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Proteasome inhibitors (PI) are extensively used for the therapy of multiple myeloma (MM) and mantle cell lymphoma. However, patients continuously relapse or are intrinsically resistant to this class of drugs. Here, to identify targets that synergize with PI, we carried out a functional screening in MM cell lines using a short hairpin RNA library against cancer driver genes. Isocitrate dehydrogenase 2 (IDH2) was identified as a top candidate, showing a synthetic lethal activity with the PI carfilzomib (CFZ). Combinations of US Food and Drug Administration–approved PI with a pharmacological IDH2 inhibitor (AGI-6780) triggered synergistic cytotoxicity in MM, mantle cell lymphoma, and Burkitt lymphoma cell lines. CFZ/AGI-6780 treatment increased death of primary CD138+ cells from MM patients and exhibited a favorable cytotoxicity profile toward peripheral blood mononuclear cells and bone marrow–derived stromal cells. Mechanistically, the CFZ/AGI-6780 combination significantly decreased tricarboxylic acid cycle activity and adenosine triphosphate levels as a consequence of enhanced IDH2 enzymatic inhibition. Specifically, CFZ treatment reduced the expression of nicotinamide phosphoribosyltransferase (NAMPT), thus limiting IDH2 activation through the NAD+-dependent deacetylase SIRT3. Consistently, combination of CFZ with either NAMPT or SIRT3 inhibitors impaired IDH2 activity and increased MM cell death. Finally, inducible IDH2 knockdown enhanced the therapeutic efficacy of CFZ in a subcutaneous xenograft model of MM, resulting in inhibition of tumor progression and extended survival. Taken together, these findings indicate that NAMPT/SIRT3/IDH2 pathway inhibition enhances the therapeutic efficacy of PI, thus providing compelling evidence for treatments with lower and less toxic doses and broadening the application of PI to other malignancies.

Proteasome inhibitors (PI) are extensively used for the therapy of multiple myeloma (MM) and mantle cell lymphoma. However, patients continuously relapse or are intrinsically resistant to this class of drugs. Here, to identify targets that synergize with PI, we carried out a functional screening in MM cell lines using a short hairpin RNA library against cancer driver genes. Isocitrate dehydrogenase 2 (IDH2)was identified as a top candidate, showing a synthetic lethal activity with the PI carfilzomib (CFZ). Combinations of US Food and Drug Administration–approved PI with a pharmacological IDH2 inhibitor (AGI-6780) triggered synergistic cytotoxicity in MM, mantle cell lymphoma, and Burkitt lymphoma cell lines. CFZ/AGI-6780 treatment increased death of primary CD138+cells from MM patients and exhibited a favorable cytotoxicity profile toward peripheral blood mononuclear cells and bone marrow–derived stromal cells. Mechanistically, the CFZ/AGI-6780 combination significantly decreased tricarboxylic acid cycle activity and adenosine triphosphate levels as a consequence of enhanced IDH2 enzymatic inhibition. Specifically, CFZ treatment reduced the expression of nicotinamide phosphoribosyltransferase (NAMPT), thus limiting IDH2 activation through the NAD+-dependent deacetylase SIRT3. Consistently, combination of CFZ with either NAMPT or SIRT3 inhibitors impaired IDH2 activity and increased MM cell death. Finally, inducible IDH2 knockdown enhanced the therapeutic efficacy of CFZ in a subcutaneous xenograft model of MM, resulting in inhibition of tumor progression and extended survival. Taken together, these findings indicate that NAMPT/SIRT3/IDH2 pathway inhibition enhances the therapeutic efficacy of PI, thus providing compelling evidence for treatments with lower and less toxic doses and broadening the application of PI to other malignancies.

Real-time quantitative PCR (qPCR) is a well-established tool for minimal residual disease (MRD) detection in mature lymphoid malignancies. Despite remarkable sensitivity and specificity, qPCR has some limitations, particularly in the need for a reference standard curve, based on target serial dilutions. In this study, we established droplet digital PCR (ddPCR) for MRD monitoring in multiple myeloma, mantle cell lymphoma, and follicular lymphoma and compared it head-to-head with qPCR. We observed that ddPCR has sensitivity, accuracy, and reproducibility comparable with qPCR. We then compared the two approaches in 69 patients with a documented molecular marker at diagnosis (18 multiple myelomas, 21 mantle cell lymphomas assessed with the immunoglobulin gene rearrangement, and 30 follicular lymphomas with the use of the BCL2/immunoglobulin gene major breakpoint region rearrangement). ddPCR was successful in 100% of cases, whereas qPCR failed to provide a reliable standard curve in three patients. Overall, 222 of 225 samples were evaluable by both methods. The comparison highlighted a good concordance (r = 0.94, P < 0.0001) with 189 of 222 samples (85.1%; 95% CI, 80.4%–89.8%) being fully concordant. We found that ddPCR is a reliable tool for MRD detection with greater applicability and reduced labor intensiveness than qPCR. It will be necessary to authorize ddPCR as an outcome predictor tool in controlled clinical settings and multilaboratory standardization programs.

Before the introduction of new drugs, we designed a trial where treatment of newly diagnosed myeloma patients was based on the presence or absence of HLA-identical siblings. First-line treatments included a cytoreductive autograft followed by a nonmyeloablative allograft or a second melphalan-based autograft. Here, we report long-term clinical outcomes and discuss them in the light of the recent remarkable advancements in the treatment of myeloma. After a median follow-up of 7 years, median overall survival (OS) was not reached (P = .001) and event-free survival (EFS) was 2.8 years (P = .005) for 80 patients with HLA-identical siblings and 4.25 and 2.4 years for 82 without, respectively. Median OS was not reached (P = .02) and EFS was 39 months (P = .02) in the 58 patients who received a nonmyeloablative allograft whereas OS was 5.3 years and EFS 33 months in the 46 who received 2 high-dose melphalan autografts. Among patients who reached complete remission in these 2 cohorts, 53% and 19% are in continuous complete remission. Among relapsed patients rescued with “new drugs,” median OS from the start of salvage therapy was not reached and was 1.7 (P = .01) years, respectively. Allografting conferred a long-term survival and disease-free advantage over standard autografting in this comparative study.

Before the introduction of new drugs, we designed a trial where treatment of newly diagnosed myeloma patients was based on the presence or absence of HLA-identical siblings. First-line treatments included a cytoreductive autograft followed by a nonmyeloablative allograft or a second melphalan-based autograft. Here, we report long-term clinical outcomes and discuss them in the light of the recent remarkable advancements in the treatment of myeloma. After a median follow-up of 7 years, median overall survival (OS) was not reached (P= .001) and event-free survival (EFS) was 2.8 years (P= .005) for 80 patients with HLA-identical siblings and 4.25 and 2.4 years for 82 without, respectively. Median OS was not reached (P= .02) and EFS was 39 months (P= .02) in the 58 patients who received a nonmyeloablative allograft whereas OS was 5.3 years and EFS 33 months in the 46 who received 2 high-dose melphalan autografts. Among patients who reached complete remission in these 2 cohorts, 53% and 19% are in continuous complete remission. Among relapsed patients rescued with “new drugs,” median OS from the start of salvage therapy was not reached and was 1.7 (P= .01) years, respectively. Allografting conferred a long-term survival and disease-free advantage over standard autografting in this comparative study.

Complete response (CR) was an uncommon event in elderly myeloma patients until novel agents were combined with standard oral melphalan-prednisone. This analysis assesses the impact of treatment response on progression-free survival (PFS) and overall survival (OS). We retrospectively analyzed 1175 newly diagnosed myeloma patients, enrolled in 3 multicenter trials, treated with melphalan-prednisone alone (n = 332), melphalan-prednisone-thalidomide (n = 332), melphalan-prednisone-bortezomib (n = 257), or melphalan-prednisone-bortezomib-thalidomide (n = 254). After a median follow-up of 29 months, the 3-year PFS and OS were 67% and 27% (hazard ratio = 0.16; P< .001), and 91% and 70% (hazard ratio = 0.15; P< .001) in patients who obtained CR and in those who achieved very good partial response, respectively. Similar results were observed in patients older than 75 years. Multivariate analysis confirmed that the achievement of CR was an independent predictor of longer PFS and OS, regardless of age, International Staging System stage, and treatment. These findings highlight a significant association between the achievement of CR and long-term outcome, and support the use of novel agents to achieve maximal response in elderly patients, including those more than 75 years. This trial was registered at www.clinicaltrials.govas #NCT00232934, #ISRCTN 90692740, and #NCT01063179.

Complete response (CR) was an uncommon event in elderly myeloma patients until novel agents were combined with standard oral melphalan-prednisone. This analysis assesses the impact of treatment response on progression-free survival (PFS) and overall survival (OS). We retrospectively analyzed 1175 newly diagnosed myeloma patients, enrolled in 3 multicenter trials, treated with melphalan-prednisone alone (n = 332), melphalan-prednisone-thalidomide (n = 332), melphalan-prednisone-bortezomib (n = 257), or melphalan-prednisone-bortezomib-thalidomide (n = 254). After a median follow-up of 29 months, the 3-year PFS and OS were 67% and 27% (hazard ratio = 0.16; P < .001), and 91% and 70% (hazard ratio = 0.15; P < .001) in patients who obtained CR and in those who achieved very good partial response, respectively. Similar results were observed in patients older than 75 years. Multivariate analysis confirmed that the achievement of CR was an independent predictor of longer PFS and OS, regardless of age, International Staging System stage, and treatment. These findings highlight a significant association between the achievement of CR and long-term outcome, and support the use of novel agents to achieve maximal response in elderly patients, including those more than 75 years. This trial was registered at www.clinicaltrials.gov as #NCT00232934, #ISRCTN 90692740, and #NCT01063179.

Cyclooxygenase 2 (COX-2) is an inflammation-associated enzyme involved in the pathogenesis of many solid tumors, but little is known about its presence and role in hematologic neoplasms. Multiple myeloma (MM) is known to involve a deregulated cytokine network with secretion of inflammatory mediators. We thus decided to investigate the involvement of COX-2 in this neoplasm. Western blotting (WB) was used to evaluate 142 bone marrow (BM) specimens, including MM and monoclonal gammopathy of undetermined significance (MGUS). Selected cases under-went further evaluation by WB on purified CD138+cells, immunohistochemistry (IC), and real-time polymerase chain reaction (PCR) for mRNA expression. COX-2 was expressed in 11% (2 of 18) of MGUS specimens, 31% (29 of 94) of MM at diagnosis, and 47% (14 of 30) of MM with relapsed/refractory disease. COX-2 positivity was associated with a poor outcome in terms of progression-free (18 vs 36 months; P< .001) and overall survival (28 vs 52 months; P< .05). Real-time PCR showed COX-2 mRNA overexpression. IC and cell separation studies demonstrated COX-2 expression to be restricted to malignant plasma cells. This is the first report of the presence and prognostic role of COX-2 expression in MM. Future studies will assess COX-2 involvement in other hematologic tumors and its potential use as a therapeutic or chemo-preventive target in onco-hematology. (Blood. 2005; 105:4784-4791)

Cyclooxygenase 2 (COX-2) is an inflammation-associated enzyme involved in the pathogenesis of many solid tumors, but little is known about its presence and role in hematologic neoplasms. Multiple myeloma (MM) is known to involve a deregulated cytokine network with secretion of inflammatory mediators. We thus decided to investigate the involvement of COX-2 in this neoplasm. Western blotting (WB) was used to evaluate 142 bone marrow (BM) specimens, including MM and monoclonal gammopathy of undetermined significance (MGUS). Selected cases under-went further evaluation by WB on purified CD138+ cells, immunohistochemistry (IC), and real-time polymerase chain reaction (PCR) for mRNA expression. COX-2 was expressed in 11% (2 of 18) of MGUS specimens, 31% (29 of 94) of MM at diagnosis, and 47% (14 of 30) of MM with relapsed/refractory disease. COX-2 positivity was associated with a poor outcome in terms of progression-free (18 vs 36 months; P < .001) and overall survival (28 vs 52 months; P < .05). Real-time PCR showed COX-2 mRNA overexpression. IC and cell separation studies demonstrated COX-2 expression to be restricted to malignant plasma cells. This is the first report of the presence and prognostic role of COX-2 expression in MM. Future studies will assess COX-2 involvement in other hematologic tumors and its potential use as a therapeutic or chemo-preventive target in onco-hematology. (Blood. 2005; 105:4784-4791)

A clinical relationship between dose-intensity of melphalan and response rate has been demonstrated in multiple myeloma. Promising results have been reported after 200 mg/m2melphalan, especially in younger patients. It is uncertain whether 100 mg/m2melphalan (MEL100) can offer similar results in older patients. To address this issue, patients were treated with 2 or 3 MEL100 courses followed by stem cell support. Seventy-one patients (median age, 64 years) entered the protocol at diagnosis. Their clinical outcome was compared with that of 71 pair mates (median age, 64 years) selected from patients treated at diagnosis with oral melphalan and prednisone (MP) and matched for age and β2-microglobulin. Complete remission was 47% after MEL100 and 5% after MP. Median event-free survival was 34 months in the MEL100 group and 17.7 months in the MP group (P< .001). Median overall survival was 56+ months for MEL100 and 48 months for MP (P< .01). In a multivariate analysis, β2-microglobulin levels and MEL100 were independent risk factors associated with outcome: superior event-free and overall survival were observed in patients presenting low β2-microglobulin levels at diagnosis and receiving MEL100 as induction regimen. In conclusion, MEL100 was superior to MP in terms of complete remission rate, event-free survival, and overall survival.

We analyzed the immunoglobulin (Ig) heavy chain gene rearrangement in the peripheral blood lymphocytes of a patient with multiple myeloma (MM). Although the morphological and immunological examination did not reveal the presence of circulating plasma cells, a monoclonal Ig gene rearrangement was detected. This observation indicates that a monoclonal expansion of circulating B cells was present in the peripheral lympocytes of this patient.

Rossi: Gilead: Honoraria, Research Funding; Janssen: Honoraria; AbbVie: Honoraria. Gaidano:Janssen: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria, Speakers Bureau; Gilead: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Morphosys: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria. Massaia:Janssen: Other: advisory board; Roche: Other: advisory board, research support; Gilead: Other: advisory board. Boccadoro:Mundipharma: Research Funding; Abbivie: Honoraria; SANOFI: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; BMS: Honoraria, Research Funding; CELGENE: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Coscia:Gilead: Honoraria; Janssen: Honoraria; ROCHE: Honoraria, Other: Advisory board; Mundipharma: Honoraria; Karyopharm: Research Funding.

Boccadoro: CELGENE: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Abbivie: Honoraria; Mundipharma: Research Funding; SANOFI: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Janssen: Honoraria, Research Funding.

Oliva: Amgen: Honoraria; Takeda: Honoraria; Celgene: Honoraria. Boccadoro:CELGENE: Honoraria, Research Funding; Mundipharma: Research Funding; Janssen: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Abbivie: Honoraria; SANOFI: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding. Hajek:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Sonneveld:Celgene: Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria, Research Funding. Palumbo:Takeda: Employment, Honoraria; Janssen Cilag: Honoraria.

Massaia: Janssen: Other: advisory board; Gilead: Other: advisory board; Roche: Other: advisory board, research support. Cavallo:JANSSEN: Honoraria; CELGENE: Honoraria; ONYX: Honoraria. Palumbo:Janssen Cilag: Honoraria; Takeda: Employment, Honoraria. Boccadoro:Janssen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Mundipharma: Research Funding; Abbivie: Honoraria; SANOFI: Honoraria, Research Funding; BMS: Honoraria, Research Funding; CELGENE: Honoraria, Research Funding.

Bringhen: Mundipharma: Other: ADVISORY BOARD; Amgen: Other: ADVISORY BOARD; Janssen-Cilag: Honoraria; Celgene: Honoraria; BMS: Honoraria; Karyopharm: Other: ADVISORY BOARD. Massaia:Janssen: Other: advisory board; Roche: Other: advisory board, research support; Gilead: Other: advisory board. Palumbo:Janssen Cilag: Honoraria; Takeda: Employment, Honoraria. Boccadoro:CELGENE: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; SANOFI: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Mundipharma: Research Funding; Abbivie: Honoraria; Novartis: Honoraria, Research Funding; Amgen: Honoraria, Research Funding.

Introduction: Before the introduction of new drugs, we designed a trial where treatment of newly diagnosed multiple myeloma (MM) patients with double autografts or autograft followed by nonmyeloablative allograft was based on the presence or absence of HLA identical siblings (Bruno B et al. N Engl J Med 2007) We reported an update with special focus on long term outcomes.

INTRODUCTION: Graft-versus-Host-Disease (GVHD) is the main cause of non-relapse mortality after Hematopoietic Stem Cells Transplantation (HSCT). Identyfing potential biomarkers of GVHD could be crucial to define patients at high risk of GVHD development and to better assess GVHD grading. One potential attractive biomarker may be represented by extracellular vesicles (EVs). EVs are membrane-enclosed structures secreted by many cell types and may be represented by exosomes, shedding vesicles (microvesicles; MVs) and apoptotic bodies. EVs are detectable in body fluids, in particular peripheral blood (PB) and urine; EVs play a key role in the regulation of physiological and pathological processes. The aim of this study was to investigate EVs in PB of allotransplanted patients (EVs count, size and phenotype) and analyze a potential correlation with acute and chronic GVHD (aGVHD, cGVHD).

INTRODUCTION: Autografting (auto-HSCT) is widely used for the treatment of hematological malignancies. Since 2010, Biosimilar Filgrastim (Nivestim™, Pfizer Inc.) (BioG-CSF) has been approved and introduced into clinical practice to mobilize hematopoietic stem cells (CD34+cells) and to reduce the duration of chemo-induced neutropenia. This single institution study was designed to evaluate its safety and efficacy in the setting of "real life" medical practice.

Background

Background:In chronic lymphocytic leukemia (CLL), disease aggressiveness and drug responsiveness can be ascribed to intrinsic genetic features of the tumor cells, such as TP53 disruption, and to interactions of CLL cells with stromal cells (SC) of the tumor microenvironment. The transcription factor HIF-1α is critically involved in the regulation of genes implicated in key cellular processes, such as cell survival and tumor progression, and also modulates the interactions of CLL cells with SC. HIF-1α expression and transcriptional activity depend on genetic alterations of tumor suppressor genes (e.g. TP53), and on extrinsic signals such as oxygen deprivation and soluble factors. In CLL cells, HIF-1α is active even in normoxia, and its expression is rapidly elevated during hypoxia. We have already reported that HIF-1α activity in CLL cells is upregulated by SC, via activation of Akt, and Ras/ERK1-2 and RhoA/RhoA kinase signaling pathways. SC are well known pro-survival factors, which protect CLL cells from spontaneous apoptosis and fludarabine-induced cytotoxicity. The cytotoxic effects of HIF-1α inhibition, and the ability of HIF-1α targeting agents to reverse constitutive or SC-induced fludarabine resistance, need to be investigated.

Marchetti: GILEAD: Consultancy, Research Funding; JANSSEN: Other: tavel, accomodation, expenses; SANOFI: Membership on an entity's Board of Directors or advisory committees; GILEAD: Other: teaching, Research Funding; NOVARTIS: Research Funding. Gaidano:MorphoSys; Roche; Novartis; GlaxoSmithKline; Amgen; Janssen; Karyopharm: Honoraria, Other: Advisory boards; Celgene: Research Funding. Boccadoro:Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees. Massaia:Gilead: Research Funding; Janssen: Honoraria; Roche: Honoraria. Coscia:Roche: Honoraria, Other: Advisory board; Mundipharma: Honoraria.

Luminari: Roche: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Teva: Membership on an entity's Board of Directors or advisory committees.

Boccadoro: Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Background. Recently, the somatic MYD88L265Pmutation has been found as the hallmark of Waldenström Macroglobulinemia (WM), being detectable in nearly 90% of cases, as well as in up to 50% of IgM MGUS, rarely in other non-Hodgkin lymphomas and never in multiple myeloma (MM). Beyond its potential diagnostic role, this mutation has been associated with tumor growth and therapy resistance. Moreover, MYD88L265Pmight represent an ideal marker for minimal residual disease (MRD) monitoring in a disease whose therapeutic scenario has been rapidly changing, with many new available and highly effective drugs (nucleoside analogues, proteasome and BTK-inhibitors). However, the current MYD88L265Pallele-specific quantitative PCR (ASqPCR) diagnostic tool lacks sensitivity (1.00E-03) and thus is not suitable for MRD. Moreover, is not useful to test peripheral blood (PB), that harbors low concentrations of circulating tumor cells (especially after immunochemotherapy), neither to assess cell-free DNA (cfDNA), usually present at very low amount in plasma. Therefore, our study aims: 1) to assess whether a highly sensitive tool as droplet digital PCR (ddPCR) might be helpful in MYD88L265Pscreening; 2) to evaluate whether MYD88L265Pmight be a suitable marker for MRD monitoring in WM.

Treatment of patients with fludarabine-resistant chronic lymphocytic leukemia (CLL) is an unmet clinical need. Fludarabine resistance in CLL can be ascribed to intrinsic genetic features of the tumor cells, mainly consisting in TP53 disruption, and to the interactions of CLL cells with stromal cells (SC) of the tumor microenvironment. One of the main players of SC-induced fludarabine resistance is the CXCL12/CXCR4 axis, which activates in CLL cells the Ras/ERK1-2 and RhoA-dependent signaling pathways. To be active transducers Ras and RhoA need to undergo isoprenylation by means of small molecules produced by the mevalonate (Mev) pathway. We reported that the Mev pathway-regulated Ras and RhoA signaling cascades and the downstream hypoxia inducible factor (HIF)-1α/P-glycoprotein axis are more active in IGHV unmutated than in mutated CLL cells, leading to a constitutive protection from doxorubicin-induced cytotoxicity. HIF-1α is a transcription factor constitutively expressed in CLL cells and controls the expression of several genes implicated in survival and cell metabolism. The Mev pathway manipulation with simvastatin (Sim), as well as the targeted inhibition of ERK1-2, RhoA kinase and HIF-1α, restore the sensitivity of CLL cells to doxorubicin. The role of the Mev pathway, the Ras and RhoA signaling, and the transcription factor HIF-1α in regulating the SC-induced fludarabine resistance of TP53 disrupted (TP53dis) CLL cells is currently unknown.

Off Label Use: Use off-label of drugs for the dose and/or schedule and/or association . Gay:Sanofi: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Honoraria. Larocca:Janssen-Cilag, Celgene: Honoraria. Caravita:Celgene: Honoraria. Gamberi:Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Mundipharma: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees. Rossi:Celgene: Research Funding. Offidani:Janssen-Cilag, Celgene, Sanofi, Amgen, Mundipharma: Honoraria. Boccadoro:Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees. Sonneveld:Janssen-Cilag, Celgene, Onyx, Karyopharm: Honoraria, Research Funding; novartis: Honoraria. Palumbo:Novartis, Sanofi Aventis: Honoraria; Celgene, Millennium Pharmaceuticals, Amgen, Bristol-Myers Squibb, Genmab, Janssen-Cilag, Onyx Pharmaceuticals: Consultancy, Honoraria.

Background.The aggressive clinical behavior of mantle cell lymphoma (MCL) is attributed to specific genetic and molecular mechanisms involved in its pathogenesis, mainly the t(11;14)(q13;q32) traslocation and cyclin D1 (CCND1) overexpression. Nevertheless, evidence of a certain degree of clinical/biological heterogeneity has been disclosed by gene expression profile (GEP) and (immuno)genetic/immunohistochemistry studies.

No relevant conflicts of interest to declare.

Palumbo: Amgen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Array BioPharma: Honoraria; Genmab A/S: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Onyx Pharmaceuticals: Consultancy, Honoraria; Sanofi Aventis: Honoraria.

Boccadoro: Celgene: Honoraria; Janssen: Honoraria; Onyx: Honoraria. Palumbo:Amgen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Array BioPharma: Honoraria; Genmab A/S: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Onyx Pharmaceuticals: Consultancy, Honoraria; Sanofi Aventis: Honoraria.

Palumbo: Bristol-Myers Squibb: Consultancy, Honoraria; Genmab A/S: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Onyx Pharmaceuticals: Consultancy, Honoraria; Array BioPharma: Honoraria; Amgen: Consultancy, Honoraria; Sanofi: Honoraria. Boccadoro:Celgene: Honoraria; Janssen: Honoraria; Onyx: Honoraria.

Palumbo: Celgene: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Onyx Pharmaceuticals: Consultancy, Honoraria; Array BioPharma: Honoraria; Amgen: Consultancy, Honoraria; Sanofi: Honoraria; Genmab A/S: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria. Off Label Use: Use off-label of Carfilzomib (proteasome inhibitor).. Bringhen:Merck Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; Janssen and Cilag: Honoraria; Celgene: Honoraria; Onyx: Consultancy. Larocca:Janssen Cilag: Honoraria; Celgene: Honoraria. Cavallo:Onyx: Honoraria; Janssen-Cilag: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Boccadoro:Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees. Gaidano:Onyx: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Sonneveld:Millenium: Honoraria, Research Funding; Onyx: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding.

Off Label Use: lenalidomide used as off-label. Ferrero:MUNDIPHARMA: Honoraria. Gay:Sanofi: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Patriarca:Merck Sharp & Dohme: Honoraria; Janssen and Cilag: Honoraria; Celgene: Honoraria. Petrucci:CELGENE: Honoraria; JANSSEN-CILAG: Honoraria; SANOFI: Honoraria; BRISTOL MYERS SQUIBB: Honoraria. Caravita:Celgene: Honoraria. Di Raimondo:CELGENE: Honoraria; JANSSEN-CILAG: Honoraria. Musto:CELGENE: Honoraria; JANSSEN-CILAG: Honoraria. Boccadoro:Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees. Palumbo:Array BioPharma: Honoraria; Onyx Pharmaceuticals: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Genmab A/S: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Sanofi: Honoraria.

Background

Background.Minimal residual disease (MRD) detection by multi-parameter flow cytometry (MFC) and real time quantitative PCR (RQ-PCR) is highly predictive of outcome in multiple myeloma (MM) patients (pts). Less is known on the ability of maintenance therapy to modulate MRD levels. The primary end-point of this study was to monitor MRD during maintenance therapy and to evaluate the impact on outcome.

BackgroundEvaluation of minimal residual disease (MRD) by molecular methods is used as a surrogate of potential eradication of myeloma cells. Prolonged high-rates of molecular remission were reported after myeloablative allografting. However, recent studies on consolidation therapy after an autograft reported 18% of PCR negativity by qualitative nested PCR and a molecular response of 63% by quantitative RQ-PCR (Ferrero et al. Leukemia 2014). The aim of our study was that of evaluating depth of response by molecular methods induced by graft-vs.-myelomafollowing tandem autologous/non-myeloablative allografting in newly diagnosed myeloma.

Background

In the recent years, numerous studies based on multicolor flowcytometry have analyzed the different subpopulations of bone marrow (BM) hematopoietic stem and progenitor cells (HSPCs) (Manz MG et al, PNAS 2002; Majeti R et al, Cell Stem Cell 2007): the common myeloid progenitors (CMPs: Lin-CD34+CD38+CD45RA-CD123+), the granulocyte-macrophage progenitors (GMPs: Lin-CD34+CD38+CD45RA+CD123+) and the megakaryocyte-erythroid progenitors (MEPs: Lin-CD34+CD38+CD45RA-CD123-) constitute the progenitor compartment, while the hematopoietic stem cells (HSCs: Lin-CD34+CD38-CD45RA-CD90+), the multipotent progenitors (MPPs: Lin-CD34+CD38-CD45RA-CD90-) and the lymphoid-myeloid multipotent progenitors (LMPPs: Lin-CD34+CD38-CD45RA+CD90-) represent the more immature HSPCs. In animal models, the progenitor compartment includes short-term repopulating cells, leading to the hematological recovery in the first 5 weeks after transplantation, whereas the stem cell compartment comprehends the long-term repopulation cells, responsible for the long-term hematological recovery. However, very little is known about the different subpopulations of HSPCs among peripheral blood (PB) CD34+ in basal state and after mobilization for harvest and transplantation.

While international stage (ISS) and the presence of absence of cytogenetic abnormalities on FISH somewhat define the clinical risk of MM patients, additional biomarkers are necessary for more precise risk-based classification. Emerging studies have shown that circulating microRNAs (miRNAs) can be detected in patients with a variety of malignancies, including MM, and they could be non-invasive biomarkers. We measured serum miRNA levels of a large cohort of well-characterized previously untreated MM patients and correlated results with clinical outcome to test their prognostic impact. Methods and Patients To profile the expression of circulating microRNAs in the serum of MM patients, we performed NanoString-nCounter microRNA assays on samples obtained from a discovery cohort of 54 newly diagnosed MM patients enrolled on a randomized GIMEMA phase 3 study comparing Velcade-Melphalan-Prednisone-Thalidomide versus Velcade-Melphalan-Prednisone followed by maintenance with Velcade-Thalidomide. To further analyze the expression of the differentially expressed microRNAs, stem-loop-RT-PCR was performed on a validation cohort of 234 MM patients enrolled in the same trial. The prognostic significance of differentially expressed microRNAs were evaluated in relation to progression-free (PFS) and overall survival (OS) using univariate and multivariate Cox proportional hazards models. The utility of incorporating microRNA expression into a risk score with known risk factors – specifically ISS stage and the presence of del17, t(4;14) or t(14;16) by FISH – was also explored.Out of the 800 miRNAs evaluated, only 25 were detectable (≥100 counts) in at least 20% of the patients. The expression of these miRNAs were then measured in a validation set, but only 10 (miRs-92a, 21, 30a, 720, 451, 223, 126, 19b, 25 and miR-16) were validated to be differentially expressed. We found that levels of miR-16 and miR-25, used as continuous variables, had significant impact on OS duration: miR-16 (HR 0.87; p=0.019) and miR-25 (HR 0.81; p=0.0012) where low expression corresponded with worse survival. Based on these observations we generated a microRNA-based risk score which was significantly associated with OS duration (p=0.008). We then integrated this score with ISS stage and presence of high risk features by FISH, generating an integrated-microRNA risk score that was significantly associated with OS (p<0.0001), and was better than a risk score that combined ISS and FISH (p=0.014), see figure.Circulating miR-16 and miR-25 can risk stratify elderly, previously untreated, MM patients beyond ISS-stage and high risk genetic features. The opportunity to isolate circulating miRNAs allows us to sequentially sample cancer patients in a relatively non-invasive manner, opening new avenues of investigation for disease stratification and response to therapy.Bringhen: Onyx: Consultancy.

Elderly multiple myeloma (MM) patients are an heterogeneous population. Aging is associated with an increased frequency of co-morbidities, frailty and disability, with negative impact on treatment tolerance and outcome. A simple and reliable scoring system, based on geriatric assessment, has been developed to predict survival and used also to predict the risk of severe toxicities or treatment discontinuation in elderly newly diagnosed MM patients treated with lenalidomide-, bortezomib- or carfilzomib-based induction regimens.Patients with newly diagnosed MM, ineligible for high-dose therapy and autologous stem cell transplantation due to age (≥65 years) or coexisting co-morbidities, enrolled in 3 prospective multicenter trials, were included in the analysis. Up-front dose reductions were performed according to patients age (full doses for patients ≤75 years and reduced for patients >75 years). Details on treatment regimens and results of these studies have previously been reported (Gay F et al EHA 2013, Larocca A et al EHA 2013, Bringhen S et al EHA 2013). At diagnosis, a geriatric assessment had been performed, to assess co-morbidities, cognitive and physical conditions.869 patients were included in the analysis: 659 enrolled in the lenalidomide-based, 152 in the bortezomib-based and 58 in the carfilzomib-based trial. Median age was 74 years, and 44% of patients were older than 75 years. Median follow-up was 18 months.In univariable analysis, the risk of death was higher in patients aged 75-80 (Hazard Ratio, HR 1.37, p=0.11), and in patients older than 80 years (HR 2.75, p<0.001), compared to patients younger than 75 years. Performance status and gender did not significantly impact overall survival (OS). In a multivariable Cox model, an additive scoring system (range 0-5), based on age, co-morbidities, cognitive and physical conditions, was categorized to identify 3 groups: fit (score=0, 39%); unfit (score=1, 31%), and frail (score≥2, 30%). The 18-month OS was 92%, 88% and 73% in the three categories (fit, unfit and frail), respectively.In a Cox's model, including ISS, gender and performance status, the HR compared to the fit category was 1.4 (p=0.18) and 2.9 (p<0.001) in unfit and frail patients. The cumulative 6-month risk of serious adverse events or treatment discontinuation was 44%, 47% and 55% in fit, unfit and frail patients, respectively. The higher mortality rate in unfit and frail patients seems mainly due to higher cumulative incidence of grade ≥3 adverse events (in particular extra hematologic toxicities) causing subsequent treatment discontinuation.The use of a simple scoring system, based on geriatric assessment, allows the identification of groups of patients with different survival and risk of severe toxicities.Larocca: Celgene: Honoraria; Janssen-Cilag: Honoraria. Bringhen:Celgene: Honoraria; Janssen-Cilag: Honoraria; Novartis: Honoraria; Merck Sharpe & Dohme: Membership on an entity’s Board of Directors or advisory committees; Onyx: Consultancy. Gay:Celgene: Honoraria; Janssen-Cilag: Honoraria; Celgene: Membership on an entity’s Board of Directors or advisory committees; Byotest: Membership on an entity’s Board of Directors or advisory committees. Boccadoro:Celgene: Research Funding; Janssen-Cilag: Research Funding; Celgene: Consultancy; Janssen-Cilag: Consultancy; Celgene: Membership on an entity’s Board of Directors or advisory committees; Janssen-Cilag: Membership on an entity’s Board of Directors or advisory committees. Palumbo:Amgen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen Pharmaceuticals: Consultancy, Honoraria; Millenium: Consultancy, Honoraria; Onyx: Consultancy, Honoraria.

The quality of response and the residual disease after treatment are important prognostic factors in several hematological diseases including multiple myeloma (MM). Several papers demonstrated that the deeper the response after treatment, the longer the survival. However few data are available on the monitoring of minimal residual disease (MRD) during the maintenance therapy in transplant eligible MM patients.to evaluate the role of maintenance therapy in reducing MRD and the role of monitoring the response to predict clinical relapse.newly diagnosed MM patients enrolled in the RV-MM-EMN-441 trial (NCT01091831) and achieving at least a very good partial response (VGPR) after consolidation were included in the study. Patients received 4 Lenalidomide-Dexamethasone (RD) courses as induction, Cyclophosphamide to mobilize bone marrow stem cells (BMSC) and then were randomized to receive 6 cycles of Cyclophosphamide-Lenalidomide-Dexamethasone (CRD) or Autologous Stem Cell Transplantation (ASCT) with Melphalan 200 mg/m2. All patients received maintenance therapy with Lenalidomide (R) or Lenalidomide-Dexamethasone (RD) until relapse. MRD analysis was performed in a single laboratory (University of Turin, Italy) using flow cytometry according to European Myeloma Network guideline (Rawstron AC, Haematologica 2008). Samples of bone marrow (BM) were collected at diagnosis, after consolidation, after 3 and 6 courses of maintenance and then every 6 months until clinical relapse. The samples were considered MRD +ve if ≥ 0.01% of PC were detected. Immunophenotypic (IF) relapse was defined as an increase of ≥ 25% in the amount of malignant plasma cells in BM compared to the previous determination.Fifty patients (27 female/23 male) with a median age of 57 yrs (40-65) entered the study. According to ISS, 27 patients were stage I, 15 stage II and 8 stage III. Fish risk profile was standard in 31 patients, high in 11 and not available in 8. Twenty-five patients received CRD as consolidation and 25 underwent ASCT. The median follow-up was 28.6 months. After consolidation 16 (32%) patients achieve a complete response (CR) and 34 (68%) a VGPR. MRD was negative in 19/48 (40%) patients, of which 12 received ASCT (out of 23, 52%) and 7 received CRD (out of 25, 28%). Patients receiving ASCT showed a lower value of residual cells (median 0.08%, range 0 – 1.00) compared to patients receiving CRD (median 0.5%, range 0 – 2.9%, p=0.0134). The lower MRD value was achieved after consolidation in 31 patients (62%), after 3 courses of maintenance in 6 patients (12%) and after 6 or more courses of maintenance in 13 patients (26%). The increase in quality of response was observed primarily in patients receiving CRD: the average amount of residual plasma cells in bone marrow was 71/uL after induction, lowering to 51/uL after 6 and 12 courses of maintenance therapy. Nine patients clinically relapsed after an average time of 25.6 months from the beginning of the therapy and in all patients this was anticipated by immunophenotypic relapse.1) consolidation therapy with ASCT determines a deeper response compared to CRD; 2) maintenance therapy can improve the quality of response, in particular in patients not receiving ASCT; 3) Immunophenotypic relapse anticipate the clinical relapse. These results suggest the possible role of MRD monitoring to better assess the response to therapy also during maintenance and as marker of early relapse.Ladetto: Celgene: Research Funding, Speakers Bureau; Janssen Cilag: Research Funding, Speakers Bureau; Mundipharma: Research Funding, Speakers Bureau; Roche: Research Funding, Speakers Bureau; Amgen: Research Funding, Speakers Bureau. Boccadoro:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Palumbo:Amgen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Millenium: Consultancy, Honoraria; Onyx: Consultancy, Honoraria.

In mature lymphoid disorders, minimal residual disease (MRD) detection based on real time quantitative PCR (RQ-PCR) of immunoglobulin heavy chain gene rearrangement (IgH) has a well-established role in prognostic assessment, particularly in Mantle cell Lymphoma (MCL) and Multiple Myeloma (MM). RQ-PCR has excellent sensitivity and specificity but has a major limitation in its relative quantification nature, as it requires a reference standard curve usually built with dilutions of diagnostic tumor DNA or on plasmids containing the target rearrangement. Droplet Digital PCR (DD-PCR), applying the principle of limiting dilution of DNA and single molecule detection allows a reliable absolute quantification of target. In this study we compared IgH-based MRD detection by RQ-PCR and DD-PCR, to assess whether DD-PCR could achieve the same performances of RQ-PCR in the absence of the limitation mentioned above.

Minimal residual disease (MRD) by multiparameter flow-cytometry recently showed a promising role in predicting outcomes in patients with multiple myeloma. However, data on immunophenotypic response (IR) after allografting are lacking.

In mature lymphoid disorders, minimal residual disease (MRD) detection based on real time quantitative PCR (RQ-PCR) of immunoglobulin heavy chain gene rearrangement (IgH) has a well-established role in prognostic assessment, particularly in Mantle cell Lymphoma (MCL) and Multiple Myeloma (MM). RQ-PCR has excellent sensitivity and specificity but has a major limitation in its relative quantification nature, as it requires a reference standard curve usually built with dilutions of diagnostic tumor DNA or on plasmids containing the target rearrangement. Droplet Digital PCR (DD-PCR), applying the principle of limiting dilution of DNA and single molecule detection allows a reliable absolute quantification of target. In this study we compared IgH-based MRD detection by RQ-PCR and DD-PCR, to assess whether DD-PCR could achieve the same performances of RQ-PCR in the absence of the limitation mentioned above.Bone marrow (BM) and peripheral blood (PB) samples were collected from patients affected by MCL and MM in which RQ-PCR based MRD analysis was already performed in the context of prospective clinical trials. In all trials patients gave the informed consent for MRD determination. IgH-based MRD detection by RQ-PCR was carried out as previously described [Ladetto et al. BBMT 2000] and results were interpreted according to the Euro-MRD guidelines [van der Velden et al. Leukemia 2007]. DD-PCR was performed by the QX100 Droplet Digital PCR system (Bio-RAD Inc.) on 500 ng of genomic DNA combined with the same Allele Specific Oligonucleotides (ASO)-primers and TaqMan-probes used in the RQ-PCR. Droplets were generated by QX100 droplet generator. End-point PCR (40 cycles) was performed on a T100 Thermal cycler (Bio-RAD Inc). The PCR product was loaded in the QX100 droplet reader and analyzed by QuantaSoft 1.2 (Bio-Rad Inc). For data interpretation RQ-PCR and DD-PCR results were expressed as amount of target copies per 1E+05 cells. Comparability of MRD results by DD-PCR and RQ-PCR was assessed by means of bivariate correlations between methods analysis (R2.15.1 package irr). Discordances were classified as follows: a positive/negative discordance was defined as major when the positive result was >1E-04 and minor when ≤1E-04; a quantitative discordance was defined as the presence of two positive results with a quantitative discrepancy >1 log.Overall, 161 samples belonging to 35 patients (18 MCL and 17 MM), 66 MCL and 95 MM were analyzed. 35 samples were taken at diagnosis and 126 at follow-up. 118 were BM while 43 were PB. A significant correlation was found between DD-PCR and RQ-PCR (R2=0.89, p<0.0001) (fig). DD-PCR and RQ-PCR showed superimposable sensitivity (10-5). Specificity in terms of appearance of non-specific amplifications signals in no-template samples (tested for all patients) and reproducibility on 30 replicates (4 samples) were superimposable. 128 out of 161 samples were fully concordant (Choen's K=0.80). MRD detection was concordantly positive in 106/161 (65.8%) samples and concordantly negative in 22/161 samples (13.7%). Only 5/161 (3.1%) samples showed major qualitative discordance. 28/161 (17.4%) samples showed minor qualitative discordance (which might be related to Poisson's statistics). Quantitative discordances were observed in 5/161 (3.1%) of cases (positive non quantifiable (PNQ) cases were conventionally placed to a value intermediate between sensitivity and quantitative range). Interestingly, 17 samples negative by RQ-PCR were scored positive by DD-PCR (median 6 copies, range 2-74) while 16 samples positive by RQ-PCR (median 5 copies, range 2-44) were negative by DD-PCR.Here we report for the first time the use of DD-PCR in the context of IgH-based MRD evaluation in lymphoproliferative disorders. DD-PCR is a feasible tool for IGH-based MRD monitoring in MCL and MM, reaching similar sensitivities compared to standardized RQ-PCR. Moreover DD-PCR allows bypassing the need of building a standard curve thus considerably reducing the complexity of IgH-based RQ-PCR (need of purified diagnostic tissue or Flow Cytometry-based quantification of tumor load or diagnosis, or building of a plasmid-derived standard curve). Finally DD-PCR might potentially overcome the problem of positive non-quantifiable samples. These features make DD-PCR a feasible and attractive alternative method for IgH-based MRD assessment.Kubiczkovà: GAP304/10/1395 : Research Funding; MUNI/11/InGA17/2012: Research Funding.

Minimal residual disease (MRD) by multiparameter flow-cytometry recently showed a promising role in predicting outcomes in patients with multiple myeloma. However, data on immunophenotypic response (IR) after allografting are lacking.To evaluate the impact of IR and compare it to conventional complete remission (CR) following allografting in myeloma patients.Sixty-six consecutive patients, median age 54 years (35-66), who underwent an allograft between January 2000 and December 2011 with a follow-up of at least 3 months were included. Disease response was evaluated by serum and urine electrophoresis, and bone marrow aspirate at baseline, 3, 6, 12, 18, 24 months after transplant and yearly thereafter. Skeletal survey or MRI were performed yearly or as clinically indicated (overt relapse or complaints of bone pain). Bone marrow aspirates had to contain at least 13000 cells/µL for flow-cytometry studies and IR was defined as absence of monoclonal plasma-cells detected by 4 or 6-colour staining with the following antibodies: CD38, CD138, CD56, CD19, CD45, cyKappa, cyLambda. CR was defined according to standard criteria (Durie et al, Leukemia 2006; 20:1467-73).Conditioning regimen was non-myeloablative 2Gy TBI-based in 55 patients, reduced intensity (fludarabine-melphalan-based) in 10 and myeloablative in 1 patient. Post-grafting immunosuppression consisted of cyclosporine with mycophenolate mofetil or methotrexate. Donors were HLA identical siblings in 58 patients and unrelated in 8. Only 1 patient received bone marrow as source of stem cells. Thirty-five/66 (53%) received the allograft as part of the first line treatment, whereas the remaining 31/66, (47%) were transplanted at relapse. At the time of transplant, 5/66 were both in IR and CR, 16 were only in IR and 4 patients were only in clinical CR. All 21 patients in IR at the time of transplant maintained it, while 26/45 (58%) entered IR after the allograft. Among patients surviving at least 3 months, overall treatment related mortality was 10.6% at 3 years. After a median follow-up of 69 months (range 19-147), the incidence of acute and chronic graft-versus-host disease was 45.6% and 49.3% without significant difference between responsive and non-responsive patients. At follow-up, overall, 24 patients achieved CR and IR (CR/IR group), 21 achieved IR but not CR because of persistence of urine/serum M-component (noCR/IR group), and 21 did not achieve either CR or IR (noCR/noIR group). Interestingly, none achieved CR without IR. Median overall survival (OS) and event-free survival (EFS) in patients who achieved IR were 96 and 55 months versus 36 and 7 months in those who did not (p<0.001). Median OS and EFS were not reached and 59 months in the CR/IR group, 77 and 15 months in the noCR/IR, and 30 and 5 months in the noCR/noIR respectively (p<0.001 for both EFS and OS-fig.1). In univariate analysis, being in the CR/IR group was the only significant predictor for prolonged OS and EFS (p<0.001). Of note, cumulative incidence of extra-medullary disease at first relapse after the allograft was 4% in the CR/IR, 32% in the noCR/IR and 15% in the noCR/noIR groups respectively (p<0.001). Receiving the allograft as first line therapy or later during the disease course did not significantly impact on OS and EFS.The achievement of IR confers a favorable impact on OS and EFS after allografting. A higher incidence of extra-medullary in the noCR/IR group (some 30% of our patient cohort) may suggest that myeloma cells escape immune control outside the bone marrow. In this group, imaging studies such as positron emission tomography may clinically be indicated during follow-up to detect early relapse.No relevant conflicts of interest to declare.