Stock Markets May 11, 2026 08:51 AM

Erasca Shares Rise After Merck Agrees to Supply KEYTRUDA for Joint RAS-Targeted Trial

AURORAS-1 will test ERAS-0015 with pembrolizumab in patients with RAS-mutant solid tumors; Merck provides drug supply while Erasca sponsors the study

By Nina Shah ERAS MRK

Erasca Inc. shares climbed 4.3% in premarket trading after the company announced a clinical trial collaboration and supply agreement with Merck. The AURORAS-1 study will assess Erasca's pan-RAS molecular glue ERAS-0015 in combination with Merck's KEYTRUDA (pembrolizumab) for RAS-mutant solid tumors; Merck will provide pembrolizumab at no cost and Erasca will sponsor the trial.

Erasca Shares Rise After Merck Agrees to Supply KEYTRUDA for Joint RAS-Targeted Trial
ERAS MRK

Key Points

  • Erasca announced a clinical trial collaboration and supply agreement with Merck, prompting a 4.3% premarket share price increase.
  • The AURORAS-1 study will test Erasca's pan-RAS molecular glue ERAS-0015 in combination with Merck's KEYTRUDA (pembrolizumab) for patients with RAS-mutant solid tumors; Merck will supply pembrolizumab at no cost and Erasca will serve as sponsor.
  • The collaboration targets RAS-driven cancers, affecting roughly 2.7 million patients diagnosed annually worldwide, and aims to evaluate whether combining pan-RAS inhibition with PD-1 blockade can improve responses and reduce resistance.

Erasca Inc. (NASDAQ:ERAS) saw its stock rise 4.3% in premarket trading Monday following disclosure of a clinical trial collaboration and a supply agreement with Merck. The companies will collaborate on a clinical proof-of-concept study that pairs Erasca's investigational pan-RAS agent with Merck's immune checkpoint inhibitor.

The study, named AURORAS-1, will evaluate ERAS-0015 in combination with Merck's KEYTRUDA (pembrolizumab) in patients with RAS-mutant solid tumors. Under the terms announced, Merck will supply pembrolizumab to the trial at no cost, while Erasca will act as the study sponsor.

Company statement

Commenting on the collaboration, Jonathan E. Lim, Erasca's chairman, CEO, and co-founder, said: "We are excited to work with Merck to advance this promising investigational combination in RAS-driven cancers. RAS mutations activate the RAS/MAPK pathway and promote an immunosuppressive environment. Non-clinical data suggest that targeting the pathway with ERAS-0015 may complement PD-1 blockade by reducing immunosuppression and driving more robust and durable tumor responses."

Scope and rationale

The collaboration focuses on tumors driven by RAS mutations, a group of cancers the companies say affects approximately 2.7 million patients diagnosed each year worldwide. Erasca highlighted the continuing difficulty of treating RAS-driven tumors, noting that a lack of broadly effective therapies and the emergence of resistance mechanisms have hindered the ability to achieve and sustain responses.

Erasca framed AURORAS-1 as an effort to determine whether pan-RAS inhibition with ERAS-0015, when combined with pembrolizumab, can enhance therapeutic benefit while limiting the development of treatment resistance.

What the agreement covers

  • Merck will provide KEYTRUDA (pembrolizumab) at no cost for the clinical proof-of-concept study.
  • Erasca will sponsor the AURORAS-1 clinical trial evaluating ERAS-0015 plus pembrolizumab.

This collaboration links a development-stage biotech and a large pharmaceutical company in a study aimed at an area of oncology with acknowledged treatment gaps. The immediate market reaction for Erasca was a modest premarket share price increase as investors responded to the news.

Risks

  • The trial is a proof-of-concept study, and it is uncertain whether the ERAS-0015 plus pembrolizumab combination will deliver improved or durable patient responses - this impacts biotech and healthcare sectors.
  • Emergence of resistance mechanisms in RAS-driven tumors presents an ongoing challenge to achieving and maintaining responses, affecting clinical outcomes and R&D investment decisions in oncology.
  • Erasca will sponsor the trial, which implies responsibility for trial execution and associated costs; this is a financial and operational consideration for the company and investors.

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