Urine immunofixation negativity is not necessary for complete response in intact immunoglobulin multiple myeloma: Retrospective real-world confirmation.

The definition of complete disease response (CR) in multiple myeloma (MM) continues to be reevaluated. The last widely accepted model of response assessment was proposed by the International Myeloma Working Group (IMWG) in 2016.1 Urine immunofixation (uIFE), one of the CR parameters, is being frequently omitted from CR evaluation in routine clinical practice. Patients with missing uIFE are then reported as having very good partial response (VGPR).2 It has been recently suggested in retrospective analysis by Lahuerta et al3 that patients with intact immunoglobulin myeloma (IIMM) who lack uIFE examination present with the very same prognosis as the patients with negative uIFE and therefore uIFE might not be necessary for CR definition in such patients.