Twitter Chat on cancer immunotherapies
Immunotherapy for Cancer was the subject of a Twitter Chat hosted by the National Cancer Institute in April following the national airing of the PBS documentary Cancer: The Emperor of All Maladies. VCU Massey Cancer Center’s Masoud Manjili, D.V.M., Ph.D., member of the Cancer Cell Signaling research program at Massey and associate professor in the Department of Microbiology and Immunology at the VCU School of Medicine, provided expert commentary as the moderator posed a series of questions and discussion topics.
Below is a recap of the chat. Responses have been slightly modified to provide context that could not fit into the original 140-character tweets. Be sure to follow @VCUMassey on Twitter to keep up with the latest groundbreaking research and clinical trials at Massey, learn about patient and caregiver resources and discover volunteer and philanthropic opportunities while connecting with others who share similar interests and life experiences.
What is precision medicine?
Precision medicine is the area in which we can deliver individualized cancer therapies. Individual genetic variations can impact the similarities or variations of individual cells within the tumor, known as tumor heterogeneity.
What are immunotherapies?
Immunotherapies are treatments designed to reprogram the patient's immune system to fight cancer. Because cancer cells are mutated from normal healthy cells, the immune system does not always recognize them as harmless. Immunotherapies reprogram the immune system to identify and take action against the tumor.
What role does the immune system play in fighting cancer?
The immune system reduces the incidence of cancer in a person and edits cancer cells, which is called “tumor immunoediting and escape.” The interplay of cancer and the immune system is really dynamic in that cancer cells can give off substances that suppress an anti-tumor immune response, and the immune system can keep tumor cells in a dormant state. Dormant tumor cells are generally resistant to conventional cancer therapies, but are the best target for immunotherapy.
Are there different types of cancer immunotherapies?
Yes, there is passive immunotherapy, active specific immunotherapy (vaccine) and adoptive immunotherapy. There is also therapy called a “checkpoint blockade” that is complimentary to tumor-specific immunotherapy and is effective against immunogenic tumors. Immunogenic tumors are those tumors that promote an immune system response.
Are some types of cancer more likely to respond to immunotherapies than others?
Immunogenic tumors, such as melanoma, are more likely to respond to immunotherapy. Weakly-immunogenic tumors could be reprogrammed by epigenetic modulators that alter the cancer cells’ epigenetic structure to make the tumor strongly immunogenic and respond to immunotherapy. Decitabine is one such drug that can induce the expression of highly immunogenic cancer-testis Ag (CTA), making tumors highly responsive to immunotherapy.
What are some challenges in developing these treatments?
One challenge is working with tumors when they secrete proteins that support particular cells that can inhibit the anti-tumor function of the immunotherapy. Another challenge is that tumors escape by losing the tumor-fighting antigen and hide under immune pressure. Dormant tumor cells, however, cannot divide; thus they cannot escape during immunotherapy. Dormant tumors, or minimal residual disease, respond best to immunotherapy while being resistant to conventional cancer therapies.
Are more of these agents being tested in clinical trials?
Immune checkpoint blockade pathways, such as PD-1 and CTLA-4, are being tested in clinical trials for immunotherapy of cancer. Anti-PD-1 therapy is poised to take the next step in the treatment of melanoma.
Where can I learn more about these treatments?
You can learn more about Massey’s clinical trials, including immunotherapy for cancer, at massey.vcu.edu.