Erasca Faces Patent Lawsuit and Clinical Setbacks Amid Pancreatic-Cancer Race

On April 24, Revolution Medicines sent Erasca a formal letter alleging that Erasca’s RAS-inhibitor ERAS-0015 is “substantially equivalent” to formulations covered by Revolution’s U.S. Patent No. 12,409,225 and therefore infringes the patent and the doctrine of equivalents. The letter also claimed a third party misappropriated Revolution trade secrets and demanded that Erasca immediately cease all U.S. making, using, offering for sale, selling, and importation of ERAS-0015, except where protected by regulatory safe-harbor provisions.

Erasca (ERAS) Stock Crashes 50% After Patient Death in Cancer Drug TrialBioSpaceBenzingaErasca Reports Promising Early Results in Pancreatic and Lung Cancer Therapy TrialErasca shares sink after patient death in early-stage cancer drug trial

Erasca released Phase 1 dose-escalation results for ERAS-0015 in RAS-mutant solid tumours. In 14 evaluable patients, all showed at least a 75 % reduction in KRAS G12X variant-allele fraction, with five achieving complete (100 %) reduction. Reported overall response rates (ORR) were 62 % in advanced non-small-cell lung cancer (NSCLC) and 40 % in pancreatic ductal adenocarcinoma (PDAC).

Erasca Reports Promising Early Results in Pancreatic and Lung Cancer Therapy Trial

Revolution’s Phase 3 data for its candidate daraxonrasib in PDAC showed a median overall survival of 13.2 months versus 6.7 months for chemotherapy, and a confirmed ORR of 38 % in a 2025 non-small-cell lung-cancer study cited by Erasca as a comparator. The cited study pertains to NSCLC, not PDAC, creating a discrepancy in the comparative claim.

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A 66-year-old PDAC patient receiving ERAS-0015 developed severe lung inflammation (pneumonitis) about one month after treatment initiation, was hospitalized, withdrew supportive care, and died. Erasca described the event as typical for the drug class and said it does not expect a broader safety signal.

Erasca shares sink after patient death in early-stage cancer drug trial

Following the combined legal, clinical, and safety news, Erasca’s shares fell between 41 % and 50 % in a single trading day, reaching roughly $11.10. Revolution Medicines’ stock rose 8 %–9 % on the same day, trading near $142.

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• Revolution’s letter demanded an immediate halt to ERAS-0015 activities in the United States and cessation of “misleading comparative statements.”

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• Erasca’s SEC filing asserted that Revolution’s claims are “without merit,” and the company will “defend its position vigorously.”

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Analysts expressed mixed views. H.C. Wainwright called the patient death “likely an isolated case in a complex patient,” while J.P. Morgan’s Anupam Rama described it as “more of a one-off case versus a clear drug-related concern.” Evercore ISI’s Jonathan Miller warned that “it’s tough to conclude what the true rate of pneumonitis is for Erasca at this point, pending full results.” Several analysts noted that the Phase 1 data do not yet demonstrate clear differentiation from daraxonrasib in safety or efficacy.

Erasca shares sink after patient death in early-stage cancer drug trial

• The comparator ORR for daraxonrasib (38 %) originates from an NSCLC study, not a PDAC trial, yet Erasca used it to benchmark pancreatic-cancer results.

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• No definitive data currently show whether ERAS-0015 offers a safety or efficacy advantage over daraxonrasib.

Erasca (ERAS) Stock Crashes 50% After Patient Death in Cancer Drug Trial

• “Erasca revealed the communication in an SEC filing on Monday, noting that Revolution claimed that Erasca’s asset, dubbed ERAS-0015, was “substantially equivalent” to certain formulations used in Revolution’s candidate daraxonrasib.” — Revolution Medicines (letter)

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• “the assertions in [Revolution’s] letters are without merit.” — Erasca (SEC filing)

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• “likely an isolated case in a complex patient” — H.C. Wainwright, analyst

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• “more of a one-off case versus a clear drug-related concern,” — Anupam Rama, J.P. Morgan analyst

Erasca shares sink after patient death in early-stage cancer drug trial

• “I’m excited about both datasets, but I think lung is more definitive at this point.” — Jonathan Lim, CEO, Erasca

Erasca Reports Promising Early Results in Pancreatic and Lung Cancer Therapy Trial

• “It’s tough to conclude what the true rate of pneumonitis is for Erasca at this point, pending full results.” — Jonathan Miller, Evercore ISI analyst

Erasca shares sink after patient death in early-stage cancer drug trial

Erasca plans to expand monotherapy cohorts at 24 mg and 32 mg doses and to initiate combination studies with anti-EGFR agents. Data from the AURORAS-1 trial are expected in the first half of 2027, while results from the ERAS-4001 program are slated for the second half of 2026. Both companies remain in pre-approval stages, making forthcoming trial outcomes pivotal for market positioning.

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