Rxdx-101, an Oral Pan-Trk, Ros1, and Alk Inhibitor, in Patients with Advanced Solid Tumors with Relevant Molecular Alterations

Abstract

Aim: RXDX-101 is a small molecule inhibitor of TrkA, TrkB, TrkC, ROS1 and ALK, with high potency and selectivity. RXDX-101 demonstrated potent pharmacological activity in preclinical studies and is potentially first-in-class against the Trk family of kinases. This study aims to determine MTD, PD, PK and anti-tumor activity in patients with advanced cancer and applicable molecular alterations.Methods: Phase 1 dose escalation in patients with advanced solid tumors. RXDX-101 was dosed orally once/day in a 4 day on, 3 day off schedule for 3 weeks, followed by a 7 day rest period, in continuous 28-day cycles. Minimum of 3 patients were enrolled at each dose level. Endpoints include safety, PK, and tumor response by RECIST.Results: 19 patients have been treated at 6 dose levels (100, 200, 400, 800,1200 and 1600 mg/m2). RXDX-101 has been well tolerated to date; the MTD has not been reached. No DLT has been seen at any dose level. The most common AEs (mainly grade 1-2) considered possibly treatment-related included asthenia, paresthesias, nausea and diarrhea. Possibly related grade 3/4 AEs include asthenia and increased lipase. No treatment-related SAEs were observed. A patient with colorectal carcinoma (TrkA+) has a PR and is in cycle 2. Two patients with NSCLC (1 ROS1 + ; 1 ALK+) have also achieved PRs. An additional patient with neuroblastoma (ALK+) has a PR and is currently in cycle 16. Two patients have had prolonged stabilization of their disease and remain on treatment: a patient with NSCLC (ALK+) in cycle 14 and a patient with pancreatic cancer (ROS1+) in cycle 11. PK analysis shows maximum concentrations of RXDX-101 were generally achieved within 2 to 4 hours following dosing and exposure increased in an approximate dose proportional manner up to doses of 800 mg/M2 with minimal accumulation following multiple doses. Mean terminal half-life was 21- 32 hours and steady state reached within 4 days.Conclusions: RXDX-101 has been well tolerated in patients with advanced solid tumors. Early responses in patients with 3 different relevant molecular alterations are promising. PK profile seems suitable for once daily dosing, which is being evaluated. A global phase I/II trial was recently initiated.Disclosure: F.G.M. De Braud: Consultant or Advisory Roles Novartis Compensated Bristol-Myers Squibb; ompensated Roche Compensated Stock Ownership No Honoraria No Research Funding Yes; E. Ardini: Senior Scientist, Nerviano Medical Sciences Employee Compensated; M. Martignoni: CLIOSS Employee, Clinical Leader Compensated; A. Isacchi: Director, Nerviano Medical Sciences Compensated Employee; P. Pearson: Consultant Role Ignyta, Inc. Compensated Stock Ownership Ignyta, Inc.; D. Luo: Ignyta, Inc. Employee Sr. Director, Clinical Operations Compensated; J.L. Freddo: Consultant Role; Member Board of Directors Ignyta, Inc. Compensated Stock Ownership, Ignyta, Inc. Yes; S. Siena: Consultant or Advisory Role Amgen Compensated Bayer Compensated Celgene Compensated Sanofi Compensated Roche Compensated; tock Ownership No Research Funding Bayer. All other authors have declared no conflicts of interest.