Final Results of Phase 1/1b Study of Tenalisib, Dual PI3K δ/γ Inhibitor in Patients with Relapsed/Refractory T-Cell Lymphoma

Abstract

Introduction: Tenalisib (RP6530) is a novel, highly specific, dual PI3K δ/γ inhibitor with nano-molar inhibitory potency at the enzyme and cellular level. PI3K plays a critical role in T-cell development and activation and several studies have validated the PI3K-AKT pathway as a potential therapeutic target in T cell lymphomas. Preliminary results of the ongoing Phase 1/1b T-cell lymphoma (TCL) study demonstrated an acceptable safety profile with encouraging clinical activity in relapsed/refractory TCL (Oki, ASCO 2018 and Iyer, ASH 2018). We now present the final results of the study (NCT02567656). Methods: This study comprised of four-dose escalation cohorts, followed by two dose expansion cohorts at MTD enrolling 20 patients each in PTCL and CTCL cohorts. Patients had histologically confirmed TCL, ECOG PS ≤2, and had received ≥1 prior therapy. Patients received Tenalisib [200 mg BID-800 mg BID (fasting), 800 mg (fed only)] orally until progression or unacceptable toxicity. The primary objectives were to determine the MTD and pharmacokinetic profile. The secondary objective was to evaluate overall response rate (ORR) and duration of response. Responses were evaluated for PTCL and CTCL based on IWG criteria (Cheson 2007) and mSWAT respectively. Adverse events were graded according to CTCAE v4.03. Results: Fifty-eight patients were enrolled in study, 19 in dose escalation and 39 in dose expansion (28 PTCL and 30 CTCL). Median number of prior therapies was 4 (range, 1-15). Safety assessment of 58 patients receiving at least one dose of Tenalisib demonstrated an acceptable safety profile. Treatment related Grade≥3 AEs were elevated ALT/AST (21%), rash (5%), and hypophosphatemia (3%). These events were reversible and managed by withholding study drug. Additionally, in few patients (N=9), steroids were used to manage elevated ALT/AST. There were six treatment related serious adverse events, none of these led to fatal outcome. At end of the study, four (3 CTCL; 1 PTCL) patients who completed minimum 8 cycles of therapy were rolled over to a compassionate use study (NCT03711604) and were followed up. Efficacy assessments demonstrated an ORR of 46% (3 CR and 13 PR) and clinical benefit rate (CR+PR+SD) of 77%. Subset efficacy analysis showed an ORR in PTCL of 47% (3 CR; 4 PR) and in CTCL of 45% (9 PR). The median time to initial response was 1.8 months and was similar in both sub-types. The overall median DOR was 4.91 months (range 0.9-26.6); in PTCL patients the DOR was 6.53 months, (range: 0.97-21.0) and 3.8 months (range: 1.67-25.67) in CTCL patients. In 3 PTCL patients who achieved CR, the median DOR was 19.5 months (range 7.5-21). Conclusion: Tenalisib demonstrated promising clinical activity and an improved safety profile in patients with relapsed/ refractory TCL. Currently, a phase I/II combination study to further evaluate safety and efficacy with romidepsin is ongoing in this target population. Disclosures Iyer: Arog: Research Funding; Bristol-Myers Squibb: Research Funding; Novartis: Research Funding; Seattle Genetics, Inc.: Research Funding; Genentech/Roche: Research Funding; Incyte: Research Funding. Zain:Spectrum: Consultancy; Seattle Genetics: Consultancy. Korman:Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Glaxo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Immune Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kyowa: Research Funding; Leo: Research Funding; Menlo: Research Funding; Merck: Research Funding; Novartis: Consultancy, Honoraria, Speakers Bureau; Pfizer: Research Funding; Principia: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Prothena: Research Funding; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Rhizen: Research Funding; Sun: Honoraria, Membership on an entity's Board of Directors or advisory committees; Syntimmune: Research Funding; UCB: Research Funding; Valeant: Honoraria, Membership on an entity's Board of Directors or advisory committees; Eli Lilly: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Dermira: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Routhu:Rhizen Pharmaceuticals S.A.: Employment. Barde:Rhizen Pharmaceuticals S.A.: Employment. Nair:Rhizen Pharmaceuticals S.A.: Employment. Huen:Galderma Inc: Research Funding; Glaxo Smith Kline Inc: Research Funding; Rhizen Pharmaceuticals: Research Funding; Innate Pharmaceuticals: Research Funding.