According to the National Cancer Institute, immunotherapy is now being referred to as the “fifth pillar” of cancer treatment. Immunotherapy refers to treatments designed to improve the ability of immune cells to recognize and attack cancer cells. Examples of immunotherapy include dendritic cell vaccination, checkpoint inhibitors, CAR T-cell therapy, and inoculation with monoclonal antibodies modified to attach to a protein in cancer cells.
The American Cancer Society has a webpage dedicated to emerging immunotherapy research and has identified benefits and disadvantages of various immunotherapy treatments for cancer. While there is hope that immunotherapy may be less harmful to the body, research is so new that little is known about its long-term effects. As a result, special precautions are taken to prevent health care providers, friends and family, and the patient from coming into improper contact with the drug. Immune checkpoint inhibitors, for example, have been associated with dangerous toxicity on account of their ability to suppress molecules that keep the immune system from attacking self-cells. Immunotherapy can be used by itself to treat cancer or as a complementary to other forms of treatment like chemotherapy. Immunotherapy is promising for many types of cancers, but appears to be more effective for certain cancers than others. The Cleveland Clinic reports that the most promising immunotherapy outcomes have been in treating melanomas, non-Hodgkin’s lymphoma, lung cancer, kidney cancer, bladder cancer, and cancers of the head and neck. These are also among the most common cancers.
According to a study in Nature, dendritic cell vaccination has been an area of particular focus for research, supplanting checkpoint inhibitors as one of the primary immunotherapy interventions. Dendritic cells, cells of the innate immune system, are found in tissues throughout the body and are capable of recognizing antigens (potentially harmful foreign or self substances), migrating to lymphoid organs, and presenting the antigen to lymphocytes capable of mounting an effective immune response. Dendritic cells, which can present tumor-associated antigens, are therefore one of the earliest warning signs of danger to our body. However, malignant tumors are sometimes able to avoid or suppress the mechanisms that activate these cells, allowing the cancer to continue growing. The idea behind dendritic cell vaccinations is to take a patient’s own dendritic cells and manipulate them to be more effective in inducing an immune response to the tumor. In past clinical trials, DC vaccinations were encouragingly effective, but responses in clinical settings have been less than stellar. In a November study however, researchers Michele De Palma and Caleb R. Perez identified ways to more precisely engineer dendritic cells. Their findings show that a particular subset of DCs–cDC1s–would be well suited for vaccine use, and they suggested a new cytokine cocktail to differentiate these cDC1 cells from stem cells. Better methods for genetic programming and improving migration of DCs were also suggested. Their suggestions provide hope for manufacturing more effective and patient-tailored vaccines.
Also in November, researchers in the Netherlands observed improved outcomes in patients with castration-resistant prostate cancer following treatment with blood-derived dendritic cell vaccinations in 21 patients. The study also reported low toxicity, with the most severe side effects being flu-like symptoms and injection site reactions. Patients were given mDC and/or pDC vaccinations, and a significant proportion showed tumor antigen-specific T cell responses following. Patients showing these antigen-specific T cell response had a longer median period of time with no tumor growth.
While DC vaccinations and other such therapies require further research, these studies and others indicate promising futures for immunotherapy treatments. These treatments may be less harmful to patients than typical treatments with surgery, radiotherapy, and chemotherapy. However, they may also be very expensive due to the complex engineering required to make them. One FDA-approved DC vaccine, Sipuleucel-T (Provenge), costs $93,000 for a full course of treatment. Already immunotherapy is being used individually and as complementary therapy for cancer patients. Since cancer cells are self cells that have gone haywire, it would make sense to enhance our body’s already-present mechanisms for identifying, infiltrating, and destroying cancer cells. Hopefully as we explore immunotherapy and other possible cures we can continue to find new and innovative ways to fight cancer and save lives.
Hannah Biowell Blog 