Demonstrates Marked Clinical Activity in Patients with Relapsed or Refractory Indolent Non-Hodgkin Lymphoma (iNHL): Results from the Phase 2 Global UNITY-NHL Trial

Background Umbralisib is an oral, once-daily inhibitor of PI3Kδ and CK1e that is highly selective for the delta isoform. The UNITY-NHL trial (NCT02793583) is a multicenter, open-label, Phase 2b study evaluating umbralisib in previously treated NHL patients. Herein, we present results from the UNITY-NHL study. Methods 208 patients with R/R marginal zone, follicular, or small lymphocytic lymphoma (MZL, FL, SLL) unresponsive to prior treatments (≥1 MZL; ≥2 FL/SLL), including ≥1 anti-CD20–based therapy, were administered umbralisib 800mg orally once-daily until disease progression, unacceptable toxicity, or study withdrawal. The primary endpoint of the study was overall response rate (ORR) as assessed by an independent review committee, according to the revised IWG criteria. Results At a median follow up of 27.8 months, MZL patients (n=69) had an ORR of 49.3% (95% CI 37.0% - 61.6%) with 15.9% achieving a complete response (CR), and a Disease Control Rate (DCR: CR+PR+SD) of 82.6%. Median time-to-response (TTR): 2.8 months (95% CI 2.7 - 2.9). No patient who achieved CR has progressed to date. At a median follow up of 27.5 months, FL patients (n=117) had an ORR of 45.3% (95% CI 36.1% - 54.8%) with 5.1% achieving a CR, and a DCR of 79.5%. Median TTR: 4.6 months (95% CI 3.0 - 5.6). At a median follow up of 29.3 months, SLL patients (n=22) had an ORR of 50.0% (95% CI 28.2 - 71.8) with 4.5% achieving a CR, and a DCR of 86.4%. Median TTR: 2.7 months (95% CI 2.4 - 2.8). At least one grade ≥3 treatment-emergent adverse event (TEAE) was reported in 53.4% of patients. TEAEs led to umbralisib discontinuation in 32 patients (15.4%). Grade ≥3 TEAEs reported in ≥10% of patients: neutropenia (11.5%) and diarrhea (10.1%). Increased ALT/AST (grade ≥3) occurred in 6.7%/7.2% of patients. Conclusions Umbralisib achieved meaningful clinical activity in a heavily pretreated iNHL population. The safety profile was manageable, with a relatively low incidence of immune-mediated toxicities and AE-related discontinuations. These results suggest umbralisib has a favorable benefit-risk profile in this patient population and have supported the Accelerated Approval of umbralisib in previously treated MZL and FL patients.