You may have heard about immunotherapy, which offers promising advances in cancer research and therapies. But you may not know exactly how immunotherapy works. “Immunotherapy asks ‘how can we enhance or target the immune system to treat cancers?’,” said Shannon Puhalla, M.D., director of the breast cancer clinical research program at Magee-Womens Hospital of UPMC in Pittsburgh, Pennsylvania. “This has been thought about for decades. But within the past five years, this field has taken off considerably.” Here’s the scoop about this complex field:
What is immunotherapy?
Immunotherapy is any treatment using the immune system to fight disease, including cancer. Immunotherapy acts on the cells of the immune system to help them attack cancer.
What are the types of immunotherapy?
The most widely used form of immunotherapy for cancer is called checkpoint inhibitors. These drugs, given intravenously, block a mechanism cancer cells use to shut down the immune system. This frees killer T-cells to attack a tumor. The Food and Drug Administration has approved four checkpoint inhibitors.
Cell therapy, another form of immunotherapy, involves removing immune cells from a patient, altering those cells genetically to help them fight cancer, multiplying them in the lab and dripping them, like a transfusion, back into the patient. This type of treatment, developed individually for each patient, is still experimental and available through clinical trials only.
Bispecific antibodies, an alternative to cell therapy, don’t not require individualized treatment for each patient. These antibodies are proteins that can attach to both a cancer cell and a T-cell, bringing them close together so the T-cell can attack the cancer.
Researchers haven’t had as much success with vaccines, another form of immunotherapy. Unlike childhood vaccines, which are used to keep a patient from developing childhood illnesses like measles, mumps or whooping cough, cancer vaccines are designed to attack the disease once a person has it. Researchers hope to someday combine vaccines and checkpoint inhibitors.
Which cancers are treated with immunotherapy?
Checkpoint inhibitors are used to treat advanced melanoma, Hodgkin’s lymphoma and cancers of the lung, kidney and bladder. Cell therapy has been used mostly for blood cancers like leukemia and lymphoma. “Early research with immunotherapy and breast cancer is lagging behind other cancers,” Dr. Puhalla said. “One option is to give immunotherapy for triple negative [breast cancer] in addition to chemotherapy. This is very promising for our patients who have triple negative.”
Does immunotherapy work?
Doctors have had remarkable success with immunotherapy in some cases, but it still works in only a minority of patients. About 20 percent to 40 percent of patients are helped by checkpoint inhibitors, though there have been cases where combining two checkpoint inhibitors increased the effectiveness. Cell therapy can produce complete remissions in 25 percent to 90 percent of patients with lymphoma or leukemia. In some cases, patients have gone into remission for for years; in others relapses occurred within a year.
Are there side effects?
Checkpoint inhibitors can cause lung inflammation, diarrhea or rheumatoid arthritis. Cell therapy can also lead to severe reactions resulting from the overstimulation of the immune system.
How much does immunotherapy cost?
Checkpoint inhibitors can cost $150,000 a year and are covered by most insurance companies if the drug has been approved for the type of cancer the patient has. Co-payments may be high, though. Because cell therapy hasn’t yet received FDA approval, the cost isn’t yet known. Experts expect them to cast a few hundred thousand dollars. Patients in clinical trials for checkpoint inhibitors and cell therapy may be able to get the treatments for free.
For more information about immunotherapy clinical trials, go to ClinicalTrials.gov.