First Patient Dosed in Phase 1 DS-1055 Trial for Solid Tumors

As the medical field develops, more companies are looking to create innovative ways to address cancer treatments. In the case of global pharmaceutical company Daiichi Sankyo Company, Ltd. (“Daiichi Sankyo”), the company has a newfound focus on Glycoprotein-A Repetitions Predominant (GARP) as a potential therapeutic target. GARP is expressed on regulatory T-cells (Tregs), which prevent anti-tumor responses in the tumor’s microenvironment. According to a recent press release from Daiichi Sankyo, the company dosed the first patient in a Phase 1 clinical trial to evaluate DS-1055 for patients with advanced or metastatic solid tumors.


Developed by Daiichi Sankyo, DS-1055 is a monoclonal antibody that targets GARP. So let’s break down what these terms mean. According to the Mayo Clinic, monoclonal antibodies (mABs):

are laboratory-produced molecules engineered to serve as substitute antibodies that can restore, enhance or mimic the immune system’s attack on cancer cells. They are designed to bind to antigens that are generally more numerous on the surface of cancer cells than healthy cells.

So by binding to these antigens, mABs can identify cancer cells, trigger an immune response to destroy cancer cells, prevent cell growth or blood vessel growth in tumors, or even deliver therapies like chemotherapy or radiation. In this case, DS-1055 binds to GARP, which is described in an article published in the Journal of Cancer Treatment & Diagnosis:

also known as leucine-rich repeats containing 32 (LRRC32), is a transmembrane protein that presents latent TGF-β1 on the surface of regulatory T cells (Tregs) and modulates its activation in tumor immunosuppressive environment. Tregs are immunosuppressive immune cells that play an important role in tumor development and progression.

When Tregs collect in the tumor microenvironment, they stimulate anti tumor activity. Thus, these solid tumors become more difficult to treat. In fact, a high level of Tregs is directly linked to worse patient outcomes. So DS-1055 is designed to destroy GARP+ Tregs, lowering the levels and allowing for easier treatment. So far, DS-1055 is still investigational.

Phase 1 Trial

In the Phase 1 clinical trial, Daiichi Sankyo will evaluate the safety, efficacy, and tolerability of DS-1055 in 40 patients with solid tumors. Generally, these tumors will be located in the head, neck, gastrointestinal system, or esophagus. During the trial, researchers will determine the maximum and recommended dosages of DS-1055.

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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