Taking abiraterone acetate (AA) with food may reverse PSA progression in some men with metastatic castration-resistant prostate cancer (mCRPC) who experience a rising PSA while on the medication, a new study suggests. It also may prolong time on AA therapy.
Researchers at Duke University in Durham, N.C., led by Andrew J. Armstrong, MD, retrospectively studied 60 mCRPC patients who experienced a rising PSA level while initially taking AA without food. Of these, 19 patients switched to taking AA with food and 41 continued to take the drug without food. The study’s primary outcome was the proportion of men who experienced any PSA decline within 3 months after changing AA administration from without food to with food.
Of the 19 men who took AA with food at PSA progression, 3 (16%) experienced a PSA decline as compared with PSA levels prior to the switch, Dr. Armstrong’s group reported online ahead of print in Prostate Cancer and Prostatic Disease. The researchers found that the men who switched to taking AA with food had a longer total median time on therapy than those who did not switch (272 vs. 177 days).
The investigators explained that taking AA with food may lead to the inhibition of additional enzymes in the androgen synthesis pathway implicated in CRPC progression.
“These results are promising and support that some patients may extend AA therapy by a median time of 2–4 months when changing administration from without food to with food in response to PSA progression, which may delay the transition to more toxic therapies,” the authors wrote.
Prior treatment with ketoconazole might have contributed to the low proportion of patients experiencing a PSA decline after switching to taking AA with food, according to the investigators. Ketoconazole has a mechanism of action similar to that of AA. Both medications block intratumoral androgen biosynthesis via CYP17 isoenzymes, they explained. In the new study, 7 (37%) of the 19 patients who switched to taking AA with food had received ketoconazole as a prior therapy, and none of these patients experienced a PSA decline, the researchers noted.