G-CSF utilization during abiraterone acetate (AA) and cabazitaxel (C) therapy: A retrospective U.S. claims analysis.

Abstract

205 Background: AA and C are two recently approved therapies shown to extend survival in men with metastatic castrate-resistant prostate cancer (mCRPC) progressing after docetaxel treatment. The toxicity profiles of AA and C differ, and therefore it was hypothesized that the utilization of concomitant medications and supportive care measures, in particular G-CSF for the treatment of neutropenia, would differ as well. Methods: The Pharmetrics database (2008 to Jan 2012), a nationally representative, nonpayer-owned, integrated, commercial U.S. claims database, was used for this analysis. Eligible patients included those identified with a diagnosis of prostate cancer (ICD 9 code 185.X or 233.4) and a claim for either AA or C (identified by the appropriate NDC or J codes). Use of G-CSF was analyzed during treatment (defined as the period between the first claim to the last claim, full months inclusive) and also analyzed for the year prior to the first claim of either AA or C (index date). Results: 278 patients were identified with a claim for both cohorts. Median ages of patients in the two cohorts were similar (69 years in the AA cohort, 67.5 years in the C cohort). Docetaxel use in the year prior to the index date was 57% and 64% in the AA and C cohorts, respectively. The median duration of follow-up post-index date was 2.6 months in the AA cohort and 6.0 months in the C cohort. While the median number of prescriptions (3) was the same for the AA and C cohorts, the mean was slightly higher for C (4.4 vs 3.3). In the AA cohort, the use of G-CSF was as follows: 35% in the year before the index date and 3% during treatment. In the C cohort, the use of G-CSF was as follows: 42% in the year before the index date, and 67% during treatment. Conclusions: Based on this claims analysis, patients who received C were more likely to receive concomitant G-CSF vs patients who were receiving AA. This finding is consistent with the known risks/precautions relating to neutropenia as described in the TROPIC study for C. Prior to treatment, both cohorts had G-CSF use, which may be attributed to neutropenia during or following docetaxel therapy.