Erasca Inc. Hit with Securities Class Action Following Patient Death and Patent Infringement Claims, $2.8 Billion Market Cap Plummets

Erasca, Inc. (NASDAQ: ERAS) is confronting a securities class action lawsuit after its stock price dropped sharply by $9.25 per share, or 48%, following critical disclosures on April 27, 2026. The company revealed it had received a legal challenge from Revolution Medicines (RevMed) alleging patent infringement related to Erasca’s investigational pan-RAS molecular glue, ERAS-0015, and reported a patient death occurring one month after treatment with ERAS-0015.

The class action seeks to represent investors who purchased or otherwise acquired Erasca common stock during the period from January 14, 2025, through April 26, 2026. National shareholder rights firm Hagens Berman Sobol Shapiro LLP is spearheading the investigation into potential violations of federal securities laws by Erasca.

Erasca’s ERAS-0015 is an oral, investigational therapy targeting RAS-mutant solid tumors, including pancreatic ductal adenocarcinoma. The company had promoted ERAS-0015 as a potentially “best-in-class” treatment and compared its 40 milligram dose cohort favorably to Revolution Medicines’ RMC-6236 400 milligram dose cohort.

According to the complaint, Erasca assured investors as recently as March 12, 2026, that its intellectual property position was secure, highlighting an in-licensed patent family from Joyo comprising one issued U.S. patent, one pending U.S. non-provisional patent application, one issued foreign patent, and thirteen pending foreign patent applications.

However, the lawsuit alleges these representations were misleading. The complaint contends that the comparisons between ERAS-0015 and RMC-6236 were improper and that Erasca’s intellectual property claims exposed the company to legal disputes, undermining the basis for its optimistic statements about ERAS-0015.

The truth surfaced on April 27, 2026, when Erasca disclosed two significant developments. Prior to market opening, the company announced it had received a letter from RevMed’s legal counsel challenging the validity of Erasca’s intellectual property claims and accusing Erasca of misappropriating RevMed’s trade secrets through a third party. Later that day, Erasca revealed that a patient treated with ERAS-0015 experienced an adverse event, presented to the emergency room one month post-treatment, and subsequently died.

These disclosures triggered a severe market reaction, with Erasca’s stock price plummeting 48% the following day and erasing over $2.8 billion in market capitalization.

Reed Kathrein, a partner at Hagens Berman leading the investigation, stated, “We’re investigating whether Erasca may have intentionally misled investors about ERAS-0015’s safety profile and about a potential moat in its particular, highly competitive cancer treatment space.”

Investors who suffered significant losses during the class period or possess information relevant to the investigation are urged to contact Hagens Berman. The firm has set a lead plaintiff deadline of August 10, 2026.

Additionally, whistleblowers with non-public information about Erasca are encouraged to consider participating in the SEC Whistleblower program, which offers rewards of up to 30% of any successful recovery. For inquiries, contact Reed Kathrein at 844-916-0895 or via email at ERAS@hbsslaw.com.

Hagens Berman Sobol Shapiro LLP is a global plaintiffs’ rights law firm specializing in complex litigation involving corporate accountability. The firm represents investors, whistleblowers, workers, and consumers in cases addressing corporate negligence and wrongdoing, having secured over $2.9 billion in recoveries to date.