SystImmune Announces First Patient Dosed in Global Phase 3 Trial of BL-M14D1 in First-Line Extensive-Stage Small Cell Lung Cancer

REDMOND, Wash., Aug. 5, 2026 /PRNewswire/ -- SystImmune, Inc., a clinical-stage biotechnology company and subsidiary of Biokin, today announced that the first patient has been dosed in BrenDeLL-Lung01 (NCT07625644), a global Phase 3 registrational trial evaluating BL-M14D1 in combination with atezolizumab for the treatment of patients with previously untreated extensive-stage small cell lung cancer (ES-SCLC).

BL-M14D1 is an investigational DLL3-targeted antibody-drug conjugate (ADC) built on SystImmune's proprietary brengitecan platform and is being developed globally for the treatment of small cell lung cancer and other neuroendocrine malignancies.

"The initiation of our global Phase 3 program marks an important milestone for BL-M14D1 and reflects our commitment to bringing innovative treatment options to patients with small cell lung cancer," said Jonathan Cheng, M.D., Chief Medical Officer of SystImmune. "Despite recent advances, outcomes for patients with extensive-stage small cell lung cancer remain poor, and there continues to be a significant need for more effective therapies. We believe BL-M14D1 has the potential to improve outcomes for these patients, and we are excited to begin evaluating the program in a registrational setting."

The Phase 3 study follows encouraging clinical activity observed in the ongoing Phase 1 BL-M14D1-101 trial recently presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting. These results demonstrated promising anti-tumor activity and a manageable safety profile in heavily pre-treated patients with small cell lung cancer and other neuroendocrine carcinomas, supporting advancement of the program into late-stage development.

About the BrenDeLL-Lung01 Phase 3 Clinical Trial
BrenDeLL-Lung01 (NCT07625644) is a global, multi-center, randomized Phase 3 trial evaluating BL-M14D1 in combination with atezolizumab versus standard-of-care platinum and etoposide induction followed by atezolizumab maintenance, with or without lurbinectedin, in patients with previously untreated extensive-stage small cell lung cancer.  The study intends to enroll approximately 580 patients and the primary endpoint for this study is progression-free survival as assessed by blinded independent central review (BICR).

About BL-M14D1
SystImmune is advancing a portfolio of next-generation antibody-drug conjugates (ADCs) built on its proprietary brengitecan platform, which utilizes a potent topoisomerase I inhibitor payload designed for targeted delivery to tumor cells.  The clinical progress of izalontamab brengitecan (iza-bren) provides initial validation of this platform's potential to deliver meaningful anti-tumor activity across multiple cancer types.

BL-M14D1 targets DLL3, which is highly expressed in small-cell lung cancer and neuroendocrine tumors, facilitating selective delivery of the brengitecan payload to DLL3-positive tumor cells.

About SystImmune
SystImmune is a clinical-stage biopharmaceutical company located in Redmond, WA. It specializes in developing innovative cancer treatments using its established drug development platforms, focusing on bi-specific, multi-specific antibodies, and antibody-drug conjugates (ADCs). SystImmune has several assets in various stages of clinical trials for solid tumor and hematologic indications. Alongside ongoing clinical trials, SystImmune has a robust preclinical pipeline of potential cancer therapeutics in the discovery or IND-enabling stages, representing cutting-edge biologics development.

Forward-Looking Statements
This press release contains forward-looking statements, including statements regarding the potential clinical benefits of iza-bren, the timing and outcomes of regulatory interactions, and the future development and commercialization of iza-bren. Forward-looking statements are subject to risks and uncertainties that may cause actual results to differ materially. SystImmune undertakes no obligation to update any forward-looking statements contained herein, except as required by law.

SOURCE SystImmune, Inc.