BlossomHill Therapeutics Announces Collaboration with Foundation Medicine to Develop First Companion Diagnostic for BH-30643 in EGFR C797S Mutated Non-Small Cell Lung Cancer

SAN DIEGO, Oct. 22, 2026 (GLOBE NEWSWIRE) -- BlossomHill Therapeutics, Inc. (Nasdaq: BLSM), a clinical-stage biopharmaceutical company applying an intentional, chemistry-based approach to design and develop innovative small molecule medicines for the treatment of cancer, today announced a collaboration with Foundation Medicine, Inc. to develop a companion diagnostic assay (CDx) for the EGFR C797S resistance mutation. The collaboration will leverage the ongoing Phase 1/2 SOLARA clinical trial evaluating BH-30643 in the targeted treatment of epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) patients to validate the assay.  

EGFR C797S is the most common EGFR mutation driving resistance to osimertinib treatment in EGFR-mutant NSCLC. BH-30643 is a macrocyclic mutant-selective OMNI-EGFR™ inhibitor that has demonstrated clinical activity against a variety of EGFR mutations, in particular the C797S mutation that drives resistance to standard therapy. Understanding and targeting resistance mechanisms to existing EGFR inhibitors is an active area of clinical investigation and drug development. To this end, the collaboration will focus on validating a reliable diagnostic assay for the detection of EGFR C797S mutation to help guide BH-30643’s ongoing development.

“Our near-term development priority for BH-30643 is to address the unmet needs of EGFR-mutant NSCLC patients with known resistance mutations following progression on prior EGFR targeted therapy,” said Geoff Oxnard, MD, Chief Medical Officer at BlossomHill. “Foundation Medicine is the most experienced developer of precision CDx assays and the ideal partner to help us characterize EGFR resistance and validate a CDx assay to support the development of our medicine.”

About BH-30643
BH-30643 is an investigational, novel, orally bioavailable, non-covalent, macrocyclic, brain active, mutant-selective, OMNI-EGFR™ inhibitor for the treatment of EGFR-mutant NSCLC. BH-30643 was designed to overcome the limitations of currently approved EGFR inhibitors, which were discovered over a decade ago without the current, modern understanding of the structure and protein dynamics of mutant EGFRs. In preclinical studies, BH-30643 demonstrated potent inhibitory activity across diverse EGFR mutation categories — classical mutations, on-target resistance mutations such as C797S with or without T790M, atypical mutations and exon 20 insertions — while maintaining marked selectivity over wild-type EGFR. BH-30643 has received Fast Track designation and is being evaluated in SOLARA, a global Phase 1/2, first-in-human clinical trial spanning more than 40 sites in 10 countries. Ongoing dose expansion cohorts are enrolling in both TKI-pretreated and TKI-naive settings, including a C797S resistance cohort. For additional information on SOLARA, including a list of study sites and how to enroll, please visit clinicaltrials.gov (NCT06706076).

About the SOLARA Trial
The Phase 1/2 SOLARA clinical trial (NCT06706076) is a global, open label, multicenter study assessing the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary anti-tumor activity of BH-30643 in patients with epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC). Phase 1 will determine the recommended Phase 2 dose (RP2D) of BH-30643 as a monotherapy and in combination with chemotherapy. Phase 2 is designed to evaluate the antitumor efficacy and safety in specified cohorts determined by mutation subtypes and/or treatment history at the RP2D, as well as the population pharmacokinetics.

About BlossomHill Therapeutics
BlossomHill Therapeutics, Inc. is a clinical-stage biopharmaceutical company applying an intentional, chemistry-based approach to design and develop innovative small molecule medicines that address significant unmet medical needs in cancer treatment. Founded and led by industry veteran J. Jean Cui, Ph.D., with her proven track record in oncology drug design and development – including three FDA-approved drugs – BlossomHill Therapeutics applies cutting-edge science with a goal to address key oncogenic drivers and improve patient outcomes in difficult-to-treat cancers. The company’s lead clinical program is BH-30643, an investigational, non-covalent, macrocyclic, brain active, mutant-selective OMNI-EGFR™ inhibitor for the treatment of EGFR-mutant non-small cell lung cancer (NSCLC), which has received Fast Track designation for the C797S resistance population after 3rd generation EGFR TKI treatment. The company is also conducting clinical development of BH-30236, an investigational macrocyclic CDC-like kinase (CLK) inhibitor initially being studied in a clinical trial for the treatment of relapsed or refractory acute myeloid leukemia (R/R AML) and higher-risk myelodysplastic syndromes (HR-MDS). The company’s pipeline also includes BH-501284, a preclinical, non-covalent, selective, pan-KRAS Switch-II inhibitor for potential future development in diverse KRAS-mutant tumors.

BlossomHill Therapeutics is headquartered in San Diego, California. For more information, visit bhtherapeutics.com and follow us on LinkedIn and X.

Cautionary Note Regarding Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, and other federal securities laws, including, without limitation, statements regarding: the therapeutic potential, clinical benefits, safety and potential competitive differentiation of the company's product candidates, including BH-30643, BH-30236 and BH-501284; the anticipated benefits of regulatory designations received, or that may be received, by the company's product candidates; the design, enrollment, timing, progress and results of the company's clinical trials and preclinical studies; the company's planned regulatory interactions and submissions; anticipated program milestones, including the timing of program and data updates; statements by the company's management; and the company's development plans and continued advancement of its pipeline, including the anticipated benefits of the company's collaboration with Foundation Medicine, Inc. to develop a companion diagnostic assay.

The words "anticipate," "believe," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "should," "target," "upcoming," "will," "would" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

Any forward-looking statements in this press release are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially, including, without limitation: the company's limited operating history, history of significant losses and the early stage of development of its product candidates; the risk that preclinical data may not be predictive of results in clinical trials; the risk that preliminary and interim clinical data are subject to further analysis and may not be predictive of, may be inconsistent with, or may be more favorable than, data generated as clinical trials continue or data from future clinical trials; uncertainties inherent in the initiation, timing, design and enrollment of clinical trials, and the availability and timing of data from ongoing and future trials; the company's ability to successfully demonstrate the safety and efficacy of its product candidates, including for any companion diagnostic, and to obtain and maintain regulatory approvals; the timing and outcome of planned interactions with, and submissions to, the FDA and other regulatory authorities, including whether an accelerated approval pathway will be available to the company; the risk that regulatory designations, including Fast Track and orphan drug designation, may not result in a faster development, review or approval process, may not increase the likelihood of regulatory approval, and may be withdrawn; competition from third parties that are developing products for similar indications; the prior success of the company's management team not being indicative of future success; the company's reliance on third parties, including contract research organizations, contract manufacturing organizations and collaborators; the company's ability to obtain, maintain and protect its intellectual property; and the company's need for additional financing and its estimates regarding operating expenses and capital requirements.

These and other risks are described in greater detail under the heading "Risk Factors" in the company's filings with the Securities and Exchange Commission (the "SEC"), including the company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2026, as well as in the company's subsequent filings with the SEC. Any forward-looking statements represent the company's views only as of the date of this press release, and the company expressly disclaims any obligation to update any forward-looking statements, except as required by law.

Company Contacts:
Investors:
Michael Moore, BlossomHill Therapeutics
michael.moore@bhtherapeutics.com

Media:
Ashlea Kosikowski, 1AB
ashlea@1abmedia.com