Under what circumstances do you consider double autologous stem cell transplants for patients with multiple myeloma?

I think younger patients who do not achieve a complete remission after first transplant should be offered a second transplant based on European data.

I agree. In addition, light chain disease and extramedullary manifestations can present with aggressive disease. However, in the right patient with aggressive disease, there are also other options to consider-including an allogeneic PBSCT or CAR-T on protocols.

Never. The data for tandem transplant shows a modest PFS but not an OS advantage. Indeed, OS maybe worse with tandem transplant. It’s hard to justify the toxicity of an additional transplant if there is no OS advantage.

Of note, recent data presented at ASCO 2020 from long-term follow up of the BMT CTN 0702 (STaMINA) trial suggested possible benefit with tandem autoSCT in high-risk myeloma patients, as defined by high B2MG and high-risk cytogenetics. (https://ascopubs.org/doi/abs/10.1200/JCO.2020.38.15_suppl.8506)