Minimal residual disease status is the prognostic determinant following high-dose treatment for patients with multiple myeloma.

BACKGROUND: The presence of minimal residual disease (MRD+) following autologous stem cell transplantation (ASCT) in multiple myeloma represents a poor prognostic factor for progression-free survival (PFS) and overall survival (OS). METHODS: At our department, we recommend lenalidomide maintenance for patients who are MRD+ after ASCT, while MRD-negative (MRD-) patients, after information about the national guidelines, were not advised to follow this regimen. RESULTS: Out of the total 228 patients, 175 received ASCT following first-line induction (MRD- 92 (53%), MRD+ 83 (47%), at 2 months post-ASCT), while 53 underwent ASCT after second-line treatment (MRD- 27 (51%), MRD+ 26 (49%), at the same time point). Comparatively, MRD- patients who did not receive maintenance demonstrated better OS than MRD+ patients who received upfront ASCT and maintenance treatment (96% vs. 86%, p = 0.030, at 3 years). However, nonsignificant difference was found in PFS (76% vs. 62%, at 3 years). Furthermore, second-line ASCT, MRD- non-maintained patients exhibited significantly better PFS than MRD+ (71% vs. 27%, p > 0.001, at 3 years). However, OS was better but nonsignificant (96% vs. 76%, at 3 years). Fluorescence in situ hybridization (FISH) analysis was performed on 141 out of the 228 patients. Of these, 85 (60%) patients were deemed standard risk (SR), and 56 (40%) were classified as high risk (HR). In the SR cohort, MRD- patients exhibited better PFS and OS than MRD+ patients (71% vs. 59% and 100% vs. 85%, respectively). In the HR cohort, the MRD- patients showed superior PFS but similar OS compared to MRD+ patients (66% vs. 42% and 81% vs. 80%, respectively). CONCLUSIONS: Our results indicate that being MRD- is a more crucial prognostic factor for the 3-year PFS and OS than the presence of high-risk cytogenetic markers or undergoing maintenance treatment. The latter appears insufficient, particularly for MRD+ patients following ASCT in the second-line setting, suggesting that these patients may require a more intensive treatment approach.

Impact of newly diagnosed extramedullary myeloma on outcome after first autograft followed by maintenance: A CMWP-EBMT study.

BACKGROUND: No adequate data exist on the impact of multiple myeloma (MM) with extramedullary disease (EMD) after autograft and maintenance therapy. METHODS: We identified 808 patients with newly diagnosed MM who received first autograft, of whom 107 had EMD (83 paraskeletal and 24 organ involvement), and who had been reported to the EBMT registry December 2018. Distribution according to type of involvement was similar between the treatment groups (p = .69). For EMD, 46 (40%) received thalidomide, 59 (51%) lenalidomide, and 11 (10%) bortezomib. RESULTS: The median follow-up from maintenance start was 44 months. Three-year progression-free survival (PFS) was 52% (48%-57%) for no EMD, 56% (44%-69%) for paraskeletal involvement, and 45% (22%-68%) for organ involvement (p = .146). Early PFS (within first year) appeared to be significantly worse for organ involvement (hazard ratio, 3.40), while no significant influence was found after first year from maintenance start. Three-year overall survival (OS) was 81% (77%-84%), 88% (80%-96%), and 68% (47%-89%; p = .064), respectively. With thalidomide as reference, lenalidomide was significantly associated with better PFS and OS, whereas bortezomib appeared to improve outcome specifically in EMD. CONCLUSION: Lenalidomide maintenance is standard of care for MM without EMD, whereas extramedullary organ involvement remains a significant risk factor for worse outcome, especially for early events after maintenance start.

Challenges in αCD38-chimeric antigen receptor (CAR)-expressing natural killer (NK) cell-based immunotherapy in multiple myeloma: Harnessing the CD38dim phenotype of cytokine-stimulated NK cells as a strategy to prevent fratricide.

BACKGROUND AIMS: Adoptive cell therapy with chimeric antigen receptor (CAR)-expressing natural killer (NK) cells is an emerging approach that holds promise in multiple myeloma (MM). However, the generation of CAR-NK cells targeting CD38 is met with obstacles due to the expression of CD38 on NK cells. Knock-out of CD38 is currently explored as a strategy, although the consequences of the lack of CD38 expression with regards to engraftment and activity in the bone marrow microenvironment are not fully elucidated. Here, we present an alternative approach by harnessing the CD38dim phenotype occurring during long-term cytokine stimulation of primary NK cells. METHODS: Primary NK cells were expanded from peripheral blood mononuclear cells by long-term IL-2 stimulation. During expansion, the CD38 expression was monitored in order to identify a time point when introduction of a novel affinity-optimized αCD38-CAR confered optimal viability, i.e. prevented fratricide. CD38dim NK cells were trasduced with retroviral vectors encoding for the CAR trasngene and their functionality was assessed in in vitro activation and cytotoxicity assays. RESULTS: We verified the functionality of the αCD38-CAR-NK cells against CD38+ cell lines and primary MM cells. Importantly, we demonstrated that αCD38-CAR-NK cells derived from patients with MM have increased activity against autologous MM samples ex vivo. CONCLUSIONS: Overall, our results highlight that incorporation of a functional αCD38-CAR construct into a suitable NK-cell expansion and activation protocol results in a potent and feasible immunotherapeutic strategy for the treatment of patients with MM.

Generation of NK cells with chimeric-switch receptors to overcome PD1-mediated inhibition in cancer immunotherapy.

Multiple myeloma (MM) is an incurable hematological cancer, in which immune checkpoint inhibition (ICI) with monoclonal antibodies (mAbs) has failed due to uncontrollable immune responses in combination therapies and lack of efficacy in monotherapies. Although NK cell-specific checkpoint targets such as NKG2A and KIRs are currently being evaluated in clinical trials, the clinical impact of NK cells on the PD1 cascade is less well understood compared to T cells. Furthermore, while NK cells have effector activity within the TME, under continuous ligand exposure, NK cell dysfunctionality may occur due to interaction of PD1 and its ligand PD-L1. Due to above-mentioned factors, we designed novel NK cell specific PD1-based chimeric switch receptors (PD1-CSR) by employing signaling domains of DAP10, DAP12 and CD3ζ to revert NK cell inhibition and retarget ICI. PD1-CSR modified NK cells showed increased degranulation, cytokine secretion and cytotoxicity upon recognition of PD-L1+ target cells. Additionally, PD1-CSR+ NK cells infiltrated and killed tumor spheroids. While primary NK cells (pNK), expressing native PD1, showed decreased degranulation and cytokine production against PD-L1+ target cells by twofold, PD1-CSR+ pNK cells demonstrated increased activity upon PD-L1+ target cell recognition and enhanced antibody-dependent cellular cytotoxicity. PD1-CSR+ pNK cells from patients with MM increased degranulation and cytokine expression against autologous CD138+PD-L1+ malignant plasma cells. Taken together, the present results demonstrate that PD1-CSR+ NK cells enhance and sustain potent anti-tumor activity in a PD-L1+ microenvironment and thus represent a promising strategy to advance adoptive NK cell-based immunotherapies toward PD-L1+ cancers.

Conditioning with melphalan 200 mg/m2 and subsequent ASCT improves progression-free and overall survival in elderly myeloma patients compared to standard of care.

OBJECTIVES: Despite the effectiveness of newer drugs for the treatment of multiple myeloma (MM), the outcomes are further improved by subsequent autologous stem cell transplantation (ASCT). Data on effectiveness in older patients are limited. We compared outcomes in patients aged 65-75 years depending on whether they were treated with ASCT or not and compared those to outcomes in patients <65 years. METHODS: This was a retrospective, single-center study. We compared progression-free survival (PFS) and overall survival (OS) for all MM patients below and above the age of 65 years treated ± ASCT at the Karolinska University Hospital between 2010 and 2020. PFS and OS were calculated by the Kaplan-Meier method. Variables affecting PFS and OS were evaluated using Cox regression model. RESULTS: Both PFS and OS were improved in the group 65-75 years treated +ASCT compared to those treated pharmacologically (p = 0.008 and p < 0.001, respectively). There were no significant differences between patients <65 years and those 65-75 years treated with ASCT. CONCLUSION: The findings indicate that even patients >65 years should be evaluated as candidates for ASCT. An individualized approach supported by a frailty/geriatric assessment score could assist clinicians to select the appropriate treatment for each patient.

Injury severity and increased socioeconomic differences: A population-based cohort study.

BACKGROUND: Several studies have documented an inverse gradient between socioeconomic status (SES) and injury mortality, but the evidence is less consistent for injury morbidity. The aim of this study was to investigate the association between SES and injury severity for acute hospitalizations in a nationwide population-based cohort. METHODS: We conducted a registry-based cohort study of all individuals aged 25-64 years residing in Norway by 1st of January 2008. This cohort was followed from 2008 through 2014 using inpatient registrations for acute hospitalizations due to all-cause injuries. We derived two measures of severity: threat-to-life using the International Classification of Disease-based Injury Severity Score (ICISS), and threat of disability using long-term disability weights from the Injury-VIBES project. Robust Poisson regression models, with adjustment for age, sex, marital status, immigrant status, municipality population size and healthcare region of residence, were used to calculate incidence rate ratios (IRRs) by SES measured as an index of education, income, and occupation. RESULTS: We identified 177,663 individuals (7% of the population) hospitalized with at least one acute injury in the observation period. Two percent (n = 4,186) had injuries categorized with high threat-to-life, while one quarter (n = 43,530) had injuries with high threat of disability. The overall adjusted IRR of hospitalization among people with low compared to high SES was 1.57 (95% CI 1.55, 1.60). Comparing low to high SES, injuries with low threat-to-life were associated with an IRR of 1.56 (95% CI 1.54, 1.59), while injuries with high threat-to-life had an IRR of 2.25 (95% CI 2.03, 2.51). Comparing low to high SES, injuries with low, medium, and high threat of disability were associated with IRRs of respectively, 1.15 (95% CI 1.11, 1.19), 1.70 (95% CI 1.66, 1.73) and 1.99 (95% CI 1.92, 2.07). DISCUSSION: We observed an inverse gradient between SES and injury morbidity, with the steepest gradient for the most severe injuries. This suggests a need for targeted preventive measures to reduce the magnitude and burden of severe injuries for patients with low socioeconomic status.

Regional differences in treatment and outcome for myeloma patients in Sweden: A population based Swedish myeloma register study.

BACKGROUND: We wanted to evaluate if health care for multiple myeloma (MM) patients is equal in different regions of Sweden. AIM: To study differences in survival for MM depending on health care region and early use of modern treatment. METHODS AND RESULTS: Data from the Swedish Myeloma Register from patients diagnosed between 2008 and 2017 was used. Cohorts were defined by the six healthcare regions (labeled A-F) in Sweden and modern initial treatment was defined as including certain drug combinations. To adjust for time to treatment bias, survival analyses were performed also for patients alive 6 months after diagnosis. In all treated MM patients (n = 5326), we observed a superior overall survival (OS) for region A compared to all other regions (p < .01 for all respectively). After adjusting for time to treatment there was also a superior survival in the region with highest use of modern initial treatment (region A) compared to the regions defined in the study as having intermediate and low use (p < .01 for both). In patients receiving autologous stem cell transplantation (ASCT) a superior survival was observed for region A compared to all regions besides region B. Similar results were seen when adjusting for a time to treatment bias. In patients not receiving ASCT, 75 years or older and adjusted for time to treatment bias, a difference was noted only between region A and E (log rank p = .04, HR 1.2, CI 1.00-1.44, p = .06). In multivariate analyses including age, international staging system stage and time period of diagnosis, differences in survival remained for patients receiving ASCT between region A versus C, D, E and F (p = .01, p < .01, p < .01, p = .03). CONCLUSION: We observed a superior survival in region A for patients receiving ASCT. Explanations may be higher usage of modern initial treatment or regional residual confounding. For patients not receiving ASCT, 75 years or older, differences in survival could be adjusted for.

Autologous NK cells as consolidation therapy following stem cell transplantation in multiple myeloma.

Few approaches have been made toward exploring autologous NK cells in settings of cancer immunotherapy. Here, we demonstrate the feasibility of infusing multiple doses of ex vivo activated and expanded autologous NK cells in patients with multiple myeloma (MM) post-autologous stem cell transplantation. Infused NK cells were detected in circulation up to 4 weeks after the last infusion. Elevations in plasma granzyme B levels were observed following each consecutive NK cell infusion. Moreover, increased granzyme B levels were detected in bone marrow 4 weeks after the last infusion. All measurable patients had objective, detectable responses after NK cell infusions in terms of reduction in M-component and/or minimal residual disease. The present study demonstrates that autologous NK cell-based immunotherapy is feasible in a setting of MM consolidation therapy. It opens up the possibility for usage of autologous NK cells in clinical settings where patients are not readily eligible for allogeneic NK cell-based immunotherapies.

Accuracy of fatal occupational injury registration in a high-income country: A comparison of two-source capture-recapture estimates with the number of cases identified in four register systems in Norway, 2000-2003.

Background: Globally, work-related deaths (injuries and diseases) are a major social and public health problem. Register data on fatal occupational injuries in high-income countries may be considered to have high quality, especially when reporting is mandatory and regulated by law. We aimed to assess the accuracy of work-related injury death statistics in Norway, with reference to the Labour Inspection Authority and three other on-going registration systems (the cause-specific mortality register, the register for governmental compensations, and the register for insurance companies). Methods: In this register-based study, we used the capture-recapture technique to adjust for undercounting. We investigated whether the capture-recapture method using two or three sources gave a valid estimate of fatal occupational injuries as compared with the number of cases identified in four registers administrated by the Norwegian Labour Inspection Authority, Statistics Norway, the Labour and Welfare Administration, and Finance Norway. The inclusion criteria were fatal unintentional injuries among residents of Norway between 2000 and 2003 that occurred while working for income in private and public land-based industries. We obtained ethical and legal approvals. Results: In a period of four years (2000-2003), the Labour Inspection Authority registered 171 occupational injury deaths among residents employed in land-based industries. Two combinations of data sources gave capture-recapture estimates of 246 [95% CI 216; 279] and 265 [95% CI 234; 299] deaths. In total, 246 cases were identified in the four registration systems, which was 44% higher than the number of deaths registered by the Labour Inspection Authority. The Labour Inspection Authority had the most complete register out of the four registration systems. Conclusions: The capture-recapture method used on two overlapping data sources gave highly valid estimates of the total deaths. We demonstrated the existence of significant weaknesses in the registration systems in a country considered to have high-quality register data.

IgD Subtype But Not IgM or Non-Secretory Is a Prognostic Marker for Poor Survival Following Autologous Hematopoietic Cell Transplantation in Multiple Myeloma. Results From the EBMT CALM (Collaboration to Collect Autologous Transplant Outcomes in Lymphomas and Myeloma) Study.

BACKGROUND: The Collaboration to Collect Autologous Transplant Outcomes in Lymphoma and Myeloma (CALM) study has provided an opportunity to evaluate the real-world outcomes of patients with myeloma. The aim of this study was to compare the outcome according to the different subtypes of myeloma using CALM data. PATIENTS: This study compared overall survival (OS), progression-free survival (PFS), and complete remission (CR) and the impact of novel versus non-novel drug containing induction regimens prior to autologous hematopoietic cell transplantation (HCT) of 2802 patients with "usual" and "rare" myelomas. RESULTS: Our data suggest that IgM and non-secretory myeloma have superior PFS and OS compared with IgD myeloma and outcomes comparable to those for usual myeloma. Patients who received novel agent induction had higher rates of CR prior to transplant. Non-novel induction regimens were associated with inferior PFS but no difference in OS. Although not the primary focus of this study, we show that poor mobilization status is associated with reduced PFS and OS, but these differences disappear in multivariate analysis suggesting that poor mobilization status is a surrogate for other indicators of poor prognosis. CONCLUSION: We confirm that IgD myeloma is associated with the worst prognosis and inferior outcomes compared with the other isotypes.

Low dose venetoclax as a single agent treatment of plasma cell malignancies harboring t(11;14).

Approximately 20% of newly diagnosed multiple myeloma (NDMM) patients harbor t(11;14), a marker of inferior prognosis, resulting in up-regulation of CCND1. These patients respond to BCL2 inhibitor experimental drug venetoclax. Furthermore, t(11;14) is reported to be associated with increased BCL2/MCL1 ratio. We investigated the use of venetoclax (400 mg daily) in a cohort of 25 multiple myeloma (MM) and AL-amyloidosis patients harboring t(11;14) and assessed safety and efficacy. Efficacy was assessed by response rate (RR) and time on treatment. Furthermore, immunohistochemistry (IHC), for BCL2 family member expression was assessed at diagnosis and relapse in the venetoclax-treated group and analyzed for correlation with clinical RR. Additionally, patient material from venetoclax non-treated group including non-t(11;14) diagnosis (n = 27), t(11;14) diagnosis (n = 17), t(11;14) relapse (n = 7), hyperdiploidy (n = 6) and hyperdiploidy + t(11;14) (n = 6) was used for RNA sequencing (RNASeq) and validation by qPCR. Venetoclax treatment in t(11;14) patients demonstrated manageable safety and promising efficacy. Partial responses or better were observed in eleven patients (44%). Responding patients had significantly higher BCL2/MCL1 (p = 0.031) as well as BCL2/BCL-XL (p = 0.021) ratio, regardless of time of measurement before venetoclax treatment. Furthermore, an IRF5 motif was enriched (p < .001) in the downregulated genes in t(11;14) relapses vs diagnoses. The RR with single agent venetoclax was 71% in AL-amyloidosis and 33% in MM, and IHC proved useful in prediction of treatment outcome. We could also demonstrate possible resistance mechanisms of t(11;14), downregulation of IRF5 targeted genes, which can be exploited for therapeutic advantages.

Improved survival in multiple Myeloma patients undergoing autologous stem cell transplantation is entirely in the standard cytogenetic risk groups.

INTRODUCTION: Novel drugs and drug combinations have improved outcomes for multiple myeloma patients. However, subgroups of patients still have a poor progression-free survival (PFS) and overall survival (OS). In an attempt to identify how the novel drugs affect the outcome in standard-risk and high-risk patients, respectively, we have investigated 715 multiple myeloma (MM) patients who have undergone high dose treatment followed by autologous stem cell transplantation at our center during 1995 - 2020. Outcomes during three time periods, 1995-1999 (period I), 2000-2009 (period II), and 2010-2020 (period III), were compared separately for standard-risk and high-risk patients. Risk stratification was based on chromosome analysis for periods II and III. RESULTS: The whole cohort of patients showed significantly improved OS with time during the three periods being at a median of 5.8, 7.0, and 10.0 years, respectively. There is also a weak tendency for improved PFS, that is, a median of 2.4, 2.6, and 2.9 years, respectively, during the same periods. However, the separate analysis of standard-risk and high-risk patients showed that the overall improvement with time was due to improved standard-risk patients (median OS 8.4 years for the period I and not reached for period II and III). In contrast, no significant improvement was seen in high-risk patients. For patients with del17p, PFS was even worse during period III as compared to period II (median 1.6 vs 3.2 years respectively). CONCLUSION: Our results show that the dramatic improvement in outcome for MM patients during the last 20 years only applies for standard-risk patients, while high-risk MM patients still are doing poorly, indicating that the novel drugs developed during this time are preferentially effective in standard-risk patients. New treatment modalities like CAR-T cells, CAR-NK cells, and/or bispecific antibodies should be tried in clinical studies early in the course of the disease, especially in patients with high-risk cytogenetics.

Incidence of injuries in Norway: linking primary and secondary care data.

Aims: Most studies of injury incidence underestimate the total burden of injury, as they do not include injuries treated in primary care. The aim of this study was to measure the total incidence of medically treated injuries in Norway. We further investigated the epidemiology of injuries treated in primary and secondary care. Methods: We collected individual-level data on injury diagnoses from the Norwegian Patient Registry and the national registry dataset for reimbursement of primary care providers for the period 2009-2014, and estimated the annual incidence of patients registered with an injury diagnosis in either or both of these registries. We also converted ICD-10 codes in secondary care into ICPC-2 codes to compare the types of injuries treated in primary and secondary care. Results: The annual incidence of medically treated injuries in Norway was 125 patients per 1000 inhabitants. Fifty-five per cent of injured patients received treatment exclusively in primary care. We observed stable time trends over the six-year period. Incidence rates were higher in primary care for the youngest children and in middle adulthood, but were higher in secondary care for older people. Overall, injury incidence was higher for men, but women became more injury prone with age. We only observed this gender reversal in secondary care. With the exception of fractures, all injury types were predominantly treated in primary care. Conclusions: A substantial proportion of injured patients in Norway are treated exclusively in primary care. The demographic profile of these patients differs from those treated in secondary care.

Upfront bortezomib, lenalidomide, and dexamethasone compared to bortezomib, cyclophosphamide, and dexamethasone in multiple myeloma.

OBJECTIVES: At our center, patients with multiple myeloma (MM) were treated upfront with bortezomib, cyclophosphamide, and dexamethasone (VCD) until cyclophosphamide was replaced with lenalidomide in the combination (VRD). These treatments have never been compared head-to-head in large real-life patient material. METHOD: A retrospective analysis of patients treated with VRD and VCD in the first line, both with and without subsequent high-dose treatment (HDT) and autologous stem cell transplantation. A total of 681 patients were included, 117 receiving VRD (71 with, 46 without HDT) and 564 receiving VCD (351 with, 213 without HDT). RESULTS: Overall response rate (≥partial response) was higher with VRD compared to VCD in the entire VRD group (98% vs 88%, P < 0.001) and in the non-HDT group (98% vs 79%, P < 0.001). Progression-free survival (PFS) at 18 months was longer with VRD compared to VCD in the entire VRD group, the non-HDT group and the HDT group (88% vs 63%, 82% vs 32% and 91% vs 73%, respectively). Overall survival at 18 months was better for VRD-treated patients in the entire VRD group (95% vs 89%, P = 0.048). CONCLUSION: Upfront VRD gives better responses and longer PFS compared to VCD in MM patients with or without subsequent HDT.

Infectious complications and NK cell depletion following daratumumab treatment of Multiple Myeloma.

Treatment with Daratumumab (Dara), a monoclonal anti-CD38 antibody of IgG1 subtype, is effective in patients with multiple myeloma (MM). However, Dara also impairs the cellular immunity, which in turn may lead to higher susceptibility to infections. The exact link between immune impairment and infectious complications is unclear. In this study, we report that nine out of 23 patients (39%) with progressive MM had infectious complications after Dara treatment. Five of these patients had viral infections, two developed with bacterial infections and two with both bacterial and viral infections. Two of the viral infections were exogenous, i.e. acute respiratory syncytial virus (RSV) and human metapneumovirus (hMPV), while five consisted of reactivations, i.e. one herpes simplex (HSV), 1 varicella-zoster (VZV) and three cytomegalovirus (CMV). Infections were solely seen in patients with partial response or worse. Assessment of circulating lymphocytes indicated a selective depletion of NK cells and viral reactivation after Dara treatment, however this finding does not exclude the multiple components of viral immune-surveillance that may get disabled during this monoclonal treatment in this patient cohort. These results suggest that the use of antiviral and antibacterial prophylaxis and screening of the patients should be considered.

A Pilot, Exploratory, Randomized, Phase II Safety Study Evaluating Tumor Cell Mobilization and Apheresis Product Contamination in Patients Treated with Granulocyte Colony-Stimulating Factor Alone or Plus Plerixafor.

Because of the potential risk of tumor cell mobilization with granulocyte colony-stimulating factor (G-CSF), it is crucial to evaluate any potential effect of plerixafor treatment in the presence of G-CSF on multiple myeloma (MM) cell mobilization. This was an open-label, multicenter, randomized, exploratory, safety study (NCT01753453) that investigated the extent of MM cell mobilization after treatment with G-CSF + plerixafor in patients who were deemed poor mobilizers of hematopoietic stem cells. The primary efficacy outcome was the number of MM cells in peripheral blood and apheresis product after G-CSF + plerixafor treatment versus G-CSF alone. Key secondary efficacy outcomes included overall survival and disease status up to 2 years after the first G-CSF dose. Twenty patients were randomized and received at least 1 dose of study treatment. There were no patients with MM cells in peripheral blood up to day 8 G-CSF administration in either treatment group. Up to day 8 no patient in the G-CSF + plerixafor arm and only 1 patient in the G-CSF arm mobilized at least 4.5 × 105 MM cells in the apheresis product. Nine of 10 patients from each treatment arm proceeded to transplantation. MM cells were detected in 5 patients from each treatment arm before and after transplantation. Adverse events observed in the G-CSF + plerixafor arm were consistent with the known safety profile of plerixafor. No MM cells were detected in peripheral blood of either treatment group up to day 8 of mobilization. Only 1 patient in the G-CSF alone group mobilized at least 4.5 × 105 MM tumor cells in apheresis product up to day 8. However, 50% of patients in both treatment arms had detectable amounts of MM cells in their peripheral blood pre- and post-transplantation. There were no new safety concerns with plerixafor.