SystImmune Announces iza-bren Meets One of the Dual Primary Endpoints in the BL-B01D1-303 Trial in Recurrent or Metastatic NPC Patients with Results Presented as a Late-Breaking Oral Presentation at ESMO

-  Results from the BL-B01D1-303 (NCT06118333) phase III trial presented in a late-breaking oral presentation at ESMO represents the first data readout for iza-bren from a registration enabling study in China

REDMOND, Wash., Oct. 19, 2025 /PRNewswire/ -- SystImmune Inc. (SystImmune), a clinical-stage biotechnology company, today announced positive topline results from the BL-B01D1-301 trial. The trial has met one of the dual primary endpoints (BICR-assessed ORR) as iza-bren has demonstrated a statistically significant and clinically meaningful improvement in BICR-assessed ORR in recurrent or metastatic NPC patients who had progressed after at least two prior lines of chemotherapy, including platinum-based chemotherapy and a PD-1/PD-L1 inhibitor. These results were presented today in a late-breaking oral presentation at the 2025 European Society of Medical Oncology (ESMO) Congress.

Iza-bren is a potentially first-in-class topoisomerase 1 inhibitor-based bispecific antibody-drug conjugate (ADC) which targets both epidermal growth factor receptor and human epidermal growth factor receptor 3 (EGFRxHER3). It is being developed by Biokin in China and jointly developed by SystImmune and Bristol Myers Squibb under a collaboration and exclusive license agreement in territories outside of China.

Iza-bren has shown a BICR-assessed ORR of 54.6% vs. 27.0% (Odds Ratio 3.3; 95% confidence interval 1.9-5.8; p<0.0001). Median duration of response (DoR) was 8.5 months for iza-bren versus 4.8 months for physician's choice of chemotherapy (Hazard ratio 0.43; 95% CI 0.22 to 0.83). Furthermore, median progression-free survival (PFS) was 8.38 months with iza-bren compared to 4.34 months for chemotherapy (hazard ratio of 0.44; 95% confidence interval 0.32-0.62). The ORR and PFS benefits were consistent across all subgroup analysis. At the time of this analysis, the overall survival (OS) data were immature.

Iza-bren was well-tolerated with a manageable safety profile. The most common adverse events were hematological toxicities, which were effectively managed with standard supportive care. Two patients in the iza-bren arm experienced Grade 2 interstitial lung disease (ILD), whereas two patients in the chemotherapy arm experienced Grade 3 ILD. The safety profile in the BL-B01D1-303 study was consistent with the known profiles of the therapy with no new safety signals identified.

"The positive topline results from the first registrational trial of iza-bren presented at ESMO demonstrated clear clinical benefits of iza-bren compared to traditional chemotherapy. These data add to the growing body of clinical evidence that continues to reinforce our confidence in iza-bren's mechanism of action and therapeutic potential. We believe iza-bren can deliver clinically meaningful benefit by targeting key cancer biological pathways to improve outcomes for patients across a broad range of advanced malignancies," added Dr. Jonathan Cheng, Chief Medical Officer of SystImmune.

The New Drug Application (NDA) for iza-bren for the treatment of recurrent or metastatic nasopharyngeal carcinoma (NPC) has been submitted by Biokin to the Center for Drug Evaluation (CDE) of the China National Medical Products Administration (NMPA) in China.

About BL-B01D1-303

BL-B01D1-303 is a phase III, randomized, open-label, multicenter study in China to evaluate the efficacy and safety of BL-B01D1 in patients with recurrent or metastatic nasopharyngeal carcinoma who have failed PD-1/PD-L1 monoclonal antibody and at least two lines chemotherapy (one line must contain platinum-based chemotherapy). For more detailed information, please visit clinical.trials.gov (NCT06118333).

About Nasopharyngeal Carcinoma (NPC)

Nasopharyngeal Carcinoma (NPC) is a type of head and neck cancer that originates in the nose. NPC is uncommon globally, but is endemic in southern China, southeast Asia and parts of Africa, and is rising among the immigrant population in US and Europe. NPC is strongly associated with EBV infection. There is a significant unmet need as 5-year overall survival rate is generally less than 10% in the later line metastatic setting.

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

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

Any research and development information provided by SystImmune is intended for general information purposes only. Such information is not intended to provide complete medical information. We do not offer patient-specific treatment advice and if you have medical conditions, please see your medical doctor or healthcare provider.

This press release may contain forward-looking statements with the meaning of Section 27A of the Securities Act of 1933, as amended, Section 21E of the Securities Exchange Act of 1934, and the Private Securities Litigation Reform Act of 1995, which reflects the expectations regarding the company's goals, strategies, results of operations, performance, business prospects, and opportunities, including but not limited to the ability to gain Investigational New Drug status for the resulting new product and the ability to develop a successful formulation. Terms such as "anticipates," "believes," "expects," "estimates," "could," "intends," "may," "plans," "potential," "projects," "will," "would" and other similar expressions, or the negative of these terms, are generally indicative of forward-looking statements.

While SystImmune, Inc. believes that expectations expressed in the forward-looking statements are based on the company's reasonable assumptions and beliefs in light of the information available to the company at the time such statements are made, it cannot give assurance that such forward-looking statements will prove to have been correct. Such forward-looking statements are not fact and are subject to uncertainties and other factors that could cause actual results to differ materially from such statements. We undertake no obligation to update any forward-looking statements contained in this press release to reflect events or circumstances occurring after its date or to reflect the occurrence of unanticipated events.

For additional information about the company, please visit https://systimmune.com/.

SOURCE SystImmune, Inc.