Real-world treatment patterns and overall survival among men with Metastatic Castration-Resistant Prostate Cancer (mCRPC) in the US Medicare population

Abstract

Background: Real-world treatment patterns and survival in metastatic castration-resistant prostate cancer (mCRPC) have not been characterized for the full fee-for-service Medicare population.

Methods: Men newly diagnosed with mCRPC were identified in Medicare fee-for-service claims during 1/1/2014-6/30/2019. Men had evidence of mCRPC and continuous insurance coverage ≥1 year before and ≥6 months after diagnosis unless patients died. Treatment patterns after diagnosis were described. Survival from mCRPC diagnosis and from start of first-line (1 L) therapy was modeled using Kaplan-Meier analysis.

Results: Among 14,780 men with mCRPC, mean age was 76 and median follow-up after mCRPC was 17.0 months. 22% received no life-prolonging therapy after mCRPC, 78% received ≥1 line of therapy (LOT), 42% underwent ≥2 LOTs, and 20% had ≥3 LOTs. Median time from start of 1 L to next LOT or end of follow-up was 13.7 months, 10.9 months from 2 L start, and 8.9 months from 3 L start. The most common 1 L to 2 L treatment sequences among men with ≥2 lines were NHT followed by a different NHT (33%), chemotherapy followed by NHT (14%), and NHT followed by chemotherapy (13%). For those initiating 1 L treatment with NHTs, only 28% received subsequent treatment with a different class of therapy. Median survival was 25.6 months after mCRPC and 23.4 months following treatment initiation.

Conclusions: More than 1 in 5 Medicare patients with mCRPC did not receive any life-prolonging therapy, and less than half received 2 L therapy. NHTs were the most common 1 L and 2 L therapies, with patients treated with NHT as 1 L followed by a different NHT for 2 L as the most common treatment sequence. Median survival from diagnosis for all patients was 25.6 months. These data highlight the dramatic undertreatment that occurs for mCRPC patients, particularly for therapies beyond NHTs as well as the common use of sequential NHTs in real-world data.

Fig. 1. Sample selection.

Evidence of castration resistance is based on any of the following: a ≥1 claim with a diagnosis code for hormone resistance (ICD-10-CM: Z19.2), b Surgical castration at any time AND ≥ 1 claim for rising prostate-specific antigen after (ICD-10-CM: R97.21), c Medication for mCRPC identifying castration resistance: (i) ≥1 claim for cabazitaxel, enzalutamide, mitoxantrone, radium-223, or sipuleucel-T; (ii) ≥1 claim for abiraterone acetate before June 2017 or initial claim for abiraterone acetate ≥90 days after initiation of ADT; or (iii) initial claim for docetaxel ≥90 days after initiation of ADT, d Initial metastatic diagnosis occurring ≥90 days after surgical castration, or e Initial metastatic diagnosis occurring after 90 days of medical castration episode (ending within 30 days of or after initial metastatic diagnosis).

Fig. 2. Proportion of patients receiving life-prolonging therapies for mCRPC by LOT.

The end of a LOT was defined as a treatment change or at least 90 days without treatment. If the LOT had not ended as of the data cut-off, patients were considered to have treatment ongoing. LOT: line of therapy; 1/2/3 L: 1^st/2^nd/3^rd LOT.

Fig. 3. Overall survival from mCRPC diagnosis.

CI: Confidence interval.