On August 13, 2013 I wrote an important post about the terrible practice beginning to rear its head called step therapy. Step therapy is the practice of insurance companies requiring less expensive drugs be prescribed prior to more expensive ones despite the comparative efficacy of the drugs and their different mechanisms of action. This practice allows insurance companies to prescribe what medications we are given despite the medical opinion of our doctors.
The specific situation I described in the August 13th post spoke specifically about some insurance company’s current practice of requiring Zytiga (Abiraterone Acetate) prior to Xtandi (Enzalutamide) despite the recommendation of our doctor’s best medical judgment.
A recent but small study (size being one of the major limiting factors of this study) was released in the Journal European Urology that examined the sequencing of Zytiga before Xtandi. For 35% of the men the sequencing made their eventual treatment with Xtandi ineffectual!
In the study thirty-five patients were identified as having received sequential therapy with abiraterone followed by enzalutamide. All patients had undergone prior docetaxel chemotherapy, and no patient had received ketoconazole.
The researchers used post treatment changes in prostate-specific antigen (PSA) we to determine the activity of enzalutamide in the men who had received prior abiraterone.
The median duration of abiraterone treatment was 9.0 month (range: 2.0–19.0 month).
Of the 35 patients, 16 (45.7%) achieved a >50% decline in PSA, and 14 (40%) had a rising PSA as the best response.
The median duration of subsequent enzalutamide treatment was 4.9 month (Kaplan-Meier estimate; 95% confidence interval