New Clinical Data for Izalontamab Brengitecan and Novel ADC Pipeline to be Presented at ASCO 2026

REDMOND, Wash., May 21, 2026 /PRNewswire/ -- SystImmune, Inc. (SystImmune), a clinical-stage biotechnology company, today announced the presentation of data on iza-bren (izalontamab brengitecan), BL-M14D1, T-Bren (BL-M07D1), and BL-M05D1, four distinct clinical programs from its antibody drug conjugate (ADC) pipeline, at the American Society of Clinical Oncology (ASCO) 2026 Annual Meeting taking place May 29 – June 2 in Chicago.  Iza-bren, a potentially first-in-class EGFRxHER3 bispecific ADC, is jointly developed by SystImmune and Bristol Myers Squibb under a collaboration and exclusive license agreement in territories outside of China.

"The data we are presenting at ASCO 2026 mark an important inflection point for SystImmune, with multiple late-stage readouts alongside continued expansion of our earlier pipeline," said Dr. Jie D'Elia, Ph.D., Chief Executive Officer of SystImmune. "From randomized Phase III trials of iza-bren to emerging proof-of-concept data across our next-generation ADC programs, we are demonstrating both the clinical potential and scalability of our platform. Together, these advances reinforce our ability to rapidly translate innovative science into differentiated therapies for patients with high unmet need worldwide."

Key data to be presented at ASCO include:

Highlighting the continued clinical advancement of iza-bren:

• Late-breaking data from the first randomized, Phase III study evaluating iza-bren versus physician's choice of chemotherapy in unresectable locally advanced or metastatic triple-negative breast cancer patients in China
• Safety and efficacy data from a randomized, open label, multi-center, Phase III study evaluating iza-bren vs physician's choice of chemotherapy in patients with recurrent or metastatic esophageal squamous cell carcinoma in China

Demonstrating breadth of ADC platform with updates from novel ADC programs:

• Results from the first Phase I study in China of BL-M14D1, a novel DLL3 directed ADC, in patients with locally advanced or metastatic small-cell lung cancer (SCLC), neuroendocrine carcinoma (NEC), and other solid tumors
• Safety and efficacy results from a Phase II study in China evaluating trastuzumab brengitecan (T-bren; BL-M07D1) in patients with recurrent or metastatic ovarian cancer
• Results from a Phase II study in China of T-Bren monotherapy or in combination with pertuzumab in patients with treatment-naïve HER2-positive unresectable locally advanced or metastatic (LA/M) breast cancer
• Results from the first Phase I study in China of BL-M05D1, a novel Claudin 18.2 directed ADC, in patients with locally advanced or metastatic Claudin18.2–expressing solid tumors

"We are particularly encouraged to present the Phase III data for iza-bren compared to standard chemotherapy in TNBC, which further supports its potential to deliver meaningful clinical benefit across multiple tumor types," said Jonathan Cheng, M.D., Chief Medical Officer of SystImmune. "In parallel, data from T-Bren, BL-M14D1, and BL-M05D1 highlight the breadth of our ADC portfolio, with early signals of activity and combination potential in several difficult-to-treat cancers.  Collectively, these results strengthen our confidence in advancing both iza-bren and our broader pipeline into later-stage development."

Details of the presentations at ASCO are below:

Izalontamab brengitecan (iza-bren) versus physician's choice of chemotherapy in patients with unresectable locally advanced or metastatic triple-negative breast cancer (TNBC): A randomized phase III study
Trial Reference: BL-B01D1-307 (NCT06382142), China
Session Title:  Oral Abstract Session – Breast Cancer (Metastatic)
Abstract: LBA1003
Speaker:  Jiong Wu (Shanghai, China)
Session Date & Time: Tuesday, June 2^nd, 2026, 9:45 AM-12:45 PM CDT

Izalontamab brengitecan (iza-bren) versus chemotherapy in patients with recurrent or metastatic esophageal squamous cell carcinoma (ESCC): A multicenter, randomized, open-label, phase III study
Trial Reference: BL-B01D1-305 (NCT06304974), China
Session Title:  Oral Abstract Session – Gastrointestinal Cancer (Gastroesophageal, Pancreatic, and Hepatobiliary)
Abstract: 4008
Speaker:  Zhihao Lu (Beijing, China)
Session Date & Time: Monday, June 1^st, 2026, 9:45 AM-12:45 PM CDT

Phase I study of BL-M14D1, a novel DLL3-directed antibody-drug conjugate (ADC), inpatients with locally advanced or metastatic small-cell lung cancer (SCLC), neuroendocrine carcinoma (NEC), and other solid tumors
Trial Reference: BL-M14D1-101 (NCT06505824), China
Session Title:  Oral Abstract Session – Developmental Therapeutics (Molecularly Targeted Agents and Tumor Biology)
Abstract: 3001
Speaker:  Wei Li (Shanghai, China)
Session Date & Time: Monday, June 1^st, 2026, 8:00 AM-11:00 AM CDT

T-Bren (BL-M07D1) in patients with recurrent or metastatic (R/M) ovarian cancer: Results from two phase II studies
Trial Reference: BL-M07D1-202/203 (NCT06031584/NCT06131450), China
Session Title:  Oral Abstract Session – Developmental Therapeutics (Molecularly Targeted Agents and Tumor Biology)
Abstract: 3003
Speaker:  Gongyi Zhang (Beijing, China)
Session Date & Time: Monday, June 1^st, 2026, 8:00 AM-11:00 AM CDT

Phase II study of izalontamab (SI-B001) in combination with paclitaxel or docetaxel in patients with recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC)
Trial Reference: SI-B001-206 (NCT05054439), China
Session Title:  Rapid Oral Abstract Session (Head and Neck Cancer)
Abstract: 6019
Speaker:  Ye Guo (Shanghai, China)
Session Date & Time: Monday, June 1^st, 2026, 4:30 PM-6:00 PM CDT

Phase I study of BL-M05D1, a novel Claudin18.2-directed antibody-drug conjugate (ADC), in patients with locally advanced or metastatic Claudin18.2–expressing solid tumors
Trial Reference: BL-M05D1-101 (NCT06349811), China
Session Title:  Poster Session - Developmental Therapeutics (Molecularly Targeted Agents and Tumor Biology)
Abstract: 3030
Speaker:  Siyuan Cheng (Beijing, China)
Onsite Poster Display Date: Saturday, May 30^th, 2026, 1:30 PM-4:30 PM CDT

Phase II study of T-Bren (BL-M07D1) monotherapy or in combination with pertuzumab in patients with treatment-naïve HER2-positive unresectable locally advanced or metastatic (LA/M) breast cancer
Trial Reference: BL-M07D1-205 (NCT06445400), China
Session Title:  Poster Session - Breast Cancer (Metastatic)
Abstract: 1049
Speaker:  Yaping Yang (Guangzhou, China)
Onsite Poster Display Date: Monday, June 1^st, 2026, 1:30 PM-4:30 PM CDT

About iza-bren
SystImmune, in collaboration with BMS outside of China, is developing iza-bren (BL-B01D1), a bispecific antibody-drug conjugate (ADC) that targets both EGFR and HER3, which are highly expressed in various epithelial cancers and are known to be associated with cancer cell proliferation and survival.  Iza-bren's dual mechanism of action blocks EGFR and HER3 signals to cancer cells, reducing proliferation and survival signals.  In addition, upon antibody mediated internalization, iza-bren's therapeutic novel Topo1i payload is released causing cytotoxic stress that leads to cancer cell death.

About SystImmune's ADC Pipeline Programs (BL-M07D1, BL-M14D1, BL-M05D1)
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.

T-Bren (BL-M07D1), BL-M14D1, and BL-M05D1 each incorporate the brengitecan payload and linker technology, paired with distinct targeting antibodies to address different tumor-associated antigens.

• T-Bren (BL-M07D1) targets HER2, a well-established driver across multiple solid tumors, enabling targeted delivery of the brengitecan payload to HER2-expressing cancer cells.
• 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.
• BL-M05D1 targets Claudin 18.2, a protein highly expressed in tumors such as pancreatic and gastric cancers, enabling targeted cytotoxic activity in Claudin 18.2–expressing tumors.

Across these programs, SystImmune's brengitecan platform is designed to combine tumor-specific targeting with efficient payload delivery, with the goal of improving therapeutic index and expanding treatment options for patients with difficult-to-treat cancers.

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.