Q&A on immunotherapy, a new class of cancer treatments - answers from oncologist Dr. John McCann
By Dr. John McCann Gazette Contributing Writer
Tuesday, August 11, 2015
(Published in print in The Daily Hampshire Gazette: Tuesday, August 11, 2015)
Editor’s note: Following is the first in a series of monthly columns about cancer-related issues that will be presented in a Q&A format written by doctors at Baystate Regional Cancer Program.
In the fight against cancer, oncologists are always looking for new and promising treatments for their patients and hoping for a cure that will one day save the 8 million people who die globally from the disease each year.
Immunotherapy is a relatively new class of cancer treatment designed to boost the body’s own immune system to fight the disease. This new weapon holds so much potential that Science magazine declared it “Breakthrough of the Year” in 2013.
Much progress has been made since then involving landmark studies showing the benefits of immunotherapy in the treatment of melanoma and lung cancer. Advances in cancer immunotherapy was the hot topic at this year’s American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, where several Baystate Regional Cancer Program oncologists joined others from around the world to learn about the latest, most significant research in the field.
Q. What is immunotherapy and how does it differ from other types of cancer therapies?
A. Advanced cancers have traditionally been treated with chemotherapy medicines that directly attack the cell division or metabolism of cancer cells. In recent years, new targeted therapies attack specific molecules that are present on the cancer cell. Both of these treatment types directly affect cancer cells.
Immunotherapy, which has been in use at Baystate as standard therapy and as part of major national clinical trials, is different because it indirectly attacks cancer cells by activating the body’s immune system. Immunotherapy causes the body to view the cancer cells as foreign and stimulates our biologic machinery to eliminate them.
Q. Why are oncologists so excited about this?
A. Immune system activation is finally beginning to affect survival in some patients with certain types of advanced cancers after years of very little success.
Our immune cells are designed to very efficiently recognize foreign invaders such as viruses. However, immune cells generally leave our own body’s cells alone. In recent years, however, new knowledge about how the immune system avoids attacking normal cells in the body has led to the discovery of certain molecular brakes on our immune system called checkpoints. These checkpoint molecules stop the immune system from attacking the body’s own cells. New antibody proteins have been designed to bind to these brakes and disable them, allowing the immune cells to target the cancer cells.
Q. How are these treatments being used?
A. Large clinical trials have shown survival benefits for patients with metastatic melanoma and more recently certain types of lung cancer. Baystate has enrolled patients to two of these major immunotherapy trials. The results of the clinical trials have led to the approval of immunotherapy in the treatment of these types of cancer.
Checkpoint inhibitors are being tested in many other cancer types as well and are showing more potential benefits.
Q. Who will benefit from immunotherapy?
A. It is difficult to predict who may gain the most benefit from immunotherapy. Some patients with melanoma skin cancer have had dramatic improvements in very advanced cancer. There may be a small group of patients with metastatic melanoma who will actually be cured with immunotherapy.
Researchers are attempting to define markers on the surface of cancer cells that will help predict which cancers have the greatest likelihood of responding well.
Q. Are there side effects?
A. Over-activation of the immune system can lead to inflammation and damage that can affect normal organs, and there is some risk of severe immune-related side effects. People with a history of autoimmune diseases may be at high risk of developing complications.
Q. What does the future hold for immunotherapy?
A. It is likely that immunotherapy will become an increasingly common means of treating cancers. Combinations of immunotherapy drugs may be more effective, but may also have more side effects. We hope to identify biomarkers on cancer cells that will help predict this.
Immunotherapy may eventually be found to be effective in preventing the recurrence of early cancers that have been surgically removed.
Cytotoxic chemotherapy will continue to be used because it works, and for some cancers it works very well. However, the new wave of drugs taking advantage of the immune system is very exciting and we are more optimistic than ever about the potential ability to control cancer.
However, years of research will be required to define the exact role and benefits of immunotherapy in the treatment of all types of cancer.
John McCann (pictured above) is an oncologist in the Baystate Regional Cancer Program in Springfield.