OBJECTIVES : Inotuzumab ozogamicin (InO) is a novel therapy approved in Europe for relapsed or refractory acute lymphoblastic leukaemia (rrALL). It was associated with higher response rates, progression-free survival (PFS), overall survival (OS), and hematopoietic stem cell transplantation (HSCT) rates compared to treatment with standard of care (SoC) chemotherapy in the INO-VATE Phase III trial. An indirect treatment comparison (ITC) of InO versus blinatumomab (Blina) showed InO patients have higher odds of responding and reaching an HSCT compared to Blina. This study assesses the cost-effectiveness of InO versus SoC or Blina in rrALL in Philadelphia chromosome-negative (Ph-) rrALL for the Netherlands.

METHODS : A partitioned survival model with states defined based on treatment response, HSCT, progression, and death was developed. Parametric survival curves were used to extrapolate PFS and OS Kaplan-Meier trial data for InO and SoC. As response- and HSCT-stratified OS and PFS were not available for Blina, OS and PFS of InO and Blina were assumed to be equal within each health state and the treatments were differentiated based on response and HSCT rates from the ITC. Trial- and literature-based utilities and Dutch costs were included in the model. Discount rates of 4.0% and 1.5% were applied for costs and utilities.

RESULTS : The discounted results showed treating Ph- patients with InO produced 3.0 life years (LYs) and 2.2 quality-adjusted life years (QALYs) per patient versus SoC at a lifetime incremental cost of €102,138, an ICER of €46,946 per QALY. Versus Blina, InO was associated with a gain of 2.5 LYs and 1.8 QALYs at an incremental cost of -€15,562, a dominant ICER.

CONCLUSIONS : The ICERs of InO versus SoC and Blina were below the Dutch willingness to pay threshold of €80,000. Versus Blina, InO improved health benefits while reducing cost. Longer-term survival for blinatumomab would further inform the comparison.