Factors impacting stem cell mobilization failure rate and efficiency in multiple myeloma in the era of novel therapies: experience at Memorial Sloan Kettering Cancer Center.

Thalidomide, lenalidomide and bortezomib have increasingly been incorporated in first-line induction therapies for multiple myeloma. Concerns regarding the impact of these agents, especially lenalidomide, on stem cell mobilization prompted us to re-evaluate the risk factors that impact mobilization, including exposure to novel induction regimens. Among 317 patients who proceeded to stem cell collection after induction therapy between 2000 and 2009, the rate of mobilization failure, defined as the inability to collect 5 × 10(6) CD34+ cells/kg following the first collection attempt, was 13%. By multivariate analysis, independent risk factors associated with mobilization failure included older age (P=0.04), lower platelet count (P=0.002) and use of single-agent G-CSF for mobilization (P<0.0001). When considering for outcome measurement stem cell collection efficiency measured by the number of CD34+ cells yielded per pheresis performed during first collection attempt, lower platelet count, use of single-agent G-CSF and older age were also associated with lower efficiency. In this population mobilized mostly with cyclophosphamide and G-CSF, the use of lenalidomide during induction was not associated with a lower stem cell collection efficiency by multivariate analysis. The data support the current International Multiple Myeloma Working Group guidelines recommending the use of cyclophosphamide and G-CSF based mobilization for patients previously exposed to lenalidomide.

Patterns of relapse and progression in multiple myeloma patients after auto-SCT: implications for patients' monitoring after transplantation.

Auto-SCT (ASCT) is widely used in first-line treatment of multiple myeloma (MM). However, most patients eventually relapse or have progression of disease (R/POD). Although precise knowledge of R/POD patterns would be important to generate evidence-based surveillance recommendations after ASCT, such data is limited in the literature, especially after introduction of the free light chain assay (FLCA). This retrospective study examined the patterns of R/POD after first-line ASCT in 273 patients, using established criteria. At the time of R/POD, only 2% of patients had no associated serological evidence of R/POD. A total of 85% had asymptomatic R/POD, first detected by serological testing, whereas 15% had symptomatic R/POD with aggressive disease, early R/POD and short survival, with poor cytogenetics and younger age identified as risk factors. Although occult skeletal lesions were found in 40% of asymptomatic patients tested following serological R/POD, yearly skeletal surveys and urine testing were poor at heralding R/POD. We found a consistent association between paraprotein types at diagnosis and R/POD, allowing informed recommendations for appropriate serological monitoring and propose a new needed criterion using FLCA for patients relapsing by FLC only. Our findings provide important evidence-based recommendations that strengthen current monitoring guidelines after first-line ASCT in MM.