Autologous stem cell transplantation for multiple myeloma patients whose myeloma‐defining event was <scp>SLiM</scp>

In 2014, the International Myeloma Working Group (IMWG) updated the criteria for diagnosing myeloma and added three additional criteria to the traditional Calcium elevation, Renal impairment, Anemia, Bone disease (CRAB) criteria, called the Sixty % marrow plama cells, Light chain ratio >60, Mri demonstates lytic lesions (SLiM) criteria (clonal bone marrow plasma cells ≥60%, involved to uninvolved free light chain ratio (FLCr) ≥100 and >1 focal lesion on magnetic resonance imaging (MRI)). We report on the outcomes of 30 patients who underwent autologous stem cell transplantation (ASCT) where therapy was initiated solely based on SLiM criteria and compared them to a matched cohort of 60 patients whose myeloma-defining event was CRAB. The SLiM cohort had a shorter median time to neutrophil (15 vs. 16 days, p = 0.049) and platelet (15 vs. 17 days, p = 0.0004) engraftment. The 36-month overall survival (OS) was 100% in the SLiM group and 93.27% in the control group (95% CI 83.06%-97.42%), with a trend towards longer OS in the SLiM cohort (p = 0.065). The 36-month progression-free survival (PFS) was 91.61% in the SLiM (95% CI 69.93%-97.87%) and 65.95% in the control group (95% CI 52.31%-76.53%). There was no difference in the PFS between the cohorts (p = 0.414). ASCT is efficacious and safe in MM patients transplanted only due to SLIM criteria. Early intervention in this asymptomatic cohort did not appear to result in deeper responses or better PFS compared to outcomes in symptomatic patients.