SystImmune's ADC Pipeline Shines Ahead of ASCO with Major Cancer Data

REDMOND, WA – May 22, 2026 – The oncology world is turning its attention to Redmond-based SystImmune, as the clinical-stage biotechnology company prepares to unveil a trove of highly anticipated data at the upcoming American Society of Clinical Oncology (ASCO) 2026 Annual Meeting. The presentations, spanning four distinct cancer-fighting drugs, are headlined by late-breaking Phase III results for its flagship asset, izalontamab brengitecan (iza-bren), which have already shown game-changing potential in one of the most challenging forms of breast cancer.

The announcements signal a pivotal moment for SystImmune, validating its proprietary drug development platform and positioning it as a formidable player in the competitive field of antibody-drug conjugates (ADCs). These "smart bomb" therapies are designed to deliver potent chemotherapy payloads directly to cancer cells, and SystImmune's pipeline appears poised to deliver on that promise across multiple fronts.

Iza-bren Challenges Treatment Standards in Tough Cancers

The centerpiece of SystImmune's ASCO showcase is iza-bren, a potentially first-in-class bispecific ADC jointly developed with pharmaceutical giant Bristol Myers Squibb for markets outside of China. The drug targets both EGFR and HER3, two proteins often overexpressed on cancer cells that drive tumor growth.

In a major development, a randomized Phase III study in China evaluating iza-bren against standard chemotherapy in patients with unresectable or metastatic triple-negative breast cancer (TNBC) has met its dual primary endpoints. The abstract reveals that iza-bren demonstrated statistically significant and clinically meaningful improvements in both progression-free survival (PFS) and overall survival (OS). This achievement is particularly noteworthy, as TNBC is a notoriously aggressive cancer with limited targeted treatment options, and improving both PFS and OS is the gold standard for a new therapy's success.

"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, in a company statement. "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."

The success of iza-bren is not limited to breast cancer. SystImmune will also present data from another Phase III trial in China, this one evaluating the drug against chemotherapy in patients with recurrent or metastatic esophageal squamous cell carcinoma (ESCC), another cancer with a high unmet need. These back-to-back late-stage readouts underscore the broad potential of iza-bren across different solid tumors.

The Brengitecan Engine: Powering a Diverse Portfolio

The impressive results from the iza-bren program serve as powerful validation for SystImmune's underlying technology: the proprietary brengitecan platform. At its core, an ADC consists of an antibody that seeks out a specific target on cancer cells, linked to a cytotoxic payload that kills the cell once delivered.

SystImmune's platform utilizes a potent topoisomerase I inhibitor (Topo1i) payload. This class of drug has proven highly effective in other successful ADCs, most notably AstraZeneca and Daiichi Sankyo's Enhertu. By combining its own novel Topo1i payload and linker technology with highly specific antibodies, SystImmune aims to create therapies with an optimized balance of efficacy and safety.

"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," stated Jonathan Cheng, M.D., Chief Medical Officer of SystImmune.

The company is betting that the success of iza-bren is just the beginning. The brengitecan platform serves as the engine for a diverse pipeline of next-generation ADCs, three of which will also have their moment in the spotlight at ASCO.

A Multi-Pronged Attack on Novel Cancer Targets

Beyond its flagship asset, SystImmune is demonstrating a strategic vision that extends to a variety of cancers and novel biological targets. This approach diversifies risk and opens up new avenues for treating previously intractable diseases.

One of the most exciting programs is BL-M14D1, an ADC targeting DLL3. This target is highly expressed in aggressive cancers like small-cell lung cancer (SCLC) and neuroendocrine carcinomas (NEC), but not on most healthy tissues, making it an ideal candidate for targeted ADC therapy. With only a few DLL3-targeting ADCs in clinical development, SystImmune is entering a relatively uncrowded space with significant potential. First-in-human Phase I data for BL-M14D1 will be presented in an oral session.

Another candidate, T-Bren (BL-M07D1), targets the well-known HER2 protein. While the HER2-positive breast cancer space is highly competitive, SystImmune is exploring T-Bren's potential in other areas, including recurrent or metastatic ovarian cancer, and as a first-line treatment for HER2-positive breast cancer, potentially in combination with other agents.

Finally, the company will present Phase I data for BL-M05D1, an ADC aimed at Claudin 18.2. This protein is a major emerging target in oncology, particularly for difficult-to-treat gastrointestinal cancers like gastric and pancreatic cancer. By advancing an ADC against this target, SystImmune is positioning itself at the forefront of another promising area of cancer research.

A Global Strategy Built on Chinese Clinical Success

A notable aspect of SystImmune's ASCO presentations is that all the clinical trial data originates from studies conducted in China. This reflects a growing trend where innovative drug development and high-quality clinical research in China are increasingly paving the way for global approvals.

The strategic partnership with Bristol Myers Squibb on iza-bren is a testament to this global strategy. While SystImmune advances the drug through late-stage trials in China, BMS holds the keys to its development and commercialization in the rest of the world, including the United States and Europe. The strong data from the Chinese TNBC trial will form a critical part of the global regulatory submission package, potentially accelerating iza-bren's path to patients worldwide. This model allows the company to leverage its strengths in research and development while partnering with a global leader for commercial reach, creating a powerful synergy that could reshape treatment paradigms for patients in desperate need of new options.