Carfilzomib combined with lenalidomide and dexamethasone (KRd) as salvage therapy for multiple myeloma patients: italian, multicenter, retrospective clinical experience with 600 cases outside of controlled clinical trials.

In combination with lenalidomide and dexamethasone (KRd), Carfilzomib has been approved for the treatment of relapsed and refractory multiple myeloma (RRMM) on ASPIRE trial. Efficacy and safety of the triplet are still the object of investigation by many groups to confirm ASPIRE results in the setting of RRMM treated in real-life who don't meet trial restrictive inclusion criteria. Therefore, we report a retrospective multicenter analysis of 600 RRMM patients treated with KRd between December 2015 and December 2018. The median age was 64 years (range 33-85), and the median number of previous therapies was two (range 1-11). After a median of 11 KRd cycles, the overall response rate was 79.9%. The median progression-free survival (PFS) was 22 months, and the 2-year probability of PFS was 47.6%. Creatinine clearance<30 ml/min, >1 line of previous therapy, and high-risk FISH were all associated with a poor prognosis in multivariate analysis. The median overall survival (OS) was 34.8 months; the 2-year probability of OS was 63.5%. At multivariate analysis, creatinine clearance<30 ml/min, >1 line of previous therapy, and high-risk FISH were significantly associated with poor prognosis. After a median follow-up of 16 months (range 1-50), 259 withdrew from therapy. The main discontinuation reason was progressive disease (81.8%). Seventy-four patients (12.3%) discontinued therapy for toxicity. The most frequent side effects were hematological (anemia 49.3%, neutropenia 42.7%, thrombocytopenia 42.5%) and cardiovascular (hypertension 14.5%, heart failure 2.5%, arrhythmias 3.6%). Our study confirms the safety and efficacy of KRd in the real-life setting of RRMM patients and encourages its use in clinical practice.

Carfilzomib, lenalidomide, and dexamethasone in relapsed/refractory multiple myeloma patients: the real-life experience of Rete Ematologica Pugliese (REP).

Carfilzomib, lenalidomide, and dexamethasone (KRd) have been approved for the treatment of relapsed and refractory multiple myeloma (RRMM) based on ASPIRE clinical trial. However, its effectiveness and safety profile in real clinical practice should be further assessed. We retrospectively evaluated 130 consecutive RRMM patients treated with KRd between December 2015 and August 2018, in 9 Hematology Departments of Rete Ematologica Pugliese (REP). The overall response rate (ORR) was 79%, with 37% complete response (CR). Treatment with KRd led to an improvement in response regardless of age, refractory disease, and number and type of previous therapies. After a median follow-up of 18 months, median PFS was 24 months and 2y-PFS was 54%. PFS was longer in patients achieving a very good partial response (VGPR) with median PFS of 32.4 months. The relapses after prior autologous transplant (ASCT) positively impact median PFS. Several baseline disease characteristics, such as III ISS scoring or elevated LDH, and prior exposure to lenalidomide were found to negatively impact PFS. Primary refractory or relapsed myeloma patients have been treated with KRd as bridge to ASCT with a great benefit. Thirty-four (83%) reached at least a partial response after KRd and 21 (61%) performed ASCT. In transplanted patients, median PFS was not reached and 2y-PFS was 100%. The treatment discontinuation rate due to adverse events (AEs) was 18%, most commonly for lenalidomide (11%). Overall, in 10% of patients, a KRd dose reduction was necessary at least once (2.5% for carfilzomib and 8% for lenalidomide). The most frequent AE was neutropenia (44%) and anemia (41%). Infections occurred in 14% of patients. Cardiovascular events occurred in 11% of patients. Elderly patients have tolerated therapy very well, without additional side effects compared to younger patients, except for cardiac impairment. Our analysis confirmed that KRd is effective in RRMM patients. It is well tolerated and applicable to the majority of patients outside clinical trials. A longer PFS was shown in patients achieving VGPR, in those lenalidomide naïve and in patients relapsing after previous ASCT. Previous ASCT should not hamper the option for KRd therapy. Accordingly, KRd should be used as bridge regimen to ASCT with remarkable improvement in response and PFS rates. Further clinical studies are needed.

Autologous stem cell transplantation in multiple myeloma.

The treatment of patients with multiple myeloma has changed in the last decades, with an improved median survival of 8-10 years. The current treatment for newly diagnosed multiple myeloma patients eligible for autologous transplantation consists of 4 phases: pretransplant, induction, transplant, post-transplant consolidation and maintenance. Even today, a long-term disease control is the goal of multiple myeloma treatment in current clinical practice. In this review we discuss the role of autologous stem cell transplantation in multiple myeloma, the eligibility of patients for transplantation and the usefulness of an upfront tandem transplantation. The assessment of frailty and significant comorbidities plays an important role in determining transplant eligibility. Careful patient selection based on overall health status is crucial to ensure a balance between risks and benefits. In the era of induction regimens with new agents, upfront autologous transplantation remains the standard of care for young patients with newly diagnosed multiple myeloma due to the longer progression-free survival showed in randomized clinical studies. With the currently available data, the tandem transplantation in multiple myeloma may be considered in patients with high-risk cytogenetics, in particular, those who did not receive a new triplet combination or those with a lower response than very good partial response following their first transplantation.

First-line therapy with either bortezomib-melphalan-prednisone or lenalidomide-dexamethasone followed by lenalidomide for transplant-ineligible multiple myeloma patients: a pooled analysis of two randomized trials.

Bortezomib-melphalan-prednisone (VMP) and continuous lenalidomide-dexamethasone (Rd) represent the standard treatment of transplant-ineligible patients with newly diagnosed multiple myeloma (MM). To date, no randomized trial has compared VMP to Rd, and there is no evidence of the optimal treatment for newly diagnosed MM, particularly in patients with high-risk cytogenetics [del(17p), t(4;14) or t(14;16)]. We pooled together data from patients with newly diagnosed MM treated with VMP or Rd induction followed by lenalidomide maintenance 10 mg (Rd-R) enrolled in the GIMEMA-MM-03-05 and EMN01 trials, to evaluate the efficacy of these treatments in different subgroups of patients, focusing on those with standard- and high-risk cytogenetics. Overall, 474 patients were analyzed (VMP: 257 patients; Rd-R: 217 patients). No differences in progression-free survival (hazard ratio=0.96) and overall survival (hazard ratio=1.08) were observed between standard-risk patients treated with VMP or Rd-R, whereas among the high-risk patients, the probabilities of progression (hazard ratio=0.54) and death (hazard ratio=0.73) were lower in the patients treated with VMP than in those treated with Rd-R. In particular, standard-risk patients >75 years benefited less from VMP than from Rd-R (hazard ratio for progression-free survival=0.96; hazard ratio for overall survival=1.81). In this non-randomized analysis, VMP and Rd-R were equally effective in younger (≤75 years), standard-risk patients, while older ones (>75 years) benefited more from Rd-R. In high-risk patients, VMP improved progression-free survival and overall survival irrespective of age. The source trials are registered at ClinicalTrials.gov (NCT01063179 and NCT01093196).

Prognostic or predictive value of circulating cytokines and angiogenic factors for initial treatment of multiple myeloma in the GIMEMA MM0305 randomized controlled trial.

BACKGROUND: Several new drugs are approved for treatment of patients with multiple myeloma (MM), but no validated biomarkers are available for the prediction of a clinical outcome. We aimed to establish whether pretreatment blood and bone marrow plasma concentrations of major cytokines and angiogenic factors (CAFs) of patients from a phase 3 trial of a MM treatment could have a prognostic and predictive value in terms of response to therapy and progression-free and overall survival and whether these patients could be stratified for their prognosis. METHODS: Blood and bone marrow plasma levels of Ang-2, FGF-2, HGF, VEGF, PDGF-ß, IL-8, TNF-α, TIMP-1, and TIMP-2 were determined at diagnosis in MM patients enrolled in the GIMEMA MM0305 randomized controlled trial by an enzyme-linked immunosorbent assay (ELISA). These levels were correlated both reciprocally and with the type of therapy and patients' characteristics and with a group of non-MM patients as controls. RESULTS: No significant differences were detected between the blood and bone marrow plasma levels of angiogenic cytokines. A cutoff for each CAF was established. The therapeutic response of patients with blood plasma levels of CAFs lower than the cutoff was better than the response of those with higher levels in terms of percentage of responding patients and quality of response. CONCLUSION: FGF-2, HGF, VEGF, and PDGF-ß plasma levels at diagnosis have predictive significance for response to treatment. The stratification of patients based on the levels of CAFs at diagnosis and their variations after therapy is useful to characterize different risk groups concerning outcome and response to therapy. TRIAL REGISTRATION: Clinical trial information can be found at the following link: NCT01063179.

Is re-challenge still an option as salvage therapy in multiple myeloma? The case of REal-life BOrtezomib re-Use as secoND treatment for relapsed patients exposed frontline to bortezomib-based therapies (the REBOUND Study).

Therapeutic re-challenge is currently a debated issue in the field of multiple myeloma (MM), given the recent availability of several new drugs and combinations. However, very few specific evidences are available about bortezomib re-use at first relapse. This multicenter, observational, retrospective study enrolled 134 MM patients with significant response after bortezomib-based frontline regimens and who had received a first salvage treatment containing bortezomib at relapse. The overall response rate was 71%, including 40% partial responses, 24% very good partial responses, and 7% complete responses. Re-treatment was well-tolerated, with no significant new or unexpected toxicities observed. The median duration of second progression-free survival (PFS) was 15 months, while median PFS2 was 55 months. With a median follow-up of 56 months, overall survival was 94 months for the entire series, without significant differences between patients undergoing or not undergoing transplant procedures. This real-life survey indicates that re-treatment including bortezomib as a first salvage therapy could be still considered in MM patients achieving durable response after initial exposure to bortezomib.

Minimal residual disease and log-reduction of plasma cells are associated with superior response after double autologous stem cell transplant in younger patients with multiple myeloma.

BACKGROUND: Optimization of chemotherapy regimens in the treatment of multiple myeloma (MM) has led to increase the frequency of cases with complete response (CR). Nonetheless, many MM patients still experience relapse, suggesting that CR represents a suboptimal response criteria, and that new therapeutic strategies are needed after single transplant. However, the role of double autologous stem cell transplant (ASCT) as new adjunctive strategy remains to be elucidated. Indeed, we investigated the role of minimal residual disease (MRD) and log-reduction of plasma cells (PCs) as predictors of outcome and in quantifying the degree of tumor reduction after any ASCT. METHODS: MRD and log-reduction were assessed by a six-color flow cytometry (FC) at different time-points: post induction, post first-, and post-second ASCT. RESULTS: A significant difference was evidenced among the three time points for both log-reduction (P < 0.001) and MRD (P = 0.005). MRD levels after double ASCT were lower than MRD levels achieved after single ASCT (P = 0.005) and after induction (P < 0.001). Frequency of MRD positive patients after double ASCT was significantly lower rather than after the first ASCT (P = 0.008) and after induction (P = 0.004). Interestingly, a significant reduction of PFS was observed in patients with an unfavorable-risk cytogenetic (P < 0.001) and patients with MRD over 0.01% (P = 0.001) as well as log-reduction lower than 2.57 (P = 0.018) after double ASCT. CONCLUSIONS: Our results show that a better clearance of myeloma cells is observed after the double ASCT, and a longer PFS is associated with a lower MRD. © 2018 International Clinical Cytometry Society.

Treatment Intensification With Autologous Stem Cell Transplantation and Lenalidomide Maintenance Improves Survival Outcomes of Patients With Newly Diagnosed Multiple Myeloma in Complete Response.

BACKGROUND: High-dose therapy with autologous stem cell transplantation (HDT-ASCT) and maintenance treatment with novel agents are the best options for patients with newly diagnosed multiple myeloma, increasing the rate of complete response (CR) and prolonging progression-free survival (PFS) and overall survival (OS). Indeed, the achievement of a CR is a predictor of long-term survival among transplant-eligible patients. However, it is unclear whether patients reaching a CR after induction treatment could receive less intense consolidation or avoid maintenance therapy. PATIENTS AND METHODS: We analyzed CR patients treated in 2 phase III trials, GIMEMA-RV-MM-PI-209 and RV-MM-EMN-441, to compare HDT-ASCT with an R-Alk (lenalidomide, alkylator) regimen as consolidation, and lenalidomide (R) maintenance with no maintenance. The primary endpoints were PFS, second PFS (PFS2), and OS from consolidation and maintenance (_m). RESULTS: Overall, the data from 166 patients in CR were analyzed, 95 in the HDT-ASCT group and 71 in the R-Alk group. The CR patients who received HDT-ASCT had a better PFS (hazard ratio [HR], 0.55; P = .01), PFS2 (HR, 0.46; P = .02), and OS (HR, 0.42; P = .03) compared with patients randomized to R-Alk. The survival benefit with HDT-ASCT was confirmed among all the subgroups, according to age, International Staging System (ISS stage, cytogenetic profile, and receipt of maintenance therapy. CR patients who received lenalidomide maintenance had a better PFS_m (4 years: 54% vs. 19%; HR, 0.43; P = .02) compared with those who received no maintenance. However, no difference was observed in terms of PFS2_m (4 years: 72% vs. 58%; HR, 0.83; P = .67) and OS_m (4 years: 79% vs. 72%; HR, 0.82; P = .73) with maintenance therapy. CONCLUSION: Even in CR patients, outcomes were improved by an intensified approach with HDT-ASCT consolidation and lenalidomide-based maintenance therapy.

Life for patients with myelofibrosis: the physical, emotional and financial impact, collected using narrative medicine-Results from the Italian 'Back to Life' project.

PURPOSE: Myelofibrosis (MF) is a chronic myeloproliferative neoplasm characterised by an aggressive clinical course, with disabling symptoms and reduced survival. Patients experience a severely impaired quality of life and their families face the upheaval of daily routines and high disease-related financial costs. The aim of this study was to investigate the perceptions of Italian patients and their caregivers about living with MF and the burden of illness associated with MF. METHODS: A quali-quantitative questionnaire and a prompted written narrative survey were administered to patients affected by primary or post-essential thrombocythemia/post-polycythaemia vera MF and their primary caregiver in 35 Italian haematological centres. RESULTS: In total, 287 questionnaires were returned by patients and 98 by caregivers, with 215 and 62, respectively, including the narrative. At the time of diagnosis, the most commonly expressed emotional states of patients were fear, distress and anger, confirming the difficulty of this phase. A high level of emotional distress was also reported by caregivers. Along the pathway of care, the ability to cope with the disease differed according to the quality of care received. The mean cost to each patient attributable to MF was estimated as €12,466 per year, with an estimated average annual cost of loss of income of €7774 per patient and €4692 per caregiver. CONCLUSIONS: Better understanding of the personal life of MF patients and their families could improve the relationships between health workers and patients, resulting in better focused healthcare pathways and more effective financial support to maintain patients in their social roles.

Ruxolitinib - better prognostic impact in low-intermediate 1 risk score: evaluation of the 'rete ematologica pugliese' (REP) in primary and secondary myelofibrosis.

We evaluated ruxolitinib in 65 patients with myelofibrosis according to age, sex, time of diagnosis, grade of fibrosis, prognostic score risk, Janus kinase (JAK) status, primary or secondary myelofibrosis, previous treatment, and dosage. Outcome measures were response rate, time to response, duration of response, and event-free survival and survival. Kaplan and Meier curves show a significant difference in event-free survival according to the prognostic score, in favor of patients with low int1 (p = 0.0009). The Cox stepwise model confirmed the result, the int2 high-risk score being the most powerful negative independent parameter (0.001), followed by JAK (0.008); other parameters, such as diagnosis more than 5 years earlier, grade III-IV fibrosis, and ruxolitinib dose have a negligible impact. Time to response was shorter (p = 0.001) in primary myelofibrosis. In conclusion, ruxolitinib is effective, with a better outcome in patients with a low-int1 risk score. This may suggest considering an earlier administration in the disease course.

Rotation of nilotinib and imatinib for first-line treatment of chronic phase chronic myeloid leukemia.

The introduction of second-generation tyrosine-kinase inhibitors (TKIs) has generated a lively debate on the choice of first-line TKI in chronic phase, chronic myeloid leukemia (CML). Despite the TKIs have different efficacy and toxicity profiles, the planned use of two TKIs has never been investigated. We report on a phase 2 study that was designed to evaluate efficacy and safety of a treatment alternating nilotinib and imatinib, in newly diagnosed BCR-ABL1 positive, chronic phase, CML patients. One hundred twenty-three patients were enrolled. Median age was 56 years. The probabilities of achieving a complete cytogenetic response, a major molecular response, and a deep molecular response (MR 4.0) by 2 years were 93%, 87%, and 61%, respectively. The 5-year overall survival and progression-free survival were 89%. Response rates and survival are in the range of those reported with nilotinib alone. Moreover, we observed a relatively low rate of cardiovascular adverse events (5%). These data show that the different efficacy and toxicity profiles of TKIs could be favorably exploited by alternating their use. Am. J. Hematol. 91:617-622, 2016. © 2016 Wiley Periodicals, Inc.

Triplet vs doublet lenalidomide-containing regimens for the treatment of elderly patients with newly diagnosed multiple myeloma.

Lenalidomide-dexamethasone improved outcome in newly diagnosed elderly multiple myeloma patients. We randomly assigned 662 patients who were age ≥65 years or transplantation-ineligible to receive induction with melphalan-prednisone-lenalidomide (MPR) or cyclophosphamide-prednisone-lenalidomide (CPR) or lenalidomide plus low-dose dexamethasone (Rd). The primary end point was progression-free survival (PFS) in triplet (MPR and CPR) vs doublet (Rd) lenalidomide-containing regimens. After a median follow-up of 39 months, the median PFS was 22 months for the triplet combinations and 21 months for the doublet (P = .284). The median overall survival (OS) was not reached in either arms, and the 4-year OS was 67% for the triplet and 58% for the doublet arms (P = .709). By considering the 3 treatment arms separately, no difference in outcome was detected among MPR, CPR, and Rd. The most common grade ≥3 toxicity was neutropenia: 64% in MPR, 29% in CPR, and 25% in Rd patients (P < .0001). Grade ≥3 nonhematologic toxicities were similar among arms and were mainly infections (6.5% to 11%), constitutional (3.5% to 9.5%), and cardiac (4.5% to 6%), with no difference among the arms. In conclusion, in the overall population, the alkylator-containing triplets MPR and CPR were not superior to the alkylator-free doublet Rd, which was associated with lower toxicity. This study was registered at www.clinicaltrials.gov as #NCT01093196.

Whole-exome sequencing of primary plasma cell leukemia discloses heterogeneous mutational patterns.

Primary plasma cell leukemia (pPCL) is a rare and aggressive form of plasma cell dyscrasia and may represent a valid model for high-risk multiple myeloma (MM). To provide novel information concerning the mutational profile of this disease, we performed the whole-exome sequencing of a prospective series of 12 pPCL cases included in a Phase II multicenter clinical trial and previously characterized at clinical and molecular levels. We identified 1, 928 coding somatic non-silent variants on 1, 643 genes, with a mean of 166 variants per sample, and only few variants and genes recurrent in two or more samples. An excess of C > T transitions and the presence of two main mutational signatures (related to APOBEC over-activity and aging) occurring in different translocation groups were observed. We identified 14 candidate cancer driver genes, mainly involved in cell-matrix adhesion, cell cycle, genome stability, RNA metabolism and protein folding. Furthermore, integration of mutation data with copy number alteration profiles evidenced biallelically disrupted genes with potential tumor suppressor functions. Globally, cadherin/Wnt signaling, extracellular matrix and cell cycle checkpoint resulted the most affected functional pathways. Sequencing results were finally combined with gene expression data to better elucidate the biological relevance of mutated genes. This study represents the first whole-exome sequencing screen of pPCL and evidenced a remarkable genetic heterogeneity of mutational patterns. This may provide a contribution to the comprehension of the pathogenetic mechanisms associated with this aggressive form of PC dyscrasia and potentially with high-risk MM.

Bortezomib-melphalan-prednisone-thalidomide followed by maintenance with bortezomib-thalidomide compared with bortezomib-melphalan-prednisone for initial treatment of multiple myeloma: updated follow-up and improved survival.

PURPOSE: Bortezomib-melphalan-prednisone (VMP) has improved overall survival in multiple myeloma. This randomized trial compared VMP plus thalidomide (VMPT) induction followed by bortezomib-thalidomide maintenance (VMPT-VT) with VMP in patients with newly diagnosed multiple myeloma. PATIENTS AND METHODS: We randomly assigned 511 patients who were not eligible for transplantation to receive VMPT-VT (nine 5-week cycles of VMPT followed by 2 years of VT maintenance) or VMP (nine 5-week cycles without maintenance). RESULTS: In the initial analysis with a median follow-up of 23 months, VMPT-VT improved complete response rate from 24% to 38% and 3-year progression-free-survival (PFS) from 41% to 56% compared with VMP. In this analysis, median follow-up was 54 months. The median PFS was significantly longer with VMPT-VT (35.3 months) than with VMP (24.8 months; hazard ratio [HR], 0.58; P < .001). The time to next therapy was 46.6 months in the VMPT-VT group and 27.8 months in the VMP group (HR, 0.52; P < .001). The 5-year overall survival (OS) was greater with VMPT-VT (61%) than with VMP (51%; HR, 0.70; P = .01). Survival from relapse was identical in both groups (HR, 0.92; P = .63). In the VMPT-VT group, the most frequent grade 3 to 4 adverse events included neutropenia (38%), thrombocytopenia (22%), peripheral neuropathy (11%), and cardiologic events (11%). All of these, except for thrombocytopenia, were significantly more frequent in the VMPT-VT patients. CONCLUSION: Bortezomib and thalidomide significantly improved OS in multiple myeloma patients not eligible for transplantation.

MET dysregulation is a hallmark of aggressive disease in multiple myeloma patients.

Abnormal activation of MET/HGF (Hepatocyte Growth Factor) pathway has been described in several tumours and increased HGF plasmatic levels have been detected in patients with aggressive multiple myeloma (MM). MET and HGF mRNA expression was investigated in 105 samples of purified plasma cells derived from newly diagnosed MM patients treated with bortezomib-based induction therapy. Gene expression was compared with response to therapy and clinical outcome. MET gene copy number was also evaluated. MET mRNA expression was higher in CD138(+) than in CD138(-) cells (median 76·90 vs. 11·24; P = 0·0009). Low MET mRNA expression characterized patients with better response (complete response or very good partial response) compared to other patients (median 56·10 vs. 134·83; P = 0·0006). After a median follow-up of 50 months, patients with high MET mRNA expression displayed a worse progression-free survival (PFS; P = 0·0029) and overall survival (OS; P = 0·0023) compared to those with low MET mRNA levels. Patients with both high MET mRNA expression and high ß2-microglobulin level (>5·5 mg/l) had further worse median PFS (P < 0·0001) and OS (P < 0·0001). Patients carrying 4 MET gene copies (8 out of 82, 9·8%) also had a short PFS. High MET mRNA expression identifies patients with dismal PFS and OS and the combination with high ß2-microglobulin further characterizes patients with worse outcome.

Biological and clinical relevance of miRNA expression signatures in primary plasma cell leukemia.

PURPOSE: Primary plasma cell leukemia (pPCL) is a rare and very aggressive form of plasma cell dyscrasia. To date, no information on microRNA (miRNA) expression in pPCL has been reported. This study aimed at investigating the involvement of miRNAs in pPCL and their possible relationship with higher tumor aggressiveness. EXPERIMENTAL DESIGN: Global miRNA expression profiles were analyzed in highly purified malignant plasma cells from 18 pPCL untreated patients included in a prospective clinical trial. MiRNA expression patterns were evaluated in comparison with a representative series of multiple myeloma patients, in relation to the most recurrent chromosomal abnormalities (as assessed by fluorescence in situ hybridization and single-nucleotide polymorphism-array analysis), and in association with clinical outcome. MiRNA expression was also integrated with gene expression profiles in pPCL and multiple myeloma samples. RESULTS: We identified a series of deregulated miRNAs in pPCL (42 upregulated and 41 downregulated) in comparison with multiple myeloma. Some of them, on the basis of their reported functions and putative target genes computed by integrative analysis, might have a role in the pathobiology of pPCL. As regards chromosomal aberrations, the expression of some miRNAs mapped to hotspot altered regions was associated with DNA copy number of the corresponding loci. Finally, 4 miRNA (miR-497, miR-106b, miR-181a*, and miR-181b) were identified as having expression levels that correlated with treatment response, and 4 (miR-92a, miR-330-3p, miR-22, and miR-146a) with clinical outcome. CONCLUSIONS: Overall, our study provides insights into the possible contribution of miRNAs in the pathogenesis of pPCL and suggests targets for future therapeutic investigations.

Transcriptional characterization of a prospective series of primary plasma cell leukemia revealed signatures associated with tumor progression and poorer outcome.

PURPOSE: Plasma cell leukemia (PCL) is a rare form of plasma cell dyscrasia that presents either as a progression of previously diagnosed multiple myeloma, namely secondary PCL, or as initial manifestation of disease, namely primary PCL (pPCL). Although the presenting signs and symptoms include those seen in multiple myeloma, pPCL is characterized by several aspects that define a more aggressive course. Here, we have investigated the transcriptome of pPCLs and correlated differential expression profiles with outcome to provide insights into the biology of the disease. EXPERIMENTAL DESIGN: The expression profiles of 21 newly diagnosed pPCLs included in a multicenter prospective clinical trial were generated using high-density microarray, then evaluated in comparison with a representative series of patients with multiple myeloma and in association with clinical outcome. RESULTS: All but one of the pPCLs had one of the main immunoglobulin heavy-chain locus translocations, whose associated transcriptional signatures resembled those observed in multiple myeloma. A 503-gene signature distinguished pPCL from multiple myeloma, from which emerged 26 genes whose expression trend was associated with progressive stages of plasma cells dyscrasia in a large dataset from multiple institutions, including samples from normal donors throughout PCL. Finally, 3 genes were identified as having expression levels that correlated with response to the first-line treatment with lenalidomide/dexamethasone, whereas a 27-gene signature was associated with overall survival independently of molecular alterations, hematologic parameters, and renal function. CONCLUSIONS: Overall, our data contribute to a fine dissection of pPCL and may provide novel insights into the molecular definition of patients with poorer prognosis.