Immuneering (IMRX) Study Update summary

Study design and objectives

• Phase II-A/1/2a trial evaluated atobemetinib (atebimetinib/IMM-1-104) plus modified gemcitabine nab-paclitaxel (mGnP) in first-line pancreatic cancer patients, enrolling 34 patients with a median age of 69, many with elevated CA 19-9 and significant tumor burden.

• Both 240 mg and 320 mg dose levels were assessed, with interim data at 320 mg as of May 26, 2025, and a median follow-up of 6 months.

• Primary endpoints included overall survival (OS) and progression-free survival (PFS); secondary endpoints were overall response rate (ORR), disease control rate (DCR), quality of life, and weight gain.

• Used a less intensive chemotherapy regimen to improve tolerability and quality of life.

• Patient population had 65% aged 65 or older and 100% ECOG PS 0 or 1.

Key efficacy results

• 94% overall survival (OS) and 72% progression-free survival (PFS) at 6 months, with median OS and PFS not yet reached.

• Overall response rate (ORR) was 39% and disease control rate (DCR) was 81%, both higher than historical benchmarks.

• Tumor responses deepened over time, with some patients achieving complete or near-complete regression of target lesions, including rare cases of undetectable liver and pancreatic lesions.

• Durable responses seen even in heavily pretreated, third-line patients.

• Results compare favorably to standard of care benchmarks (67% OS, 44% PFS at 6 months).

Safety and tolerability

• Markedly favorable tolerability profile; no Grade 3 or higher adverse events in most categories typical for standard chemotherapy.

• Grade ≥3 neutropenia occurred in 15% of patients, fatigue in 6.2%, and anemia in 18%; other severe adverse events were rare or absent.

• No grade 5 events reported; lower rates of sensory neuropathy, diarrhea, and leukopenia compared to historical controls.

• Tolerability profile enabled improved quality of life and frequent weight gain.

• Atebimetinib plus mGnP demonstrated a potential best-in-class safety profile.