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Plerixafor, although costly, is added to mobilizing chemotherapy and G-CSF to overcome poor stem cell mobilization. We demonstrate that it can be safely administered mostly once as a single dose in preemptive and rescue settings, leading to apheresis yields of >2 and >4×10 CD34 + cells/kg body weight (bw) in 83% and 48%, respectively. Of note, 35/46 (76%) patients showed a substantial benefit with increased peripheral blood (PB) CD34 + cells prior to apheresis (8.84 vs. 1.72/μl, p < .001), and 5-fold increased CD34 + cells collected per single apheresis (2.25 vs. 0.43 × 10 CD34+/kg bw, respectively, p < .001). Patients profiting most (76%) vs. less (24%) had >5 vs. <5/μl PB CD34 + cells before plerixafor application, respectively, thus careful patient selection in the latter group is advised. To the best of our knowledge, this is the first report demonstrating that favorable apheresis results can be obtained using this cost-efficient, single fixed-dose plerixafor schedule.

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Patients often experience bone marrow examinations (BMEs) as frightening and painful. Varying operators and uncertainty about who will perform the BME worsen their anxiety. In our study, clinical nurse specialists (CNSs) were trained to perform BMEs to ensure continuity and to test the feasibility, patient satisfaction, and biopsy quality. This exploratory evaluation assessed 574 BMEs at our tertiary center between January 2012 and February 2013, 398 BMEs performed by CNS and 176 by physicians. Our aims were to determine whether BMEs by CNS yield results similar to those of physicians, analyzing (1) patient satisfaction with the BME (a) consent and (b) performance, (2) induced pain, and (3) quality of aspirates and length of trephine biopsies. When performed by CNS, 100 % of the patients were satisfied with the consent procedure and 99 % with the BME performance (physicians 99 and 91 %, respectively). The median pain score was low when both CNS and physicians performed the BME, with no or only mild pain in 92 and 76 % of patients, respectively. Bone marrow (BM) aspirates by CNS and physicians were assessed as technically evaluable in ~70 %; moreover, the median length of trephine biopsies was similar when performed by CNS or physicians with 12 and 13 mm, respectively. In conclusion, BMEs conducted by motivated CNS and within a structured training program are feasible and yield equal outcomes compared to physicians. The use of adequate pain management during BMEs by trained and experienced operators results in an extremely rare use of sedatives, low pain scores, and high patient satisfaction.

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Introduction: MM is characterized by the accumulation of aberrant BM plasma cells (aPCs). The use of novel agents for anti-MM treatment has enabled the achievement of deeper responses and prolonged progression free survival (PFS) and overall survival (OS). These advances have created the need for sensitive means to detect residual PCs. MFC allows aPC detection with high sensitivity and is used with NGS in clinical trials (CTs) (Paiva, 2015-2018). It allows the detection of residual cells after anti-MM therapies and is a risk denominator of pt subgroups and post-therapeutic outcome. The incorporation of cost-effective, readily available and standardized MRD tools into CTs and clinical practice seems a key requisite. It may allow the improvement of clinical decisions: 1) timing of stem cell transplantation (SCT), 2) need for consolidation, 3) duration of maintenance, 4) therapy modulations and 5) early relapse detection. Since MRD gains importance for novel agents' potency to achieve MRD negativity, including FDA/EMA-approvals, we assessed MFC for detection of aPCs, their change to treatment and over time. Methods: We systematically validated a 6-, 8- and 10-color panel using CD38, CD138, CD19, CD45, CD27, CD56, CD28, CD81, CD117, CD200 and kappa/lambda (k/l) in 9 different MM cell lines (MMCLs) and 213 BM, PB, leukapheresis (LA), extramedullary (EM) samples of 122 different MM pts and 14 healthy individuals (HI). These were immediately analyzed after sampling, using a bulk-lysis protocol. To reach a high sensitivity, >3x106 viable nucleated cells were analyzed. MFC validation included fluorescence-minus-one-(FMO), isotype- and spike-in-controls to evaluate the reliability and sensitivity of our panels. Spike-in controls were performed using a dilution assay to recover defined MMCL cells in the PB of HI. Data analysis was accomplished using the BeckmanCoulter software Kaluza®. We compared MFC using BM and PB samples of HI, MM pts at initial diagnosis (ID) or with progression (PD), after standard therapy (ST) and SCT. Additionally, BM samples at ID were sorted into each 4 aPC- and normal PC- (nPC) subpopulations for DNA and RNA sequencing and follow-up. The study was performed with written consent of all pts and HIs and approval of the ethics committee. Results: The antigen expression levels in 9 MMCLs using our 6-, 8- and 10-color panel could be confirmed as reported. The expression levels of antigens included in all panels were similar in all MMCLs (RPMI 8226; U266; IM-9; MM1.S; MM1.R; L363; Karpas620; NCI-H929; OPM-2). For all panels, we established easy to adapt gating strategies, using commercially available software to identify aPCs vs. nPCs in all analyzed samples. Using the 6-color panel, differentiation into up to 4 phenotypic subpopulations of aPCs and nPCs in MM pts and up to 4 subpopulations of nPCs in HI was achieved, depending on the heterogeneous phenotype the individual was expressing. Moreover, both DNA and RNA of obtained subpopulations were collected and analyzed via sequencing. Since in 1% of our samples, aPCs remained undetected via 6-color panel using surface antigens exclusively, we added k/l and did detect aPCs in all pts. The 10-color panel identified aPC- and nPC-subpopulations in even more detail. We determined a MRD sensitivity of 10-5, confirmed via independent dilution assays. In 48% of BM and PB samples, aPCs were determined at ID and PD; 52% were assessed for MRD after ST and SCT. Of the latter, 55% were BM samples, of which 5% showed MRD negativity of <0.001%. The median time from ST- or SCT-treatment to 1rst MRD evaluation was 44 days; this being assessed at subsequent time points currently. These data will be shown at the meeting. Conclusion: Our 6-, 8-, and 10-color panels allow highly sensitive detection of aPCs vs. nPCs in MM samples. These panels have been validated using various controls, dilution assays, 9 MMCLs, MM pt samples and HI and can be implemented into routine diagnostics. The analysis of DNA and RNA expression patterns in distinct subpopulations will generate relevant insight, which subclones contribute to response vs. resistance mechanisms. The EuroFlow Consortium have established a two 8-color tubes test for identification of aPCs, which - albeit used worldwide - may not be applicable for every center and every pt outside CTs. Therefore, meticulously validated alternatives as shown here are of interest. Our 8-color panel has been included into our CT portfolio. Disclosures Azab: Cellatrix LLC: Equity Ownership, Other: Founder and owner; Targeted Therapeutics LLC: Equity Ownership, Other: Founder and owner; Ach Oncology: Research Funding; Glycomimetics: Research Funding. Zeiser:Jazz Pharmaceuticals: Research Funding. Wäsch:Pfizer: Honoraria.

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