Abstract CT242: KRYSTAL-16: A phase I/Ib trial of adagrasib (MRTX849) in combination with palbociclib in patients with advanced solid tumors with KRASG12C mutation
Authors: Sommerhalder David , Thevathasan Jeena , Ianopulos Xenophon , Volinn Weining , Hong David 
Published: June 2022

Background: KRAS is a key mediator of the RAS/MAPK signaling cascade and promotes cellular growth and proliferation. It is the most frequently mutated oncogene in cancer, and KRASG12C mutations occur in 3-4% of colorectal cancers (CRC) and in up to 14% of non-small-cell lung cancers (NSCLC). The investigational agent adagrasib, a potent, covalent inhibitor of KRASG12C, irreversibly and selectively binds to KRASG12C and locks it in its inactive state. Adagrasib was optimized for favorable pharmacokinetic (PK) properties, including long half-life (~24 h), dose-dependent PK, and central nervous system penetration. Initial results have shown encouraging antitumor activity and tolerability of adagrasib monotherapy or combination therapy in patients with CRC or NSCLC harboring KRASG12C mutations. Cyclin D1 and cyclin-dependent kinases (CDK) 4 and 6 are downstream of signaling pathways that lead to cellular proliferation. Palbociclib, a CDK4/6 inhibitor, disrupts cancer cell proliferation by inducing cell cycle arrest by preventing the G1 to S phase transition. Preclinical data in KRASG12C mouse models suggest enhanced antitumor activity when combining adagrasib and palbociclib compared with either agent as a monotherapy.

Trial Design: KRYSTAL-16 (NCT05178888) is a multicenter phase I/Ib trial evaluating the safety, PK, pharmacodynamics, and preliminary clinical activity of adagrasib in combination with palbociclib in patients with solid tumors harboring a KRASG12C mutation previously treated with at least 1 standard therapy. The first stage of the trial will comprise a PK lead-in to evaluate potential drug-drug interactions. Exploration of the dose and regimen will continue for the combination of adagrasib (starting dose 400 mg BID) and palbociclib, with expansion cohorts implemented as applicable to further evaluate the safety and preliminary clinical activity of the combination. Decisions regarding dose escalation, expansion, or de-escalation will be determined using the modified Toxicity Probability Interval (mTPI-2) design. Study endpoints include safety, maximum tolerated dose (MTD) and/or recommended Phase II combination dose regimen (RP2D), plasma PK parameters, and preliminary clinical activity (objective response rate [RECIST v1.1], duration of response, progression-free survival, and overall survival). Patients will receive treatment until disease progression, unacceptable adverse events, patient withdrawal, or death. This study will be enrolling at sites in the United States.

Citation Format: David Sommerhalder, Jeena Thevathasan, Xenophon Ianopulos, Weining Volinn, David Hong. KRYSTAL-16: A phase I/Ib trial of adagrasib (MRTX849) in combination with palbociclib in patients with advanced solid tumors with KRASG12C mutation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT242.