Brentuximab Vedotin Plus CHP in Frontline sALCL: Adjusted Estimates of Efficacy and Cost-Effectiveness Removing the Effects of Re-Treatment with Brentuximab Vedotin

Background In the randomised controlled trial ECHELON-2 (NCT01777152; January 2013), brentuximab vedotin (BV) plus cyclophosphamide, doxorubicin and prednisone (CHP) demonstrated improved efficacy compared with CHOP (CHP and vincristine) in frontline CD30+ peripheral T-cell lymphoma (PTCL), an aggressive cancer with poor survival. In ECHELON-2, 70% of patients had systemic anaplastic large cell lymphoma (sALCL), a subtype of PTCL. Of sALCL patients who progressed from BV+CHP and CHOP, 36% ( n = 17) and 56% ( n = 36) received subsequent BV-containing therapy, respectively. As BV re-treatment was not funded in England at the time, our objective was to estimate adjusted efficacy and cost-effectiveness by excluding BV re-treatment from BV+CHP. Methods To remove the effects of BV re-treatment, the inverse probability of censoring weights (IPCW) and two-stage estimator (TSE) approaches, with and without re-censoring, were applied to overall survival (OS) in the BV+CHP arm of the ECHELON-2 sALCL population. Cost-effectiveness was determined in a three-state partitioned survival (PartSA) model from the perspective of the National Health Service (NHS) in England. Results The unadjusted hazard ratio (HR) for death in patients with sALCL with BV+CHP versus CHOP was 0.54 (95% CI 0.34, 0.87; p = 0.011). The model base case used TSE analysis without re-censoring, which provided an adjusted HR for death of 0.55 (95% CI 0.33, 0.86; p = 0.014). Incremental cost-effectiveness ratios (ICERs) including and excluding re-treatment with BV were £29,760/QALY and £27,761/QALY, respectively. Conclusion TSE without re-censoring provided the most clinically plausible estimate of survival whilst retaining sufficient information for OS extrapolation. After adjustment for BV re-treatment, BV+CHP remains an efficacious and cost-effective treatment in frontline sALCL compared with CHOP.