Thyroid cancer has become one of the most prevalent cancers in North America. Our growing understanding of the relationship between tumour cells and the human immune system allows us to develop immune-based therapies that could provide improved patient outcome.
Thyroid cancer has become one of the most commonly found cancers in North America, with incidence only increasing over time. Traditional therapies to date have focussed on targeting the cancer cells themselves or parts of pathways that lead to cancer progression, but in some cases, these treatments can be ineffective due to biological changes that have already taken place or the cancer cells can grow resistant. To tackle these complex cases, scientists have suggested targeting the immune system’s relationship with tumors. A new review in The Lancet Diabetes & Endocrinology journal looks at the immunotherapies for thyroid cancer.
Cancer and immune cell interactions have been divided into three categories. The immune cells can eliminate the cancer cells, the cancer cells can adapt to evolve traits that allow for evasion of the immune cells, and the evolved cancer cells can escape immune cell pressures, leading to cancer growth. Researchers have identified a number of critical components of this process to target, to interrupt tumor growth and promote cancer cell death.
Tumors have been analyzed and are shown to attract tumor-associated macrophages, a type of white blood cell which normally contributes to the immune system but can promote cancer growth after mutation. A number of genes have been identified that are commonly mutated in tumors, altering macrophage function, and targeting these genes could have positive results in treating advanced cancers. Other potential targets of immunotherapy include αβ T cells, meant to aid in destruction of cancer cells, regulatory T cells, which have shown immunosuppressive and tumour-promoting effects, and specific proteins in immune pathways that have been mutated to aid cancer growth.
Another aspect that needs to be addressed in immunotherapies is that not all patients are receptive to it. Some patients do not respond to the therapy, creating a need to identify patients where the treatment will be effective so patients can be directed to treatment that will be most effective for them as quickly as possible. Researchers have identified a number of biomarkers that they hypothesize will be predictive of patient’s sensitivity to certain immunotherapies, and further investigation into the accuracy of these biomarkers is being done.
While traditional treatments are quite effective and can be utilized for most of the population, in select cases these therapies are not viable and alternatives must be discovered. The high immunogenic activity of thyroid tissue and the efficacy of immunotherapy in treating tumors at other sites makes immunotherapy an attractive option for these patients. As we improve our knowledge of the immune system and its relation with cancer cells, we can utilize this information to target critical components of this association and improve patient outcomes in those with tumours unresponsive to traditional treatment.
Written By: Wesley Tin, BMSc