Reported cumulative MMR rate of 44% by 24 weeks, with stable or deepening responses between weeks 12 and 24, continuing to surpass prior Phase 1 trials of approved BCR::ABL1 TKIs

ELVN-001 remains well-tolerated with no dose reductions reported across 39 patients enrolled, and a median treatment duration of 20 weeks at cutoff

Enliven Therapeutics, Inc. (Enliven or the Company) (Nasdaq: ELVN), a clinical-stage biopharmaceutical company dedicated to developing small molecule therapeutics, today announced positive updated data from its Phase 1 trial evaluating ELVN-001 in patients with chronic myeloid leukemia (CML). The data, presented at the European Society of Hematology International Chronic Myeloid Leukemia Foundation (ESH-iCMLf) 26th Annual John Goldman Conference, highlight the continued promise of ELVN-001 for CML patients who have failed, are intolerant to, or are not candidates for existing treatments.

ELVN-001 is a potent, highly selective, and potentially best-in-class small molecule kinase inhibitor designed to target the BCR-ABL gene fusion, which drives CML.

Dr. Fabian Lang, M.D., from Goethe University Hospital Frankfurt, who presented the data, commented: “ELVN-001 continues to show clinical benefit in heavily pretreated CML patients. We are particularly encouraged by stable or deepening responses between weeks 12 and 24, and the drug’s favorable safety profile. As treatment options evolve, there remains a need for more effective and well-tolerated TKIs for patients who have failed allosteric inhibitors. I am excited to see ELVN-001's progress as the trial continues."

The trial enrolled 39 patients at various dose levels, 18 of whom were evaluable for molecular response at 24 weeks. A cumulative major molecular response (MMR) rate of 44% (8/18) was observed by 24 weeks, and ELVN-001 demonstrated excellent tolerability with no dose reductions required and a median treatment duration of 20 weeks.

Dr. Helen Collins, M.D., Chief Medical Officer of Enliven, added, “We are thrilled by the sustained efficacy and safety of ELVN-001 in this challenging patient population. With more patients enrolled and longer follow-up, we continue to see encouraging anti-CML activity and a well-maintained safety profile. These data reaffirm ELVN-001’s potential to address unmet needs across the CML treatment landscape.”

Patient Demographics and Efficacy As of the June 25, 2024 cutoff, 39 patients were enrolled across five dose levels (10-120 mg QD). The majority remain on treatment with a median duration of 20 weeks. The patient population was heavily pretreated:

• 69.2% had ≥3 prior tyrosine kinase inhibitors (TKIs)
• 25.6% had ≥5 prior TKIs
• 53.8% had received prior asciminib
• 69.2% had discontinued their last TKI due to lack of efficacy.

At 24 weeks, 18 patients were evaluable for molecular response. Key efficacy results include:

• Cumulative MMR rate of 44% (8/18)
• 41.7% (5/12) MMR in TKI-resistant patients
• 40.0% (4/10) MMR in post-asciminib patients
• 23.1% (3/13) of patients not in MMR at baseline achieved MMR by 24 weeks.

Safety Profile ELVN-001 continues to demonstrate a favorable safety profile:

• No dose reductions or discontinuations due to treatment-emergent adverse events (TEAEs)
• No ≥ Grade 3 non-hematologic treatment-related adverse events (TRAEs)
• No TRAE occurring in >11% of patients.

Sam Kintz, Co-founder and CEO of Enliven, stated, "With these promising data, we are confident in ELVN-001’s potential as a novel active-site TKI for CML, especially in conjunction with other new treatment options. We remain encouraged by ELVN-001’s progress as we continue enrolling and advancing the study."