Introduction:

Six products approved for first-line treatment of mCRPC have been available in the U.S. since 2012 including abiraterone acetate plus prednisone, cabazitaxel, docetaxel, enzalutamide, radium-223 and sipuleucel-T. Given the evolving treatment landscape for patients with metastatic prostate cancer, we sought to examine patterns of first-line mCRPC treatments utilizing a Medicare Fee for Service (FFS) claims database of over 40 million patients.

Methods:

Using the 2013-2017 Medicare FFS 100% Part A, B and D Identifiable Research data, we identified all Medicare beneficiaries having Part A, B and D eligibility and no HMO enrollment in all months through 2017 or until death. For each calendar year, we identified patients with prostate cancer as men having 1+ qualifying claim coded with prostate cancer (ICD-9 185, ICD-10 C-61) in any position of the claim. Men with treatment naïve mCRPC were defined as individuals not having received a mCRPC approved therapy 12 months prior to their first mCRPC therapy during each indexed year. Utilization of mCRPC approved drug therapies was identified using HCPCS codes for infused products and NDC codes for oral products. Patients were grouped into cohorts based on first-line mCRPC treatment utilized and followed for 12 months after their index date. The index date was defined as the first mCRPC approved therapy claim in each indexed year.  The proportion of patients receiving a first-line treatment without a subsequent second-line treatment within 1-year of the initial treatment index date was described.

Results:

The proportion of prostate cancer men receiving an approved mCRPC drug therapy during each year remained relatively constant over the four year period at 3.2%-3.6%; the proportion receiving first-line therapy fell slightly between 2014 and 2017 (47.4% to 44.6%). Abiraterone had the highest utilization in all years except 2016, enzalutamide had the highest use in 2016 and second highest for all other years evaluated. In order of decreasing use across years, the remaining products were docetaxel followed by sipuleucel-T, radium-223 and cabazitaxel (Table 1). A proportion of mCRPC men were treated with combination therapy; however, sample sizes fell below CMS suppression requirements. Table 2 shows the proportion of patients having received first-line with no subsequent second-line mCRPC therapy within 1 year. Patterns of use of abiraterone and enzalutamide as first-line treatments were relatively constant during 2014-2016. For mCRPC men using abiraterone and enzalutamide as a first-line treatment, the proportion not having second line therapy within 1-year of the index date remained consistent from 2014-2016, increasing at 0.9% and 2.2%, respectively. Over this same time period, the proportion of docetaxel and cabazitaxel first-line use with no second-line therapy rose +8.7% and +6.9% respectively. Utilization of sipuleucel-T in first-line without receiving a second-line therapy rose +15.3% from 26.0% (2014) to 41.3% (2016). Finally, the proportion of men receiving first-line radium-223 treatment with no second-line treatment within one year of index fell by -3.2% (2015-2016).  Use of docetaxel and abiraterone may be overreported given these may be used in castration-sensitive prostate cancer.

Conclusion:

The proportion of prostate cancer men receiving an approved mCRPC drug therapy during each year remained relatively constant over the four year period at 3.2%-3.6%; the proportion receiving first-line therapy fell slightly between 2014 and 2017 (47.4% to 44.6%). Abiraterone had the highest utilization in all years except 2016, enzalutamide had the highest use in 2016 and second highest for all other years evaluated. In order of decreasing use across years, the remaining products were docetaxel followed by sipuleucel-T, radium-223 and cabazitaxel (Table 1).  A proportion of mCRPC men were treated with combination therapy; however, samples sizes fell below CMS suppression requirements. Table 2 shows the proportion of patients having received first-line with no subsequent second-line mCRPC therapy within 1 year. Patterns of use of abiraterone and enzalutamide as first-line treatments were relatively constant during 2014-2016. For mCRPC men using abiraterone and enzalutamide as a first-line treatment, the proportion not having second line therapy within 1-year of the index date remained consistent from 2014-2016, increasing at 0.9% and 2.2%, respectively. Over this same time period, the proportion of docetaxel and cabazitaxel first-line use with no second-line therapy rose +8.7% and +6.9% respectively. Utilization of sipuleucel-T in first-line, without receiving a second-line therapy, rose +15.3% from 26.0% (2014) to 41.3% (2016).  Finally, the proportion of men receiving first-line radium-223 treatment with no second-line treatment within one year of index fell by -3.2% (2015-2016).  Use of docetaxel and abiraterone may be overreported given these may be used in castration-sensitive prostate cancer.

Funding: Medical Affairs, Dendreon Pharmaceuticals, LLC