Izalontamab Brengitecan (Iza-Bren) Reduced Risk of Disease Progression or Death by 59% versus Chemotherapy in Patients with Advanced HR+/HER2- Breast Cancer in Phase 3 PANKU-Breast01 Study

Overall survival data remained immature despite the improvement in the trial’s primary disease-progression endpoint.

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Late-breaking results to be presented in an oral presentation at ESMO 2026

With two positive Phase 3 trials in breast cancer, these data reinforce the potential of iza-bren to further redefine treatment across breast cancer subtypes

Iza-bren, a potentially first-in-class dual-targeting EGFRxHER3 bispecific antibody-drug conjugate, has now demonstrated clinical benefit in five distinct tumor types

BOTHELL, Wash. & PRINCETON, N.J.--(BUSINESS WIRE)-- SystImmune, Inc. (SystImmune), a clinical-stage biotechnology company, and Bristol Myers Squibb (NYSE: BMY) today announced that SystImmune’s parent company Sichuan Biokin Pharmaceutical, Ltd. (Biokin) reported positive results from a prespecified interim analysis of the randomized Phase 3 PANKU-Breast01 study (NCT06343948) evaluating izalontamab brengitecan (iza-bren), an investigational, potentially first-in-class, dual-targeting EGFRxHER3 bispecific antibody-drug conjugate (ADC), versus chemotherapy in patients with unresectable locally advanced, recurrent or metastatic hormone receptor-positive (HR+)/HER2-negative (HER2-) breast cancer who have failed at least one prior line of chemotherapy. Results will be presented today in a late-breaking oral presentation at the European Society for Medical Oncology (ESMO) 2026 Annual Congress taking place October 23–27 in Madrid, Spain, and simultaneously published in The Lancet.

With a median follow-up for progression-free survival (PFS) of 15.2 months, results showed iza-bren (n=190) reduced the risk of disease progression or death, the study’s primary endpoint, by 59%, with median PFS vs. chemotherapy (n=193) of 8.2 months vs. 4.0 months as assessed by Blinded Independent Central Review (BICR) [HR: 0.41; 95% CI: 0.33-0.53, p<0.0001]. Overall survival, a key secondary endpoint of the study, was immature at the time of interim analysis. Confirmed objective response rate (cORR) by BICR was 40.5% with iza-bren vs. 20.2% with chemotherapy, and median duration of response (mDOR) was 6.9 months vs. 4.2 months, respectively.

“While there have been advances in the treatment landscape for HR-positive, HER2-negative advanced breast cancer, options can become increasingly limited as patients progress through available therapies, with most ultimately relying on chemotherapy,” said Professor Binghe Xu, Academician of the Chinese Academy of Engineering, Cancer Hospital Chinese Academy of Medical Sciences. “PANKU-Breast01 provides encouraging evidence for a new therapeutic approach. Unlike other ADCs, izalontamab brengitecan is designed to target both EGFR and HER3, and the reduction in the risk of disease progression or death suggests it could offer patients a meaningful new treatment option.”

The safety profile for iza-bren was manageable and no new safety signals were identified. Grade ≥3 treatment-related adverse events (TRAEs) were predominantly hematologic in nature. TRAEs were manageable with supportive care, and only 1.6% of patients discontinued iza-bren treatment due to TRAEs. Adjudicated interstitial lung disease (ILD) occurred in two (1.1%) patients with iza-bren (Grade 1 or 2).

“The 59% reduction in progression or death we see with iza-bren represents a substantial advance for patients who have limited treatment options after prior chemotherapy,” said Dr. Jonathan Cheng, Chief Medical Officer of SystImmune. “This Phase 3 data, combined with our positive results in triple-negative breast cancer, demonstrates that our dual EGFRxHER3-targeting approach can meaningfully address the biology of multiple breast cancer subtypes and represents an important step towards more effective, precision-based treatment strategies.”

“The positive PANKU-Breast01 results are an important validation of iza-bren’s potential as an innovative scientific approach to overcome disease resistance and the limitations of currently available treatment options,” said Cristian Massacesi, MD, executive vice president, chief medical officer and head of development, Bristol Myers Squibb. “Together with the clinical benefit iza-bren has shown in other tumor types, these data position iza-bren as a potentially first-in-class dual-targeting ADC therapy with the potential to become a new standard of care across the cancer treatment paradigm.”

Iza-bren has demonstrated clinical benefit in five Phase 3 trials across five distinct indications, including previously-treated HR+/HER2-negative breast cancer, previously-treated EGFR-mutated non-small cell lung cancer, nasopharyngeal carcinoma after prior treatment, previously-treated esophageal squamous cell carcinoma, and advanced triple-negative breast cancer, underscoring iza-bren’s broad therapeutic potential in areas of critical unmet need. Iza-bren has also received Breakthrough Therapy Designation from the U.S. Food and Drug Administration for previously-treated advanced EGFR-mutated NSCLC.

The PANKU-Breast01 study is sponsored by SystImmune’s parent company, Sichuan Biokin Pharmaceutical Co., Ltd. (Biokin), in Mainland China. Outside of China, iza-bren is jointly developed by SystImmune and Bristol Myers Squibb under a collaboration and exclusive license agreement.

About izalontamab brengitecan (iza-bren)

Izalontamab brengitecan (iza-bren, BL-B01D1) is a bispecific antibody-drug conjugate (ADC) that targets both EGFR and/or HER3, antigens that are highly expressed in various epithelial cancers and are known to be associated with cancer cell proliferation and survival. Upon target binding and internalization, iza-bren's therapeutic novel Topo1i payload is released, causing cytotoxic stress that leads to cancer cell death. Iza-bren's dual mechanism of action also blocks EGFR and HER3 signals to cancer cells, reducing proliferation and survival signals. Iza-bren is being developed under a license and collaboration agreement by and between SystImmune and Bristol Myers Squibb.

About SystImmune

SystImmune is a clinical-stage biotechnology company located in Bothell, 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.

About Bristol Myers Squibb: Transforming Patients’ Lives Through Science

At Bristol Myers Squibb, our mission is to discover, develop and deliver innovative medicines that help patients prevail over serious diseases. We are pursuing bold science to define what’s possible for the future of medicine and the patients we serve. For more information, visit us at BMS.com and follow us on LinkedIn, X, YouTube, Facebook and Instagram.

Bristol Myers Squibb Cautionary Statement Regarding Forward-Looking Statements

This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995 regarding, among other things, the research, development and commercialization of pharmaceutical products. All statements that are not statements of historical facts are, or may be deemed to be, forward-looking statements. Such forward-looking statements are based on current expectations and projections about our future financial results, goals, plans and objectives and involve inherent risks, assumptions and uncertainties, including internal or external factors that could delay, divert or change any of them in the next several years, that are difficult to predict, may be beyond our control and could cause our future financial results, goals, plans and objectives to differ materially from those expressed in, or implied by, the statements. These risks, assumptions, uncertainties and other factors include, among others, that future study results may not be consistent with the results to date, that izalontamab brengitecan (iza-bren) may not achieve its primary study endpoints or receive regulatory approvals for the indications described in this release in the currently anticipated timeline or at all, any marketing approvals, if granted, may have significant limitations on their use, and, if approved, whether such treatment for such indication will be commercially successful. No forward-looking statement can be guaranteed. Forward-looking statements in this press release should be evaluated together with the many risks and uncertainties that affect Bristol Myers Squibb’s business and market, particularly those identified in the cautionary statement and risk factors discussion in Bristol Myers Squibb’s Annual Report on Form 10-K for the year ended December 31, 2025, as updated by our subsequent Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and other filings with the Securities and Exchange Commission. The forward-looking statements included in this document are made only as of the date of this document and except as otherwise required by applicable law, Bristol Myers Squibb undertakes no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events, changed circumstances or otherwise.

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Key Terms

progression-free survival medical

Progression-free survival is the length of time during and after a treatment that a patient's disease does not get worse, measured from the start of treatment until the disease shows measurable signs of progression or the patient dies. Investors care because longer progression-free survival in clinical trials often signals that a drug is effective, improving chances of regulatory approval, market adoption, and revenue potential—think of it as a stopwatch showing how long a therapy can keep the illness at bay.

blinded independent central review medical

Blinded independent central review is a quality-control step in clinical trials where outside medical experts, who do not know which patients received the experimental therapy, re-examine key measurements (like scans or lab results) to prevent bias. Think of it as neutral referees watching game footage without knowing the teams, which gives investors greater confidence that the trial results are fair, more reliable for regulators, and less likely to be overturned or disputed.

objective response rate medical

The objective response rate (ORR) is the percentage of patients in a clinical trial whose tumors measurably shrink or disappear according to preset rules. Investors use it as a quick, objective signal of a drug’s ability to produce a clear treatment effect—like counting how many plants visibly respond after applying a new fertilizer—and higher ORR can improve odds of regulatory approval, commercial success, and company valuation.

duration of response medical

Duration of response is the length of time a patient’s condition stays improved after a treatment until it starts to worsen again; think of it as how long a freshly charged battery continues to power a device. For investors, longer duration of response implies a treatment provides sustained benefit, which can boost a drug’s commercial value, support stronger regulatory labeling and payer coverage, and reduce the need for additional therapies.

interstitial lung disease medical

A group of lung conditions that cause inflammation and scarring of the thin tissue between the air sacs, which makes it harder for oxygen to pass into the blood; imagine the lungs’ fine filters becoming stiff and less effective. Investors care because reports of interstitial lung disease can affect a drug’s safety profile, trigger regulatory warnings or label changes, and shift demand for treatments or create liability risks that influence a company’s valuation.

antibody-drug conjugate medical

An antibody-drug conjugate is a targeted medicine that combines an antibody, which can identify specific cells, with a powerful drug designed to destroy those cells. This approach allows for precise treatment, minimizing damage to healthy tissue. For investors, developments in this area can signal advances in cancer therapies and potential growth opportunities in the biotech sector.