SystImmune Unveils Encouraging Phase 1 Results for BL-M14D1 in Small-Cell Lung Cancer at ASCO 2026

SystImmune, Inc., a biotechnology firm in the clinical development stage, presented new findings on its investigational drug BL-M14D1 at the American Society of Clinical Oncology (ASCO) 2026 Annual Meeting held in Chicago. This oral presentation disclosed initial Phase 1 data focusing on patients afflicted with small-cell lung cancer (SCLC), neuroendocrine carcinoma (NEC), and other solid tumors. As a DLL3-targeting antibody-drug conjugate, BL-M14D1 aims to provide targeted therapy for this challenging group of cancers.

The Phase 1 study, which treated a cohort of 127 patients with advanced solid tumors, reported promising outcomes. Among these, 87 patients were specifically diagnosed with SCLC, while 40 had NEC. Most participants had undergone extensive prior treatments, indicating a particularly hard-to-treat population. The safety profile of BL-M14D1 demonstrated manageable adverse effects, predominantly hematological, which were effectively addressed through standard supportive care. Notably, the most common side effect was neutropenia, which seldom resulted in dose reductions or serious complications.

As of the data cutoff on November 30, 2025, BL-M14D1 exhibited effective antitumor activity, with an impressive overall response rate of 62% among SCLC patients treated with a dosage of 4.0 mg/kg once every three weeks. Furthermore, the median progression-free survival for these patients was recorded at 7.2 months, suggesting potential longevity in treatment effectiveness. These compelling results have prompted SystImmune to push forward with plans to commence a global registrational trial targeting first-line treatment for extensive-stage SCLC.

Dr. Jonathan Cheng, Chief Medical Officer at SystImmune, commented, "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. 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

The BL-M14D1-101 clinical trial (NCT06505824) is designed as a multi-center, Phase I study focused on assessing the safety, tolerability, pharmacokinetics, and preliminary efficacy of BL-M14D1 in patients suffering from locally advanced or metastatic solid tumors. This study comprises several phases, including dose escalation, dose finding, and dose expansion, with patients receiving treatment starting on Day 1 of a continuous 21-day cycle. The primary endpoint of the study is the assessment of safety, while secondary endpoints encompass objective response rates as defined by RECIST 1.1 criteria, duration of response (DoR), disease control rate (DCR), and pharmacokinetic analysis.

About SystImmune

SystImmune is situated in Redmond, Washington, specializing in innovative cancer therapies using its state-of-the-art drug development platforms. The company’s focus lies on advancing bi-specific and multi-specific antibodies as well as antibody-drug conjugates (ADCs). With several products at different clinical trial phases targeting solid tumors and hematologic malignancies, SystImmune is devoted to pushing forward its promising preclinical pipeline featuring prospective cancer therapeutics.

As the landscape of cancer therapies evolves, SystImmune’s commitment to developing groundbreaking treatments positions it as a pivotal player in the fight against cancer. The data released at ASCO 2026 serves as a beacon of hope for patients and healthcare professionals alike, highlighting the untapped potential of targeted therapies in addressing the critical gaps in cancer treatment.