Beamion PANTUMOR-1: rationale and design of a Phase II trial of zongertinib in HER2-overexpressed/amplified or HER2 -mutant solid tumors

Human epidermal growth factor receptor 2 (HER2, encoded by ERBB2) alterations are known oncogenic drivers in many solid tumors. Zongertinib is a novel, oral, irreversible, HER2-selective tyrosine kinase inhibitor that spares wild-type epidermal growth factor receptor, thereby limiting associated toxicities. In a Phase Ia/Ib trial (NCT04886804), zongertinib demonstrated encouraging activity with a manageable safety profile in HER2-altered tumors (HER2 overexpression, amplification, or mutations).The Phase II, open-label, Beamion PANTUMOR-1 basket trial (NCT06581432) is evaluating the efficacy and safety of zongertinib monotherapy in previously treated patients with HER2-positive (HER2-overexpressed/amplified) or HER2-mutant solid tumors. Patients with HER2-positive tumors will be enrolled to one of eight cohorts: urothelial, biliary tract, uterine, cervical, non-squamous lung, salivary gland, colorectal or tumor agnostic. Patients with HER2-mutant tumors will be enrolled to one of five cohorts: urothelial, breast, gastroesophageal, biliary tract or tumor agnostic. Patients will receive zongertinib 120 mg orally once daily until disease progression (RECIST v1.1), unacceptable toxicity, death, or withdrawal of patient consent, whichever occurs first. The primary endpoint is objective response (central independent review, RECIST v1.1). Secondary endpoints include duration of response, progression-free survival, disease control, occurrence of treatment-emergent adverse events, and health-related quality of life. Recruitment is ongoing in 13 countries globally.Clinical trial registration http://www.clinicaltrials.gov identifier is NCT06581432.