Economic Evaluation of Duvelisib Versus Ofatumumab in Relapsed/Refractory CLL/SLL in Japan

OBJECTIVES: Duvelisib, a new Pl3K-d inhibitor, has been shown to have statistically significant PFS and ORR, but its cost-effectiveness is not necessarily clear. This study aimed to evaluate the cost-effectiveness of duvelisib comparing with ofatumumab for patients with relapsed and refractory CLL, SLL from the perspective of Japanese payers.

METHODS: A partitioned survival analysis model was developed to predict costs and quality-adjusted life years (QALYs) in duvelisib and ofatumumab group. Survival data were derived from the Phase-3 RCT (DUO trial). As duvelisib is currently unapproved in Japan, its drug price was estimated based on foreign prices. Cost parameters other than drug cost were estimated by using the JMDC claims database. Utilities were derived from previous studies. Lifetime horizon and discount rate of 2% was applied. The incremental cost-effectiveness ratio (ICER) of duvelisib compared with ofatumumab was estimated. Sensitivity analyses (SA) were performed to assess heterogeneity and parameter uncertainty.

RESULTS: Compared with ofatumumab, duvelisib incurred an additional cost of JPY27,828,733 and conferred an additional 0.21 QALY which results in an ICER of JPY132,006,375/QALY gained. SA showed that the parameters which most affected the ICER was the utility of duvelisib PD status, with ICER variation ranged from JPY67,944,472 to JPY2,310,095,413/QALY. Probabilistic SA estimated a 0% probability that duvelisib would be cost-effective when the ICER threshold was set at JPY15million/QALY.

CONCLUSIONS: Applying the threshold of JPY15 million/QALY, duvelisib was not cost-effective compared to ofatumumab. Under the Japan's public health insurance system, ofatumumab is preferable in terms of value for money.