Real-World Treatment Patterns in Patients with Castrate-Resistant Prostate Cancer and Bone Metastases.

BACKGROUND

Prostate cancer is the most frequently diagnosed cancer in men in the United States. There is scant real-world evidence characterizing the care utilization and clinical outcomes associated with the use of therapies currently approved by the US Food and Drug Administration (FDA) for patients with metastatic castrate-resistant prostate cancer (CRPC).

OBJECTIVE

To describe the real-world treatment patterns, healthcare costs, and survival rates of patients with metastatic CRPC and bone metastases who have commercial or Medicare coverage.

METHODS

This retrospective observational study was conducted using medical and pharmacy claims from the Humana research database for male patients who had Medicare or commercial coverage and were aged 55 to 89 years at the initiation of treatment for metastatic CRPC. Three inclusion criteria were used to identify appropriate patients for the 2 cohorts, including (1) a diagnosis of prostate cancer ( [] code 185.x); (2) a diagnosis of bone metastasis ( code 198.5) between 2013 and 2014; and (3) a healthcare insurance claim indicating a prescription for an FDA-approved first-line treatment for metastatic CRPC. Subsequent lines of treatment were also identified through the healthcare claims data. The 2-year survival rate was calculated and controlled for demographic and clinical characteristics, and the total costs (medical plus pharmacy) were calculated for the 6 months postindex.

RESULTS

A total of 1855 patients met the study inclusion criteria. Of these patients, 660 (35.6%) received at least 1 medication. The patient count by line of treatment was 660 (100%) who received first-line therapy, 380 (57.6%) who received second-line treatment, 204 (30.9%) who received third-line therapy, and 107 (16.2%) who received fourth-line therapy. The medication distribution by line of treatment (using first-, second-, third-, or fourth-line therapy for each drug) was abiraterone acetate (50.5%, 61.3%, 68.6%, 75.7%); enzalutamide (15.6%, 39.2%, 54.4%, 71.0%); sipuleucel-T (9.2%, 13.9%, 20.1%, 20.6%); radium-223 dichloride (1.7%, 2.6%, 7.4%, 13.1%); cabazitaxel (2.3%, 5.5%, 16.2%, 19.6%); and docetaxel (22.1%, 32.1%, 42.6%, 48.6%). The total monthly unadjusted healthcare costs for patients who received an FDA-approved treatment was much higher ($9435) than for patients with metastatic prostate cancer who did not receive an FDA-approved treatment ($5055), and the 2-year survival rate for patients who received an FDA-approved treatment was 57.1% (25th percentile, 250 days; 50th percentile, 541 days).

CONCLUSIONS

The most common first-line treatment for patients with commercial or Medicare coverage who had metastatic CRPC was abiraterone or enzalutamide. Hormone therapies used as monotherapy were the most frequently used treatment, and their concomitant administration with other treatments was the second most common treatment pattern. Additional clinical studies are needed to further elucidate the treatment sequencing for patients with metastatic CRPC.