OBJECTIVES: Multiple myeloma (MM) is the second most prevalent blood cancer in Canada. In patients who have undergone autologous stem cell transplant (ASCT); post-transplant maintenance therapy (MT) has been associated with substantial prolongation of progression-free survival. Consensus guidelines support the use of lenalidomide and bortezomib as post-transplant MTs, though these agents are supported by differing levels of clinical evidence. We sought to quantify and compare potential cost differences between two MTs, bortezomib and lenalidomide, in MM patients who have undergone ASCT. METHODS: The total annual drug cost of the two MT options were calculated. Costs were based on 1.3 mg/m of bortezomib every two weeks, or 10 mg of lenalidomide daily. The cost of administration including oncology nursing time and pharmacist workload was added to the acquisition cost of bortezomib. Pharmacy costs including a 10% markup and dispensing fees were added to the acquisition cost of lenalidomide. Unit and labour costs were obtained from public Canadian sources. Additional analyses were conducted to consider the impact of several variables including the management of adverse events, treatment duration and alternate costing assumptions. RESULTS: The total annual costs of treatment per patient were $32,560 and $144,976 for bortezomib and lenalidomide, respectively. The incremental differences were robust to changes in inputs and assumptions (to be presented in poster). CONCLUSIONS: In the absence of clear comparative clinical efficacy, the choice of MT may be influenced by patient characteristics as well as patient and physician preference. Taken together, the results of this analysis suggest that when comparing MTs, bortezomib is much less costly than lenalidomide and therefore there are important cost differences that should also be considered.