The use of single armed observational data to closing the gap in otherwise disconnected evidence networks: a network meta-analysis in multiple myeloma

BACKGROUND

Network meta-analysis (NMA) allows for the estimation of comparative effectiveness of treatments that have not been studied in head-to-head trials; however, relative treatment effects for all interventions can only be derived where available evidence forms a connected network. Head-to-head evidence is limited in many disease areas, regularly resulting in disconnected evidence structures where a large number of treatments are available. This is also the case in the evidence of treatments for relapsed or refractory multiple myeloma.

METHODS

Randomised controlled trials (RCTs) identified in a systematic literature review form two disconnected evidence networks. Standard Bayesian NMA models are fitted to obtain estimates of relative effects within each network. Observational evidence was identified to fill the evidence gap. Single armed trials are matched to act as each other's control group based on a distance metric derived from covariate information. Uncertainty resulting from including this evidence is incorporated by analysing the space of possible matches.

RESULTS

Twenty five randomised controlled trials form two disconnected evidence networks; 12 single armed observational studies are considered for bridging between the networks. Five matches are selected to bridge between the networks. While significant variation in the ranking is observed, daratumumab in combination with dexamethasone and either lenalidomide or bortezomib, as well as triple therapy of carfilzomib, ixazomib and elozumatab, in combination with lenalidomide and dexamethasone, show the highest effects on progression free survival, on average.

CONCLUSIONS

The analysis shows how observational data can be used to fill gaps in the existing networks of RCT evidence; allowing for the indirect comparison of a large number of treatments, which could not be compared otherwise. Additional uncertainty is accounted for by scenario analyses reducing the risk of over confidence in interpretation of results.

Ixazomib: A Review in Relapsed and/or Refractory Multiple Myeloma

The oral proteasome inhibitor ixazomib (Ninlaro^®) is approved in the USA, EU and Japan in combination with lenalidomide and dexamethasone, for the treatment of patients with multiple myeloma (MM) who have received at least one prior therapy. In adults with relapsed and/or refractory MM who had received one to three prior therapies, progression-free survival (PFS) was significantly prolonged in patients who received the ixazomib- versus placebo-based triple therapy in the pivotal, global TOURMALINE-MM1 trial and its regional expansion (China continuation study). A significantly longer time to progression and favourable hazard ratios for PFS were observed across all prespecified subgroups, including patients with high cytogenetic risk. Overall response was achieved in a significantly higher proportion of patients receiving ixazomib- than placebo-based treatment. Ixazomib had a manageable tolerability profile in patients with MM. Ixazomib is the first orally-administered proteasome inhibitor approved for patients with MM, and in combination with lenalidomide and dexamethasone represents an important new option for use in patients with relapsed and/or refractory MM who have previously received at least one prior therapy.