- Prior treatment with bortezomib or other proteasome inhibitor is allowed, provided ALL of the following criteria are met: Disease is NOT refractory to any proteasome inhibitor, defined as no disease progression (i.e., PD, per IMWG or European Society for Blood and Marrow Transplantation [EBMT] criteria) while receiving proteasome inhibitor therapy or within 60 days after the last dose, AND best response achieved with any proteasome inhibitor therapy (alone or in combination) was at least a PR, AND participant did not discontinue any proteasome inhibitor due to intolerance or greater than or equal to Grade 3 related toxicity.