Phase 1 Study Of The Novel Pan-Pim Kinase Inhibitor LGH447 In Patients With Relapsed/ Refractory Multiple Myeloma
Authors: Raab Marc S , Ocio Enrique M. , Thomas Sheeba K. , Günther Andreas , Lebovic Daniel , Kumar Shaji K , Jakubowiak Andrzej J. , Song Dongweon , Xiang Fang , Hynds David , Vanasse K. Gary , Goh Yeow Tee 
Published: October 2019

Abstract

Background
LGH447 is a novel, specific pan-Pim kinase inhibitor in development for the treatment of patients with multiple myeloma (MM) and other hematologic malignancies. The PIM kinase gene family encodes 3 serine/threonine protein kinases that have roles in cell cycle progression and survival. In human disease, elevated levels of Pim1 and Pim2 are associated with hematologic malignancies, with MM showing the highest level of Pim2 expression. In preclinical studies, a majority of MM cell lines proved sensitive in vitro to LGH447-mediated Pim inhibition, exhibiting a dose-dependent decrease in cell proliferation. Furthermore, LGH447 was well tolerated and demonstrated significant inhibition of tumor growth in xenograft mouse models of MM as compared with control animals, supporting the clinical development of LGH447 in MM patients.

Methods
Patients with relapsed/refractory MM for whom no effective treatment options exist were enrolled on this first-in-human, multicenter, open-label phase 1 dose-escalation study (CLGH447X2101). Escalating doses of single-agent LGH447 were administered orally on a continuous daily dosing schedule. Treatment continued until disease progression, unacceptable toxicity, consent withdrawal, or death. The primary objective was to estimate the maximum tolerated dose (MTD) of LGH447 administered as a single agent, orally, once daily. Secondary objectives included assessing the safety, tolerability, preliminary antimyeloma activity, and pharmacokinetic (PK) profiles of LGH447. Dose escalation followed a Bayesian logistic regression model based on dose-limiting toxicities (DLTs) occurring in cycle 1. Adverse events (AEs) were graded according to National Cancer Institute-Common Terminology Criteria for Adverse Events v4.03. Efficacy assessments were made by investigators according to International Myeloma Working Group (IMWG) uniform response criteria with modifications. Following determination of the MTD for LGH447, additional patients will be enrolled in an expansion cohort to further characterize the safety and tolerability profile of LGH447.

Results
At the data cutoff, 19 patients have been treated at the following doses: 70 mg (n = 5), 150 mg (n = 6), 200 mg (n = 4), 250 mg (n = 4), with enrollment ongoing in dose escalation. Median age was 66 years (range, 41-75 years). Most patients (94.7%) presented with baseline Eastern Cooperative Oncology Group performance status 0-1. Most patients (73.7%) had received ≥ 2 prior regimens (median 4; range, 1-11), 89.5% had received prior bortezomib, and 84.2% had received prior lenalidomide and/or thalidomide (68.4% and 47.4%, respectively). Ten patients are ongoing at doses between 150-250 mg, with a median duration of exposure of 6 weeks (range, 1-26.6 weeks), and 9 patients discontinued (disease progression [n = 6], AEs [n = 2], withdrawal of consent [n = 1]). There was 1 DLT consisting of grade 3 thrombocytopenia at the 200 mg dose level and no reported suspected unexpected serious AEs. The majority of AEs regardless of study drug relationship were grade 1/2. Most common grade 3/4 AEs were thrombocytopenia (31.6%), anemia (21.1%), and neutropenia (15.8%). No deaths have occurred on study. LGH447 displayed time-dependent PK with a 3- to 6-fold accumulation from day 1 to steady state (day 14). After a single oral dose, area under the curve and maximum concentration increased somewhat more than in proportion to the dose from 70 to 250 mg. Evidence of single-agent activity, as determined by investigators using IMWG criteria, has been seen in multiple patients, with best response to date being a very good partial response (VGPR).

Conclusion
In heavily treated patients with relapsed/refractory MM, LGH447 was generally well tolerated and exhibited evidence of single-agent efficacy in multiple patients, validating Pim kinase inhibition as a promising therapeutic rationale and supporting its further clinical development in patients with MM and other hematologic malignancies. Dose escalation is ongoing and updated results will be presented.

Disclosures:
Ocio: BMS: Consultancy; Arry-520: Consultancy; Pharmamar: Research Funding; Celgene: Honoraria, Research Funding; Onyx: Consultancy, Research Funding; Novartis: Honoraria. Thomas:Novartis: Research Funding; Celgene: Research Funding; Immunomedics: Research Funding; Pharmacyclics: Membership on an entity’s Board of Directors or advisory committees; Onyx: Membership on an entity’s Board of Directors or advisory committees; Millenium: Research Funding. Günther:Novartis: Consultancy, Research Funding. Lebovic:Celgene: Speakers Bureau; Allos/Spectrum: Speakers Bureau; Genentech: Speakers Bureau; Onyx: Speakers Bureau. Kumar:Onyx: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding. Jakubowiak:Onyx: Consultancy, Honoraria, Speakers Bureau; Millennium: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria. Song:Novartis: Employment. Xiang:Novartis: Employment. Hynds:Novartis: Employment. Vanasse:Novartis: Employment. Goh:Jannsen: Research Funding; BMS: Membership on an entity’s Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Hospira: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding.