Phase 1b trial of anti-HER2 antibody inetetamab and pan-HER inhibitor pyrotinib in HER2-positive advanced lung cancer.

There remains an unmet need for targeted therapies against advanced non-small-cell lung cancer (NSCLC) with HER2 mutations. To improve the antitumor activity of single anti-HER2 agent, this prospective, single-arm clinical trial (NCT05016544) examined the safety profile and efficacy of anti-HER2 antibody inetetamab and pan-HER TKI pyrotinib in HER2-posivite advanced NSCLC patients. Enrolled patients received inetetamab every 3 weeks and pyrotinib once per day (pyrotinib, dose-escalation part, 240 mg, 320 mg; dose-expansion part, 320 mg). Primary endpoints were dose-limiting toxicity (DLT) dosage and safety. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and disease control rate (DCR). A total of 48 patients were enrolled. During the dose-escalation period, no DLT occurred. Diarrhea was the most commonly reported treatment-related adverse event (TRAE). Grade 3 TRAEs occurred in seven patients. The median PFS (mPFS) was 5.5 months [95% confidence interval (CI): 4.4-8.6 months]. The confirmed ORR and DCR reached 25% (11/44) and 84.1% (37/44), respectively. Responses were shown in patients with distinct HER2 aberrations. In summary, inetetamab in combination with pyrotinib demonstrated acceptable safety and antitumor activity among patients with advanced HER2-mutant NSCLC.