SystImmune Reports Phase 1 Data for BL-M14D1 Demonstrating Promising Activity in Small-Cell Lung Cancer at ASCO

REDMOND, Wash., June 1, 2026 /PRNewswire/ -- SystImmune, Inc., a clinical-stage biotechnology company, today announced the oral presentation of Phase 1 data for BL-M14D1 in patients with small-cell lung cancer (SCLC), neuroendocrine carcinoma (NEC), and other solid tumors (BL-M14D1-101, NCT06505824) at the American Society of Clinical Oncology (ASCO) 2026 Annual Meeting in Chicago.  BL-M14D1 is a DLL3 targeting antibody drug conjugate being developed globally by SystImmune, a subsidiary of Biokin.

This study evaluated the safety and efficacy of BL-M14D1 in Chinese patients with advanced SCLC, NEC, and other solid tumors. As of the November 30, 2025 data cut-off, BL-M14D1 demonstrated:

• Promising antitumor activity in heavily pre-treated patients across multiple tumor types, including SCLC and other NECs
• Manageable safety profile, with hematologic adverse events managed with standard supportive care

A total of 127 patients with advanced solid tumors were treated, including 87 with SCLC and 40 with NEC. Most patients were heavily pre-treated. The most common adverse events were hematologic, including neutropenia, which were generally manageable and infrequently led to dose reductions or serious complications.  The safety profile is consistent with other brengitecan based topo1 ADCs.  One case of grade 3 interstitial lung disease was seen, and one treatment related death was reported.

Among patients with SCLC treated at 4.0 mg/kg D1Q3W, the confirmed objective response rate was 62% (21 of 34 patients), with a median progression-free survival of 7.2 months. Based on these results, SystImmune plans to initiate a global registrational study in first-line extensive-stage SCLC.

"These initial Phase 1 results for BL-M14D1 demonstrate compelling anti-tumor activity, including a 62% confirmed response rate and encouraging durability, in heavily pre-treated patients with small-cell lung cancer," said Jonathan Cheng, M.D., Chief Medical Officer of SystImmune. "Given the significant unmet need in this population, we believe these data support the potential for BL-M14D1 to become an important new treatment option, and we are rapidly advancing the program into global registrational studies in the first-line setting."

About the BL-M14D1-101 Phase I clinical trial

BL-M14D1-101 (NCT06505824) is a multi-center, Phase I study to evaluate the safety, tolerability, pharmacokinetic characteristics and preliminary efficacy of BL-M14D1 in locally advanced or metastatic solid tumors.  The study is being conducted in three parts (dose escalation, dose finding, and dose expansion) with patients being dosed on Day 1 of a continuous 21-day treatment cycle (D1Q3W).  In the dose escalation and dose expansion phase, patients were treated with BL-M14D1 at 0.66, 2.0, 3.5, 4.0, 4.5, 5.0, and 6.0 mg/kg.  In the dose expansion phase, SCLC and NEC patients were treated at 4.0 and 4.5mg/kg D1Q3W.  The primary endpoint includes safety.  Secondary endpoints include objective response rate (ORR) by RECIST 1.1 criteria, duration of response (DoR), disease control rate (DCR), and PK analysis.

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.