BlossomHill Therapeutics Presents Encouraging Data for BH-30643 in EGFR C797S-Positive NSCLC

BlossomHill Therapeutics, a clinical-stage biopharmaceutical company, has presented updated data from its ongoing Phase 1/2 SOLARA trial at the International Association for the Study of Lung Cancer (IASLC) 2026 World Conference on Lung Cancer. The findings, presented by Dr. Hidehito Horinouchi from the National Cancer Center Hospital in Tokyo, highlight the promising anti-tumor activity of the company’s investigational EGFR inhibitor, BH-30643, in patients with EGFR C797S-positive non-small cell lung cancer (NSCLC).

The data reveal that among 40 patients with EGFR C797S-positive resistance to prior EGFR inhibitor treatment, with or without concurrent T790M, 18 patients achieved a confirmed or ongoing unconfirmed partial response, representing a 45% objective response rate (ORR). Additionally, 88% of the patients experienced disease control, with 25 patients remaining on treatment at the time of efficacy follow-up. The median follow-up period was 6.9 months.

Dr. Horinouchi emphasized the significance of these results, stating, "C797S-driven resistance to third-generation EGFR inhibitors was first described over a decade ago, yet patients whose tumors develop this mutation currently have no approved targeted treatment options. The responses observed with BH-30643 in this heavily pretreated population, together with encouraging early evidence of durability, support the potential of BH-30643 to directly target this resistance mechanism."

BlossomHill Therapeutics also highlighted the favorable safety profile of BH-30643. Among 174 patients treated at doses of 40 mg, 50 mg, and 60 mg twice daily, treatment-related dose reductions and discontinuations occurred in 9% and 3% of patients, respectively. The most common treatment-related adverse event was bilirubin elevation, which was generally asymptomatic and predominantly unconjugated, consistent with UGT1A1 inhibition by BH-30643.

Geoff Oxnard, M.D., Chief Medical Officer of BlossomHill Therapeutics, commented, "We are encouraged to see meaningful anti-tumor activity across a molecularly diverse group of patients with C797S-positive disease, including patients with concurrent T790M and those who have received multiple prior therapies, with a favorable safety profile. Together with the recent FDA Fast Track designation, these data strengthen our conviction in the potential of BH-30643 and support our plans to advance into a Phase 2 trial in patients with C797S-positive NSCLC in 2027."

The SOLARA trial, a global, open-label, multicenter study, is assessing the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary anti-tumor activity of BH-30643 in patients with EGFR mutant 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.

BlossomHill Therapeutics, founded and led by industry veteran J. Jean Cui, Ph.D., is applying an intentional, chemistry-based approach to design and develop innovative small molecule medicines that address significant unmet medical needs in cancer treatment. The company’s lead clinical program, BH-30643, is an investigational, non-covalent, macrocyclic, brain active, mutant-selective OMNI-EGFR™ inhibitor for the treatment of EGFR-mutant NSCLC. The company also has other clinical programs in development, including BH-30236, an investigational macrocyclic CDC-like kinase (CLK) inhibitor for the treatment of relapsed or refractory acute myeloid leukemia (R/R AML) and higher-risk myelodysplastic syndromes (HR-MDS), and BH-501284, a preclinical, non-covalent, selective, pan-KRAS Switch-II inhibitor for potential future development in diverse KRAS-mutant tumors.