In June, the FDA approved a brand new treatment for a sophisticated style of prostate cancer. Patients who've this condition, called metastatic castration-resistant prostate cancer (mCRPC), have few treatment options, so the approval helps address an urgent need.
MCRPC is diagnosed when the front-line hormonal treatments that doctors previously used to treat metastatic prostate cancer stop working. These drugs limit the body's production of testosterone, a hormone that fuels the expansion of prostate cancer. If they're not effective, doctors switch to a special class of medication called antiandrogens, which further block testosterone by blocking its cell receptor. One of those drugs known as enzalutamide.
The newly approved treatment combines enzalutamide with one other drug, talazoparib, which was already in the marketplace for cancer patients in women who test positive for BRCA mutations. These inherited gene defects increase the chance of breast and ovarian cancer, but they may also increase the chance of prostate cancer in men. In fact, an estimated 10% of men with metastatic prostate cancer are BRCA positive.
Talazoparib blocks a DNA repair system called PARP that tumor cells must keep their genes as a way to work. When PARP is blocked by treatment, cancer cells will eventually die. Other PARP inhibitors, including olaparib and rucaparib, are already approved for prostate cancer in BRCA-positive men.
During the study resulting in this latest approval, 399 men with mCRPC were randomly divided into two groups. One group received talazoparib plus enzalutamide; The second group was treated with enzalutamide plus placebo. The men were on average 70 years old, and most had already been treated with chemotherapy and/or a special anti-androgen called abiraterone. All men were positive for either BRCA mutations or defects affecting other DNA-repair genes.
What the study showed
Results The as-yet-unpublished study was presented on the 2023 American Society of Oncology Annual Meeting in June. After a median follow-up of roughly 17 months, the enzalutamide/talazoparib combination reduced the chance of death or overt signs of tumor progression by 55%.
In a particular subgroup of BRCA-positive patients, “there was an 80 percent reduction in risk of progression or death, which is very high for these men and obviously very welcome,” said Dr. Karim Fazizi, a professor on the University of Paris. said — Saclay in France.
Scientists had hoped that combining PARP inhibitors with anti-androgens would also profit prostate cancer patients with no DNA repair defects, however the evidence is proscribed. A different study Dr. Fizzazi and his colleagues show that they don't.
For this reason, the FDA approved the brand new compound just for mCRPC patients who test positive for mutations affecting DNA repair genes. Dr. Fizzazi and colleagues are continuing to observe the enrolled patients for improvements in other areas, corresponding to overall survival, quality of life, and the necessity for subsequent chemotherapy.