Erasca (ERAS) shares fell 48% Tuesday after the company reported preliminary phase 1 dose-escalation data for its experimental ERAS-0015 in patients with RAS-mutant solid tumors, including colorectal cancer, non-small-cell lung cancer and pancreatic adenocarcinoma.

The preliminary data, from ongoing trials in the US and China, suggest ERAS-0015 may be combined with standard-of-care doses of panitumumab, positioning it as a potential backbone therapy for future combination regimens, the company said.

The therapy was generally "well tolerated," with no dose-limiting toxicities or treatment discontinuations due to adverse events, according to a statement.

Erasca said it selected 24 mg and 32 mg once daily as recommended doses for further study and said the drug showed "promising clinical potential" for combination use with panitumumab.

In a regulatory filing, the company said a patient, who was a 66 year-old male with heavily pretreated metastatic pancreatic adenocarcinoma, had died. The company said grade 3 treatment-related adverse events of pneumonitis progressed to grade 5 following withdrawal of supportive care per patient decision.

Price: 9.96, Change: -9.20, Percent Change: -48.02