Bio-Thera Solutions has announced that the first patient has been dosed in a Phase 1 clinical trial evaluating BAT8013, an investigational Antibody-Drug Conjugate (ADC) targeting CD25, also known as the interleukin-2 receptor alpha chain (IL-2Rα), for the treatment of advanced solid tumours.

The multicentre, open-label, dose-escalation study is designed to assess the safety, tolerability, pharmacokinetics and preliminary anti-tumour activity of BAT8013. The trial will also determine the Maximum Tolerated Dose (MTD) and establish the recommended Phase 2 dose (RP2D) for future clinical development.

BAT8013 combines Bio-Thera's proprietary anti-CD25 antibody with the company's in-house ADC linker-payload platform, featuring a systemically stable, cleavable linker and a topoisomerase I inhibitor payload. The therapy is designed to selectively target regulatory T cells (Tregs), which are known to be overexpressed in the tumour microenvironment and play a key role in suppressing anti-tumour immune responses.

By eliminating these immunosuppressive Treg cells, BAT8013 is expected to enhance the effectiveness of immune checkpoint inhibitors, including PD-1 and PD-L1 monoclonal antibodies.

According to the company, preclinical studies demonstrated that BAT8013 exhibited favourable stability and safety while delivering strong anti-tumour activity, particularly when used in combination with BAT1308, Bio-Thera's investigational PD-1 inhibitor.

The ADC also incorporates a membrane-permeable topoisomerase I inhibitor payload capable of producing a bystander effect, allowing the released cytotoxic agent to eliminate neighbouring regulatory T cells after targeted tumour cell destruction. This mechanism is expected to further enhance anti-tumour immune responses.

Bio-Thera stated that both in vitro and in vivo pharmacology studies have demonstrated encouraging efficacy and safety, positioning BAT8013 as a potential best-in-class CD25-targeting ADC for the treatment of solid tumours.

The initiation of the Phase 1 study marks another milestone in Bio-Thera's oncology research programme. In addition to BAT8013, the company is advancing several other antibody-drug conjugates targeting Folate Receptor α, Trop2 and HER2, alongside novel immuno-oncology candidates, including PD-L1/4-1BB and PD-1/IL-15 bispecific antibodies, which are currently in early-stage clinical development.

Bio-Thera Solutions continues to expand its pipeline of innovative biologics and biosimilars aimed at addressing unmet medical needs across oncology, autoimmune, cardiovascular and ophthalmic diseases.