Immuneering Corporation (NASDAQ:IMRX), a late-stage clinical oncology company focused on keeping cancer patients alive and helping them thrive, today announced it will present a poster on one of the three key mechanisms by which atebimetinib aims to improve overall survival: shrinking tumors durably. The poster will be presented at the American Association for Cancer Research (AACR) Annual Meeting taking place April 17-22, 2026 in San Diego, CA.

Inhibitors of RAS, RAF, or MEK often provide only temporary benefit due to resistance, as tumors acquire new mutations or mechanisms of escape within the MAPK pathway. Atebimetinib, a novel Deep Cyclic Inhibitor of MEK, is engineered to mitigate the selective pressure that typically drives these resistance mechanisms, with the goal of more durable anti-tumor activity. Immuneering will present an analysis of circulating tumor DNA (ctDNA) from ≥64 patients with RAS-mutant solid tumors treated with atebimetinib, showing that acquired MAPK pathway alterations are rarely seen in patients treated with atebimetinib. These findings suggest that Deep Cyclic Inhibitors have the potential to overcome the limitations of conventional MAPK inhibition and provide a more sustained clinical benefit for patients.

Poster Presentation Details:

Title: Atebimetinib's Deep Cyclic Inhibition of MEK Constrains MAPK-Axis Adaptive and Acquired Alterations in Patients with RAS-Mutant Tumors

Session Category: Experimental and Molecular Therapeutics

Session Title: Targeting Drug Resistance 2: RAS Signaling

Poster Number: 1873

Poster Board Number: 6

Session Date: April 20, 2026

Session Time: 9:00 AM – 12:00 PM ET

Location: Poster Section 19

The abstract will be available on the AACR website. Following presentation, the poster will be available on the publications section of Immuneering's website at https://immuneering.com/publications.