BioNTech (NASDAQ: BNTX) ADC meets Phase 3 goal in breast cancer trial

Rhea-AI Filing Summary

BioNTech SE reported that a pivotal Phase 3 trial of its antibody-drug conjugate candidate trastuzumab pamirtecan (BNT323/DB-1303), developed with Duality Biologics, met its primary goal. The study, conducted by DualityBio in China, compares BNT323/DB-1303 with trastuzumab emtansine (T-DM1) in patients with HER2-positive unresectable or metastatic breast cancer who have already received trastuzumab and a taxane-based chemotherapy.

At a pre-specified interim analysis, the trial achieved its primary endpoint of progression free survival, meaning patients on BNT323/DB-1303 lived longer without their cancer worsening than those on the comparator. A detailed press release with more information on the results is referenced as an exhibit to this report.

Positive

• BNT323/DB-1303 Phase 3 success: The pivotal Phase 3 trial in HER2-positive unresectable or metastatic breast cancer met its primary endpoint of progression free survival at an interim analysis.

Negative

• None.

Insights

Biotech and oncology analyst

Pivotal Phase 3 success for BioNTech’s ADC in HER2+ breast cancer.

The report states that trastuzumab pamirtecan (BNT323/DB-1303), an antibody-drug conjugate developed by BioNTech and Duality Biologics, met the primary endpoint of progression free survival in a pivotal Phase 3 trial in China. The study compares BNT323/DB-1303 with trastuzumab emtansine (T-DM1) in HER2-positive unresectable or metastatic breast cancer previously treated with trastuzumab and taxane-based chemotherapy.

Reaching the primary endpoint at a pre-specified interim analysis suggests a clinically meaningful delay in disease progression versus T-DM1 in this difficult-to-treat setting. As a pivotal Phase 3 trial, these data can be an important part of potential registration packages, particularly in China, subject to full data review and regulatory requirements.

The disclosed information highlights a notable late-stage pipeline milestone for BioNTech beyond vaccines, in solid tumor oncology. Further details on safety, overall survival, and regulatory plans are not included here and would typically be clarified in the referenced press release and subsequent communications.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a‑16 OR 15d‑16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

FOR THE MONTH OF SEPTEMBER 2025

COMMISSION FILE NUMBER 001-39081

BioNTech SE
(Translation of registrant’s name into English)

An der Goldgrube 12

D-55131 Mainz

Germany

+49 6131-9084-0
(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20‑F or Form 40‑F: Form 20‑F ☒ Form 40‑F ☐

Indicate by check mark if the registrant is submitting the Form 6‑K in paper as permitted by Regulation S‑T Rule 101(b)(1): ☐

Indicate by check mark if the registrant is submitting the Form 6‑K in paper as permitted by Regulation S‑T Rule 101(b)(7): ☐

DOCUMENTS INCLUDED AS PART OF THIS FORM 6-K

On September 5, 2025, BioNTech SE and Duality Biologics (Suzhou) Co., Ltd. (“DualityBio”) announced that the pivotal Phase 3 trial (NCT06265428) which DualityBio is conducting in China to evaluate trastuzumab pamirtecan (BNT323/DB-1303) versus trastuzumab emtansine (T-DM1) in patients with HER2-positive unresectable or metastatic breast cancer who have previously received trastuzumab and a taxane-based chemotherapy met its primary endpoint of progression free survival at a pre-specified interim analysis. The press release is attached hereto as Exhibit 99.1.

SIGNATURE

Pursuant to the requirements of the Exchange Act, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

BioNTech SE

By:

/s/ Ramón Zapata-Gomez

By:

/s/ Dr. Sierk Poetting

Name: Ramón Zapata-Gomez

Name: Dr. Sierk Poetting

Title: Chief Financial Officer

Title: Chief Operating Officer

Date: September 5, 2025

EXHIBIT INDEX

Exhibit			Description of Exhibit
99.1			BioNTech and DualityBio Announce Phase 3 Trial of ADC Candidate BNT323/DB-1303 Met Primary Endpoint of Progression Free Survival in HER2-Positive Metastatic or Unresectable Breast Cancer

FAQ

What did BioNTech (BNTX) disclose in this Form 6-K?

BioNTech reported that a pivotal Phase 3 trial in China of its antibody-drug conjugate candidate trastuzumab pamirtecan (BNT323/DB-1303), conducted with Duality Biologics, met its primary endpoint of progression free survival.

Which cancer indication is targeted by BioNTech’s BNT323/DB-1303 trial?

The trial targets patients with HER2-positive unresectable or metastatic breast cancer who have previously received trastuzumab and a taxane-based chemotherapy.

What treatment is BNT323/DB-1303 being compared against in the Phase 3 study?

BNT323/DB-1303 is being evaluated versus trastuzumab emtansine (T-DM1) in the pivotal Phase 3 trial.

What was the primary endpoint in the BNT323/DB-1303 Phase 3 trial?

The primary endpoint was progression free survival, and the report states that this endpoint was met at a pre-specified interim analysis.

Where is the BNT323/DB-1303 Phase 3 trial being conducted and by whom?

The pivotal Phase 3 trial (NCT06265428) is being conducted in China by Duality Biologics (Suzhou) Co., Ltd.

Where can investors find more detailed information on the Phase 3 results?

A detailed press release titled "BioNTech and DualityBio Announce Phase 3 Trial of ADC Candidate BNT323/DB-1303 Met Primary Endpoint of Progression Free Survival in HER2-Positive Metastatic or Unresectable Breast Cancer" is included as Exhibit 99.1.