BlossomHill Therapeutics, Inc. (Nasdaq: BLSM) announced updated data from its ongoing Phase 1/2 SOLARA clinical trial of BH-30643, an investigational oral inhibitor targeting epidermal growth factor receptor (EGFR) resistance mutations. The data were presented at the International Association for the Study of Lung Cancer (IASLC) 2026 World Conference on Lung Cancer in Seoul, South Korea.
The trial focused on patients with non-small cell lung cancer (NSCLC) who had developed secondary EGFR resistance mutations, specifically the C797S mutation, following treatment with prior EGFR inhibitors. As of the May 12, 2026 data cutoff, with efficacy follow-up through August 10, 2026, the company reported a 45% objective response rate (ORR) among 40 patients in this cohort. Of these patients, 18 achieved a confirmed partial response, while 2 had ongoing unconfirmed responses. The disease control rate was 88%.
The patient population was characterized as heavily pretreated, with a median of two prior lines of therapy. Specifically, 98% of patients had received prior osimertinib, 53% had received prior chemotherapy or an antibody-drug conjugate, and 53% had a history of brain metastases. Additionally, 35% of patients had concurrent T790M mutations. At the time of follow-up, 63% of patients (25/40) remained on treatment with a median follow-up of 6.9 months.
BlossomHill noted that BH-30643 demonstrated a favorable safety profile. 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.
BH-30643 has received Fast Track designation from the FDA for the treatment of advanced or metastatic EGFR C797S-positive NSCLC. BlossomHill plans to initiate a global Phase 2 study targeting this patient population in the first quarter of 2027.
