A COST-EFFECTIVENESS EVALUATION OF IBRUTINIB FOR PATIENTS WITH RELAPSED CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IN BRITISH COLUMBIA, CANADA
Ongoing discoveries into the biology of chronic lymphocytic leukemia (CLL) have uncovered genomic alterations that are associated with poor survival outcomes. The drug ibrutinib (Imbruvica®; Janssen) offers an effective alternative to standard chemo-immunotherapy for patients with partial deletion of chromosome 17 (17p del); however, its relative cost-effectiveness for relapsed disease in British Columbia (BC) is unknown.
A Markov model was designed to evaluate the cost-effectiveness of offering single-agent ibrutinib compared to standard care in 2 scenarios: scenario-1, relapsed patients with 17p del only, and scenario 2, all relapsed patients.
We simulated a patient cohort transitioning between progression-free and relapsed disease health states, with an absorbing state of death. Time-dependent transitions and costs of care were calculated from a retrospective cohort of patients previously treated in BC. Transitions for ibrutinib-guided therapy were derived from published clinical trials, with costs taken from the literature. Incremental costs and life-years gained (LYG) accrued by patients over 5- and 15-year time horizons were calculated to determine the incremental cost-effectiveness ratio (ICER). Probabilistic sensitivity analysis was conducted on all model parameters.
Offering ibrutinib to 17p del patients (scenario-1) over a 5-year horizon was associated with higher mean costs ($133,490 vs. $55,333) and LYG (2.69 vs. 2.28) compared to standard care, at an ICER of $190,805/LYG (95% CI: $141,689-291,084). Over a 15-year time horizon, the ICER was $122,038/LYG (95% CI: $89,851-178,551).
Offering ibrutinib to all relapsed patients (scenario-2) over a 5-year time horizon resulted in increased mean costs ($297,377 vs. $54,750) and LYG (3.59 vs. 2.37) compared to standard care, at an ICER of $199,663/LYG (95% CI: $166,533-246,968). Over a 15-year time horizon, the ICER was $126,089/LYG (95% CI: $110,751-146,340).
The probability that either strategy is cost-effective at a given willingness-to-pay (WTP) threshold of $100,000 over a 15-year horizon is 10% for scenario-1, and <1% for scenario-2 (Fig.1).
Treatment of relapsed CLL patients in BC with ibrutinib may be cost-effective over a 15-year time horizon as gains in survival are realized. However, the cost-effectiveness of ibrutinib in a relapsed care setting can be improved. An area of current exploration is the impact on cost-effectiveness of using targeted gene sequencing to identify patients with resistance to, or need for, ibrutinib at the point of relapse.