BioNTech and DualityBio Announce Topline Results of the DYNASTY-Breast02 Global Phase 3 Clinical Trial Evaluating Trastuzumab Pamirtecan in HR+/HER2-low Metastatic Breast Cancer

The companies see limited potential patient benefit despite meeting the trial endpoint, with severe and fatal lung events reported.

Rhea-AI Summary

BioNTech (BNTX) and DualityBio announced that trastuzumab pamirtecan met the primary endpoint in the global Phase 3 DYNASTY-Breast02 breast cancer trial. Treatment delivered a statistically significant but modest improvement in progression-free survival, the time before disease worsens, versus investigator-selected chemotherapy in chemotherapy-naïve patients with HR+/HER2-low metastatic breast cancer after endocrine therapy. Overall survival data were immature at the interim analysis.

Interstitial lung disease occurred more frequently than in prior trastuzumab pamirtecan trials. Most cases were Grade 1–2, but a small proportion of patients experienced severe or fatal Grade 3–5 events. Otherwise, safety was consistent with prior trials, with no new safety signals. The companies said available efficacy and safety data suggest limited potential patient benefit in this treatment setting; they will discuss the data and determine next steps.

1 point · 1 major

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0 major · 3 points

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Positive

• Major pointTrastuzumab pamirtecan achieved a statistically significant but modest progression-free survival improvement versus investigator-selected chemotherapy.

Negative

• Moderate pointInterstitial lung disease increased versus prior trials; most cases were Grade 1–2, with severe and fatal Grade 3–5 events in a small proportion.
• Moderate pointAvailable efficacy and safety data suggest limited potential patient benefit in this treatment setting, the companies said.
• Minor pointOverall survival data remained immature at the interim analysis.

News Explained

Alongside DYNASTY-Breast02, BioNTech and DualityBio report two other ongoing trials of trastuzumab pamirtecan: a global Phase 3 study in recurrent endometrial cancer and a global Phase 1/2 study in advanced or metastatic solid tumors.

Key Figures

Patients randomized: 541 patients Randomization ratio: 1:1

Patients randomized

541 patients

DYNASTY-Breast02 Phase 3 trial

Randomization ratio

1:1

Trastuzumab pamirtecan or investigator's choice chemotherapy

Key Terms

pfs, os, ild, adc, +1 more

5 terms

pfs medical

"met its primary endpoint demonstrating a statistically significant, yet modest improvement in progression-free survival"

Progression-free survival (PFS) is a clinical-trial measure that records how long, on average, patients live without their disease getting worse after starting a treatment. For investors, PFS acts like a stopwatch of a drug’s effectiveness: longer PFS can signal meaningful patient benefit, improve chances of regulatory approval or label strength, and raise a drug’s commercial value, while shorter or unchanged PFS can weigh on a company’s prospects.

os medical

"data were not mature"

Overall survival (OS) measures the length of time from a defined starting point, usually treatment or trial enrollment, until death from any cause; it tells how much a therapy extends life. For investors, OS is a hard, widely accepted clinical endpoint that regulators and doctors use to judge a drug’s real-world benefit, and strong OS results can drive approvals, market adoption, and a company’s valuation — like a clear safety rating boosting confidence in a car model.

ild medical

"A higher rate of interstitial lung disease (”ILD”) was reported"

Interstitial lung disease (ILD) is a group of conditions that cause scarring and inflammation of the lung tissue responsible for moving oxygen into the bloodstream; think of it as the spongy part of the lungs becoming stiff and less able to stretch. For investors, ILD matters because it drives demand for diagnostic tests, treatments, and clinical trials, affects regulatory and safety profiles for drugs, and can influence the commercial outlook and risk profile of companies in respiratory and biotech sectors.

adc medical

"a third-generation topoisomerase-1 inhibitor-based ADC targeting HER2"

An antibody-drug conjugate (ADC) is a targeted cancer medicine that pairs an antibody that recognizes specific markers on tumor cells with a potent cell-killing drug, connected so the toxic payload is delivered directly to the cancer. For investors, ADCs matter because successful ADCs can improve patient outcomes and reduce side effects compared with traditional chemotherapy, shaping clinical trial success, regulatory approval chances, commercial demand, and a company’s valuation much like a guided missile versus a general bomb.

cdk 4/6 inhibitor medical

"plus cyclin-dependent kinase (CDK) 4/6 inhibitor in the metastatic setting"

A CDK 4/6 inhibitor is a type of targeted cancer drug that blocks the activity of the enzymes cyclin-dependent kinase 4 and cyclin-dependent kinase 6, which drive cells from the G1 phase into DNA-replicating S phase. By inhibiting these kinases the drugs slow or stop proliferation of cancer cells that depend on this pathway; they are most commonly used in hormone receptor–driven breast cancers and are often given alongside endocrine therapy. The effect is pharmacologic cell‑cycle arrest rather than direct cell killing, and treatment has characteristic laboratory and clinical effects (for example on blood counts) that are tracked in regulatory approvals and safety monitoring.

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MAINZ, Germany and SHANGHAI, China, October 26, 2026 – BioNTech SE (Nasdaq: BNTX, “BioNTech”) and DualityBiologics (Suzhou) Co., Ltd. (“DualityBio”, HKEX: 9606.HK) announced today that the DYNASTY-Breast02 global Phase 3 clinical trial (NCT06018337) met its primary endpoint demonstrating a statistically significant, yet modest improvement in progression-free survival (“PFS”) with trastuzumab pamirtecan (BNT323/DB-1303) compared to investigator’s choice of chemotherapy in chemotherapy-naïve patients with HR+/HER2-low metastatic breast cancer who have progressed on endocrine therapy. At this interim analysis for the secondary endpoint of overall survival (“OS”), data were not mature.

A higher rate of interstitial lung disease (“ILD”) was reported in this trial compared to prior trials with trastuzumab pamirtecan, with most cases being Grade 1 and 2. Severe and fatal events were reported in a small proportion of patients (Grade 3-5). Otherwise, the overall safety profile was consistent with prior clinical trials and no new safety signals were observed.

The available efficacy and safety data, as of this data cut-off date, suggest that the potential benefit to patients would be limited in the context of the HR+/HER2-low metastatic breast cancer treatment landscape. The companies will discuss the data and determine next steps.

BioNTech and DualityBio are developing trastuzumab pamirtecan in three ongoing clinical trials, including two global Phase 3 clinical trials, in HR+/HER2-low metastatic breast cancer (NCT06018337) and in HER2-expressing recurrent endometrial cancer (NCT06340568), as well as in a global Phase 1/2 clinical trial (NCT05150691) in patients with advanced/metastatic solid tumors.

About DYNASTY-Breast02
DYNASTY-Breast02 is a global Phase 3 randomized, multi-center, open-label clinical trial in patients living with HR+/HER2-low metastatic breast cancer whose disease has progressed on at least two lines of prior hormone therapy or within six months of first line hormone therapy plus cyclin-dependent kinase (CDK) 4/6 inhibitor in the metastatic setting. The primary endpoint of the clinical trial is PFS with a key secondary endpoint of OS. In the trial, 541 patients with HER2-low expression (IHC 2+/ISH- and IHC 1+) were randomized 1:1 to receive either trastuzumab pamirtecan or investigator's choice single-agent chemotherapy (capecitabine, paclitaxel or nab-paclitaxel).

About trastuzumab pamirtecan
Trastuzumab pamirtecan (BNT323/DB-1303) is a third-generation topoisomerase-1 inhibitor-based ADC targeting HER2 being developed by BioNTech and Duality Biologics. Trastuzumab pamirtecan was built from DualityBio’s proprietary Duality Immune Toxin Antibody Conjugates (“DITAC”) platform. HER2 is a surface-expressed protein on solid tumors and has been linked to the aggressive growth and spread of cancer cells.

Trastuzumab pamirtecan is being evaluated in an ongoing Phase 1/2 trial (NCT05150691) in patients with advanced/metastatic solid tumors, in Fern-EC-01, a randomized Phase 3 clinical trial (NCT06340568) evaluating trastuzumab pamirtecan compared with investigator's choice of single agent chemotherapy in previously treated patients with HER2-expressing advanced recurrent endometrial cancer, and in DYNASTY-Breast02, a randomized Phase 3 clinical trial (NCT06018337) in chemotherapy-naïve patients with HR+/HER2-low metastatic breast cancer who have progressed on endocrine therapy.

About BioNTech
BioNTech is a global next generation biopharmaceutical company pioneering novel investigative therapies for cancer and other serious diseases. In oncology, BioNTech is committed to transforming how cancer is treated. Its ambition is to develop innovative medicines with pan-tumor or synergistic potential to address cancer from multiple angles and across the full continuum of the disease from early- to late-stage. Its growing late-stage oncology pipeline comprises complementary treatment approaches spanning immunomodulators, antibody-drug conjugates, and mRNA cancer immunotherapies. BioNTech has partnered with multiple global and specialized pharmaceutical collaborators leveraging complementary expertise and resources to accelerate innovation and drive progress, including Bristol Myers Squibb, Duality Biologics, Genentech, a member of the Roche Group, Genmab, MediLink, OncoC4, and Pfizer.

For more information, please visit www.BioNTech.com.

BioNTech Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, but not limited to, statements concerning: the collaboration between BioNTech and DualityBio to jointly clinically develop antibody-drug conjugates (ADCs) including trastuzumab pamirtecan (BNT323/DB-1303); the initiation, timing, progress, and results of BioNTech’s research and development programs, including data from the DYNASTY-Breast02 Phase 3 clinical trial (NCT06018337) evaluating trastuzumab pamirtecan in HR+/HER2-low metastatic breast cancer; the expected timing of initiation, enrollment, and completion of trials and related preparatory work and the availability of results; and discussions with regulatory agencies. In some cases, forward-looking statements can be identified by terminology such as “will,” “may,” “should,” “expects,” “intends,” “plans,” “aims,” “anticipates,” “believes,” “estimates,” “predicts,” “potential,” “continue,” or the negative of these terms or other comparable terminology, although not all forward-looking statements contain these words.

The forward-looking statements in this press release are based on BioNTech’s current expectations and beliefs of future events and are neither promises nor guarantees. You should not place undue reliance on these forward-looking statements because they involve known and unknown risks, uncertainties, and other factors, many of which are beyond BioNTech’s control, and which could cause actual results to differ materially and adversely from those expressed or implied by these forward-looking statements. These risks and uncertainties include, but are not limited to: the uncertainties inherent in research and development, including the ability to meet anticipated clinical endpoints, commencement and/or completion dates for clinical trials, regulatory submission dates, regulatory approval dates and/or launch dates, as well as risks associated with clinical data, and including the possibility of unfavorable new preclinical, clinical or safety data and further analyses of existing preclinical, clinical or safety data; the nature of clinical data, which is subject to ongoing peer review, regulatory review and market interpretation; the impact of tariffs and escalations in trade policy; competition related to BioNTech’s product candidates; the timing of and BioNTech’s ability to obtain and maintain regulatory approval for its product candidates; BioNTech’s ability to identify research opportunities and discover and develop investigational medicines; the ability and willingness of BioNTech’s third-party collaborators to continue research and development activities relating to BioNTech’s development candidates and investigational medicines; unforeseen safety issues and potential claims that are alleged to arise from the use of products and product candidates developed or manufactured by BioNTech; BioNTech’s and its collaborators’ ability to commercialize and market its product candidates, if approved; BioNTech’s ability to manage its development and related expenses; regulatory and political developments in the United States and other countries; BioNTech’s ability to effectively scale its production capabilities and manufacture its products and product candidates; and other factors not known to BioNTech at this time.

You should review the risks and uncertainties described under the heading “Risk Factors” in BioNTech’s Report on Form 6-K for the period ended June 30, 2026, and in subsequent filings made by BioNTech with the SEC, which are available on the SEC’s website at www.sec.gov.These forward-looking statements speak only as of the date hereof. Except as required by law, BioNTech disclaims any intention or responsibility for updating or revising any forward-looking statements contained in this press release in the event of new information, future developments or otherwise.

About DualityBio

DualityBio is a clinical-stage innovative biopharmaceutical company dedicated to developing next-generation antibody-drug conjugates (ADCs) for patients with cancer and autoimmune diseases. The Company has successfully built multiple next-generation ADC technology platforms with global intellectual property rights. Grounded in a deep understanding of disease biology, DualityBio has established a robust clinical-stage ADC pipeline and is conducting multiple global, multicenter clinical trials across nearly 20 countries, with over 3,500 patients enrolled to date. Furthermore, DualityBio has entered into several out-licensing collaborations with global pharmaceutical companies and leading innovative biotech firms. Serving as a global engine for ADC innovation, DualityBio continues to develop next-generation novel ADCs, including bispecific ADCs, ADCs with novel payloads, and autoimmune ADCs.

For more information, please visit www.dualitybiologics.com.

CONTACTS

BioNTech
Media Relations
Jasmina Alatovic
Media@biontech.de

Investor Relations
Douglas Maffei, PhD
Investors@biontech.de

DualityBio
Media Relations
PR@dualitybiologics.com

Investor Relations
IR@dualitybiologics.com

FAQ

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What did BioNTech's DYNASTY-Breast02 trial show for trastuzumab pamirtecan?

Trastuzumab pamirtecan met the primary endpoint with a statistically significant but modest improvement in progression-free survival versus investigator-selected chemotherapy. The trial evaluated chemotherapy-naïve patients with HR+/HER2-low metastatic breast cancer who had progressed on endocrine therapy. Overall survival data were immature at the interim analysis.

What lung safety findings were reported in BioNTech's DYNASTY-Breast02 trial?

Interstitial lung disease occurred more frequently than in prior trastuzumab pamirtecan trials. Most cases were Grade 1 and 2, while severe and fatal Grade 3–5 events occurred in a small proportion of patients. Otherwise, the overall safety profile was consistent with prior trials, with no new safety signals.

How was BioNTech's DYNASTY-Breast02 trial designed?

DYNASTY-Breast02 randomized 541 patients 1:1 to trastuzumab pamirtecan or investigator-selected single-agent chemotherapy: capecitabine, paclitaxel or nab-paclitaxel. The global Phase 3 trial was open-label and multi-center. Eligible patients had progressed on at least two prior hormone therapy lines or within six months of first-line hormone therapy plus a CDK4/6 inhibitor in the metastatic setting.