BlossomHill Therapeutics Sets Terms for $125 Million IPO, Bringing an OMNI-EGFR Inhibitor With Phase 1 Activity Against Resistance Mutations to Public Markets

BlossomHill Therapeutics, Inc. (NASDAQ: BLSM), a clinical-stage biopharmaceutical company developing small molecule cancer medicines, announced terms for its IPO on August 3, 2026. The San Diego-based company plans to raise $125 million by offering 7.8 million shares at $15 to $17, implying a fully diluted market value of approximately $478 million at the midpoint. J.P. Morgan, Leerink Partners, Guggenheim Securities, LifeSci Capital, and H.C. Wainwright serve as joint bookrunners, with pricing expected during the week of August 3. The offering brings BH-30643, an OMNI-EGFR™ inhibitor with Phase 1 activity across resistance mutations that defeat existing therapies, to public market investors for the first time.

BH-30643 Targets the Resistance Mutations That Make EGFR-Mutant NSCLC So Difficult to Treat

EGFR-mutant non-small cell lung cancer responds well to first- and second-line targeted therapies, most notably osimertinib (Tagrisso). The problem is resistance. After osimertinib, patients frequently develop on-target resistance mutations, particularly C797S, alone or in combination with T790M, for which no approved therapy exists. BH-30643 is a non-covalent, macrocyclic OMNI-EGFR™ inhibitor purpose-built to address that gap. Its macrocyclic architecture targets a broad spectrum of EGFR mutations simultaneously: classical activating mutations, atypical mutations including PACC mutations, exon 20 insertions, and on-target resistance mutations including C797S with or without T790M. The non-covalent binding mode allows BH-30643 to engage these structurally diverse mutations without the vulnerability to resistance that covalent inhibitors face, while maintaining selectivity over wild-type EGFR to limit toxicity.

Phase 1 SOLARA Data Presented at ASCO 2026 Shows Responses Across Hard-to-Treat Genotypes

BlossomHill presented preliminary Phase 1 dose escalation and backfill data from the SOLARA trial as an oral presentation at the 2026 ASCO Annual Meeting on June 2, 2026. Among 39 previously treated EGFR-mutant NSCLC patients dosed across 20 to 160 mg total daily doses, plasma exposures at candidate doses exceeded EC90 targets and tumor regressions appeared across difficult genotypes including C797S plus exon 19 deletion, C797S plus T790M plus exon 19 deletion, exon 20 insertion, and patients with brain metastases. Crucially, confirmed responses appeared in patients with C797S resistance mutations, a population where current treatment options are limited and outcomes are poor. CMO Geoff Oxnard, M.D., described the data as demonstrating encouraging clinical activity with a favorable tolerability profile at high pharmacokinetic exposures. Phase 1 dose expansion is ongoing to determine the recommended Phase 2 dose, and BlossomHill plans to seek an End-of-Phase 1 FDA meeting in Q4 2026 to discuss recommended Phase 2 dosing and a potential accelerated approval pathway for C797S-positive patients.

A Three-Asset Platform and $125 Million to Advance Phase 2 and Beyond

Beyond BH-30643, BlossomHill advances BH-30236, a CLK inhibitor in an ongoing Phase 1 trial for relapsed or refractory acute myeloid leukemia and higher-risk myelodysplastic syndromes, and BH-501284, a preclinical pan-KRAS program targeting one of oncology’s most sought-after targets. The three-asset pipeline reflects a chemistry-first approach to cancer drug design: rather than repurposing existing scaffolds, BlossomHill engineers compounds from the ground up against structurally defined target conformations. The company was founded in 2020 and counts Westlake Village BioPartners and other institutional investors among its backers. IPO proceeds fund BH-30643 Phase 2 development, the Phase 1 expansion cohort, and advancement of BH-30236 and BH-501284, with the FDA meeting in Q4 2026 representing the next material regulatory catalyst ahead of public investors.

Strategic Investment Summary

• IPO Terms: BlossomHill Therapeutics (NASDAQ: BLSM) plans to raise $125 million at $15 to $17 per share, implying a fully diluted market value of approximately $478 million at the midpoint, with pricing expected during the week of August 3, 2026.
• Lead Asset: BH-30643 is a non-covalent, macrocyclic OMNI-EGFR™ inhibitor designed to target classical, atypical, exon 20 insertion, and on-target resistance mutations including C797S and T790M simultaneously, addressing the post-osimertinib resistance population where no approved option currently exists.
• ASCO 2026 Data: Phase 1 SOLARA trial data presented as an oral session at ASCO 2026 showed tumor regressions across diverse EGFR genotypes in 39 previously treated patients, with confirmed responses in C797S-positive patients and activity in those with brain metastases.
• Near-Term Catalyst: BlossomHill plans an End-of-Phase 1 FDA meeting in Q4 2026 to discuss the recommended Phase 2 dose and a potential accelerated approval pathway for C797S-positive NSCLC patients.
• Pipeline: BH-30236, a CLK inhibitor for AML and higher-risk MDS, is in Phase 1; BH-501284, a pan-KRAS inhibitor, is preclinical. Both extend the company’s chemistry-first oncology platform beyond EGFR.
• Early-Stage Risk: BH-30643 remains in Phase 1 dose expansion; all clinical data are preliminary and from heavily pretreated patients, with no confirmed ORR or Phase 2 results yet established. The $478 million valuation prices in a significant clinical success assumption ahead of Phase 2 readouts.

Find out more about BlossomHill’s clinical pipeline at the BlossomHill Therapeutics pipeline page.