Erasca Inc. (NASDAQ:ERAS) saw its shares fall about 5% in after-hours trading Monday following the publication of early-stage clinical data for ERAS-0015, a candidate described by the company as a pan-RAS molecular glue. The information released reflects preliminary Phase 1 dose escalation findings from two ongoing studies: AURORAS-1 in the United States and JYP0015M101 in China, the latter sponsored by Joyo Pharmatech Co., Ltd.
The company reported response data in specified patient subsets. In individuals with KRAS G12X non-small cell lung cancer receiving ERAS-0015 at doses of 16-32 mg once daily in second-line or later settings, the unconfirmed overall response rate was 62%. In a comparable second-line cohort of patients with KRAS G12X pancreatic cancer treated at the same 16-32 mg once-daily dose range, the unconfirmed overall response rate was 40%.
Erasca described the investigational agent as generally well-tolerated through the available data cutoff points. Most adverse events were low-grade; no dose-limiting toxicities had been observed as of the cutoffs, and there were no discontinuations attributed to treatment-related adverse events. The company also provided preliminary observations on a combination regimen: ERAS-0015 administered alongside standard-of-care doses of panitumumab appeared to be feasible from a safety perspective, and one patient with metastatic colorectal cancer recorded an unconfirmed partial response.
Based on the dose escalation results, Erasca selected 24 mg and 32 mg once daily as the recommended doses for the upcoming expansion cohorts. The company also adjusted its projected timing for additional disclosures, narrowing the expected release window for select ERAS-0015 monotherapy dose expansion and combination dose escalation cohort data to the first half of 2027.
Data cutoffs for the reported analyses were April 4, 2026 for AURORAS-1 and February 27, 2026 for JYP0015M101. The preliminary nature of the results and the designation of responses as unconfirmed are notable qualifiers in the dataset the company shared.
Market reaction to early clinical readouts can be volatile; investors and observers will likely monitor forthcoming expansion and combination cohort data when disclosed in the first half of 2027.