Using Immunotherapy to Treat Prostate Cancer

The challenge to overcome cancer has been around as long as the human race has known about cancer. An Egyptian papyrus from 1600 B.C. identifies cancer and describes removal of a breast tumor by cauterizing (burning) it. The writer notes that there is no known cure for cancer. In modern times, the three main methods of battling cancer have been surgery, radiation, and chemotherapy. Each of these is an attack from outside the body.

Now a new approach attempts to activate or boost the body’s own defense system to beat cancer from within. Because this is so promising, huge investments are being poured into research.  There are several categories of immunotherapy that are currently in clinical trials:

  1. Checkpoint inhibitors are intravenous (IV) drugs that block the ability of cancer cells to put the brakes on the immune system. By “aborting” the cancer’s “mission”, the action of the drug allows the killer T-cells to proceed with their work of attacking and destroying tumor cells. There are checkpoint inhibitors available for certain cancers: melanoma, lung, and others. They are not equally effective for every patient.
  2. Cell therapy uses a patient’s own immune cells that are harvested from the patient, genetically manipulated and multiplied in the lab, and returned to the patient’s body. This approach tailors the treatment to each unique patient.
  3. Bispecific antibodies are proteins that can attach to both a T-cell and a cancer cell, bringing them into close enough contact for the T-cell to do its job.
  4. We all had vaccines in childhood in which an inactive form of an illness such as measles is injected as a way to prompt the immune system to prevent us from getting the illness, and this is called inoculation. Cancer vaccines, on the other hand, help the body go after a cancer that already exists in the patient. Prostate cancer is the first type of cancer to have an FDA-approved vaccine, Provenge®, which is available for patients with metastatic disease. In clinical trials testing Provenge vs. a placebo, patients receiving the vaccine added months to their survival.

Unlike chemotherapy, immunotherapy does not have the kind of side effects caused by the toxic chemicals that harm healthy cells as well as cancer.

With immunotherapy, some patients do have an autoimmune reaction in which the immune system “goes overboard”. This can include inflammation and other problems, but these can often be managed with steroids. However, the positive results can be dramatic, and therein lies the promise of immunotherapy. In particular, the checkpoint inhibitors have inspired hope for thousands of patients, and the growing number clinical trials involving experimental combinations of existing drugs, and brand new drugs, give occasion for great optimism.

On the other hand, none of today’s immunotherapies has proven curative, and for those patient whose cancer goes into remission, relapse is likely to occur within a year to five years. This is disappointing, to be sure, but much gratitude is due to the patients whose experience and clinical records illuminate future directions. The New York Times carried the personal account of one patient’s journey with Hodgkin’s lymphoma, with its powerful ups and downs, and his amazing courage in the midst of it. See the full article here.  As his story shows, immunotherapy is very much a work in progress, and yet every step makes the journey worth it. For information on clinical trials, visit here.

Copyright by Dan Sperling, MD. Reprint permission courtesy of Sperling Prostate Center (New York, Florida), the leading U.S. center for multiparametric detection, diagnosis and image-guided focal treatment of prostate cancer.

Read more in our Prostate Cancer Health Center.

References

History of cancer. Wikipedia

Grady D, Pollack A. What is immunotherapy? The basics on these cancer treatments. New York Times 2016 Jul 30

Ricthel M. “Immunotherapy offers hope to a cancer patient, but no certainty.” New York Times July 31, 2016.