KIR3DL3 as an HHLA2 Receptor, Anti-HHLA2 Antibodies, and Uses Thereof Targeting a Newly Mapped Immune Checkpoint in Cancer

This patent covers monoclonal antibodies that bind to a protein called HHLA2, along with the discovery that a receptor named KIR3DL3 is one of its binding partners. The work comes from Dana-Farber Cancer Institute and is aimed at diagnosing, predicting the course of, and treating cancer by acting on an immune checkpoint.

The Problem

The body’s immune system is kept in balance by molecular brakes known as immune checkpoints. These checkpoints stop immune cells from attacking healthy tissue, but tumours can hijack them to switch off the very immune response that would otherwise destroy the cancer. Drugs that release these brakes, called checkpoint inhibitors, have transformed cancer treatment, but they only work in some patients, and the way each checkpoint behaves varies from person to person and from tissue to tissue. There is a continuing need to identify new checkpoints and to understand exactly which molecules bind to them, so that new and more precise therapies can be designed.

What This Invention Does

The invention rests on two linked discoveries. First, it identifies KIR3DL3 as a receptor for HHLA2, a member of the B7 family of immune regulators that influences how T cells behave. Mapping this receptor-ligand relationship clarifies a previously uncharacterised coinhibitory pathway, meaning a route through which the immune response is damped down. Second, the patent describes monoclonal antibodies, and antigen-binding fragments of them, that specifically bind HHLA2. It also covers the related immunoglobulins, polypeptides, and nucleic acids, and methods of using these antibodies for diagnostic, prognostic, and therapeutic purposes. In practice that means the antibodies could be used to detect HHLA2 in a sample, to help predict how a cancer might progress, or to interfere with the HHLA2 pathway as a treatment.

Key Features

• New checkpoint pathway. Identifies KIR3DL3 as a receptor for the B7 family molecule HHLA2.
• Specific antibodies. Provides monoclonal antibodies and fragments that bind HHLA2 selectively.
• Therapeutic use. The antibodies can be used to modulate the HHLA2 immune pathway in treatment.
• Diagnostic and prognostic use. The antibodies can detect HHLA2 to support diagnosis and outlook prediction.
• Supporting biology. Covers the related immunoglobulins, polypeptides, and nucleic acids.

Who Is Behind It

The applicant is Dana-Farber Cancer Institute, Inc., a leading cancer research and treatment centre affiliated with Harvard Medical School in Boston. The named inventors are Gordon J. Freeman and Antonio R. Arulanandam. This filing is a divisional application stemming from an earlier related application.

Why It Matters

Immunotherapy has become one of the most important advances in cancer care, but its benefit is still uneven. Pinning down a new checkpoint and the antibodies that act on it opens a fresh avenue for therapies that might help patients who do not respond to existing drugs, and for tests that better match patients to treatment. Securing the rights in Australia supports the institute’s research and any future clinical or commercial partners working in the local market.

Related Concepts

• Immune checkpoint – the type of immune brake this invention targets.
• Monoclonal antibody – the class of molecule the patent provides.
• Cancer immunotherapy – the treatment field the work belongs to.
• T cell – the immune cell whose activity HHLA2 helps regulate.
• Dana-Farber Cancer Institute – the research centre behind the application.

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AU 2026201937 was published in the Australian Official Journal of Patents on 2 April 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.