This approval is an expansion of the use of this drug from two prior FDA approvals. The first, in 2011 was for use of abiraterone acetate for patients with metastatic castration-resistant prostate cancer (CRPC) after chemotherapy fails to stop cancer progression. The second approval, in 2012, was for use in men with metastatic CRPC, regardless of prior chemotherapy use. Abiraterone acetate (hereafter called abiraterone) works by inhibiting a critical enzyme (cytochrome P450c17) that is responsible for androgen synthesis. Androgens, like testosterone, fuel prostate tumor growth and metastases.
What did the study show?
This recent FDA approval is based on results from the LATITUDE study, conducted between 2013 and 2017 with 1,999 men diagnosed with metastatic high-risk CSPC. The study was a placebo-based random controlled trial. Patients were randomized to either receive androgen-deprivation therapy (ADT) plus abiraterone and prednisone or ADT plus placebos. Men in the abiraterone group had better outcomes for both overall survival and progression-free survival compared to the placebo group. In the abiraterone group, risk of death was reduced 38% and cancer progression was delayed by an average of 18 months.2
The study also demonstrated better outcomes for the abiraterone group for each of the secondary outcome measures. These included time until pain progression, time for next therapy for prostate cancer, need for chemotherapy, PSA progression, and reduction in bone “progression” events.
An option to treat advanced prostate cancer sooner
Metastatic CSPC, also called advanced prostate cancer, accounts for approximately 3% of all new prostate cancer diagnoses in the U.S. For decades, some form of ADT has been the standard of care for men with advanced prostate cancer.2 Although the majority of men with prostate cancer have an initial response to ADT, those with metastatic prostate cancer have progression to CRPC within an average of a year.
The LATITUDE study defined “high risk” to include three factors associated with poor prognosis in men with prostate cancer. These high-risk factors include: a Gleason score of 8 or more, at least three bone lesions, and the presence of metastasis to visceral organs. Using these high-risk factors to initiate a new therapeutic option prior to the development of metastatic CRPC offers an approach that may help slow disease progression in many men and may help usher in a new standard of care.
The most common adverse reactions among men receiving abiraterone in the LATITUDE study were hypertension, hot flushes, hypokalemia, increase signs of liver, kidney or heart disease, headache, urinary tract infection, upper respiratory tract infection, and cough. For inclusion in this listing, these reactions occurred in at least five percent of men receiving abiraterone in the LATITUDE study.3
FDA approves abiraterone acetate in combination with prednisone for high-risk metastatic castration-sensitive prostate cancer. Found at: https://www.fda.gov/Drugs/InformationOnDrugs/ApprovedDrugs/ucm596015.htm
Fizazi, K., NanPhuong, T., Fein et al. Abiraterone plus Prednisone in Metastatic, Castration-Sensitive Prostate Cancer. July 27, 2017. N Engl J Med 2017; 377:352-360. DOI: 10.1056/NEJMoa1704174
Full prescribing information is available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/202379s024lbl.pdf.