TCR Therapy Targeting MAGE-A4

Recently at the 2022 CTOS Conference, Adaptimmune announced the SPEARHEAD-1 clinical trial data of its T cell receptor-engineered T cell (TCR-T) therapy, Afamitresgene autoleucel (afami-cel), for synovial sarcoma. The results showed that the overall response rate of afami-cel was 39% and the median duration of response was 50 weeks [1]. Results show afami-cel can effectively activate and promote the infiltration of proliferative cytotoxic T cells into the tumor. The drug has completed and reached the primary clinical endpoint, bringing good news for TCR-T therapy and broader tcr t cell therapies in cancer treatment.

Afami-cel is a TCR-T cell therapy drug targeting MAGE-A4. It is an autologous T cell therapy approach where t cells are collected from a patient’s blood and re-engineered to express a t cell receptor (also called a cell receptor tcr) that can recognize the MAGE-A4 230-239 (GVYDGREHTV) peptide restricted by HLA-A2 [2]. This engineered cell therapy relies on precise cell receptor recognition of a specific antigen presented on the cell surface of tumor cells. Given the specificity of TCR recognition depends heavily on the precise configuration of the peptide-MHC complex, having access to highly tailored MHC monomers and tetramers that accurately present the MAGE-A4 epitope is essential for optimizing TCR binding and improving functional assays. Utilizing an MHC complex custom service allows researchers to control key variables such as peptide loading and allele specificity, which can substantially influence the outcome of T cell response assessments and therapeutic validation.  MAGE-A4 is a member of the MAGE-A subfamily of the melanoma antigen gene family. Its full name is Melanoma-associated antigen 4. It is highly expressed in a variety of tumor cells and low in normal tissue cells. It is a very attractive target for solid tumor cell therapy, especially TCR-T therapy.

How TCR therapies Work in Solid Tumors

TCR T cell therapies are a cellular therapy strategy designed to help immune cells recognise abnormal proteins (tumor antigens) produced by cancer cells. Once activated, engineered t cells can increase t cell activity, migrate into the tumor microenvironment, and help eliminate tumor cells through natural mechanisms of cytotoxic killing. This is particularly relevant for treating solid tumors and other tumor types where tumor antigens are intracellular proteins presented via human leukocyte antigen (HLA) molecules.

TCR-T vs CAR-T (where each fits)

Unlike chimeric antigen receptor approaches (CAR T), which typically recognize surface proteins directly on tumor cells, T cell receptor therapies can recognize peptide fragments from certain proteins presented by human leukocyte antigen complexes on the cell surface. This difference helps explain why TCR therapy has become a promising therapy for multiple solid tumors, while CAR T has been widely used in certain blood cancers and other blood cancers that express accessible surface targets.

Figure 1. MAGE-A4 Protein

KACTUS has a refined protein preparation technology and has successfully launched MHC polypeptide complex products of MAGE-A4, including MHC-MAGE-A4 polypeptide complex monomers and tetramers in different forms. These provide high-quality antigen research tools for cell therapy such as TCR-T, and assist customers in drug development and optimization. KACTUS also provides MHC polypeptide complexes of other target proteins, covering different popular targets such as MAGE-A3, AFP, NY-ESO-1, KRAS, p53, and Survivin. These proteins can support antigen presenting cells and assay workflows that study signal transduction, receptor engagement, and response durability, including t cell exhaustion in long-running stimulation models.

Advantages of KACTUS MHC Peptide Complex Products

• Mammalian cell expression system for a more realistic conformation and better biological activity
• Does not require renaturation, greatly shortening the lead time
• Customized services for MHC peptide complexes can be provided including various species, various genotypes, various antigenic peptides, monomers/tetramers, biotinylated tetrameric complexes, fluorescent labeling complexes, etc.

MHC Monomers & Tetramers with MAGE-A4 Antigens

Clinical Context and Patient Pathway Notes

In practice, patients are typically screened at a cancer center for HLA type and antigen expression as part of clinical trials. For solid cancers, treatment planning may involve bridging therapy or systemic therapy while engineered cells expand before infusion back into the patient's bloodstream. After dosing, persistence in patient's blood and functional activity in the tumor microenvironment are key readouts, especially in metastatic disease.

Where MAGE-A4 Programs Are Being Studied

MAGE-A4 programs have been explored across solid tumors, with activity signals reported in synovial sarcoma and ongoing interest in tumor types such as esophageal cancer, gastric cancer, ovarian cancer, and urothelial cancer.

Request Custom Project