Abstract CT184: Preliminary dose escalation results of ERAS-601 in combination with cetuximab in FLAGSHP-1: a phase I study of ERAS-601, a potent and selective SHP2 inhibitor, in patients with previously treated advanced or metastatic solid tumors

Abstract

Abstract Background: SHP2 is an oncogenic tyrosine phosphatase that transduces receptor tyrosine kinase signaling to the RAS/MAPK pathway via its phosphatase-mediated regulation of guanine nucleotide exchange factors. ERAS-601 is a potent, selective, and orally bioavailable allosteric inhibitor of SHP2. In combination with cetuximab, an antibody that targets epidermal growth factor receptor (EGFR), ERAS-601 has demonstrated robust nonclinical activity in human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) and RAS/RAF wild-type colorectal cancer (CRC) tumors. Method: FLAGSHP-1 is the first-in-human trial of ERAS-601 administered as monotherapy and in combination with other cancer therapies in patients with advanced or metastatic solid tumors. The primary objectives are to characterize the safety profile, determine the maximum tolerated dose (MTD)/recommended dose (RD), and characterize the pharmacokinetics (PK) profile of ERAS-601 as a monotherapy and in combination with other cancer therapies. Secondary objectives include tolerability and antitumor activity in solid tumors. Presented here are results from the combination dose escalation cohorts in which patients received ERAS-601 twice a day for three weeks followed by a one-week break (BID 3/1) in combination with cetuximab (500mg/m2) administered every 2 weeks (Q2W) on a 28-day cycle. Results: As of October 31, 2022, a total of 15 patients with previously treated advanced or metastatic solid tumors received ERAS-601 BID 3/1 at the following dose levels: 20 mg BID 3/1 (n=4), 40 mg BID 3/1 (n=8), or 60 mg BID 3/1 (n=3) in combination with cetuximab. Combination therapy MTD was determined​ to be 40 mg BID 3/1. ERAS-601 Treatment Related Adverse Events (TRAEs) at or below the MTD were all Grade 1 and 2. TRAEs occurring in ≥20% of patients included diarrhea (27%), AST increase (27%), ALT increase (20%), dermatitis acneiform (20%). Grade ≥3 TRAEs included Grade 4 hypokalaemia, Grade 3 diarrhea, platelet count decreased anemia (each 7%); high grade TRAEs were only observed at 60 mg BID 3/1 (above the MTD). Dose limiting toxicities (DLTs) were only observed at the 60mg BID 3/1 dose levels and included Grade 3 platelet count decreased (n=1) and Grade 4 hypokalemia (n=1). Pharmacokinetics of ERAS-601 and cetuximab in combination were generally comparable to historical monotherapy PK values, suggesting lack of drug-drug interaction. The evaluation of clinical activity is still ongoing. Conclusions: ERAS-601 in combination with cetuximab in patients with previously treated advanced or metastatic solid tumors shows promising preliminary safety and tolerability with reversible and manageable TRAEs. Further evaluation in relevant tumor types are ongoing. Citation Format: Meredith McKean, Ezra Rosen, Minal Barve, Tarek Meniawy, Judy Wang, David S. Hong, Jennifer Yang, Zhengrong Li, Roxana Picard, Les Brail, Daniela Vecchio, Thomas John, Ezra Cohen, Gregory Obara, Aparna Parikh. Preliminary dose escalation results of ERAS-601 in combination with cetuximab in FLAGSHP-1: a phase I study of ERAS-601, a potent and selective SHP2 inhibitor, in patients with previously treated advanced or metastatic solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT184.