Erasca dips on patient death

28 April 2026

ERAS-0015 data look good, but the company is punished for a pneumonitis death.

Erasca’s stock has surged on broad interest in pan-RAS inhibition, but the group hit a speed bump on Monday evening after slipping out a pneumonitis death in the phase 1 Auroras-1 trial of its lead project, ERAS-0015.Evercore ISI’s Jonathan Miller described the data themselves as a “home run”, but there are still plenty of questions about how ERAS-0015 might ultimately stack up against the pan-RAS leader, Revolution Medicines’ daraxonrasib. Investors, apparently spooked by the death, sent Erasca’s share price down 47% on Tuesday morning.However, the group still has a market cap of over $3bn, a meaty valuation for such an early-stage company. It’s even more remarkable considering Erasca gained ERAS-0015, a pan-RAS molecular glue, via a $12.5m up-front deal with China’s Joyo in 2024. The agreement also gave Erasca access to a pan-KRAS inhibitor, ERAS-4001.Not so shiny?The latest data came from a pooled analysis of two phase 1 trials: the US Auroras-1 and the Chinese JYP0015M101. Both are in various RAS-mutated solid tumours, but Monday’s update focused largely on non-small cell lung cancer and pancreatic ductal adenocarcinoma.Erasca claimed a 62% ORR among 37 second-line or later NSCLC patients, and a 40% ORR among 20 second-line PDAC patients – both at a 16-32mg daily dose. However, these numbers included unconfirmed responses. Excluding these, confirmed response rates were 32% and 20% respectively.Still, the numbers look good in a cross trial comparison versus daraxonrasib, based on early data reported by Revolution at ESMO 2023. Daraxonrasib is sometimes also described as a pan-RAS molecular glue.  Pan-RAS cross-trial comparison NSCLCPDAC ERAS-0015DaraxonrasibERAS-0015DaraxonrasibTrial(s)Auroras-1 (US) & JYP0015M101 (China)RMC-6236-001Auroras-1 (US) & JYP0015M101 (China)RMC-6236-001VenueApr 2026 company presentationESMO 2023Apr 2026 company presentationESMO 2023Setting2nd-line-plus2nd-line-plusSecond-lineSecond-line-plusDose16-32mg daily80-400mg daily16-32mg daily80-400mg dailyN37402046uORR62%38%40%20%cORR32%30%20%11%Source: Company release & OncologyPipeline. The usual caveats about cross-trial comparisons apply, especially in PDAC, where Revolution’s figures came in second-line or later patients, and at a relatively early follow-up. More recently, Revolution has reported a confirmed ORR of 35% with daraxonrasib at 300mg daily in second-line only patients, and also prevailed on PFS in the pivotal Rasolute-302 study in relapsed PDAC.But the main issue for Erasca was the patient death and, in particular, the way it was reported. The company made no mention of either a grade 5 event or pneumonitis in its press release, only disclosing this in an after-hours conference call.The company described the fatality, in a PDAC patient, as a “related grade 3 pneumonitis case that progressed to grade 5 after the patient decided to discontinue aggressive supportive care”. The subject received 24mg of ERAS-0015, one of the go-forward doses, along with 32mg.The safety data only came from the US Auroras-1 trial, so it’s unclear if there were any more serious adverse events in the Chinese study. Erasca execs said it focused on Auroras-1 here because reporting treatment-related adverse events in China is “different and difficult to generalise to the US population”.Aside from this event, ERAS-0015’s safety profile looked fairly benign, with only one grade 3 report of rash – a known issue with daraxonrasib. There were also no grade 3 or higher treatment-related events of diarrhoea, stomatitis or nausea in Auroras-1.Mizuho analysts described Erasca’s data as competitive, but added that more information was needed, “including confirmation of responses [and] demonstration of durability”, as well as the apparently improved safety profile holding up.Meanwhile, it also emerged on Monday that Revolution has alleged that ERAS-0015 infringes its patents. Erasca said it intends to “contest the allegations vigorously”, but this could add to any doubt around the project.

Evercore ISI’s Jonathan Miller described the data themselves as a “home run”, but there are still plenty of questions about how ERAS-0015 might ultimately stack up against the pan-RAS leader, Revolution Medicines’ daraxonrasib. Investors, apparently spooked by the death, sent Erasca’s share price down 47% on Tuesday morning.

However, the group still has a market cap of over $3bn, a meaty valuation for such an early-stage company. It’s even more remarkable considering Erasca gained ERAS-0015, a pan-RAS molecular glue, via a $12.5m up-front deal with China’s Joyo in 2024. The agreement also gave Erasca access to a pan-KRAS inhibitor, ERAS-4001.

Not so shiny?

The latest data came from a pooled analysis of two phase 1 trials: the US Auroras-1 and the Chinese JYP0015M101. Both are in various RAS-mutated solid tumours, but Monday’s update focused largely on non-small cell lung cancer and pancreatic ductal adenocarcinoma.

Erasca claimed a 62% ORR among 37 second-line or later NSCLC patients, and a 40% ORR among 20 second-line PDAC patients – both at a 16-32mg daily dose. However, these numbers included unconfirmed responses. Excluding these, confirmed response rates were 32% and 20% respectively.

Still, the numbers look good in a cross trial comparison versus daraxonrasib, based on early data reported by Revolution at ESMO 2023. Daraxonrasib is sometimes also described as a pan-RAS molecular glue.

Pan-RAS cross-trial comparison

	NSCLC		PDAC
	ERAS-0015	Daraxonrasib	ERAS-0015	Daraxonrasib
Trial(s)	Auroras-1 (US) & JYP0015M101 (China)	RMC-6236-001	Auroras-1 (US) & JYP0015M101 (China)	RMC-6236-001
Venue	Apr 2026 company presentation	ESMO 2023	Apr 2026 company presentation	ESMO 2023
Setting	2nd-line-plus	2nd-line-plus	Second-line	Second-line-plus
Dose	16-32mg daily	80-400mg daily	16-32mg daily	80-400mg daily
N	37	40	20	46
uORR	62%	38%	40%	20%
cORR	32%	30%	20%	11%

Source: Company release & OncologyPipeline.

The usual caveats about cross-trial comparisons apply, especially in PDAC, where Revolution’s figures came in second-line or later patients, and at a relatively early follow-up. More recently, Revolution has reported a confirmed ORR of 35% with daraxonrasib at 300mg daily in second-line only patients, and also prevailed on PFS in the pivotal Rasolute-302 study in relapsed PDAC.

But the main issue for Erasca was the patient death and, in particular, the way it was reported. The company made no mention of either a grade 5 event or pneumonitis in its press release, only disclosing this in an after-hours conference call.

The company described the fatality, in a PDAC patient, as a “related grade 3 pneumonitis case that progressed to grade 5 after the patient decided to discontinue aggressive supportive care”. The subject received 24mg of ERAS-0015, one of the go-forward doses, along with 32mg.

The safety data only came from the US Auroras-1 trial, so it’s unclear if there were any more serious adverse events in the Chinese study. Erasca execs said it focused on Auroras-1 here because reporting treatment-related adverse events in China is “different and difficult to generalise to the US population”.

Aside from this event, ERAS-0015’s safety profile looked fairly benign, with only one grade 3 report of rash – a known issue with daraxonrasib. There were also no grade 3 or higher treatment-related events of diarrhoea, stomatitis or nausea in Auroras-1.

Mizuho analysts described Erasca’s data as competitive, but added that more information was needed, “including confirmation of responses [and] demonstration of durability”, as well as the apparently improved safety profile holding up.

Meanwhile, it also emerged on Monday that Revolution has alleged that ERAS-0015 infringes its patents. Erasca said it intends to “contest the allegations vigorously”, but this could add to any doubt around the project.