A phase I, open-label, dose-escalation trial of BI 1701963 as monotherapy and in combination with trametinib in patients with KRAS mutated advanced or metastatic solid tumors.

Abstract

TPS3651 Background: Activating mutations of KRAS drive many types of cancer. Activation of KRAS relies on guanine nucleotide exchange factors, such as SOS1, to mediate exchange of GDP for GTP. BI 1701963 is a small-molecule protein–protein interaction inhibitor that prevents the interaction between KRAS and SOS. Binding of BI 1701963 to the catalytic site of SOS1 inhibits binding of SOS1 to RAS–GDP, thereby hindering the exchange from RAS–GDP (inactive form) to RAS–GTP (active form). In preclinical studies this has been shown to lead to cytostasis in cancer cells addicted to KRAS signaling. Methods: NCT04111458 is a first-in-human trial of BI 1701963 in patients aged ≥18 years with tumors harboring KRAS mutations. Primary objectives are to determine the maximum tolerated dose (MTD) and recommended Phase II dose of BI 1701963 as monotherapy and in combination with trametinib, based on dose-limiting toxicities (DLTs). Secondary objectives are to evaluate safety, tolerability, pharmacokinetics/-dynamics and preliminary efficacy. The study will have two arms (mono- and combination therapy), and be divided into dose escalation (Part A), confirmation (Part B) and expansion (Part C, combination only) phases. Inclusion criteria include activating KRAS mutation, ≥1 evaluable lesion (RECIST 1.1), ECOG PS ≤1 and adequate organ function. Exclusion criteria include history of: RAS, MAPK or SOS1 targeting therapies; retinal vein occlusion; retinal pigment epithelial detachment; and decreased cardiac function. Parts B and C will be conducted in patients with advanced NSCLC. Treatment will continue until confirmed clinical benefit, defined toxicities, or withdrawal of consent. The primary endpoints are: Part A, the MTD, and the number of patients with DLTs during Cycle 1; Part B (monotherapy), the number of patients with DLTs; Part C, objective response (OR, RECIST 1.1). Starting doses of BI 1701963 in Part A will be 50 mg once daily (QD) orally (monotherapy) and 100 mg QD (combination, once proved safe as monotherapy) and will be escalated until the MTD is reached. The starting dose of trametinib will be 1 mg QD, escalated to the MTD or a max. of 2 mg QD. Dose cohorts will include ≥3 patients, with two therapeutic relevant doses (TRDs) established in each arm. In Part B, patients will be randomized to groups receiving one of the TRDs. If an OR is observed at a TRD in the combination arm, additional patients will be recruited into expansion cohorts receiving the relevant dose. As of Feb 11, 2020 three patients have been treated. Clinical trial information: NCT04111458 .