BlossomHill’s BH-30643 Gets FDA Fast Track Designation for EGFR C797S-Positive NSCLC

BlossomHill Therapeutics’ investigational EGFR inhibitor BH-30643 has received FDA Fast Track designation for adults with advanced or metastatic EGFR C797S-positive non-small cell lung cancer (NSCLC) after treatment with a third-generation EGFR tyrosine kinase inhibitor (TKI). The regulatory designation supports accelerated development of an oral targeted therapy for a resistance setting with limited treatment options.

FDA Fast Track Designation Targets an Unmet Resistance Setting

The FDA granted Fast Track designation to BH-30643 for patients whose tumors harbor the EGFR C797S resistance mutation following prior third-generation EGFR TKI therapy. C797S can emerge as an on-target resistance mechanism after treatment with third-generation EGFR inhibitors, limiting continued activity of these drugs.

BH-30643 Uses a Reversible, Mutant-Selective EGFR Approach

BH-30643 is an orally bioavailable, non-covalent macrocyclic inhibitor that selectively targets mutant EGFR. Unlike third-generation EGFR TKIs that rely on irreversible binding involving C797, BH-30643 uses reversible inhibition and retains activity against EGFR variants carrying C797S.

Preclinical studies reported activity across classical EGFR alterations, atypical mutations and exon 20 insertions, as well as resistance mutations including C797S and T790M. The compound also showed marked selectivity over wild-type EGFR, a property that could potentially reduce toxicities associated with inhibiting normal EGFR signaling.

The scientific rationale is particularly relevant because C797S can undermine the covalent binding mechanism used by third-generation EGFR TKIs. In laboratory studies, BH-30643 maintained potent activity against EGFR-mutant models containing C797S alone or together with T790M.

SOLARA Is Evaluating BH-30643 in First-in-Human Development

BH-30643 is being evaluated in SOLARA (NCT06706076), a global Phase 1/2, open-label, multicenter first-in-human study. The trial is assessing safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary antitumor activity in adults with locally advanced or metastatic NSCLC harboring EGFR and/or HER2 mutations.

Phase 1 includes dose escalation and expansion to establish the recommended Phase 2 dose and, if applicable, the maximum tolerated dose. Phase 2 will evaluate antitumor activity and safety in cohorts defined by mutation subtype and treatment history.

The study is currently recruiting, with an estimated enrollment of 266 participants and estimated primary completion in January 2029.

Clinical Data Will Determine the Next Development Step

BlossomHill Chief Medical Officer Geoff Oxnard said the Fast Track designation reflects FDA recognition of the potential for BH-30643 to address an unmet need in EGFR C797S-positive NSCLC and provides opportunities for closer regulatory interaction during development.

The designation does not establish clinical efficacy or safety. Those questions remain under evaluation in SOLARA. Earlier AACR data provide the preclinical rationale for the program, while ongoing clinical development will determine whether BH-30643 can translate its mutant-selective profile into meaningful tumor responses and tolerability in patients with EGFR-driven NSCLC.

For now, the FDA action gives BlossomHill an expedited regulatory framework as it advances BH-30643 through Phase 1/2 development, with the C797S-resistant population representing a key test of the compound’s ability to overcome a major mechanism of EGFR TKI resistance.

Reference

BlossomHill Therapeutics Announces FDA Fast Track Designation for BH-30643, a Macrocyclic OMNI-EGFR™ Inhibitor for the Treatment of Advanced EGFR C797S-positive NSCLC | Tue, 08/18/2026 – 07:00