On January 22, 2024 BioNTech SE (Nasdaq: BNTX, "BioNTech") and Duality Biologics (Suzhou) Co., Ltd. ("DualityBio") reported that the first patient with metastatic breast cancer has been treated in a pivotal Phase 3 trial evaluating the efficacy and safety of the next-generation antibody-drug conjugate ("ADC") candidate BNT323/DB-1303 targeting the Human Epidermal Growth Factor Receptor 2 ("HER2"), a cancer cell surface protein (Press release, BioNTech, JAN 22, 2024, View Source [SID1234639405]).

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Breast cancer is the most commonly diagnosed cancer worldwide and the leading cause of death from malignant tumors in women globally.1,2 The breast cancer subtype, which is defined by the expression of hormone receptors ("hormone receptor-positive", "HR+") and a low expression level of the HER2 protein ("HER2-low") on the cancer cell surface, accounts for approximately 40 % to 45 % of patients in advanced, metastatic disease stage.3 HER2 has been shown to be a suitable target structure for the treatment of breast cancers with intermediate and high HER2 expression.4 HER2-directed therapies have been ineffective in the past in patients with tumors with low expression levels of the protein.5 Recent studies have indicated that next-generation ADCs may have the potential to transfer the impact of HER2-directed therapies to HER2-low tumors.6

The global, multi-center, open-label, randomized Phase 3 trial (NCT06018337) will assess the efficacy and safety of BNT323/DB-1303 compared to standard-of-care single-agent chemotherapy in chemotherapy-naïve patients with HR+ and HER2-low metastatic breast cancer that have progressed on hormone therapy. The trial is expected to enroll 532 patients at more than 223 clinical sites worldwide, initially in China, followed by sites in the United States, Europe, and additional regions. The study’s primary endpoint is progression-free survival. Secondary endpoints include overall survival, objective response rate, duration of response, and safety.

"For patients with advanced HR+/HER2-low breast cancers who progressed after primary therapy, single-agent palliative chemotherapy is the most common regimen to control the disease and reduce mortality. BNT323/DB-1303 has been designed with the aim to combine the selectivity of antibodies with the cancer cell-killing properties of chemotherapy, thereby aiming to minimize the toxicity of the chemotherapeutic agents for patients," said Prof. Özlem Türeci, M.D., Chief Medical Officer and Co-Founder at BioNTech. "Our objective is to further expand the impact of HER2-targeted ADC therapies to chemotherapy naïve patients in metastatic disease stage who express HER2 at low levels at earliest possible treatment lines, seeking to extend the therapeutic window and improve outcomes for these patients."

"The initiation of the Phase 3 trial marks an important step in the development of our next-generation ADC candidate with the first indication progressing into pivotal evaluation," said Vivian Gu, M.D., Chief Medical Officer at DualityBio. "Results from our Phase 1/2 clinical study indicate a robust mechanism of action of BNT323/DB-1303 and have demonstrated preliminary efficacy and a manageable safety profile. We look forward to further advancing this differentiated ADC candidate."

The Phase 3 trial is based on positive safety and efficacy data from a Phase 1/2 study (NCT05150691) with BNT323/DB-1303 in patients with advanced/metastatic solid tumors. Data presented at ASCO (Free ASCO Whitepaper) 2023 demonstrated encouraging anti-tumor activity in heavily pretreated patients with HER2-low breast cancer with an objective response rate of 38.5% and a disease control rate of 84.6%. BNT323/DB-1303 was well tolerated with a manageable safety profile across all evaluated patients with advanced/metastatic solid tumors.

The milestone is in furtherance of BioNTech and DualityBio’s strategic objective to advance the product candidate into late-stage development in multiple high unmet medical need cancer indications. The Phase 3 trial initiation marks a major landmark in BioNTech’s and DualityBio’s strategic collaboration initiated in April 2023. The collaboration aims to accelerate the development of differentiated antibody-drug conjugate therapeutics for solid tumors. BioNTech will hold commercial rights globally (excluding Mainland China, Hong Kong Special Administrative Region, and Macau Special Administrative Region), while DualityBio will retain commercial rights for Mainland China, Hong Kong Special Administrative Region, and Macau Special Administrative Region.

Further information for media: Fact Sheet about BNT323/DB-1303

About BNT323/DB-1303
BNT323/DB-1303 is a third-generation topoisomerase-1 inhibitor-based ADC targeting HER2 which 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, making it a potential target for innovative cancer therapeutics. The candidate has exhibited antitumor activity in both HER2-positive and HER2-low tumor models as well as in several solid tumor indications, including patients with breast, gastric, endometrial, biliary tract cancers, and other advanced solid tumors. Preclinical data and preliminary clinical data for BNT323/DB-1303 indicate its potential to target HER2 receptors on solid tumors irrespective of expression level with a manageable safety profile and a potentially expanded therapeutic window. BNT323/DB-1303 is currently being evaluated in an ongoing Phase 1/2 study (NCT05150691) in patients with advanced/metastatic solid tumors and in a pivotal Phase 3 study (NCT06018337) in patients with Hormone Receptor-positive ("HR+") and Human Epidermal Growth Factor Receptor 2 ("HER2")-low, metastatic breast cancer that have progressed on hormone and/or cyclin-dependent kinase 4/6 ("CDK4/6") therapy. The BNT323/DB-1303 program received the Fast Track designation and Breakthrough Therapy designation from the U.S. Food and Drug Administration ("FDA") for the treatment of endometrial cancer in 2023.