Researchers reported a number of important findings in prostate cancer treatment at the 2017 Annual Meeting of the American Society of Clinical Oncology:

Adding abiraterone to standard therapy for men with high-risk metastatic disease improves overall survival

According to results from the LATITUDE and STAMPEDE clinical trials, adding the drug abiraterone to the current standard of care (hormonal therapy) had benefit in the treatment of men with locally advanced or hormone-sensitive metastatic prostate cancer.

The STAMPEDE trial showed that adding abiraterone to standard hormonal therapy resulted in an improvement in overall survival (OS) of 37 percent. In the LATITUDE trial, the OS rate at three years was 66 percent with abiraterone and prednisone, compared to 49 percent with standard hormonal therapy.

In the last few years, the chemotherapy docetaxel has been added to hormonal therapy for some patients with significantly advanced disease. The results of the LATITUDE and STAMPEDE trials suggested that abiraterone added to hormonal therapy results in a level of effectiveness comparable to hormonal therapy plus docetaxel, with fewer side effects.

What Patients Need to Know

While abiraterone was found to be generally well-tolerated, several severe side effects were more common when abiraterone was added to the standard hormonal therapy, including high blood pressure, low potassium level, and liver enzyme abnormalities.

Targeted therapy being studied for treatment of gene-mutated mCRPC

A phase lll trial, TRITON3, is investigating the targeted therapy rucaparib for the treatment of metastatic castration-resistant prostate cancer (mCRPC) in men who received hormonal therapy as initial treatment, and who have a mutation in the BRCA1, BRCA2, or ATM genes.

The trial will compare the effectiveness of rucaparib as a single agent against one of three standard drugs: abiraterone or enzalutamide (both of which are hormonal treatments) or the chemotherapy docetaxel.

Rucaparib is a PARP inhibitor. This type of drug is designed to prevent cancer cells from repairing their damaged DNA; this prevention can cause the cancer cells to die.

What Patients Need to Know

In December 2016, the Food and Drug Administration (FDA) approved rucaparib for the treatment of women with recurrent ovarian cancer that expresses BRCA gene mutations. Prior studies have shown PARP inhibitors to be effective in treating mCRPC.

Studies show that reevaluation of genetic testing protocols is needed

Recent studies have shown that a substantial percentage of prostate cancer patients have clinically significant genetic variants that would not have been identified through genetic testing.

In some cases, the variants would have been missed because, under current guidelines, patients would not be considered qualified to undergo genetic testing. One study found that 17.2 percent of patients exhibited genetic variants across a number of genes; among these patients, 37 percent would not have qualified for testing under current guidelines.

In other cases, the patient does qualify for genetic testing, but has variants that are not included in the testing. The only two genes tested under current guidelines are BRCA1/2, but the majority of variants (66 percent) occur in genes other than BRCA1/2.

What Patients Need to Know

The conclusion from the studies is that a reevaluation is needed of how prostate patients are tested for genetic variants. Gene variations may be associated with more aggressive disease, and information about those variants have implications for treatment decisions.