Obinutuzumab has recently been marketed in Spain for administration in combination with Clb (GClb) in adults with previously untreated CLL and with comorbidities which make them unsuitable for full-dose fludarabine-based therapy.9 Obinutuzumab is a recombinant monoclonal humanized anti-CD20 immunoglobulin G1 isotype type II antibody modified through glycoengineering; it targets the CD20 protein present in B-lymphocytes, inducing cell death.9 In 2012, obinutuzumab was granted orphan designation for the treatment of CLL by the Committee for Orphan Medicinal Products of the European Medicines Agency.10 The efficacy and safety of GClb was demonstrated in the CLL11 trial, which compared GClb with RClb or Clb monotherapy in 781 patients with previously untreated CLL for whom full-dose fludarabine-based therapy was contraindicated because of comorbidities.7
The objective of the present study was to evaluate the cost-effectiveness of treatment with GClb versus RClb in adults with previously untreated CLL and with comorbidities that make them unsuitable for full-dose fludarabine-based therapy, from the perspective of the Spanish National Health System (NHS).
A Markov model was developed with three mutually exclusive health states: progression-free survival (PFS) (with or without treatment), progression, and death (Figure 1). This was considered to be the most appropriate structure, which has been frequently used in the evaluation of cancer treatments, according to a systematic review of the medical and economic literature.11–14 Each health state was assigned a specific cost and utility value (patient-perceived quality of life).
The model simulated a cohort of CLL patients based on the CLL11 trial, who start in the PFS state and during the course of the simulation, they can either remain in the PFS state or transit toward the other states (progression or death). The PFS state separately considered patients “with treatment” and patients “without treatment” in order to account for differences in treatment administration both in economic terms and in patients’ quality of life during and after treatment.
It was assumed that transitions between the Markov states would occur every 7 days (model cycle length); accordingly, each 28-day GClb or RClb treatment cycle would comprise four cycles of the model. Patients received up to six treatment cycles, unless disease progression was previously confirmed or the treatment had to be discontinued because of toxicity, according to the CLL11 trial.7