A phase 1/2 study of BLU-945 in patients with common activating EGFR-mutant non–small cell lung cancer (NSCLC): SYMPHONY trial in progress.

TPS9156 Background: Although EGFR-targeted therapies have improved outcomes in patients with EGFR-mutant ( EGFRm) NSCLC, such as EGFR ex19del and L858R, resistance to these drugs is inevitable. BLU-945 is an investigational next-generation EGFR tyrosine kinase inhibitor (TKI) designed to suppress common activating and on-target resistance EGFR mutations, such as C797S and T790M. Preclinically it has shown activity as monotherapy in osimertinib-resistant patient-derived xenograft (PDX) models. In addition, BLU-945 has > 450-fold selectivity for C797S and T790M mutants over wildtype, advantageous for combinations with complementary EGFR-targeting agents, such as osimertinib. These combinations have shown enhanced activity in PDX models. The SYMPHONY trial (BLU-945-1101; NCT04862780) is an international, open-label, first-in-human, phase 1/2 study designed to evaluate safety, tolerability, and antitumor activity of BLU-945 as monotherapy and in combination with osimertinib in patients with EGFRm NSCLC. Methods: Key eligibility criteria include adults with pathologically confirmed metastatic NSCLC with an activating EGFR mutation, Eastern Cooperative Oncology Group performance status 0–1, and previous treatment with ≥1 EGFR-targeted TKI. Patients with asymptomatic brain metastases who are on stable doses of corticosteroids are eligible. Tumors with additional known driver alterations, including EGFR exon 20 insertions and other kinase drivers, are excluded. Primary endpoints are maximum tolerated dose, recommended phase 2 dose (RP2D) and safety (phase 1); and overall response rate (ORR) by RECIST 1.1 (phase 2). Key secondary endpoints include ORR, duration of response (DOR), pharmacokinetics (PK), and pharmacodynamics (PD; phase 1); and DOR, progression-free survival, overall survival, CNS efficacy, PK, and safety (phase 2). Phase 1 dose escalation will be done using Bayesian optimal interval design; ̃85 patients will receive BLU-945 monotherapy and ̃18 will receive combination BLU-945 and osimertinib. In the phase 2 dose expansion, patients will receive BLU-945 at the RP2D of the monotherapy in 3 groups based on EGFR mutational profile: T790M and C797S (n≈37), T790M, but not C797S (n≈12), and C797S, but not T790M (n≈12). In a combination group, BLU-945 plus osimertinib will be administered at RP2D of the combination to n≈24 patients, ≥12 with both T790M and C797S mutations. Patients may receive treatment until disease progression or unacceptable toxicity. Recruitment has started and approximately 30 sites will be open for enrollment across North America, Europe, and Asia. Clinical trial information: NCT04862780.