Advancements In Prostate Cancer Treatment
- Actor James Michael Tyler who played the constantly caustic coffee-slinger Gunther on all ten seasons of Friends lost his battle with prostate cancer over the weekend at the age of 59. Diagnosed three years ago, his cancer metastasized during the pandemic when he could not see his doctor.
- Immune Checkpoint Inhibitors have been successful in prostate cancer patients whose cancer progressed following treatment and whose tumors show evidence of defective mismatch repair and microsatellite instability. These are injections of a patient’s own immune cells that are stimulated in a lab to fight cancer
- Targeted radiation is also becoming a quick and effective treatment thanks to advancements which allow for stronger doses over shorter periods of time, a process known as hypofractionation
Tributes to the actor began pouring in soon after from his co-stars, including Jennifer Aniston, Lisa Kudrow, and Courteney Cox. The Friends cast reunited with Tyler briefly when he made a virtual appearance at the show’s reunion special earlier this year, and Tyler corresponded with David Schwimmer throughout his battle with the disease.
Read MoreIn those interviews, Tyler stressed that the best way to beat the disease is early detection. According to the American Cancer Society, prostate cancer has a five-year survival rate of 98 percent overall, but only 30 percent in stage IV patients.
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Three years after Tyler first received news of his diagnosis, there have been remarkable changes in the treatment of prostate cancer, with more on the horizon. Here is a look at a few:
Immune Checkpoint Inhibitors
Immune checkpoint inhibitors are a class of drugs designed to strengthen the immune system. The drug targets the proteins on immune cells, which function as the on/off switch when fighting foreign invaders such as cancer.
Those proteins are manipulated in patients with cancer, resulting in immune cells that stop fighting the disease. A checkpoint inhibitor reverses that process by resetting the proteins, which stimulates the immune cells to start attacking the cancer growing inside the body.
However, the Food and Drug Administration sets precise guidelines when it approves the use of a checkpoint inhibitor to treat any form of cancer. In prostate cancer patients, the agency approved pembrolizumab (Keytruda). An intravenous treatment, it is also approved for use in patients with melanoma, lung cancer, head and neck cancer, Hodgkin lymphoma, stomach cancer, colon cancer and cervical cancer.
Prostate cancer patients whose cancer progressed following treatment and whose tumors show evidence of defective mismatch repair and microsatellite instability are approved to use pembrolizumab. The mismatch repair system is the pathway that reverses any mismatches, insertions, or deletions in the DNA system. Microsatellite instability is the series of short and repetitive DNA sequences that appear when that mismatch repair system becomes defective.
A 2018 study by Memorial Sloan Kettering Cancer Center found that these cells appear in less than three percent of prostate cancer patients.
In August, the FDA also granted accelerated approval to dostarlimab (Jemperli) for “adult patients with mismatch repair-deficient recurrent or advanced solid tumors, as determined by an FDA-approved test, that have progressed on or following prior treatment and who have no satisfactory alternative treatment options.”
Sipuleucel-T (Provenge) is another immunotherapy used to treat prostate cancer. That functions like a vaccine and received FDA approval in 2010 for treating individuals with “asymptomatic or minimally symptomatic metastatic castrate-resistant (hormone-refractory) prostate cancer.”
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PARP Inhibitors
In May 2020, the FDA approved the inhibitors olaparib (Lynparza) and rucaparib (Rubraca) for prostate cancer patients.
These treatments block the activity of the PARP enzyme, which helps cells mend specific types of damage to DNA. In this case, the cancer cells are unable to repair DNA damages and die off as a result.
Both olaparib and rucaparib are administered orally in pill form and are approved in only in patients with castration-resistant metastasized prostate cancer. Castration-resistant cancer is the term used when cancer stops responding to hormone treatments.
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Targeted Radiation
There are currently two forms of targeted radiation used to treat prostate cancer.
External beam radiation therapy (EBRT) treats patients with early-stage prostate cancer. Beams of radiation focus on the prostate gland from a machine outside the body in treatments generally administered five days a week for four-to-six weeks. The process lasts just a few minutes each time and is painless.
A 2019 study released by researchers at the University of Pennsylvania’s Penn Medicine found that the process known as hypofractionation had great success in prostate cancer patients. Hypofractionation is a form of EBRT that delivers large doses of radiation and requires fewer treatment sessions than traditional radiotherapy.
Brachytherapy is a form of internal radiation where small radioactive pellets that are the size of a corn kernel are placed directly in the prostate. It is also for use in individuals with early-stage prostate cancer and, in some cases, may be used in addition to EMRT if a patient is at a higher risk of having cancer grow outside the prostate.
Positron Emission Tomography Imaging of Prostate-Specific Membrane Antigen
The FDA has approved two drugs for positron emission tomography (PET) imaging of prostate-specific membrane antigen (PSMA) positive lesions in men with prostate cancer over the past year.
In December, the agency approved Gallium 68 PSMA-11 (Ga 68 PSMA-11) followed by Pylarify (piflufolastat F 18) in May for use in individuals with suspected prostate cancer metastasis who are potentially curable by surgery or other therapy.
Doctors inject these treatments that then bind to PSMA. This makes it easier to identify the presence of PSMA-positive prostate cancer lesions in the body’s tissues during PET imaging, allowing for more precise surgery and treatment.
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Hormone Therapy
The male hormone androgen fuels the growth of prostate cancer. Hormone therapies work to deprive cancer cells of these building blocks by reducing the production of androgens.
G(GnRH) antagonists are drugs that block the pituitary gland from making hormones that stimulate testosterone production.
Relugolix is a Gonadotropin-releasing hormone (GnRH) approved by the FDA in December 2020. GnRH antagonists work by blocking the pituitary gland from releasing the hormones that fuel the production of testosterone.
Prostate cancer stops responding to hormone therapy over time, which is known as metastatic castration-resistant prostate cancer. At that stage, oncologists may prescribe antiandrogen drugs to try and prevent androgen from binding to androgen receptors on prostate cancer cells to slow or stop growth.
Abiraterone (Zytiga), apalutamide (Erleada), and enzalutamide (Xtandi) are three examples of FDA-approved antiandrogen drugs that have improved the survival of men with metastatic castrate-sensitive prostate cancer when added to standard hormone therapy.
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