Abstract CT019: ASN003, a novel highly selective BRAF and PI3K dual inhibitor: Phase I PK/PD results in patients with advanced solid tumors

Abstract

Abstract Background RAS-RAF-MEK and PI3K-AKT-mTOR are two major pathways involved in tumor cell signaling and growth. Components of these pathways are frequently mutated in a broad range of tumors. ASN003 is a highly selective and potent (low nM IC50) inhibitor of BRAF and PI3K-α and -δ. ASN003 shows strong antitumor activity in tumor models harboring BRAF and PIK3CA mutations, and also in patient-derived xenograft (PDX) models that are resistant to selective BRAF and MEK inhibitors. Patients and Methods: Oral once-daily ASN003 is being evaluated for safety/tolerability and preliminary efficacy in eligible patients with advanced solid tumors using an accelerated dose titration design (Part A) and enrolling cohorts of patients diagnosed with melanoma, CRC, NSCLC and other solid tumors with a BRAF, PIK3CA mutations at MTD (Part B). Pharmacokinetic (PK) profile and the pharmacodynamic (PD) effects of ASN003 on tumor tissue biomarkers such as pERK and pS6 are being investigated in both parts of the study. Results: Patient accrual in Part A is ongoing. As of January 2018, fifteen eligible patients were enrolled in dose levels ranging from 10 - 400 mg QD and 400 mg BID. ASN003 has been well tolerated. Treatment-related adverse events (TRAEs) were mostly mild (G1) to moderate (G2). TRAEs include, rash (G3), hypersensitivity (G3) (n=1), diarrhea (G2) (n=1), hyperglycemia (G2) (n=1), rash maculo-papular (G2) (n=1), vomiting (G1) (n=3), nausea (G1) (n=2), hyperglycemia (G1) (n=2), and dry mouth/lips/skin, transient blurred vision, rash acneiform, ALT increase, cognitive disturbance and hyperkalemia. The PK profile showed dose-dependent increase in systemic exposure at steady state (Cmax up to 5,990 ng/mL, AUC0-T up to 110,000 ng.h/mL) and a half-life of 14-25 hours in general. Early evidence of biomarker changes in repeat biopsies, and clinical disease control have been observed. Conclusions: ASN003 is a novel small molecule, with uniquely selective and potent inhibition of BRAF, PI3K-α and -δ kinases. To date, ASN003 was well tolerated at doses up to 400 mg QD/BID and achieved good systemic exposure. Updated and detailed clinical safety/efficacy and PK/PD results will be presented. Citation Format: Drew Rasco, Nehal Lakhani, Ryan Sullivan, Monica Mita, Jaimini Shah, Helen Usansky, Sanjeeva Reddy, Niranjan S. Rao, Sarper Toker, Louis Denis, Keith Flaherty, Anthony Tolcher. ASN003, a novel highly selective BRAF and PI3K dual inhibitor: Phase I PK/PD results in patients with advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT019.