Therapeutic and Prophylactic Cancer Vaccines

Cancer vaccines are an important weapon in the growing armamentarium of cancer immunotherapy. In contrast to standard cancer therapies, such as radiation and/or chemotherapy that cause excessive damage to normal tissue, immune responses elicited by vaccines specifically target and destroy cancer cells while preserving healthy tissues. Importantly, vaccines generate tumor-specific immune memory that provides long-term protection from cancer development or cancer recurrence. Prophylactic cancer vaccines based on viral antigens such as human papillomavirus and hepatitis B virus have successfully prevented cervical cancer and hepatocellular carcinoma. Various vaccine formulations based on antigens expressed by tumors that do not have a viral origin have also been developed and tested in animal models and in clinical trials. Therapeutic use of these vaccines has led to important new knowledge about the suppressed state of the immune system in the tumor-bearing individual. Administration of prophylactic vaccines prior to tumor development offers an opportunity for better vaccine efficacy by avoiding immunosuppression and immune escape mechanisms used by advanced tumors.