Luis A. Corchete

SNP-based mapping arrays reveal high genomic complexity in monoclonal gammopathies, from MGUS to myeloma status

Genetic events mediating transformation from premalignant monoclonal gammopathies (MG) to multiple myeloma (MM) are unknown. To obtain a comprehensive genomic profile of MG from the early to late stages, we performed high-resolution analysis of purified plasma cells from 20 MGUS, 20 smoldering MM (SMM) and 34 MM by high-density 6.0 SNP array. A progressive increase in the incidence of copy number abnormalities (CNA) from MGUS to SMM and to MM (median 5, 7.5 and 12 per case, respectively) was observed (P=0.006). Gains on 1q, 3p, 6p, 9p, 11q, 19p, 19q and 21q along with 1p, 16q and 22q deletions were significantly less frequent in MGUS than in MM. Although 11q and 21q gains together with 16q and 22q deletions were apparently exclusive of MM status, we observed that these abnormalities were also present in minor subclones in MGUS. Overall, a total of 65 copy number-neutral LOH (CNN-LOH) were detected. Their frequency was higher in active MM than in the asymptomatic entities (P=0.047). A strong association between genetic lesions and fragile sites was also detected. In summary, our study shows an increasing genomic complexity from MGUS to MM and identifies new chromosomal regions involved in CNA and CNN-LOH.

A multiparameter flow cytometry immunophenotypic algorithm for the identification of newly diagnosed symptomatic myeloma with an MGUS-like signature and long-term disease control

Achieving complete remission (CR) in multiple myeloma (MM) translates into extended survival, but two subgroups of patients fall outside this paradigm: cases with unsustained CR, and patients that do not achieve CR but return into a monoclonal gammopathy of undetermined significance (MGUS)-like status with long-term survival. Here, we describe a novel automated flow cytometric classification focused on the analysis of the plasma-cell compartment to identify among newly diagnosed symptomatic MM patients (N=698) cases with a baseline MGUS-like profile, by comparing them to MGUS (N=497) patients and validating the classification model in 114 smoldering MM patients. Overall, 59 symptomatic MM patients (8%) showed an MGUS-like profile. Despite achieving similar CR rates after high-dose therapy/autologous stem cell transplantation vs other MM patients, MGUS-like cases had unprecedented longer time-to-progression (TTP) and overall survival (OS; ∼60% at 10 years; P<0.001). Importantly, MGUS-like MM patients failing to achieve CR showed similar TTP (P=0.81) and OS (P=0.24) vs cases attaining CR. This automated classification also identified MGUS patients with shorter TTP (P=0.001, hazard ratio: 5.53) and ultra-high-risk smoldering MM (median TTP, 15 months). In summary, we have developed a biomarker that identifies a subset of symptomatic MM patients with an occult MGUS-like signature and an excellent outcome, independently of the depth of response.

Phenotypic identification of subclones in multiple myeloma with different chemoresistant, cytogenetic and clonogenic potential

Knowledge about clonal diversity and selection is critical to understand multiple myeloma (MM) pathogenesis, chemoresistance and progression. If targeted therapy becomes reality, identification and monitoring of intraclonal plasma cell (PC) heterogeneity would become increasingly demanded. Here we investigated the kinetics of intraclonal heterogeneity among 116 MM patients using 23-marker multidimensional flow cytometry (MFC) and principal component analysis, at diagnosis and during minimal residual disease (MRD) monitoring. Distinct phenotypic subclones were observed in 35/116 (30%) newly diagnosed MM patients. In 10/35 patients, persistent MRD was detected after 9 induction cycles, and longitudinal comparison of patient-paired diagnostic vs MRD samples unraveled phenotypic clonal tiding after therapy in half (5/10) of the patients. After demonstrating selection of distinct phenotypic subsets by therapeutic pressure, we investigated whether distinct fluorescence-activated cell-sorted PC subclones had different clonogenic and cytogenetic profiles. In half (5/10) of the patients analyzed, distinct phenotypic subclones showed different clonogenic potential when co-cultured with stromal cells, and in 6/11 cases distinct phenotypic subclones displayed unique cytogenetic profiles by interphase fluorescence in situ hybridization, including selective del(17p13). Collectively, we unravel potential therapeutic selection of preexisting diagnostic phenotypic subclones during MRD monitoring; because phenotypically distinct PCs may show different clonogenic and cytogenetic profiles, identification and follow-up of unique phenotypic-genetic myeloma PC subclones may become relevant for tailored therapy.

Genomic analysis of high-risk smoldering multiple myeloma

Smoldering myeloma is an asymptomatic plasma cell dyscrasia with a heterogeneous propensity to progress to active myeloma. In order to investigate the biology of smoldering myeloma patients with high risk of progression, we analyzed the genomic characteristics by FISH, SNP-arrays and gene expression profile of a group of patients with high-risk smoldering myeloma included in a multicenter randomized trial. Chromosomal abnormalities detected by FISH and SNP-arrays at diagnosis were not associated to risk of progression to symptomatic myeloma. However, the overexpression of four SNORD genes (SNORD25, SNORD27, SNORD30 and SNORD31) was correlated with shorter time to progression (P<0.03). When plasma cells from high-risk smoldering patients who progressed to symptomatic myeloma were sequentially analyzed, newly acquired lesions together with an increase in the proportion of plasma cells carrying a given abnormality were observed. These findings suggest that gene expression profiling is a valuable technique to identify smoldering myeloma patients with high risk of progression. (Clinical Trials NCT00443235)

The cellular origin and malignant transformation of Waldenström macroglobulinemia

Although information about the molecular pathogenesis of Waldenström macroglobulinemia (WM) has significantly advanced, the precise cell of origin and the mechanisms behind WM transformation from immunoglobulin-M (IgM) monoclonal gammopathy of undetermined significance (MGUS) remain undetermined. Here, we undertook an integrative phenotypic, molecular, and genomic approach to study clonal B cells from newly diagnosed patients with IgM MGUS (n = 22), smoldering (n = 16), and symptomatic WM (n = 11). Through principal component analysis of multidimensional flow cytometry data, we demonstrated highly overlapping phenotypic profiles for clonal B cells from IgM MGUS, smoldering, and symptomatic WM patients. Similarly, virtually no genes were significantly deregulated between fluorescence-activated cell sorter-sorted clonal B cells from the 3 disease groups. Interestingly, the transcriptome of the Waldenström B-cell clone was highly different than that of normal CD25(-)CD22(+) B cells, whereas significantly less genes were differentially expressed and specific WM pathways normalized once the transcriptome of the Waldenström B-cell clone was compared with its normal phenotypic (CD25(+)CD22(+low)) B-cell counterpart. The frequency of specific copy number abnormalities [+4, del(6q23.3-6q25.3), +12, and +18q11-18q23] progressively increased from IgM MGUS and smoldering WM vs symptomatic WM (18% vs 20% and 73%, respectively; P = .008), suggesting a multistep transformation of clonal B cells that, albeit benign (ie, IgM MGUS and smoldering WM), already harbor the phenotypic and molecular signatures of the malignant Waldenström clone.

Transcriptome analysis reveals molecular profiles associated with evolving steps of monoclonal gammopathies

A multistep model has been proposed of disease progression starting in monoclonal gammopathy of undetermined significance continuing through multiple myeloma, sometimes with an intermediate entity called smoldering myeloma, and ending in extramedullary disease. To gain further insights into the role of the transcriptome deregulation in the transition from a normal plasma cell to a clonal plasma cell, and from an indolent clonal plasma cell to a malignant plasma cell, we performed gene expression profiling in 20 patients with monoclonal gammopathy of undetermined significance, 33 with high-risk smoldering myeloma and 41 with multiple myeloma. The analysis showed that 126 genes were differentially expressed in monoclonal gammopathy of undetermined significance, smoldering myeloma and multiple myeloma as compared to normal plasma cell. Interestingly, 17 and 9 out of the 126 significant differentially expressed genes were small nucleolar RNA molecules and zinc finger proteins. Several proapoptotic genes (AKT1 and AKT2) were down-regulated and antiapoptotic genes (APAF1 and BCL2L1) were up-regulated in multiple myeloma, both symptomatic and asymptomatic, compared to monoclonal gammopathy of undetermined significance. When we looked for those genes progressively modulated through the evolving stages of monoclonal gammopathies, eight snoRNA showed a progressive increase while APAF1, VCAN and MEGF9 exhibited a progressive downregulation. In conclusion, our data show that although monoclonal gammopathy of undetermined significance, smoldering myeloma and multiple myeloma are not clearly distinguishable groups according to their gene expression profiling, several signaling pathways and genes were significantly deregulated at different steps of the transformation process.

Phenotypic and genomic analysis of multiple myeloma minimal residual disease tumor cells: a new model to understand chemoresistance

Persistence of chemoresistant minimal residual disease (MRD) plasma cells (PCs) is associated with inferior survival in multiple myeloma (MM). Thus, characterization of the minor MRD subclone may represent a unique model to understand chemoresistance, but to our knowledge, the phenotypic and genetic features of the MRD subclone have never been investigated. Here, we compared the antigenic profile of MRD vs diagnostic clonal PCs in 40 elderly MM patients enrolled in the GEM2010MAS65 study and showed that the MRD subclone is enriched in cells overexpressing integrins (CD11a/CD11c/CD29/CD49d/CD49e), chemokine receptors (CXCR4), and adhesion molecules (CD44/CD54). Genetic profiling of MRD vs diagnostic PCs was performed in 12 patients; 3 of them showed identical copy number alterations (CNAs), in another 3 cases, MRD clonal PCs displayed all genetic alterations detected at diagnosis plus additional CNAs that emerged at the MRD stage, whereas in the remaining 6 patients, there were CNAs present at diagnosis that were undetectable in MRD clonal PCs, but also a selected number of genetic alterations that became apparent only at the MRD stage. The MRD subclone showed significant downregulation of genes related to protein processing in endoplasmic reticulum, as well as novel deregulated genes such as ALCAM that is prognostically relevant in MM and may identify chemoresistant PCs in vitro. Altogether, our results suggest that therapy-induced clonal selection could be already present at the MRD stage, where chemoresistant PCs show a singular phenotypic signature that may result from the persistence of clones with different genetic and gene expression profiles. This trial was registered atwww.clinicaltrials.gov as #NCT01237249.

In vivo murine model of acquired resistance in myeloma reveals differential mechanisms for lenalidomide and pomalidomide in combination with dexamethasone

The development of resistance to therapy is unavoidable in the history of multiple myeloma patients. Therefore, the study of its characteristics and mechanisms is critical in the search for novel therapeutic approaches to overcome it. This effort is hampered by the absence of appropriate preclinical models, especially those mimicking acquired resistance. Here we present an in vivo model of acquired resistance based on the continuous treatment of mice bearing subcutaneous MM1S plasmacytomas. Xenografts acquired resistance to two generations of immunomodulatory drugs (IMiDs; lenalidomide and pomalidomide) in combination with dexamethasone, that was reversible after a wash-out period. Furthermore, lenalidomide–dexamethasone (LD) or pomalidomide–dexamethasone (PD) did not display cross-resistance, which could be due to the differential requirements of the key target Cereblon and its substrates Aiolos and Ikaros observed in cells resistant to each combination. Differential gene expression profiles of LD and PD could also explain the absence of cross-resistance. Onset of resistance to both combinations was accompanied by upregulation of the mitogen-activated protein kinase/extracellular signal–regulated kinase (ERK) kinase (MEK)/ERK pathway and addition of selumetinib, a small-molecule MEK inhibitor, could resensitize resistant cells. Our results provide insights into the mechanisms of acquired resistance to LD and PD combinations and offer possible therapeutic approaches to addressing IMiD resistance in the clinic.

Immune status of high-risk smoldering multiple myeloma patients and its therapeutic modulation under LenDex: a longitudinal analysis.

There is significant interest in immunotherapy for the treatment of high-risk smoldering multiple myeloma (SMM), but no available data on the immune status of this particular disease stage. Such information is important to understand the interplay between immunosurveillance and disease transformation, but also to define whether patients with high-risk SMM might benefit from immunotherapy. Here, we have characterized T lymphocytes (including CD4, CD8, T-cell receptor γδ, and regulatory T cells), natural killer (NK) cells, and dendritic cells from 31 high-risk SMM patients included in the treatment arm of the QUIREDEX trial, and with longitudinal peripheral blood samples at baseline and after 3 and 9 cycles of lenalidomide plus low-dose dexamethasone (LenDex). High-risk SMM patients showed at baseline decreased expression of activation-(CD25/CD28/CD54), type 1 T helper-(CD195/interferon-γ/tumor necrosis factor-α/interleukin-2), and proliferation-related markers (CD119/CD120b) as compared with age-matched healthy individuals. However, LenDex was able to restore the normal expression levels for those markers and induced a marked shift in T-lymphocyte and NK-cell phenotype. Accordingly, high-risk SMM patients treated with LenDex showed higher numbers of functionally active T lymphocytes. Together, our results indicate that high-risk SMM patients have an impaired immune system that could be reactivated by the immunomodulatory effects of lenalidomide, even when combined with low-dose dexamethasone, and support the value of therapeutic immunomodulation to delay the progression to multiple myeloma. The QUIREDEX trial was registered to www.clinicaltrials.gov as #NCT00480363.

Targeting of PI3K/AKT/mTOR pathway to inhibit T cell activation and prevent graft- versus-host disease development

BackgroundGraft-versus-host disease (GvHD) remains the major obstacle to successful allogeneic hematopoietic stem cell transplantation, despite of the immunosuppressive regimens administered to control T cell alloreactivity. PI3K/AKT/mTOR pathway is crucial in T cell activation and function and, therefore, represents an attractive therapeutic target to prevent GvHD development. Recently, numerous PI3K inhibitors have been developed for cancer therapy. However, few studies have explored their immunosuppressive effect.MethodsThe effects of a selective PI3K inhibitor (BKM120) and a dual PI3K/mTOR inhibitor (BEZ235) on human T cell proliferation, expression of activation-related molecules, and phosphorylation of PI3K/AKT/mTOR pathway proteins were analyzed. Besides, the ability of BEZ235 to prevent GvHD development in mice was evaluated.ResultsSimultaneous inhibition of PI3K and mTOR was efficient at lower concentrations than PI3K specific targeting. Importantly, BEZ235 prevented naïve T cell activation and induced tolerance of alloreactive T cells, while maintaining an adequate response against cytomegalovirus, more efficiently than BKM120. Finally, BEZ235 treatment significantly improved the survival and decreased the GvHD development in mice.ConclusionsThese results support the use of PI3K inhibitors to control T cell responses and show the potential utility of the dual PI3K/mTOR inhibitor BEZ235 in GvHD prophylaxis.