Imara M&A

Concentration (ng/mL) 10000 1000 100- 10 0.1- 0 ELVN-002 Achieved a Wide Safety Margin in Preclinical Species = CHI • ELVN-002 28-day GLP Tox NHP TK ● 10 hours 20 pEGFR IC 50 (A431, 50% human serum) HER2 YVMA GI90 (Ba/F3, protien adj.) pHER2 YVMA IC 50 (Beas2B, 100% human serum) 15 mg/kg 10 mg/kg 5 mg/kg 5 mg/kg NOD-SCID mouse (highly efficacious dose) Dose (mg/kg) 5 10 15 ELVN-002 Safety Margin at NHP NOAEL Fold vs. Highly Fold vs. Tucatinib Efficacious Exposure TGI-matched exposure 2 5 8 5 12 22 Based on preclinical exposures (AUC), ELVN-002 had a >10x larger safety margin compared to tucatinib in NHPs (HER2 amp setting) At its 28-day NOAEL, ELVN-002 had a wide safety margin in non-human primates (NHPs) and even wider safety margin in rats NHP = Non-human primate. NOAEL = No observed adverse event level. Highly Efficacious Exposure equals the total AUC of ELVN-002 at 5 mg/kg in NOD-SCID mouse (836 ng*hr/mL), which yielded robust tumor regression in a HER YVMA xenograft To determine Fold vs. Tucatinib TGI-matched exposure, we use the linearly extrapolated AUC of ELVN-002 at 2.5 mg/kg in Nude mouse, which roughly matches the TGI of Tucatinib at 20 mg/kg BID measured in an NCI-N87 xenograft model ELVN-002 NHP data shown are measured averages from Day 1 TK male animals in a 28-day GLP tox study References: Tucatinib NDA; Moulder, SL; et al. Data from a Completed Phase 1 Study to Assess the Safety, Tolerability and PK of ARRY-380-an Oral Inhibitor of HER2. SABCS, December 8-12, 2010, San Antonio, TX. NHP NOAEL At its approved dose, tucatinib only achieves IC., all day in ~40% of patients • Due to its larger safety margin, irreversible inhibition and improved PK profile, we believe ELVN-002 has the potential to achieve better target inhibition and improved efficacy compared to tucatinib 43

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