Citations

Key Points NK cells and their expression of FcRγIII (CD16) are decreased in MDS and inversely correlate with a substantial increase in MDSCs. CD16xCD33 BiKE potently activates blood and marrow MDS-NK cells at all diseases stages to lyse CD33+ MDS and CD33+ MDSC targets.

BACKGROUNDTwo randomized trials have demonstrated improved progression‐free survival (PFS) with lenalidomide maintenance after autologous transplantation for multiple myeloma (MM). Overall survival (OS) results are conflicting, and quality‐of‐life (QOL) data are lacking. The authors conducted a systematic survey of patients with MM regarding what constitutes a meaningful benefit that would make burdens of maintenance treatments (toxicity and cost) acceptable.METHODSA self‐administered survey was mailed to 1159 consecutive, living patients who were evaluated at Mayo Clinic. The survey provided background information on the standard of care for MM and data on maintenance. Patients were asked to estimate the magnitude of OS benefit that would be acceptable for various degrees of toxicity and cost.RESULTSOf 1159 surveys sent, 886 patients (83.2%) responded, and 736 patients returned a completed survey (66% raw response rate). The most worrisome potential toxicity was identified as peripheral neuropathy by 27% of patients, cytopenias by 24%, deep vein thrombosis by 20%, fatigue by 15%, nausea by 8%, and diarrhea/constipation by 7%. If treatment was free, had no toxicity, and the OS benefit was ≤1 year, then 49% of patients indicated that they would choose maintenance; with moderate toxicity, this proportion decreased to 42%. Adding a treatment cost of $25 per month decreased the proportion that would choose maintenance to 39% of patients.CONCLUSIONSThe current results indicated that willingness to receive maintenance treatment declined when actual benefits were provided in concrete numeric terms compared with a general statement of PFS benefit. The authors also observed that the magnitude of benefit required to consider maintenance was affected by cost and toxicity. Cancer 2013;119:4308–4315. © 2013 American Cancer Society.

Lenalidomide is the first karyotype-selective therapeutic approved for the treatment of myelodysplastic syndromes (MDS) owing to high rates of erythroid and cytogenetic response in patients with chromosome 5q deletion [del(5q)]. Although haploinsufficiency for the RPS14 gene and others encoded within the common deleted region (CDR) have been implicated in the pathogenesis of the del(5q) phenotype, the molecular basis of the karyotype specificity of lenalidomide remains unexplained. We focused our analysis on possible haplodeficient enzymatic targets encoded within the CDR that play key roles in cell-cycle regulation. We show that the dual specificity phosphatases, Cdc25C and PP2Acα, which are coregulators of the G 2 -M checkpoint, are inhibited by lenalidomide. Gene expression was lower in MDS and acute myeloid leukemia (AML) specimens with del(5q) compared with those with alternate karyotypes. Lenalidomide inhibited phosphatase activity either directly (Cdc25C) or indirectly (PP2A) with corresponding retention of inhibitory phospho-tyrosine residues. Treatment of del(5q) AML cells with lenalidomide induced G 2 arrest and apoptosis, whereas there was no effect in nondel(5q) AML cells. Small interfering RNA (shRNA) suppression of Cdc25C and PP2Ac α gene expression recapitulated del(5q) susceptibility to lenalidomide with induction of G 2 arrest and apoptosis in both U937 and primary nondel(5q) MDS cells. These data establish a role for allelic haplodeficiency of the lenalidomide inhibitable Cdc25C and PP2Acα phosphatases in the selective drug sensitivity of del(5q) MDS.