For decades, the various types of cancer have classically been treated with combinations of chemotherapy, surgery, and radiation depending on the type and stage of cancer. While this strategy led to great and historical success and cures for some types of cancer, significant limitations and relatively few treatment options remained for more advanced, metastatic, or treatment-resistant disease.
This article reviews the recent and unprecedented acceleration in the understanding of cancer pathophysiology which has led to the subsequent development of novel cancer immunotherapies. In part, this new direction in cancer treatment has been advanced by a greater understanding of individual patient genomics and has contributed to the realisation of the so-called “precision medicine” era.
Cancer and the Immune System
Cancers develop through a combination of genetic and epigenetic changes that lead to cellular immortality. Simultaneously, these changes create new cell surface antigens, called neo-antigens, which should be recognised as foreign by the host immune system and then eliminated. However, tumours have evolved several mechanisms to evade immune detection including induction of tolerance, systemic disruption of T-cell signalling, and immune editing. The latter process is defined as a selective process in which tumour cells which are less immunogenic and more resistant to apoptosis (programmed death) go unrecognised and increase in number unchecked.
The concept of utilising an individual’s own immune system to treat cancer is not new, but has been relatively unsuccessful historically. While the above paragraph describes how tumours can evade the host’s immune system, it is well known that the immune system can be quite efficient at eliminating many tumours after early malignant transformation. This is termed immune surveillance. Thus, if new therapies could be directed at blocking the underlying mechanisms of tumour evasion this would allow the immune system to successfully perform its role in eliminating tumours and would represent a renaissance in cancer treatment based on immunotherapy.
That time has now arrived...Read More +