Monoclonal Antibody — Targeted Immune Therapy

Monoclonal antibodies are synthetic molecules engineered to mimic or enhance the body's natural immune response. In standard biology, antibodies are produced by B lymphocytes to neutralise foreign pathogens. Scientists produce monoclonal antibodies by cloning a single unique white blood cell, ensuring that every resulting antibody binds to the exact same antigen.

In oncology, these agents target specific antigens that are overexpressed or mutated on malignant cells or within the tumour microenvironment. Depending on their design, they may block cellular signaling pathways, recruit immune cells to trigger cytotoxicity, or deliver attached chemotherapy drugs directly into tumours.

Monoclonal antibodies have transformed modern oncology by providing precise, targeted alternatives or complements to standard chemotherapy. Because they focus primarily on specific proteins associated with cancer cells, they often cause different side-effect profiles compared to traditional cytotoxic drugs. For patients, testing for matching targets allows clinicians to select therapies tailored to the specific biology of their tumour, improving outcomes while preserving normal tissues.

Before prescribing a monoclonal antibody, doctors usually test tumour tissue or blood samples to verify that the target antigen is present. Techniques include immunohistochemistry (IHC) to detect cell-surface proteins and fluorescence in situ hybridisation (FISH) or next-generation sequencing (NGS) to detect gene amplifications, such as HER2 or EGFR alterations.

These agents are used across a broad spectrum of cancers. Notable examples include breast and gastric cancers expressing the HER2 protein, lymphomas and leukaemias expressing CD20, colorectal and head and neck cancers with EGFR abnormalities, and numerous solid tumours treated with checkpoint inhibitors that target PD-1, PD-L1, or CTLA-4.

Monoclonal antibodies are delivered intravenously or subcutaneously. They may be used alone, combined with chemotherapy, or paired with radiation. Some are engineered as antibody-drug conjugates, which carry chemotherapy directly to tumours, or as bispecific antibodies, which physically tether cancer cells to immune killer cells.