CD45 expression by bone marrow plasma cells in multiple myeloma: clinical and biological correlations

RNA-loaded nanoparticles for the treatment of hematological cancers

Hematological cancers encompass a diverse group of malignancies affecting the blood, bone marrow, lymph nodes, and spleen. These disorders present unique challenges due to their complex etiology and varied clinical manifestations. Despite significant advancements in understanding and treating hematological malignancies, innovative therapeutic approaches are continually sought to enhance patient outcomes. This review highlights the application of RNA nanoparticles (RNA-NPs) in the treatment of hematological cancers. We delve into detailed discussions on in vitro and preclinical studies involving RNA-NPs for adult patients, as well as the application of RNA-NPs in pediatric hematological cancer. The review also addresses ongoing clinical trials involving RNA-NPs and explores the emerging field of CAR-T therapy engineered by RNA-NPs. Finally, we discuss the challenges still faced in translating RNA-NP research to clinics.

LILRB4 on multiple myeloma cells promotes bone lesion by p-SHP2/NF-κB/RELT signal pathway

BACKGROUND

Leukocyte Ig-like receptor B family 4 (LILRB4) as an immune checkpoint on myeloid cells is a potential target for tumor therapy. Extensive osteolytic bone lesion is the most characteristic feature of multiple myeloma. It is unclear whether ectopic LILRB4 on multiple myeloma regulates bone lesion.

METHODS

The conditioned medium (CM) from LILRB4-WT and -KO cells was used to analyze the effects of LILRB4 on osteoclasts and osteoblasts. Xenograft, syngeneic and patient derived xenograft models were constructed, and micro-CT, H&E staining were used to observe the bone lesion. RNA-seq, cytokine array, qPCR, the activity of luciferase, Co-IP and western blotting were used to clarify the mechanism by which LILRB4 mediated bone damage in multiple myeloma.

RESULTS

We comprehensively analyzed the expression of LILRB4 in various tumor tissue arrays, and found that LILRB4 was highly expressed in multiple myeloma samples. The patient's imaging data showed that the higher the expression level of LILRB4, the more serious the bone lesion in patients with multiple myeloma. The conditioned medium from LILRB4-WT not -KO cells could significantly promote the differentiation and maturation of osteoclasts. Xenograft, syngeneic and patient derived xenograft models furtherly confirmed that LILRB4 could mediate bone lesion of multiple myeloma. Next, cytokine array was performed to identify the differentially expressed cytokines, and RELT was identified and regulated by LILRB4. The overexpression or exogenous RELT could regenerate the bone damage in LILRB4-KO cells in vitro and in vivo. The deletion of LILRB4, anti-LILRB4 alone or in combination with bortezomib could significantly delay the progression of bone lesion of multiple myeloma.

CONCLUSIONS

Our findings indicated that LILRB4 promoted the bone lesion by promoting the differentiation and mature of osteoclasts through secreting RELT, and blocking LILRB4 singling pathway could inhibit the bone lesion.

Immunophenotypic Profile and Measurable Residual Disease Monitoring in Multiple Myeloma: A Prospective Study From a Tertiary Care Centre in Southern India

BACKGROUND

Multiple myeloma (MM) immunophenotyping (IPT) and measurable residual disease (MRD) monitoring by flow cytometry is a surrogate for progression-free survival and overall survival in clinical trials. However, plasma cell enumeration is challenging owing to morphological discrepancies and plasma cell (PC) loss during the sample processing.

METHODS

In (n=87) newly diagnosed MM patients, we evaluated the immunophenotype of PCs at baseline, and for a subset of 35 patients MRD at post-induction was quantified and analyzed for association with outcomes and survival. The software Statistical Package for Social Sciences (SPSS), version 16.0 (SPSS Inc., Chicago, IL, USA) was used for all the statistical analysis.

RESULTS

Immunophenotyping showed strong positive expression of CD56 (83%), CD200 (94%), CD38 (92%), and CD117 (91%) and negative/weak expression of CD19 (83%), CD45 (89%), CD27 (74%), and CD81 (90%) respectively. Negative/weak expression of CD19 was significantly associated with age ≥56 years (p<0.048), with lower albumin (<3.4g/dL, p<0.001). Strong positive CD56 expression was significantly associated with the presence of M-protein (p<0.03). Strong positive CD117 expression was significantly associated with lower albumin (p<0.02). Strong positive CD200 expression was significantly associated with a good response (p<0.02). The median (IQR) value of bone marrow (BM)-MRD% was 0.005 (0.002-0.034). We found that there was no significant difference in the correlation, association, and survival outcomes with MRD%.

CONCLUSION

This study sheds light on the utility of IPT as an invaluable diagnostic tool in disease management. The findings of this study could be important when it comes to modifying the criteria for high-risk diseases and implementing a risk-adapted first therapy in clinical practice.

Phenotypic and Functional Characterization of Bovine Adipose-Derived Mesenchymal Stromal Cells

BACKGROUND

Mesenchymal stem cells (MSCs) are increasingly trialed in cellular therapy applications in humans. They can also be applied to treat a range of diseases in animals, particularly in cattle to combat inflammatory conditions and aging-associated degenerative disorders. We sought to demonstrate the feasibility of obtaining MSCs from adipose tissue and characterizing them using established assays.

METHODS

Bovine adipose MSCs (BvAdMSCs) were isolated using in-house optimized tissue digestion protocols and characterized by performing a colony formation assay, cell growth assessments, cell surface marker analysis by immunocytochemistry and flow cytometry, osteogenic and adipogenic differentiation, and secretion of indoleamine 2,3-dioxygenease (IDO).

RESULTS

Our results demonstrate the feasibility of successful MSC isolation and culture expansion from bovine adipose tissues with characteristic features of colony formation, in vitro multilineage differentiation into osteogenic and adipogenic lineages, and cell surface marker expression of CD105, CD73, CD90, CD44, and CD166 with negative expression of CD45. BvAdMSCs secreted significant amounts of IDO with or without interferon-gamma stimulation, indicating ability for immunomodulation.

CONCLUSIONS

We report a viable approach to obtaining autologous adipose-derived MSCs that can be applied as potential adjuvant cell therapy for tissue repair and regeneration in cattle. Our methodology can be utilized by veterinary cell therapy labs for preparing MSCs for disease management in cattle.

A comparative analysis of transcriptomics of newly diagnosed multiple myeloma: exploring drug repurposing

Multiple myeloma (MM) is an incurable malignant plasma cell disorder characterized by the infiltration of clonal plasma cells in the bone marrow compartment. Gene Expression Profiling (GEP) has emerged as a powerful investigation tool in modern myeloma research enabling the dissection of the molecular background of MM and allowing the identification of gene products that could potentially serve as targets for therapeutic intervention. In this study we investigated shared transcriptomic abnormalities across newly diagnosed multiple myeloma (NDMM) patient cohorts. In total, publicly available transcriptomic data of 7 studies from CD138+ cells from 281 NDMM patients and 44 healthy individuals were integrated and analyzed. Overall, we identified 28 genes that were consistently differentially expressed (DE) between NDMM patients and healthy donors (HD) across various studies. Of those, 9 genes were over/under-expressed in more than 75% of NDMM patients. In addition, we identified 4 genes (MT1F, PURPL, LINC01239 and LINC01480) that were not previously considered to participate in MM pathogenesis. Meanwhile, by mining three drug databases (ChEMBL, IUPHAR/BPS and DrugBank) we identified 31 FDA-approved and 144 experimental drugs that target 8 of these 28 over/under-expressed MM genes. Taken together, our study offers new insights in MM pathogenesis and importantly, it reveals potential new treatment options that need to be further investigated in future studies.

Immunophenotypic profile defines cytogenetic stability and unveils distinct prognoses in patients with newly-diagnosed multiple myeloma (NDMM)

Prognostic significance of multiple immune antigens in multiple myeloma has been well established. However, a level of uncertainty remains regarding the intrinsic relationship between immunophenotypes and cytogenetic stability and precise risk stratification. To address these unresolved issues, we conducted a study involving 1389 patients enrolled in the National Longitudinal Cohort of Hematological Diseases in China (NCT04645199). Our results revealed that the correlation between antigen expression and cytogenetics is more prominent than cytopenia or organ dysfunction. Most immune antigens, apart from CD38, CD138, and CD81, exhibit significant associations with the incidence of at least one cytogenetic abnormality. In turn, we identified CD138-low/CD27-neg as specific adverse immunophenotypic profile, which remaining independent impact on progression-free survival (HR, 1.49; P = 0.007) and overall survival (HR, 1.77; P < 0.001) even in the context of cytogenetics. Importantly, CD138-low/CD27-neg profile was also associated with inferior survival after first relapse (P < 0.001). Moreover, the antigen expression profiles were not strictly similar when comparing diagnosis and relapse; in particular, the CD138-low/CD27-neg pattern was notably increased after disease progression (19.1 to 29.1%; P = 0.005). Overall, our study demonstrates that diverse immune profiles are strongly associated with cytogenetic stability, and a specific immunophenotype (CD138-low/CD27-neg) could effectively predict prognoses across different disease stages.

CD45 inhibition in myeloid leukaemia cells sensitizes cellular responsiveness to chemotherapy

Myeloid malignancies are a group of blood disorders characterized by the proliferation of one or more haematopoietic myeloid cell lineages, predominantly in the bone marrow, and are often caused by aberrant protein tyrosine kinase activity. The protein tyrosine phosphatase CD45 is a trans-membrane molecule expressed on all haemopoietic blood cells except that of platelets and red cells. CD45 regulates various cellular physiological processes including proliferation, apoptosis, and lymphocyte activation. However, its role in chemotherapy response is still unknown; therefore, the aim of this study was to investigate the role of CD45 in myeloid malignancies in terms of cellular growth, apoptosis, and response to chemotherapy. The expression of CD45 on myeloid leukaemia primary cells and cell lines was heterogeneous with HEL and OCI-AML3 cells showing the highest level. Inhibition of CD45 resulted in increased cellular sensitivity to cytarabine and ruxolitinib, the two main therapies for AML and MPN. Bioinformatics analysis identified genes whose expression was correlated with CD45 expression such as JAK2, ACTR2, THAP3 Serglycin, and PBX-1 genes, as well as licensed drugs (alendronate, allopurinol, and balsalazide), which could be repurposed as CD45 inhibitors which effectively increases sensitivity to cytarabine and ruxolitinib at low doses. Therefore, CD45 inhibition could be explored as a potential therapeutic partner for treatment of myeloid malignancies in combination with chemotherapy such as cytarabine especially for elderly patients and those showing chemotherapy resistance.

Identification of key genes and immune infiltration in multiple myeloma by bioinformatics analysis

OBJECTIVE

Multiple Myeloma (MM) is a hematologic malignant disease with unclear molecular mechanisms. This integrated bioinformatic study aimed to identify key genes, pathways and immune cell infiltration pattern in MM.

METHODS

Differentially expressed genes (DEGs) from GSE6477 and GSE16558 dataset were filtrated with R package 'limma', whose function were explored by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. The key genes were selected from Protein-protein interaction network (PPI) and logistic regression model. The correlation between key genes and survival in MM was evaluated using the survival and survminer package. Additionally, immune filtration analysis was accomplished by CIBERSORT tools.

RESULTS

118 DEGs (92 up-regulated and 26 down-regulated) from two GSE datasets were identified, which were closely related with B cell receptor signaling pathway and Epstein-Barr virus infection. Furthermore, CD24 and PTPRC of five hub genes identified in PPI network were further screened out by the logistic regression model. Besides, CD24 and PTPRC expression were significantly correlated to the survival time in MM patients. Finally, MM might cause different infiltrating immune cell compositions, including increased infiltrations of B cells memory, Plasma cells, T cells CD4 memory resting, T cells follicular helper, Tregs, NK cells resting, Macrophages(M0/M1), Dendritic cells resting and Mast cells activating, and lower proportions of B cells naïve, T cells CD4 naïve, Macrophages M2 and Neutrophils.

CONCLUSION

Targeting CD24 and PTPRC as molecular markers of MM is valuable to MM therapy. Moreover, the immune cell infiltration will provide new insights into MM immunopathology.

Encapsulation of Nano-Bortezomib in Apoptotic Stem Cell-Derived Vesicles for the Treatment of Multiple Myeloma

Extracellular vesicles (EVs) are lipid bilayer nanovesicles released from living or apoptotic cells that can transport DNA, RNA, protein, and lipid cargo. EVs play critical roles in cell-cell communication and tissue homeostasis, and have numerous therapeutic uses including serving as carriers for nanodrug delivery. There are multiple ways to load EVs with nanodrugs, such as electroporation, extrusion, and ultrasound. However, these approaches may have limited drug-loading rates, poor EV membrane stability, and high cost for large-scale production. Here, it is shown that apoptotic mesenchymal stem cells (MSCs) can encapsulate exogenously added nanoparticles into apoptotic vesicles (apoVs) with a high loading efficiency. When nano-bortezomib is incorporated into apoVs in culture-expanded apoptotic MSCs, nano-bortezomib-apoVs show a synergistic combination effect of bortezomib and apoVs to ameliorate multiple myeloma (MM) in a mouse model, along with significantly reduced side effects of nano-bortezomib. Moreover, it is shown that Rab7 regulates the nanoparticle encapsulation efficiency in apoptotic MSCs and that activation of Rab7 can increase nanoparticle-apoV production. In this study, a previously unknown mechanism to naturally synthesize nano-bortezomib-apoVs to improve MM therapy is revealed.

Mass Cytometry reveals unique phenotypic patterns associated with subclonal diversity and outcomes in multiple myeloma

Multiple myeloma (MM) remains an incurable plasma cell (PC) malignancy. Although it is known that MM tumor cells display extensive intratumoral genetic heterogeneity, an integrated map of the tumor proteomic landscape has not been comprehensively evaluated. We evaluated 49 primary tumor samples from newly diagnosed or relapsed/refractory MM patients by mass cytometry (CyTOF) using 34 antibody targets to characterize the integrated landscape of single-cell cell surface and intracellular signaling proteins. We identified 13 phenotypic meta-clusters across all samples. The abundance of each phenotypic meta-cluster was compared to patient age, sex, treatment response, tumor genetic abnormalities and overall survival. Relative abundance of several of these phenotypic meta-clusters were associated with disease subtypes and clinical behavior. Increased abundance of phenotypic meta-cluster 1, characterized by elevated CD45 and reduced BCL-2 expression, was significantly associated with a favorable treatment response and improved overall survival independent of tumor genetic abnormalities or patient demographic variables. We validated this association using an unrelated gene expression dataset. This study represents the first, large-scale, single-cell protein atlas of primary MM tumors and demonstrates that subclonal protein profiling may be an important determinant of clinical behavior and outcome.

Understanding the Bioactivity and Prognostic Implication of Commonly Used Surface Antigens in Multiple Myeloma

Multiple myeloma (MM) progression is dependent on its interaction with the bone marrow microenvironment and the immune system and is mediated by key surface antigens. Some antigens promote adhesion to the bone marrow matrix and stromal cells, while others are involved in intercellular interactions that result in differentiation of B-cells to plasma cells (PC). These interactions are also involved in malignant transformation of the normal PC to MM PC as well as disease progression. Here, we review selected surface antigens that are commonly used in the flow cytometry analysis of MM for identification of plasma cells (PC) and the discrimination between normal and malignant PC as well as prognostication. These include the markers: CD38, CD138, CD45, CD19, CD117, CD56, CD81, CD27, and CD28. Furthermore, we will discuss the novel marker CD24 and its involvement in MM. The bioactivity of each antigen is reviewed, as well as its expression on normal vs. malignant PC, prognostic implications, and therapeutic utility. Understanding the role of these specific surface antigens, as well as complex co-expressions of combinations of antigens, may allow for a more personalized prognostic monitoring and treatment of MM patients.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

A phase-1 trial of linsitinib (OSI-906) in combination with bortezomib and dexamethasone for the treatment of relapsed/refractory multiple myeloma

We report results of a phase-1 study evaluating the safety and anti-cancer activity of the small molecule insulin-like growth factor-1 receptor (IGF-1R) inhibitor, linsitinib combined with bortezomib, and dexamethasone in relapsed/refractory multiple myeloma. Nineteen patients were enrolled across four dose-escalation cohorts (75-150 mg bid). The maximum tolerated dose of linsitinib was 125 mg. The most frequent Grade 3/4 AEs occurring in ≥10% of patients were thrombocytopenia (53%), bone pain (26%), neutropenia (21%), diarrhea (14%), anemia (14%), rash (10%), and lung infection (10%). Study discontinuation due to treatment-related AEs was low (16%). Across all cohorts the ORR was 61% (95% CI: 28.9-75.6%). Three partial response or greater and one stable disease were observed in proteasome inhibitor (PI) refractory patients (n = 5). Median PFS was 7.1 months (95% CI: 3.6-NA). Linsitinib plus bortezomib and dexamethasone demonstrate a manageable safety profile while the clinical benefit particularly in PI refractory patients warrants further exploration.

Protein tyrosine phosphatases in multiple myeloma

Many cell signaling pathways are activated or deactivated by protein tyrosine phosphorylation and dephosphorylation, catalyzed by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), respectively. Even though PTPs are as important as PTKs in this process, their role has been neglected for a long time. Multiple myeloma (MM) is a cancer of plasma cells, which is characterized by production of monoclonal immunoglobulin, anemia and destruction of bone. MM is still incurable with high relapse frequency after treatment. In this review, we highlight the PTPs that were previously described in MM or have a role that can be relevant in a myeloma context. Our purpose is to show that despite the importance of PTPs in MM pathogenesis, many unanswered questions in this field need to be addressed. This might help to detect novel treatment strategies for MM patients.

Atypical Mature T-Cell Neoplasms: The Relevance of the Role of Flow Cytometry

Lymphoproliferative disorders are a heterogeneous group of malignant clonal proliferations of lymphocytes whose diagnosis remains challenging, despite diagnostic criteria are now well established, due to their heterogeneity in clinical presentation and immunophenotypic profile. Lymphoid T-cell disorders are more rarely seen than B-cell entities and more difficult to diagnose for the absence of a specific immunophenotypic signature. Flow cytometry is a useful tool in diagnosing T-cell lymphoproliferative disorders since it is not only able to better characterize T-cell neoplasms but also to resolve some very complicated cases, in particular those in which a small size population of neoplastic cells is available for the analysis. Here, we report three patients with mature T-cell neoplasms with atypical clinical and biological features in which analysis of peripheral blood and bone marrow specimens by means of multicolor flow cytometry was very useful to identify and characterize three rare T-cell lymphoproliferative disorders, such as angioimmunoblastic T-cell lymphoma, peripheral T-cell lymphoma not otherwise specified and T-cell prolymphocytic leukemia. The aim of this case series report is not only to describe three rare cases of lymphoproliferative neoplasms but also to raise awareness that a fast, highly sensitive, and reproducible procedure, such as flow cytometry immunophenotyping, can have a determinant diagnostic role in these patients.

CD19-positive antibody-secreting cells provide immune memory

Long-lived antibody-secreting cells (ASCs) are critical for the maintenance of humoral immunity through the continued production of antibodies specific for previously encountered pathogen or vaccine antigens. Recent reports describing humoral immune memory have suggested the importance of long-lived CD19^- bone marrow (BM) ASCs, which secrete antibodies recognizing previously encountered vaccine antigens. However, these reports do not agree upon the unique contribution of the CD19⁺ BM ASC subset toward humoral immunity. Here, we found both CD19⁺ and negative ASCs from human BM were similar in functional capacity to react to a number of vaccine antigens via ELISpot assays. The CD19⁺ cells were the predominant ASC population found in lymphoid tissues, and unlike the CD19^- ASCs, which were found only in spleen and BM, the CD19⁺ ASCs were found in tonsil and blood. CD19⁺ ASCs from the BM, spleen, and tonsil were capable of recognizing polio vaccine antigens, indicating the CD19⁺ ASC cells play a novel role in long-lasting immune defense. Comparative gene expression analysis indicated CD19⁺ and negative BM ASCs differed significantly by only 14 distinct messenger RNAs and exhibited similar gene expression for cell cycle, autophagy, and apoptosis control necessary for long life. In addition, we show identical CDR-H3 sequences found on both BM ASC subsets, indicating a shared developmental path. Together, these results provide novel insight for the distribution, function, genetic regulation, and development of long-lived ASCs and may not only impact improved cell therapies but also enhance strategies for vaccine development.

[Expression of CD45 in newly diagnosed multiple myeloma and the relationship with prognosis]

Objective: To explore the expression of CD45 in newly diagnosed multiple myeloma (MM) and its relationship with clinical efficacy and prognosis. Methods: This study retrospectively analyzed expression and distribution of CD45 in 130 cases of newly diagnosed MM, comparing clinical efficacy and prognosis in CD45(+)/CD45(-) groups. Results: ①The CD45(+) group was 33 cases (25.38%) , and CD45(-) group was 97 cases (74.62%) . ②The objective remission rate (ORR) of CD45(+) and CD45(-)group was 33.33% and 64.95%, respectively. The difference was statistically significant (P=0.002) . For patients in Bortezomib regimen, the ORR of CD45(+) and CD45(-) group was 35.71% and 66.25%, respectively. The difference was statistically significant (P=0.005) . ③The median progress free survival (PFS) of CD45(+) group and CD45(-) group was 29.8 (95%CI 10.0-59.0) months vs 34.5 (95%CI 6.0-69.0) months (χ(2)=14.59, P<0.001) and the median overall survival (OS) was 32.5 (95%CI 10.0-68.0) months vs 37.6 (95%CI 6.0-78.0) months (χ(2)=11.42, P=0.001) , respectively. Among the patients in bortezomib regimen, The median PFS and median OS of CD45 (+) group and CD45(-) group were 30.3 (95%CI 10.0-59.0) months vs 36.3 (95%CI 6.0-69.0) months (χ(2)=14.75, P=0.001) and 34.0 (95%CI 10.0-68.0) months vs 39.5 (95%CI 6.0-78.0) months (χ(2)=10.62, P=0.001) . ④Cox risk regression model analysis showed that serum creatinine≥176.8 μmol/L (HR=5.078, 95%CI 1.744-14.723, P=0.001) , CD45 positive (HR=14.504, 95%CI 0.168-0.42, P=0.001) , LDH≥220 IU/L (HR=1.308, 95%CI 1.16-2.417, P=0.015) were independent risk prognostic factors. Conclusion: CD45 expression is a risk prognostic factor of MM patients. Bortezomib did not improve the poor prognosis of CD45(+) MM patients.

Multiple Myeloma Exemplifies a Model of Cancer Based on Tissue Disruption as the Initiator Event

The standard model of multiple myeloma (MM) oncogenesis is based on the genetic instability of MM cells and presents its evolution as the emergence of clones with more and more aggressive genotypes, giving them surviving and proliferating advantage. The micro-environment has a passive role. In contrast, many works have shown that the progression of MM is also characterized by the selection of clones with extended phenotypes able to destroy bone trabeculae, suggesting a major role for early micro-environmental disruption. We present a model of MM oncogenesis in which genetic instability is the consequence of the disruption of normal interactions between plasma cells and their environment, the bone remodeling compartment. These interactions, which normally ensure the stability of the genotypes and phenotypes of normal plasma cells could be disrupted by many factors as soon as the early steps of the disease (MGUS, pre-MGUS states). Therapeutical implications of the model are presented.

Microfluidic enrichment of plasma cells improves treatment of multiple myeloma

Cytogenetic alterations form the basis for risk stratification for multiple myeloma (MM) and guide the selection of therapy; however, current pathology assays performed on bone marrow samples can produce false‐negatives due to the unpredictable distribution and rarity of MM cells. Here, we report on a microfluidic device used to facilitate CD45 depletion to enhance the detection of cytogenetic alterations in plasma cells (PCs). Bone marrow samples from 48 patients with MM were each divided into two aliquots. One aliquot was subjected to classic flow cytometry and fluorescent in situ hybridization (FISH). The other first went through CD45⁺ cell depletion, further enriched by microfluidic size selection. The enriched samples were then analyzed using flow cytometry and FISH and compared to those analyzed using the classic method only. Unlike the traditional method, the microfluidic device removed the CD45⁺ leukocytes and specifically selected PCs from the remaining white blood cells. Therefore, the microfluidic method (MF‐CD45‐TACs) significantly increased the percentage of CD38⁺/CD138⁺ cells to 37.7 ± 20.4% (P < 0.001) from 10.3 ± 8.5% in bone marrow. After the MF‐CD45‐TAC enrichment, the detection rate of IgH rearrangement, del(13q14), del(17p), and 1q21 gains, rose to 56.3% (P < 0.001), 37.5% (P < 0.001), 22.9% (P < 0.001), and 41.7% (P = 0.001), respectively; all rates of detection were significantly increased compared to the classically analyzed samples. In this clinical trial, this microfluidic‐assisted assay provided a precise detection of cytogenetic alterations in PCs and improved clinical outcomes.

Pre-treatment red blood cell distribution width provides prognostic information in multiple myeloma

BACKGROUND

The red blood cell distribution width (RDW), a credible marker for abnormal erythropoiesis, has recently been studied as a prognostic factor in oncology, but its role in multiple myeloma (MM) hasn't been thoroughly investigated.

METHODS

We performed a retrospective study in 162 patients with multiple myeloma. Categorical parameters were analyzed using Pearson chi-squared test. The Mann-Whitney and Wilcoxon tests were used for group comparisons. Comparisons of repeated samples data were analyzed with the general linear model repeated-measures procedure. The Kaplan-Meier product-limit method was used to determine OS and PFS, and the differences were assessed by the log-rank test.

RESULTS

High RDW baseline was significantly associated with indexes including haemoglobin, bone marrow plasma cell infiltration, and cytogenetics risk stratification. After chemotherapy, the overall response rate (ORR) decreased as RDW baseline increased. In 24 patients with high RDW baseline, it was revealed RDW value decreased when patients achieved complete remission (CR), but increased when the disease progressed. The normal-RDW baseline group showed both longer overall survival (OS) and progression-free survival (PFS) than the high-RDW baseline group.

CONCLUSION

Our study suggests pre-treatment RDW level is a prognostic factor in MM and should be regarded as an important parameter for assessment of therapeutic efficiency.

CD45 in human physiology and clinical medicine

CD45 is an evolutionary highly conserved receptor protein tyrosine phosphatase exclusively expressed on all nucleated cells of the hematopoietic system. It is characterized by the expression of several isoforms, specific to a certain cell type and the developmental or activation status of the cell. CD45 is one of the key players in the initiation of T cell receptor signaling by controlling the activation of the Src family protein-tyrosine kinases Lck and Fyn. CD45 deficiency results in T- and B-lymphocyte dysfunction in the form of severe combined immune deficiency. It also plays a significant role in autoimmune diseases and cancer as well as in infectious diseases including fungal infections. The knowledge collected on CD45 biology is rather vast, but it remains unclear whether all findings in rodent immune cells also apply to human CD45. This review focuses on human CD45 expression and function and provides an overview on its ligands and role in human pathology.

HIV integrase inhibitor, Elvitegravir, impairs RAG functions and inhibits V(D)J recombination

Integrase inhibitors are a class of antiretroviral drugs used for the treatment of AIDS that target HIV integrase, an enzyme responsible for integration of viral cDNA into host genome. RAG1, a critical enzyme involved in V(D)J recombination exhibits structural similarity to HIV integrase. We find that two integrase inhibitors, Raltegravir and Elvitegravir, interfered with the physiological functions of RAGs such as binding, cleavage and hairpin formation at the recombination signal sequence (RSS), though the effect of Raltegravir was limited. Circular dichroism studies demonstrated a distinct change in the secondary structure of RAG1 central domain (RAG1 shares DDE motif amino acids with integrases), and when incubated with Elvitegravir, an equilibrium dissociation constant (K_d) of 32.53±2.9 μM was determined by Biolayer interferometry, leading to inhibition of its binding to DNA. Besides, using extrachromosomal assays, we show that Elvitegravir inhibited both coding and signal joint formation in pre-B cells. Importantly, treatment with Elvitegravir resulted in significant reduction of mature B lymphocytes in 70% of mice studied. Thus, our study suggests a potential risk associated with the use of Elvitegravir as an antiretroviral drug, considering the evolutionary and structural similarities between HIV integrase and RAGs.

Clinical effect of immunophenotyping on the prognosis of multiple myeloma patients treated with bortezomib

In the present study, the effect of immunophenotyping on the prognoses of patients with multiple myeloma (MM) treated with bortezomib plus dexamethasone was investigated. The study involved 46 patients with MM, and analyzed the prognostic significance of the expression of cluster of differentiation (CD)45, CD56 and mature plasma cell (MPC)-1, and other factors including the International Staging System (ISS) stage, age, gender, the immunoglobulin subtype and the treatment line number prior to bortezomib treatment. Although CD56 and MPC-1 expression did not appear to affect the time to next treatment (TNT) or overall survival rate (OS), the univariate analysis determined that CD45 positivity was an adverse prognostic factor for TNT and OS, and that being male was significantly associated with inferior TNT and OS. Multivariate analyses determined that CD45 expression was prognostically significant for TNT and OS. In conclusion, CD45 positivity is an adverse prognostic factor in MM patients treated with bortezomib. The data from the present study demonstrate the clinical importance of classifying MM cells immunophenotypically to determine the prognoses of patients.

The prognostic significance of CD45 expression by clonal bone marrow plasma cells in patients with newly diagnosed multiple myeloma

Evaluation of clonal plasma cells (PCs) in the bone marrow (BM) of multiple myeloma (MM) patients reveals two distinct clonal PC populations based on the presence or absence of CD45 expression. We explored the prognostic significance of CD45 expression by clonal PCs in the BM of MM patients in the era of novel agent therapy. All 156 MM patients seen at the Mayo Clinic, Rochester from 2009 to 2011 who had their BM evaluated by multiparametric flow cytometry were included. Patients whose BM had ≥20% of the clonal PCs expressing CD45 were classified as CD45 positive (+) and the rest as CD45 negative (-). Of these patients, the median overall survival (OS) for patients in the CD45 (+) group (n=43, 28%) was 38 months versus not reached for the CD45 (-) group (n=113, 72%) (P=0.009). In a multivariable analysis, CD45 (+) status was an independent predictor of inferior OS among newly diagnosed patients with MM. CD45 expression may be a surrogate for a more aggressive phenotype of MM and warrants further investigation.

The prognostic impact of multiparameter flow cytometry immunophenotyping and cytogenetic aberrancies in patients with multiple myeloma

OBJECTIVES

The aim of this study was to evaluate the prognostic impact of immunophenotyping in patients with multiple myeloma (MM), as well as other markers of disease, such as serum hyaluronan and cytogenetic aberrancies.

METHODS

We have prospectively analyzed the prognostic impact of antigenic markers, assessed by multiparametric flow cytometry (MFC), in a series of newly diagnosed MM patients (n = 79).

RESULTS AND DISCUSSION

Our results show that the expression of CD44, CD45, and CD28 and the absence of CD117 were associated with a significantly shorter progression free-survival (PFS). Clinical characteristics were collected; Cytogenetic aberrancies were assessed in 40 patients. Multivariate survival analyses identified that the CD117(-), CD28(+), CD45(+), and the percentage of bone marrow plasma cells by MFC are survival predictor, along with the International Staging System stage. Interestingly, the CD117(-) patients were associated with chromosomal aberrancies, including del (17p), +1q21, and IgH translocations.

CONCLUSION

The incorporation of multiparameter flow cytometry immunophenotyping into the routine diagnostic evaluation of MM patients can help to identify patients at a high risk of progression.

MDX-1097 induces antibody-dependent cellular cytotoxicity against kappa multiple myeloma cells and its activity is augmented by lenalidomide

MDX-1097 is an antibody specific for a unique B cell antigen called kappa myeloma antigen (KMA) that consists of cell membrane-associated free kappa light chain (κFLC). KMA was detected on kappa human multiple myeloma cell lines (κHMCLs), on plasma cells (PCs) from kappa multiple myeloma (κMM) patients and on κPC dyscrasia tissue cryosections. In primary κMM samples, KMA was present on CD38+ cells that were CD138 and CD45 positive and/or negative. MDX-1097 exhibited a higher affinity for KMA compared to κFLC and the latter did not abrogate binding to KMA. MDX-1097-mediated antibody-dependent cellular cytotoxicity (ADCC) and in vitro exposure of target cells to the immunomodulatory drug lenalidomide resulted in increased KMA expression and ADCC. Also, in vitro exposure of peripheral blood mononuclear cells (PBMCs) to lenalidomide enhanced MDX-1097-mediated ADCC. PBMCs obtained from myeloma patients after lenalidomide therapy elicited significantly higher levels of MDX-1097-mediated ADCC than cells obtained prior to lenalidomide treatment. These data establish KMA as a relevant cell surface antigen on MM cells that can be targeted by MDX-1097. The ADCC-inducing capacity of MDX-1097 and its potentiation by lenalidomide provide a powerful rationale for clinical evaluation of MDX-1097 alone and in combination with lenalidomide.

Immune cell inhibition by SLAMF7 is mediated by a mechanism requiring src kinases, CD45, and SHIP-1 that is defective in multiple myeloma cells

Signaling lymphocytic activation molecule F7 (SLAMF7) is a receptor present on immune cells, including natural killer (NK) cells. It is also expressed on multiple myeloma (MM) cells. This led to development of an anti-SLAMF7 antibody, elotuzumab, showing efficacy against MM. SLAMF7 mediates activating or inhibitory effects in NK cells, depending on whether cells express or do not express the adaptor EAT-2. Since MM cells lack EAT-2, we elucidated the inhibitory effectors of SLAMF7 in EAT-2-negative NK cells and tested whether these effectors were triggered in MM cells. SLAMF7-mediated inhibition in NK cells lacking EAT-2 was mediated by SH2 domain-containing inositol phosphatase 1 (SHIP-1), which was recruited via tyrosine 261 of SLAMF7. Coupling of SLAMF7 to SHIP-1 required Src kinases, which phosphorylated SLAMF7. Although MM cells lack EAT-2, elotuzumab did not induce inhibitory signals in these cells. This was at least partly due to a lack of CD45, a phosphatase required for Src kinase activation. A defect in SLAMF7 function was also observed in CD45-deficient NK cells. Hence, SLAMF7-triggered inhibition is mediated by a mechanism involving Src kinases, CD45, and SHIP-1 that is defective in MM cells. This defect might explain why elotuzumab eliminates MM cells by an indirect mechanism involving the activation of NK cells.

Antigen Expression Patterns of Plasma Cell Myeloma: An Association of Cytogenetic Abnormality and International Staging System (ISS) for Myeloma

BACKGROUND

Immunophenotyping of plasma cell has become an important diagnostic tool for plasma cell myeloma. There have been a few studies for association of antigen expression and cytogenetic abnormality of plasma cell myeloma.

METHODS

A total of 68 symptomatic/smoldering plasma cell myeloma case were analyzed by multicolor flow cytometry using CD38 and CD138 for primary gating of plasma cells. A conventional cytogenetics and fluorescence in situ hybridization (FISH) studies for detection of del(13q) or aneuploidy, del(17p), and IGH/FGFR translocation were done. We statistically analyzed the association of antigen expression and cytogenetic abnormality/myeloma stage (international staging system for multiple myeloma).

RESULTS

Positive expression of CD19, CD28, CD45, CD56, CD117, and CD274 was detected in 8.8%, 50.0%, 50.0%, 75.0%, 39.7%, and 2.9% of cases, respectively. CD117-negative cases were associated with hypodiploidy (P = 0.017). CD45-negative cases were associated with deletion 13 or aneuploidy (P < 0.001) and del(17p)(P = 0.011) by FISH. CD45-negativity or CD117-negativity was associated with advanced stage (P = 0.012 and P = 0.016, respectively).

CONCLUSION

The antigen expression patterns of myeloma plasma cell were associated with cytogenetic abnormality and stage.

Flow cytometric pattern recognition of lymph node biopsies with lymphomas that lack lineage characteristics

Although immunophenotyping (IPT) using flow cytometry is a routine technique that is applied in many laboratories as a diagnostic tool for lymphadenopathy, some diagnostic challenges persist. In this review, we will discuss pitfalls in the daily practice of lymph node diagnostics with the focus on general characteristics as lymphoid scatter patterns and lineage specific antigens that are used to define lymphoid populations. The absence of these characteristics on proliferating lymphoid cells can potentially lead to a wrong diagnosis. At the same time, this provides evidence for malignant transformation. Sporadic examples of reactive lymphoid proliferations with similar phenotypes are also discussed, illustrating the need for correlating IPT with morphology and clinical features.

Polyclonal serum IgM level identifies a subgroup of multiple myeloma patients with low-risk clinicobiological features and superior survival

Normal plasma cells (PCs) are either undetectable or outnumbered by the myelomatous PC compartment in bone marrow of multiple myeloma (MM). However, residual normal PCs have been detected in a minority of symptomatic MM patients with superior survival. The number of normal PCs is also an important factor to identify monoclonal gammopathy of undetermined significance (MGUS)-like MM. We speculate that the polyclonal serum IgM level in non-IgM myelomas may reflect the number of residual normal PCs. Here we investigated the prognostic relevance of polyclonal serum IgM level in a series of 485 newly diagnosed symptomatic MM (NDMM) patients. Our results showed that symptomatic MM patients with polyclonal IgM more than 0.5g/L displayed a favorable baseline clinical feature, together with a significantly lower frequency of high-risk cytogenetic abnormalities. This group of patients had a significantly prolonged progression-free survival (PFS) and overall survival (OS) regardless of thalidomide or bortezomib therapy. Furthermore, the superior outcome was independent of the depth of response. Our findings suggest that polyclonal IgM level is capable of identifying a group of symptomatic MM patients with distinct clinicobiological characteristics and favorable survival, similar with MGUS-like MM.

Bortezomib influences the expression of malignant plasma cells membrane antigens

Multiple myeloma cells can be characterized immunophenotypically as the expression levels of several membrane antigens differ from those of normal plasma cells. These antigens are important for making a diagnostic of multiple myeloma; they have a significant role in survival and proliferation of multiple myeloma cells. Analyzing the effect of bortezomib on the expression of surface antigens CD138, CD56, CD27, CD28, CD45 and CD221 and xenograft models, we have found that bortezomib increases the level of CD45 and decreases all other antigens. Bortezomib induces the reduction of IGF-1R (CD221) and syndecan 1 (CD138). This effect was associated with the reduced activation of Ras/MAPK, mTOR/p70S6K and JAK/STAT pathways in response to IGF-1 and IL-6. These results suggest that bortezomib may influence the sensitivity of myeloma cells to soluble growth factors by down-regulation of membrane receptors.

Simplified flow cytometric immunophenotyping panel for multiple myeloma, CD56/CD19/CD138(CD38)/CD45, to differentiate neoplastic myeloma cells from reactive plasma cells

Background

Flow cytometric immunophenotyping has been used to identify neoplastic plasma cell populations in patients with multiple myeloma (MM). Previous reports have described the use of several antigens, including CD38, CD138, CD56, CD117, CD52, CD19 and CD45, to distinguish distinct populations of plasma cells. The aim of this study was to evaluate a simplified immunophenotyping panel for MM analysis.

Methods

A total of 70 patients were enrolled in the study, 62 of which were newly diagnosed with MM (untreated), whereas the remaining 8 were undergoing bone marrow assessment as part of follow-up after treatment (treated). Treated cases included 3 patients with relapse and 5 patients with persistence of MM. Multiparametric flow cytometric immunophenotyping was performed using monoclonal antibodies against CD56, CD19, CD138 (CD38), and CD45.

Results

In differential counts, plasma cells in bone marrow (BM) accounted for 3.6-93.2% of the total nucleated cell count. The positive expression rates of CD56, CD19, CD138, and CD45 in neoplastic myeloma cells were 83.9%, 0%, 98.4%, and 37.1%, respectively, among the 62 untreated cases, and 75.0%, 0%, 87.5%, and 37.5%, respectively, among the 8 treated cases. CD19 expression of neoplastic plasma cells was negative in both untreated and treated cases.

Conclusion

The simplified immunophenotyping panel, CD56/CD19/CD138(CD38)/CD45, is useful for distinguishing neoplastic myeloma cells from reactive plasma cells in clinical practice. In addition, CD19 represents the most valuable antigen for identifying neoplastic myeloma cells in patients with MM.

An activated JAK/STAT3 pathway and CD45 expression are associated with sensitivity to Hsp90 inhibitors in multiple myeloma

The molecular chaperone Hsp90 is required to maintain the activity of many signaling proteins, including members of the JAK/STAT and the PI3K pathways. Inhibitors of Hsp90 (Hsp90-Is) demonstrated varying activity against multiple myeloma (MM) in clinical trials. We aimed to determine which signaling pathways that account for the differential sensitivity to the Hsp90-I 17DMAG on a panel of MM cell lines and freshly obtained MM cells. Three CD45(+) cell lines with an activated JAK/STAT3 pathway were sensitive to 17DMAG and underwent prominent apoptosis upon treatment, while the majority of CD45(-) cell lines, that were dependent on the activated PI3K pathway, were more resistant to the drug. Culturing the most resistant cell line, LP1, in the presence of IL-6 resulted in up-regulation of CD45 and pSTAT3, and sensitized to 17DMAG-induced apoptosis, primarily in the induced CD45(+) sub-population of cells. The high CD45 expressers among primary myeloma cells also expressed significantly higher levels of pSTAT3, as compared to the low CD45 expressers. Ex vivo treatment of primary myeloma cells with 17DMAG resulted in a stronger caspase3 activation in tumor samples with the prevalence of high CD45 expressers. STAT3 activity was efficiently inhibited by Hsp90-Is in both cell lines and primary cells suggesting an importance of STAT3 inactivation for the pro-apoptotic effects of HSP90-Is. Indeed, over-expression of STAT3C, a variant with an increased DNA binding activity, in U266 cells protected them from 17DMAG-induced cell death. The down-regulation of the STAT3 target gene Mcl-1 at both the mRNA and protein levels following 17DMAG treatment was significantly attenuated in STAT3C-expressing cells, and transient over-expression of Mcl-1 protected U266 cells from 17DMAG-induced cell death. The finding that CD45(+) MM cells with an IL-6-activated JAK/STAT3 pathway are particularly sensitive to Hsp90-Is as compared to the low CD45 expressers may provide a rational basis for selection of MM patients amenable to Hsp90-I treatment.

The role of microenvironment in tumor angiogenesis

Tumor microenvironment is essential for tumor cell proliferation, angiogenesis, invasion and metastasis through its provision of survival signals, secretion of growth and pro-angiogenic factors, and direct adhesion molecule interactions. This review examines its importance in the induction of an angiogenic response in tumors and in multiple myeloma. The encouraging results of pre-clinical and clinical trials in which tumors have been treated by targeting the tumor microenvironment are also discussed.

Increased expression of extracellular matrix metalloproteinase inducer (CD147) in multiple myeloma: role in regulation of myeloma cell proliferation

Multiple myeloma (MM) is preceded by the asymptomatic pre-malignant state, monoclonal gammopathy of undetermined significance (MGUS). Although MGUS patients may remain stable for years, they are at increased risk of progressing to MM. A better understanding of the relevant molecular changes underlying the transition from an asymptomatic to symptomatic disease state is urgently needed. Our studies show for the first time that the CD147 molecule (extracellular matrix metalloproteinase inducer) may be having an important biological role in MM. We first demonstrate that CD147 is overexpressed in MM plasma cells (PCs) vs normal and pre-malignant PCs. Next, functional studies revealed that the natural CD147 ligand, cyclophilin B, stimulates MM cell growth. Moreover, when MM patient PCs displaying bimodal CD147 expression were separated into CD147(bright) and CD147(dim) populations and analyzed for proliferation potential, we discovered that CD147(bright) PCs displayed significantly higher levels of cell proliferation than did CD147(dim) PCs. Lastly, CD147-silencing significantly attenuated MM cell proliferation. Taken together, these data suggest that the CD147 molecule has a key role in MM cell proliferation and may serve as an attractive target for reducing the proliferative compartment of this disease.

Extraosseous (extramedullary) plasmacytomas: a clinicopathologic and immunophenotypic study of 32 Chinese cases

Background

Extraosseous plasmacytoma, so called extramedullary plasmacytoma (EMP) is relatively rare in China. The aim was investigate the clinicopathologic features of EMP and the role of Immunophenotype and genotype detection in diagnosis of EMP.

Methods

Thirty-two cases of EMP were investigated retrospectively by histopathology, immunophenotype, genotype and survival analysis.

Results

Clinically, the mean age of the patients was 53.4. Most of the patients received no treatment after the diagnosis was established, and the prognosis was relatively poor. Histologically, in 40% of the cases, the neoplastic cells were grade II or III. The neoplastic cells expressed one or more PC associated antigens. The immunophenotype of EMP and inflammation of sinonasal regions with numerous PC infiltrations were compared and showed some difference in expression of CD45, CD27, CD44v6 and Bcl-2 as well. Ig light chain restriction was detected in 87.5% of the cases.

Conclusions

we described 32 Chinese cases of EMP, compare with that reported in the literature, some differences are presented, including higher percentage of grade II and III cases, clinically inconsistent treatment and management as well as poor outcome of the disease.

The novel JAK inhibitor CYT387 suppresses multiple signalling pathways, prevents proliferation and induces apoptosis in phenotypically diverse myeloma cells

Janus kinases (JAKs) are involved in various signalling pathways exploited by malignant cells. In multiple myeloma (MM), the interleukin-6/JAK/signal transducers and activators of transcription (IL-6/JAK/STAT) pathway has been the focus of research for a number of years and IL-6 has an established role in MM drug resistance. JAKs therefore make a rational drug target for anti-MM therapy. CYT387 is a novel, orally bioavailable JAK1/2 inhibitor, which has recently been described. This preclinical evaluation of CYT387 for treatment of MM demonstrated that CYT387 was able to prevent IL-6-induced phosphorylation of STAT3 and greatly decrease IL-6- and insulin-like growth factor-1-induced phosphorylation of AKT and extracellular signal-regulated kinase in human myeloma cell lines (HMCL). CYT387 inhibited MM proliferation in a time- and dose-dependent manner in 6/8 HMCL, and this was not abrogated by the addition of exogenous IL-6 (3/3 HMCL). Cell cycling was inhibited with a G(2)/M accumulation of cells, and apoptosis was induced by CYT387 in all HMCL tested (3/3). CYT387 synergised in killing HMCL when used in combination with the conventional anti-MM therapies melphalan and bortezomib. Importantly, apoptosis was also induced in primary patient MM cells (n=6) with CYT387 as a single agent, and again synergy was seen when combined with conventional therapies.

Utility of flow cytometry immunophenotyping in multiple myeloma and other clonal plasma cell-related disorders

In recent years, multiparameter flow cytometry (MFC) immunophenotyping has become mandatory in the clinical management of hematological malignancies, both for diagnostic and monitoring purposes. Multiple myeloma (MM) and other clonal plasma cell-related (PC) disorders should be no exception to this paradigm, but incorporation of immunophenotypic studies in the management of patients with PC disorders is still far from being routinely established in many diagnostic flow cytometry laboratories. For clonal PC disorders, MFC is of clear and established clinical relevance in: (1) the differential diagnosis between MM and other PC-related disorders; (2) the identification of high-risk MGUS and smoldering MM; (3) minimal residual disease investigation after therapy; additionally it may also be useful for (4) the definition of prognosis-associated antigenic profiles; and (5) the identification of new therapeutic targets. In this article, we review the clinical value of MFC in the study of PC disorders, with specific emphasis in those areas where consensus exists on the need to incorporate MFC into routine evaluation of MM and other clonal PC-related disorders.

TG101209, a novel JAK2 inhibitor, has significant in vitro activity in multiple myeloma and displays preferential cytotoxicity for CD45+ myeloma cells

Interaction of myeloma cells with the bone marrow microenvironment is mediated in large part through different cytokines, especially VEGF and IL6. These cytokines, especially IL6, leads to upregulation of the JAK/STAT pathway in myeloma cell, contributing to increased proliferation, decreased apoptosis, and acquired drug resistance. Here, we examined the preclinical activity of a novel JAK2 inhibitor TG101209. TG101209 induced dose- and time-dependent cytotoxicity in a variety of multiple myeloma (MM) cell lines. The induction of cytotoxicity was associated with inhibition of cell cycle progression and induction of apoptosis in myeloma cell lines and patient-derived plasma cells. Evaluation of U266 cell lines and patient cells, which have a mix of CD45 positive and negative cells, demonstrated more profound cytotoxicity and antiproliferative activity of the drug on the CD45+ population relative to the CD45- cells. Exploring the mechanism of action of TG101209 indicated downregulation of pJak2, pStat3, and Bcl-xl levels with upregulation of pErk and pAkt levels indicating cross talk between signaling pathways. TG101209, when used in combination with the PI3K inhibitor LY294002, demonstrated synergistic cytotoxicity against myeloma cells. Our results provide the rationale for clinical evaluation of TG101209 alone or in combination with PI3K/Akt inhibitors in MM.