Izalontamab Brengitecan (Iza-Bren), a First-in-Class EGFR-HER3 Bispecific Antibody-Drug Conjugate in Extensive-Stage Small Cell Lung Cancer: Results From a Phase Ib Study
Year: 2026
Type: article
Study design: Clinical Trial
Abstract: PURPOSE: Small cell lung cancer (SCLC) remains one of the most aggressive malignancies, with limited treatment options beyond frontline chemo-immunotherapy. Izalontamab brengitecan (iza-bren, BL-B01D1) is a first-in-class bispecific antibody-drug conjugate cotargeting epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 3 (HER3). We expanded the SCLC cohort to further evaluate the efficacy and safety of iza-bren in patients with extensive-stage SCLC (ES-SCLC). METHODS: This open-label, multicenter, dose-expansion phase Ib study (ClinicalTrials.gov identifier: NCT05194982) enrolled patients with ES-SCLC who had progressed on prior systemic therapies. Patients received iza-bren 2.5 mg/kg once daily on days 1 and 8 of each 3-week cycle. The primary end points were objective response rate (ORR) and safety/tolerability. Secondary end points included disease control rate (DCR), duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Exploratory end point included the assessment of potential associations between EGFR/HER3 expression and clinical outcomes. RESULTS: As of December 5, 2024, 52 patients were enrolled. The ORR was 48.1% (95% CI, 34.0 to 62.4), with a median PFS of 4.1 months (95% CI, 3.0 to 5.5) and a median OS of 12.2 months (95% CI, 9.1 to 13.2). In patients who received iza-bren as second-line treatment (n = 22), the ORR was 72.7% (95% CI, 49.8 to 89.3), median PFS 6.2 months (95% CI, 3.7 to 8.2), and median OS 15.0 months (95% CI, 8.7 to not reached). The most common treatment-related adverse events were hematologic toxicities (neutropenia, thrombocytopenia, anemia, and leukopenia). Exploratory biomarker analysis suggested that positive HER3 expression may be associated with better treatment response. CONCLUSION: Iza-bren showed encouraging antitumor activity in relapsed ES-SCLC, particularly in the second-line setting. A phase III randomized controlled trial of iza-bren compared with topotecan (ClinicalTrials.gov identifier: NCT06500026) is ongoing.
Source: Journal of Clinical Oncology
DOI: 10.1200/jco-26-00243
Institutions: Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Zhengzhou University, Henan Cancer Hospital, Wuhan Union Hospital, Huazhong University of Science and Technology, Chongqing University, Chongqing Cancer Hospital, Renmin Hospital of Wuhan University, Shanxi Provincial Cancer Hospital, Fujian Medical University, Fujian Provincial Cancer Hospital, Sichuan University, West China Hospital of Sichuan University, Sichuan Baili Pharmaceutical Co., Ltd. (China)
Language: English
Topic: Lung Cancer Research Studies
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
OpenAlex ID: W7170671993