MICA: Immunotherapy for oral cancer prevention and treatment

Worldwide, oral cancer (OSCC) is the eighth most common cancer and a major global health concern, with an annual incidence of around 398,000 and more than 222,000 deaths worldwide. OSCC is often difficult to treat; surgery and radiotherapy remain the standard treatments but, despite improvements, are associated with significant morbidity and a relatively static 5-year survival rate of around 50-60%.

Around 15-80% of OSCC develop from a precursor lesion (OPL), most commonly a white patch (leukoplakia). The current gold standard for determining leukoplakia management is pathological diagnosis of dysplasia, with transformation rates of 24.1% being reported in severe dysplasia. At present, the only effective treatment is surgical excision. However, studies indicate that this is not likely to reduce the risk of recurrence or malignant change. It is clear that more effective treatments are required for both premalignant lesions and established OSCC.

Immunotherapy represents the most promising new cancer therapy for several decades. These treatments harness the power of the patient's immune system to fight the cancer, in the same way that the immune system might fight a virus. Cancers are recognised by the immune system as "foreign' because they express proteins (antigens) not usually found in normal tissues. Some patients have a strong immune response against their cancer; this can be seen in the tumour tissue as immune cells (lymphocytes) attacking the cancer cells. However, most cancers are not well recognised by the immune system, and the immune system needs to be stimulated to respond. If we identify the abnormal proteins on the cancer cells, then we can design vaccines against these antigens to generate an immune response against the cancer cell (just like vaccinating against a virus); recent studies have shown that premalignant lesions in the cervix can be successfully cleared through vaccination. This type of cancer is caused by a virus (human...