Formosa Pharmaceuticals Files Clinical Trial Application for TSY-110, an Antibody-Drug Conjugate Biosimilar Targeting HER2-Positive Breast Cancers

TSY-110 is positioned to become the first biosimilar alternative to Roche's Kadcyla^® (ado-trastuzumab emtansine) in major regulated markets.

TAIPEI, Aug. 28, 2026 /PRNewswire/ -- Formosa Pharmaceuticals, Inc. (TWSE: 6838), today announced the submission of a Clinical Trial Application (CTA) to European regulatory authorities to conduct a pivotal clinical trial for TSY-110. TSY-110 is a biosimilar candidate referencing Roche's antibody-drug conjugate (ADC) Kadcyla^® (ado-trastuzumab emtansine), indicated for HER2-positive metastatic and early-stage breast cancer.

Designed following regulatory guidance from both US and EU authorities, the upcoming trial will evaluate the safety, tolerability, pharmacokinetics, and immunogenicity profile of TSY-110 compared with the reference product. This milestone advances Formosa Pharmaceuticals' and EirGenix's shared goal of providing cost-effective biosimilar ADC treatments to patients across regulated global markets.

"Filing this CTA marks a significant achievement for Formosa Pharmaceuticals and underscores our strategic alliance with EirGenix," said Erick Co, Ph.D., President and Chief Executive Officer of Formosa Pharmaceuticals. "Antibody-drug conjugates have established themselves as mainstays in oncology, including HER2-positive breast cancer care, but patient access remains constrained by high treatment costs. Advancing TSY-110 into clinical evaluation is a momentous step toward fulfilling our goal of delivering world-class, accessible ADC options to oncologists and patients."

About TSY-110

TSY-110, also designated as EG12043, is an antibody-drug conjugate (ADC) biosimilar co-developed by Formosa Pharmaceuticals and EirGenix, Inc. (TWSE: 6589). The conjugate links HER2 monoclonal antibody, trastuzumab, with a cytotoxic payload (mertansine) to selectively eradicate HER2-overexpressing cancer cells while minimizing systemic toxicity. Comprehensive preclinical assessments demonstrate high biosimilarity, drug-antibody ratio (DAR) consistency, and comparable plasma kinetics to the reference product.

About HER2-Positive Breast Cancer Market

HER2-positive breast cancer accounts for a significant portion of all breast cancer diagnoses globally. Approximately 2.4 million breast cancer cases were diagnosed in 2024, with HER2+ disease affecting roughly 360,000 to 480,000 of these patients based on the standard 15–20% prevalence rate. HER2-targeted therapies continue to be a prominent tool in modern oncological care. Kadcyla^®, approved by the FDA in 2013, generated approximately $2.5 billion in global sales in 2025.

About Formosa Pharmaceuticals, Inc.

Formosa Pharmaceuticals, Inc. (TWSE: 6838) is a Taiwan-based biopharmaceutical company focused on the development and commercialization of novel therapeutics in ophthalmology and oncology. The company leverages its proprietary APNT^® nanoparticle formulation platform to optimize drug solubility and bioavailability. Formosa's pipeline includes FDA-approved APP13007 for post-surgical ocular inflammation and pain, alongside a robust portfolio of biosimilar and novel oncology assets. For more information, please visit www.formosapharma.com.

About EirGenix, Inc.

EirGenix Inc. (TWSE: 6589) operates on a dual business model combining CDMO with Product Development to fully leverage its cGMP manufacturing facilities and highly qualified technical staff. The company's core competitiveness stems from its dual technical capabilities in both mammalian cell line development and microbial fermentation, paired with comprehensive expertise across R&D, manufacturing, and analytics. Through a vertically integrated operational model, EirGenix maintains strict quality control and cost management and is Taiwan's largest biologics CDMO. For more information, please visit www.eirgenix.com.

SOURCE Formosa Pharmaceuticals Inc.,