Erasca and Merck collaborate on ERAS-0015 plus Keytruda for RAS-mutant solid tumors

Edited by Robert McTiernan··3 min read

A clinical-stage combination strategy for RAS-mutant solid tumors moves forward as Erasca (Nasdaq: ERAS), a San Diego-based precision oncology company, announced a clinical trial collaboration and supply agreement with Merck to evaluate ERAS-0015 in combination with Keytruda (pembrolizumab) in patients with RAS-mutant solid tumors.

The agreement is a clinical trial collaboration and supply agreement, a structure under which Erasca sponsors and operationally manages the AURORAS-1 Phase I study while Merck supplies pembrolizumab at no cost. Each company retains independent rights to its respective asset; the collaboration does not grant either party commercialization rights over the other’s compound.

Erasca is sponsoring the study, bearing the financial and regulatory responsibilities of trial execution. Merck’s contribution is limited to drug supply, reflecting a conventional CTCSA structure in which a large pharma partner enables combination evaluation without taking on broader development obligations.

ERAS-0015 asset profile and scientific rationale

ERAS-0015 is an investigational oral pan-RAS molecular glue designed to inhibit RAS signaling across multiple RAS mutant variants, including wildtype RAS. The compound is currently being evaluated in the AURORAS-1 Phase I trial (NCT06983743) in patients with RAS-mutant advanced or metastatic solid tumors. Erasca licensed full global rights to the molecule from China-based Joyo Pharmatech Co., Ltd in a March 2026 deal.

Early dose escalation data from AURORAS-1 showed favorable safety and tolerability, linear pharmacokinetics, and confirmed and unconfirmed partial responses across multiple tumor types harboring different RAS mutations, including responses observed at doses as low as 8 mg once daily. The compound is also designed to inhibit wildtype RAS variants, a property Erasca states may help prevent resistance to mutant-selective inhibitors.

The scientific rationale for the pembrolizumab combination therapy rests on the observation that RAS mutations can contribute to an immunosuppressive tumor microenvironment. Erasca’s position is that pan-RAS pathway inhibition with ERAS-0015 may reduce that immunosuppression and thereby complement PD-1 blockade, potentially producing more durable tumor responses. This rationale is company-stated and has not yet been tested in a controlled clinical setting; the AURORAS-1 combination arm represents the first clinical test of this hypothesis.

The AllSci BriefSystematic R&D and deal news. Daily.

Pembrolizumab is an approved anti-PD-1 therapy with an established profile across multiple tumor types. Its inclusion as the immunotherapy backbone in this study reflects the broader oncology field’s interest in pairing targeted pathway inhibitors with checkpoint blockade, particularly in indications where single-agent responses remain limited.

Approximately 2.7 million patients are diagnosed annually with RAS-mutant tumors worldwide, according to Erasca. The absence of broadly effective pan-RAS targeting agents and the emergence of resistance mechanisms in existing RAS-directed therapies have left a substantial unmet need across this patient population.

The Keytruda ERAS-0015 collaboration follows a consistent pattern of CTCSA dealmaking by Erasca. The company has pursued supply-based combination study agreements with multiple large pharma partners across its RAS/MAPK-focused pipeline.

In February 2024, Erasca entered two CTCSAs with Novartis to secure supply of trametinib for the SEACRAFT-1 Phase Ib and SEACRAFT-2 Phase III studies, evaluating the pan-RAF inhibitor naporafenib in combination across RAS-mutant solid tumors and NRAS-mutant melanoma. That same partnership extended in May 2024 when Erasca in-licensed a RAS-targeting franchise from Novartis, deepening its pipeline of RAS/MAPK pathway assets ahead of pivotal trial initiation. The Merck agreement adds a third large pharma supply relationship to Erasca’s combination development strategy, this time incorporating PD-1 blockade alongside direct RAS pathway targeting.

The AURORAS-1 study design evaluates ERAS-0015 both as monotherapy and in combination arms, meaning the trial will generate parallel data streams relevant to both the single-agent profile of ERAS-0015 and the combination hypothesis.

This article was generated with AI assistance and reviewed and edited by the AllSci editorial team Explore more at AllSci News: https://allsci.com/news/