Presentation Authors: Scott C. Flanders, Seattle, WA, Ben H. Lowentritt, Towson, MD, Jason M. Hafron, West Bloomfield, MI, Bruce A. Brown, Seattle, WA, David S. Morris*, Nashville, TN
Introduction: Clinicians may offer abiraterone plus prednisone (ABI), enzalutamide (ENZA), or sipuleucel-T (SIP-T) to patients with asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). The objective of this research was to indirectly compare the treatment effects between ABI, ENZA, and SIP-T using number needed to treat to benefit (NNTB). Per-treated-patient costs and cost per-responder are also calculated.
Methods: Defined as the reciprocal of the absolute risk reduction (ARR), NNTB is the average number of patients needed to be treated to prevent death in 1 additional patient compared to control. The analysis was based on primary data from 3 randomized controlled trials (COU-AA-302, IMPACT, and PREVAIL). The 12-mo and 24-mo ARR estimates and NNTB values were derived from published Kaplan-Meier curves for overall survival (OS). The total drug expenditures needed to achieve these incremental OS benefits (i.e., cost per NNTB) were calculated by multiplying the cost of the brand drug (2018 Medicare Part-B or Part-D drug price), times each NNTB value, and by the drug&[prime]s median duration of treatment. For SIP-T, drug costs were averaged over the 24-mo.
Results: The NNTB values to prevent 1 additional mCRPC patient death at 12-mo were estimated at: SIP-T = 12, ENZA = 15, and ABI = 100 (Table 1). At 24-mo, the NNTB values were estimated at: SIP-T = 10, ENZA = 12, and ABI = 16. Median treatment costs for each drug: SIP-T = $130,258, ENZA = $194,343, and ABI = $151,438. Total drug costs to obtain an additional patient alive at 12-mo was $1,563,099 for SIP-T; $2,107,332 for ENZA; and $13,168,560 for ABI. At 24-mo, drug costs for these NNTB outcomes ranged from $651,291 for SIP-T, $2,332,114 for ENZA, and $2,423,015 for ABI. SIP-T had $0 (zero) incremental costs in year-2 of treatment.
Conclusions: This NNTB analysis shows that the clinical benefit of OS in mCRPC patients treated with SIP-T compares favorably to ENZA and ABI over time. The estimated total drug cost to achieve an additional patient OS benefit is lower for SIP-T and declines over time compared to either ENZA or ABI, whose costs increase with continued therapy for similar clinical outcomes.
Source of Funding: Dendreon