Cost-Effectiveness Analysis of Tisagenlecleucel for the Treatment of Pediatric and Young Adult Patients with Relapsed or Refractory B Cell Acute Lymphoblastic Leukemia in Japan

Abstract

Until recently, treatment options were relatively limited for children and young adults with relapsed or refractory (r/r) acute lymphoblastic leukemia (ALL). Tisagenlecleucel is a chimeric antigen receptor T cell (CAR-T) immunotherapy with promising efficacy and manageable safety that was approved in Japan in 2019 for the treatment of CD19-positive r/r B cell ALL (B-ALL). However, there is no publication assessing the cost-effectiveness of CAR-T in Japan. The objective of this study was to assess the cost-effectiveness of a tisagenlecleucel treatment strategy compared to a blinatumomab treatment strategy and a clofarabine combination treatment strategy (i.e., clofarabine+cyclophosphamide+etoposide) in Japan for pediatric and young adult patients up to 25 years of age with r/r B-ALL. A partitioned survival model with a lifetime horizon and monthly cycle was constructed from a Japanese public healthcare payer's perspective. Patients were distributed across the following partitioned health states: event-free survival (EFS), progressive disease, and death, which were informed by the EFS and overall survival (OS) data of respective clinical trials before year 5. For the tisagenlecleucel arm, a decision-tree structure was used to partition patients based on the infusion status; those who discontinued prior to receiving infusion were assigned efficacy and cost inputs of blinatumomab and those who received infusion were assigned efficacy and costs inputs based on tisagenlecleucel-infused patients. As trial data for blinatumomab and clofarabine ended before year 5, matching-adjusted indirect comparisons were used to extrapolate OS between the end of trial observation and up to year 5. All surviving patients followed the mortality risk of long-term ALL survivors without additional risk of disease relapse after year 5, regardless of initial treatment strategies. The model accounted for pretreatment costs, treatment costs, adverse event costs, follow-up costs, subsequent allogeneic hematopoietic stem cell transplantation costs, and terminal care costs. Incremental cost-effectiveness ratios (ICERs) per life-years (LYs) gained and ICERs per quality-adjusted life-years (QALYs) gained were evaluated using a 2% discount rate, and a threshold of ¥7.5 million was used to assess cost-effectiveness. Deterministic and probabilistic sensitivity analyses were performed. The total LYs (discounted) for tisagenlecleucel, blinatumomab, and clofarabine combination treatment strategies were 13.3, 4.0, and 2.7 years, respectively; the corresponding QALYs were 11.6, 3.1, and 2.1 years, respectively. The ICERs per QALY gained for tisagenlecleucel were ¥2,035,071 versus blinatumomab and ¥2,644,702 versus clofarabine combination therapy. Extensive sensitivity analyses supported the findings. Tisagenlecleucel is a cost-effective treatment strategy for pediatric and young adult patients with r/r B-ALL from a Japanese public healthcare payer's perspective.