In the practice of word association, the mention of “cancer” might bring to mind “chemotherapy.” Thought to go hand-in-hand for decades, chemotherapy has been used to blast cancer cells for nearly 60 years. While chemotherapy is generally largely successful, it is often ineffective or minimally effective in a subset of cancers. With the use of genetic testing technologies on the rise, new, highly personalized therapies for cancer come into play. These therapies, dubbed “immunotherapies,” have advanced exponentially since their discovery.
Cancer immunotherapy, or biologic therapy, is a technique that uses the body’s own immune system to fight cancer. Immunotherapies boost the body’s natural defenses and work to either stop/slow the growth of cancer cells, prevent cancer cells from spreading, or destroy cancer cells all together. Immunotherapies exploit the fact that cancer cells are often recognizable to the immune system via molecules on their surface. With this mechanism of recognition, immunotherapies are highly selective and efficient at identifying and destroying tumor tissue. Immunotherapies can be either passive or active, and are split into several classes including cellular immunotherapies, antibody therapies, and cytokine therapies.
While immunotherapies for cancer have existed for some time, the worldwide work toward a cure for cancer continues to highlight new and novel immunotherapeutic targets. To healthcare professionals, the past two years stand out as the season in which immunotherapy became a household name. During this period, the market for immunotherapeutic cancer therapies has seen an unprecedented number of FDA approvals. In 2019, the number of agents available to patients will only continue to grow.
Today, one of the most notable advancements in cancer immunotherapy is its simultaneous use with cytotoxic therapy. Known as “joint therapy,” the integration of immunotherapy and cytotoxic therapy (chemotherapy) has been studied in several patient populations with great success. In a sample of patients with metastic, nonsquamous, non-small cell lung cancer, joint therapy has been incredibly effective – more than doubling the cancer response rate from its rate with chemotherapy alone. In 2017, the FDA approved the first combination of chemotherapy and immunotherapy for patients of this cohort.
Checkpoint inhibitor therapy is another immunotherapy changing cancer treatment. The therapy targets immune checkpoints, key regulators of the immune symptom, which tumors can use to protect themselves from attacks by the immune system. In blocking inhibitory checkpoints, immune system function is restored. Voted our #6 medical innovation in 2015, immune checkpoint inhibitor therapy has made great progress since then. Recent studies show the production of significant, durable responses with these therapies. In October of 2018, immunotherapy pioneers James P. Allison and Tasuku Honjo were awarded the Nobel Prize in Physiology or Medicine for their research of the science behind checkpoint inhibitor therapies.
Other innovations on the immunotherapy front involve therapies derived from T-cells. Following hot on the trail of the wildly successful CAR-T cell therapy, new forms of engineered T-cells have exhibited enhanced anti-tumor activity and selectivity in a variety of cancers. T-cells are a subtype of white blood cell that play a central role in cell-mediated immunity. Produced in the thymus, T-cells acquire antigen receptors that enable them to identify foreign substances in the body. In engineering these receptors, T-cell therapies are able to recognize specific target antigens on tumor cells allowing the body’s immune defenses to attack the cancers within a patient.
In early 2018, engineered T-cell technology gained popularity with the kickoff of several clinical studies for its use in new types of cancer. This popularity is expected to grow in the coming year. The agent with the most promise in 2019 is that of a T-cell receptor (TCR-T) therapy developed for use in liver cancer – the world’s third most deadly. With the near daily discovery of new immunotherapeutic targets, it is the hope that effective therapies will soon exist for all tumor profiles.