Panobinostat Plus Bortezomib Versus Lenalidomide in Patients with Relapsed and/or Refractory Multiple Myeloma: A Matching-Adjusted Indirect Treatment Comparison of Survival Outcomes using Patient-level Data

Background In the UK, the standard of care for patients with multiple myeloma who received ≥2 prior treatments is lenalidomide plus dexamethasone (LEN + DEX) and pomalidomide plus DEX (POM + DEX) (in Wales only). Recently, panobinostat plus bortezomib and DEX (PAN + BTZ + DEX) was licensed in this setting. The current study assessed the progression-free survival (PFS) and overall survival (OS) outcomes with PAN + BTZ + DEX versus LEN + DEX (primary comparator) and POM + DEX (exploratory comparator). Methods Since an anchor-based indirect treatment comparison was not feasible, the matching-adjusted indirect treatment comparison approach was used. To compare the survival outcomes, patient-level data were generated for the comparators utilizing published Kaplan–Meier survival estimates. The use of approximated patient-level data and matched data for PAN + BTZ + DEX allowed the use of Cox proportional hazards models and the assessment of the proportional hazards assumption. In cases where there was evidence that the proportional hazards assumption was violated, time-dependent hazard ratios (HRs) were estimated. Median and mean values for PFS and OS were predicted. Results For both PFS and OS, the proportional hazards assumption was not satisfied, therefore time-dependent HRs were estimated. Using time-dependent HRs, the mean PFS was estimated to be 11.83 months for PAN + BTZ + DEX and 10.96 months for LEN + DEX. The corresponding mean OS estimates were 30.73 and 27.76 months, respectively. Comparisons with POM + DEX were affected by large uncertainty and did not allow making robust inferences. Conclusions To our knowledge, this is the first study that combined matching-adjusted indirect treatment comparison with time-dependent HRs to address changing patterns in the HR. The results suggest that treatment with PAN + BTZ + DEX and LEN + DEX are associated with similar mean PFS and OS in the third-line treatment setting of multiple myeloma.