TGR-1202, a Novel Once Daily PI3Kδ Inhibitor, Demonstrates Clinical Activity with a Favorable Safety Profile, Lacking Hepatotoxicity, in Patients with Chronic Lymphocytic Leukemia and B-Cell Lymphoma

Abstract Background: TGR-1202 is a novel oral, next generation PI3Kδ inhibitor which notably lacks the hepatotoxicity associated with other PI3Kδ inhibitors. Preliminary data from an ongoing Ph I study of TGR-1202 demonstrated clinical activity in patients with advanced hematologic malignancies (ASCO 2014). Herein we present updated results from this Phase I, first in human study of TGR-1202 in patients with relapsed and/or refractory CLL and B-cell lymphoma. Methods: TGR-1202 is administered orally once daily following a 3+3 dose escalation design. Previously treated patients with an ECOG PS ≤ 2 and confirmed diagnosis of B-cell non-Hodgkin lymphoma (NHL), chronic lymphocytic leukemia (CLL), or other lymphoproliferative disorders are eligible. Endpoints include safety, PK/PD, and efficacy. Results: 49 patients have been enrolled to date of various lymphoma subtypes including CLL, follicular lymphoma (FL), Hodgkin’s lymphoma (HL), DLBCL, mantle cell lymphoma (MCL), and marginal zone lymphoma (MZL). Demographics: 76% male, ECOG 0/1/2: 17/31/1, median age of 59 yrs (range: 22-85), median prior treatment regimens: 3 (range: 1-14), and 43% were refractory to prior treatment. 35 patients have been treated at doses ≥ 800 mg of a previous formulation where a threshold effect in activity was observed, and 6 have been treated with an improved micronized formulation (≥ 200 mg). TGR-1202 was well tolerated and no MTD has been reached to date. The only Gr≥3 AE occurring in >5% of patients was neutropenia (8%). AE’s of all grades occurring in >20% of patients were limited to diarrhea (24%), cough (22%), fatigue (20%), and nausea (20%). Notably, in comparison to other PI3Kδ inhibitors, no hepatotoxicity and no cases of colitis have been observed to date. Rates of infection and pneumonia have also been low (12% and 6%, respectively), and no cases of febrile neutropenia have been reported. Of the 41 patients treated at ≥ 800 mg of the previous formulation or with the micronized formulation, 32 are evaluable for efficacy (6 too early to evaluate, 2 non-compliant, 1 did not meet I/E criteria). Responses have been limited in patients with aggressive lymphoma and HL. Of the 9 evaluable CLL patients, 8 (89%) achieved a nodal PR (median nodal reduction of 71%), of which 5 achieved a PR per Hallek 2008 criteria with the remaining 4 having persistent lymphocytosis. The 1 CLL patient with SD had a >40% nodal reduction and remains on study. Of the 7 evaluable FL patients, all have shown clinical benefit with a reduction in tumor burden with 2 having achieved a PR, and the remaining 5 patients in SD. Additionally 2 MZL patients each achieved SD with >25% nodal reductions and remain on study. Notably, no patient with CLL or indolent lymphoma (FL & MZL) treated at ≥800 mg has progressed to date (median time on study of 20 weeks, range 6 – 73+), and no patient who achieved >50% reduction in tumor burden (including patients with CLL, FL, and HL) has progressed, with median time on study of 34 weeks (range 7 – 68+). Pharmacodynamic analysis in CLL patients indicates rapid suppression of pAKT at doses of 400 mg QD of the previous formulation. Conclusions: TGR-1202 is well tolerated in patients with relapsed and/or refractory hematologic malignancies with no reported hepatotoxicity or events of colitis and promising clinical activity. Enrollment continues in expansion cohorts and with the micronized formulation. Disclosures Brander: Celgene: Mentor received research funding Other. O'Connor:Celgene: Consultancy; Millennium Pharmaceuticals: Consultancy. Miskin:TG Therapeutics, Inc.: Employment, Equity Ownership. Sportelli:TG Therapeutics: Employment, Equity Ownership. Vakkalanka:Rhizen: Employment, Equity Ownership. Flinn:Infinity Pharmaceuticals: Consultancy.