Radically different
Sometimes a patient’s death is enough to send a stock tumbling. Other times, the fear of litigation that often arises whenever a new therapeutic approach emerges can send shares sinking. This past week, Erasca (NASDAQ: ERAS)—whose name is a portmanteau for “erase cancer”—ran into both, causing its share price to nosedive 53%.
The precision oncology company, whose drugs and combination therapies focus on fighting cancer by shutting down the RAS/MAPK pathway, shared preliminary positive albeit early clinical dose escalation data for ERAS-0015, pooled from two Phase I trials. The oral pan-RAS molecular glue is being developed to treat solid tumors that include non-small cell lung cancer (NSCLC) and pancreatic cancer (formally pancreatic ductal adenocarcinoma or PDAC).
ERAS-0015 achieved unconfirmed overall response rates (uORR) of 62% to 75% in KRAS G12X NSCLC patients dosed at 16–32 mg once daily, with the low percentage in second line or greater KRAS G12X NSCLC (37 patients), and the high percentage in post-ICI/platinum (second and third line) KRAS G12X NSCLC (37 patients). In pancreatic cancer, which has an overall five-year survival rate of just 13%, ERAS-0015 achieved unconfirmed overall response rates ranging from 40% to 50% in second-line positive KRAS G12X PDAC.
However, tucked in footnotes on pages 25 and 43 of its investor presentation detailing the positive data was the disclosure that a 66-year-old male patient died after his grade 3 treatment-related adverse event (TRAE) of pneumonitis progressed to grade 5 after supportive care was withdrawn at the patient’s direction. The patient, who had “heavily pretreated” metastatic pancreatic cancer, received 24 mg of ERAS-0015, Erasca said.
“The patient had pulmonary metastases, a history of right lung cryoablation, and no history of lung radiation. The patient presented to the ER approximately a month after starting ERAS-0015 with grade 3 pneumonitis that was treated aggressively with immediate discontinuation of ERAS-0015, high-dose steroids, and infliximab,” Erasca explained. “The patient requested withdrawal of supportive care and ultimately died of the event.”
During an April 27 conference call, Jonathan E. Lim, MD, Erasca’s chairman, CEO, and co-founder, told analysts the death was “a very rare event” as pneumonitis is a rare drug-related toxicity seen in many oncology drugs.
“The withdrawal of supportive care is really why this progressed from grade 3 to grade 5,” Lim said. “The investigator told us directly that he thought that if the patient had continued supportive care, then it might have been a different outcome. So yes, it’s very unfortunate for the patient, but that was the feedback.”
Lim added that Erasca hasn’t seen any other grade 4 or grade 5 TRAEs. He told analysts that both FDA-approved KRAS G12C inhibitors have warnings and precautions for pneumonitis in their labels—Lumakras® (sotorasib), marketed by Amgen (NASDAQ: AMGN); and Krazati® (adagrasib), marketed by Bristol Myers Squibb (NYSE: BMY). Lim also cited Revolution Medicine (NASDAQ: RVMD)’s daraxonrasib (formerly RMC-6236), which Erasca is citing as a comparator to ERAS-0015, had also reported pneumonitis at a level of 1 out of 50 patients for monotherapy.
The same day as the data release and patient death disclosure, Erasca also revealed in a regulatory filing that it had received a letter from legal counsel for Revolution, Erasca’s arch-rival developer of RAS inhibitors against cancer. Revolution told Erasca that ERAS-0015 was “substantially equivalent” to compositions claimed by Revolution in its U.S. Patent No. 12,409,225, titled “RAS Inhibitors”, and as a result, Erasca “infringes” the patent.
“The disclosure features macrocyclic compounds, and pharmaceutical compositions and protein complexes thereof, capable of inhibiting Ras proteins, and their uses in the treatment of cancers,” according to the text of the patent, which lists Revolution as its assignee.
Revolution also contended that Erasca was liable as licensee for ERAS-0015, and that Erasca “improperly” compared preclinical data of ERAS-0015 and daraxonrasib publicly.
Erasca insists it did nothing wrong, stating in the filing that it “intends to contest the allegations vigorously.”
Lim echoed the company’s response in the filing during an interview with GEN, where he stated that the company believes Revolution’s assertions to be without merit.
“We have no reason to believe that ERAS 15 infringes any patent—including RevMed’s accusation, which is based on the doctrine of equivalence, rather than an accusation of direct infringement,” Lim said. “RevMed did not provide details to support its claim that others engaged in trade secret misappropriation, and we have no reason to believe any such thing occurred.”
“In addition, we believe that all of our preclinical data comparisons have been appropriate. And all of our data presented on the R&D Day were not based on head-to-head studies but on cross-trial comparisons. We made that very clear during the presentation,” Lim added.
Through a spokesperson, Revolution told GEN the company was acting to defend its inventions and the IP behind them.
“We are committed to protecting the strong foundation of innovation we have built over more than a decade through transformative science and significant investment,” Revolution stated. “While we do not comment on the specifics of ongoing legal matters, we remain confident in the strength of our intellectual property. Our focus remains on advancing our science to deliver innovative medicines that make a meaningful impact for patients.
Erasca investors reacted coolly to the patient death and prospect of a legal wrangle with Revolution. Erasca shares slumped 11% from $21.49 to $19.15 the day of the data announcement and regulatory filing. The share price plunged 48% to $9.90 Tuesday and fell another 8% Wednesday to $9.11 before bouncing back 17% to $10.65 Thursday as investors bought the dip, then finished Friday sliding 6%, closing at $10.03.
Despite the selloff, Erasca shares have more than quadrupled over the past six months, rocketing 314% from $2.42 on October 31 and catapulting 573% over the past year (from $1.49 on May 1, 2025).
Revolution shares rose 3% this week. After sliding nearly 3% from $135.30 to $131.67 on April 27, the stock benefited from Erasca’s slump by jumping 10% to $144.83 before fluctuating, closing Friday at $139.48.
“We view the (-)ve [negative] post‑data reaction as overdone, as ERAS‑0015 looks like a formidable competitor in the pan‑RAS landscape,” Maury Raycroft, PhD, equity analyst with Jefferies, wrote in a research note.
Raycroft cited Erasca’s comparing its 62%/75% uORR in NSCLC to the confirmed 38% ORR cited for daraxonrasib in a 2025 study by researchers from Revolution and several clinical partners. Among second and third-line treatment patients post‑ICI/platinum, efficacy appeared broadly consistent across geographies, Raycroft noted, w/ uORR of 71% in the United States (12 patients), where ERAS-0015 was studied in the Phase I AURORAS-1 trial (NCT06983743), and 73% in China (11 patients), where partner Joyo Pharmatech sponsored a trial known as STAR or JYP0015M101 (NCT06895031).
“Early durability is also encouraging, w/ progression observed in 1/27 pts in the China study and 2/12 in the U.S. study; though, follow‑up remains limited (median likely ~3–4 mos), so durability conclusions are premature,” Raycroft cautioned.
In pancreatic cancer, pooled U.S. and Chinese patient data ranged from 40% uORR at 16–32 mg (20 patients), to 42% uORR at 24–32 mg (12 patients), and 50% uORR at 32 mg once daily (two patients).
“Right now, we think the lower doses at 8 and 16 milligrams, for instance, seem to be relatively underpowered against pancreatic cancer compared to 24 to 32 milligrams. So, based on the totality of efficacy, safety, tolerability, and PK data, we have determined 24 and 32 milligrams to be the recommended doses for expansion,” Lim told GEN. “So we have already begun to expand out those doses to treat patients at both 24 and 32 milligrams.”
All but one of 24 responding NSCLC patients, and 20 out of 23 responding PDAC patients, remain on treatment, including all responders treated at the 24 and 32 mg once daily recommended doses for expansion (RDEs).
Erasca said ERAS-0015 showed clinical potential for combinability with standard-of-care doses of the anti-EGFR monoclonal antibody panitumumab in fighting colorectal cancer (CRC), where EGFR is a key mechanism for acquired resistance. Through the data cutoff date of March 31, Erasca showed no dose-limiting toxicities among three patients, of which one showed an unconfirmed partial response in an efficacy-evaluable patient with metastatic CRC: “That’s really exciting to have,” Lim said.
“For monotherapy, we think lung and pancreatic are compelling opportunities, and then for colorectal cancer, combination therapy will likely be required, so we’re focused on the combination with EGFR antibody for colorectal cancer,” Lim said.
“The fact that we have been able to successfully combine ERAS15 with panitumumab in three patients, with two of them passing the DLT window, is exciting. And we did that with a 16 milligram dose of ERAS-15, which is within the pharmacologically active dose range of 16 to 32 milligrams. It’s really exciting to have safety and tolerability that is promising with that combination and activity within the PAD.”
The Erasca-Revolution dispute appears to explain a decline early this past week in the American depositary shares of another cancer drug developer whose pipeline includes RAS-targeting therapies: Adlai Nortye (NASDAQ: ANL) shares skidded 10.5% from $14.80 to $13.25 the day of Erasca’s announcement and filing, then dropped another 8% to $12.17 Tuesday before rebounding 27% the rest of the week, closing Friday at $15.50.
Adlai Nortye is developing AN9025, an oral, small-molecule pan-RAS(ON) inhibitor designed to treat a variety of advanced solid tumors with RAS mutations. AN9025 is under study in a Phase I trial (NCT07252479) whose first patient was dosed in the United States in February. The trial is being conducted with Jiangsu Aosaikang Pharmaceutical, which holds rights to AN9025 in China, Hong Kong, and Macao.
Andrew Berens, MD, senior managing director, targeted oncology, and a senior research analyst with Leerink Partners, wrote in a research note that a conversation with Adlai Nortye management offered reasons for confidence that the company will avoid legal trouble in connection with AN9025.
“ANL’s discovery of AN9025 was conducted in-house and independently, suggesting that trade secret misappropriations are unlikely,” Berens reported. “Further, while both drugs feature a macrocyclic scaffold, according to ANL, ERAS-0015 has significantly less branch change modifications and features a bridge, while 9025 underwent numerous branch modifications and the addition of a ring to the scaffold.”
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