Potential therapeutic biomarkers in plasma cell myeloma: a flow cytometry study

CAR T therapies in multiple myeloma: unleashing the future

In recent years, the field of cancer treatment has witnessed remarkable breakthroughs that have revolutionized the landscape of care for cancer patients. While traditional pillars such as surgery, chemotherapy, and radiation therapy have long been available, a cutting-edge therapeutic approach called CAR T-cell therapy has emerged as a game-changer in treating multiple myeloma (MM). This novel treatment method complements options like autologous stem cell transplants and immunomodulatory medications, such as proteasome inhibitors, by utilizing protein complexes or anti-CD38 antibodies with potent complement-dependent cytotoxic effects. Despite the challenges and obstacles associated with these treatments, the recent approval of the second FDA multiple myeloma CAR T-cell therapy has sparked immense promise in the field. Thus far, the results indicate its potential as a highly effective therapeutic solution. Moreover, ongoing preclinical and clinical trials are exploring the capabilities of CAR T-cells in targeting specific antigens on myeloma cells, offering hope for patients with relapsed/refractory MM (RRMM). These advancements have shown the potential for CAR T cell-based medicines or combination therapies to elicit greater treatment responses and minimize side effects. In this context, it is crucial to delve into the history and functions of CAR T-cells while acknowledging their limitations. We can strategize and develop innovative approaches to overcome these barriers by understanding their challenges. This article aims to provide insights into the application of CAR T-cells in treating MM, shedding light on their potential, limitations, and strategies employed to enhance their efficacy.

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.

Targeting TGF-β signaling in the multiple myeloma microenvironment: Steering CARs and T cells in the right direction

Multiple myeloma (MM) remains a lethal hematologic cancer characterized by the expansion of transformed plasma cells within the permissive bone marrow (BM) milieu. The emergence of relapsed and/or refractory MM (RRMM) is provoked through clonal evolution of malignant plasma cells that harbor genomic, metabolic and proteomic perturbations. For most patients, relapsed disease remains a major cause of overall mortality. Transforming growth factors (TGFs) have pleiotropic effects that regulate myelomagenesis as well as the emergence of drug resistance. Moreover, TGF-β modulates numerous cell types present with the tumor microenvironment, including many immune cell types. While numerous agents have been FDA-approved over the past 2 decades and significantly expanded the treatment options available for MM patients, the molecular mechanisms responsible for drug resistance remain elusive. Multiple myeloma is uniformly preceded by a premalignant state, monoclonal gammopathy of unknown significance, and both conditions are associated with progressive deregulation in host immunity characterized by reduced T cell, natural killer (NK) cell and antigen-presenting dendritic cell (DC) activity. TGF-β promotes myelomagenesis as well as intrinsic drug resistance by repressing anti-myeloma immunity to promote tolerance, drug resistance and disease progression. Hence, repression of TGF-β signaling is a prerequisite to enhance the efficacy of current and future immunotherapeutics. Novel strategies that incorporate T cells that have been modified to express chimeric antigen receptor (CARs), T cell receptors (TCRs) and bispecific T cell engagers (BiTEs) offer promise to block TGF-β signaling, overcome chemoresistance and enhance anti-myeloma immunity. Here, we describe the effects of TGF-β signaling on immune cell effectors in the bone marrow and emerging strategies to overcome TGF-β-mediated myeloma growth, drug resistance and survival.

Lymphoplasmacytic lymphoma with IgG or IgA paraprotein: a study of 29 cases including cases that can mimic plasma cell neoplasms

Lymphoplasmacytic lymphoma (LPL) with IgG or IgA paraprotein is rare and a subset of cases can mimic a plasma cell neoplasm (PCN). We studied 29 such cases to explore their clinicopathological features and the best diagnostic approaches with a focus on bone marrow findings. The cohort included 18 men and 11 women with a median age of 68 years. The median M protein was 3.1 g/dL, IgG in 19 patients (66%), IgA in 9 (31%), and dual IgG/IgA in 1 (3%). All patients had bone marrow involvement with CD138+ plasma cells (PCs) ranging from 1 to 35% (median, 10%). Two patients also had amyloidosis. Immunoglobulin light chain concordant monotypic PCs and monotypic B cells were identified in 96% of cases assessed by flow cytometry. Notably, the neoplastic PCs were consistently positive for CD45 (dim, 100%), CD19 (96%), CD81 (89%), CD27 (83%), rarely and only weakly or partially express CD56 (16%), whereas CD117 was consistently negative. Eleven cases analyzed by fluorescence in situ hybridization were negative for CCND1::IGH and myeloma-related aberrations. MYD88 mutation was detected in 17 of 24 cases (71%), and CXCR4 mutation was identified in 6 of 19 cases (32%), of which 4 had concurrent MYD88 mutation. In conclusion, the results highlight a potential diagnostic pitfall of LPL associated with marked plasmacytic differentiation and an IgG or IgA paraprotein that can resemble a PCN. Useful features in favor of LPL against PCN include the characteristic immunophenotypic profile of the PCs in LPL, absence of CCND1::IGH, and the presence of MYD88 and/or CXCR4 mutations.

Multiple Myeloma Immunophenotype Related to Chromosomal Abnormalities Used in Risk Assessment

(1) Background: At diagnosis, multiplemyeloma risk estimation includes disease burden, end-organ damage, and biomarkers, with increasing emphasis on genetic abnormalities. Multicolor flow cytometry (MFC) is not always considered in risk estimation. We demonstrate associations found between genetic abnormalities and antigen expression of plasma cells measured by MFC. (2) Methods: Single nucleotide polymorphism microarray (SNP-A) karyotyping as well as MFC using standardized next-generation flow (NGF) panels and instrument settings were performed from bone marrow aspirates at the time of diagnosis. (3) Results: We uncovered specific immunophenotype features related to different genetic risk factors. Specifically, we found higher malignant/normal plasma cell ratio and lower expression of CD27, CD38, CD45, CD56, CD117 and CD138 in higher-risk genetic groups or risk categories.

Any closer to successful therapy of multiple myeloma? CAR-T cell is a good reason for optimism

Despite many recent advances on cancer novel therapies, researchers have yet a long way to cure cancer. They have to deal with tough challenges before they can reach success. Nonetheless, it seems that recently developed immunotherapy-based therapy approaches such as adoptive cell transfer (ACT) have emerged as a promising therapeutic strategy against various kinds of tumors even the cancers in the blood (liquid cancers). The hematological (liquid) cancers are hard to be targeted by usual cancer therapies, for they do not form localized solid tumors. Until recently, two types of ACTs have been developed and introduced; tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR)-T cells which the latter is the subject of our discussion. It is interesting about engineered CAR-T cells that they are genetically endowed with unique cancer-specific characteristics, so they can use the potency of the host immune system to fight against either solid or liquid cancers. Multiple myeloma (MM) or simply referred to as myeloma is a type of hematological malignancy that affects the plasma cells. The cancerous plasma cells produce immunoglobulins (antibodies) uncontrollably which consequently damage the tissues and organs and break the immune system function. Although the last few years have seen significant progressions in the treatment of MM, still a complete remission remains unconvincing. MM is a medically challenging and stubborn disease with a disappointingly low rate of survival rate. When comparing the three most occurring blood cancers (i.e., lymphoma, leukemia, and myeloma), myeloma has the lowest 5-year survival rate (around 40%). A low survival rate indicates a high mortality rate with difficulty in treatment. Therefore, novel CAR-T cell-based therapies or combination therapies along with CAT-T cells may bring new hope for multiple myeloma patients. CAR-T cell therapy has a high potential to improve the remission success rate in patients with MM. To date, many preclinical and clinical trial studies have been conducted to investigate the ability and capacity of CAR T cells in targeting the antigens on myeloma cells. Despite the problems and obstacles, CAR-T cell experiments in MM patients revealed a robust therapeutic potential. However, several factors might be considered during CAR-T cell therapy for better response and reduced side effects. Also, incorporating the CAT-T cell method into a combinational treatment schedule may be a promising approach. In this paper, with a greater emphasis on CAR-T cell application in the treatment of MM, we will discuss and introduce CAR-T cell's history and functions, their limitations, and the solutions to defeat the limitations and different types of modifications on CAR-T cells.

Concurrent immunoglobulin G-lambda type multiple myeloma and mixed cellularity classical Hodgkin lymphoma: A case report

A 66-year-old man with a swollen right inguinal lymph node (LN) had pain on the lower side of the back. Computed tomography revealed bone disease in the back and swollen right inguinal LNs. Laboratory studies showed anemia and serum immunoglobulin G-lambda (IgG-λ) type monoclonal protein. The bone marrow contained 39.6% plasma cells. He was diagnosed with IgG-λ type multiple myeloma (MM). However, the pathological findings of the right inguinal LN were mixed cellular classical Hodgkin lymphoma (HL). The administration of melphalan, prednisone, and bortezomib (MPB) was started for MM; however, swelling in the right inguinal LN increased. After three cycles of MPB, the administration of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) was started for HL. However, HL was refractory to ABVD. Pancytopenia subsequently progressed and rapid swelling occurred in his LNs. He died 7 months after diagnosis. Multiple myeloma was diagnosed, based on the typical symptoms, although the pathological findings of the LN indicated a diagnosis of HL. We analyzed the molecular relationship between MM and HL cells using a direct sequencing method. The sequencing results demonstrated that the variable-diversity-joining (VDJ) region of the IgH gene was identified with 94.4% of IGLV3-32*01 in the bone marrow sample at diagnosis. Furthermore, clonotypic IgH sequence was identified in CD30-positive cells from the LN. These results suggested that the clonal HL cells were derived from the same source as the clonal MM cells and demonstrated that MM and HL in this patient may have originated from the same B cell progenitor.

Chimeric Antigen Receptor-Modified T Cell Therapy in Multiple Myeloma: Beyond B Cell Maturation Antigen

Chimeric antigen receptor (CAR)-modified T cell therapy is a rapidly emerging immunotherapeutic approach that is revolutionizing cancer treatment. The impressive clinical results obtained with CAR-T cell therapy in patients with acute lymphoblastic leukemia and lymphoma have fueled the development of CAR-T cells targeting other malignancies, including multiple myeloma (MM). The field of CAR-T cell therapy for MM is still in its infancy, but remains promising. To date, most studies have been performed with B cell maturation antigen (BCMA)-targeted CARs, for which high response rates have been obtained in early-phase clinical trials. However, responses are usually temporary, and relapses have frequently been observed. One of the major reasons for relapse is the loss or downregulation of BCMA expression following CAR-T therapy. This has fostered a search for alternative target antigens that are expressed on the MM cell surface. In this review, we provide an overview of myeloma target antigens other than BCMA that are currently being evaluated in pre-clinical and clinical studies.

CARs and other T cell therapies for MM: The clinical experience

Harnessing the endogenous immune system to eliminate malignant cells has long been an intriguing approach. After considerable success in the treatment of B-cell acute lymphoblastic leukemia, chimeric antigen receptor (CAR)-modified T cells have entered early clinical evaluation in the field of multiple myeloma (MM). The choice of suitable non-CD19 target antigens is challenging and a variety of myeloma-associated surface molecules have been under preclinical investigation. Most recent clinical protocols have focused on targeting B-cell maturation antigen (BCMA), and early results are promising. The trials differ in receptor constructs, patient selection, dosing strategies and conditioning chemotherapy and will thus pave the way to eventually define the optimal parameters. Other sources for autologous T-cell therapy of MM include affinity-enhanced T-cell receptor-modified cells and marrow infiltrating lymphocytes. In summary, adoptive T-cell transfer for the treatment of MM is still in its infancy, but if early response rates indicate durability, will be a paradigm changing therapeutic modality for the treatment of MM.

Clinical implications of c-maf expression in plasma cells from patients with multiple myeloma

BACKGROUND

Multiple myeloma (MM) is a type of hematological malignancy with significant heterogeneity in clinical features and prognosis. Cytogenetic abnormalities are the major factors affecting patient outcomes. Studies have shown that immunohistochemistry (IHC)-based detection of cancer-related genes expression could be alternative indicators for the prognosis of MM.

METHODS

Nuclear expression of c-maf protein in the bone marrow plasma cells of 128 multiple myeloma patients were examined by IHC, and its association with the clinicopathological features of MM patients was analyzed as well.

RESULTS

Among the 128 patients, the positive rate of c-maf protein expression was up to 30.5%, which had no correlation with patient age, M protein type, Durie-Salmon staging system, the International Staging System, abnormal plasma cell ratio in the bone marrow, or the level of peripheral blood hemoglobin, serum calcium or lactate dehydrogenase. However, the c-maf-positive patients had a significantly higher rate of hypoproteinemia (p = 0.026) and higher serum β2-microglobulin levels (>2500 μg/L) (p = 0.007). Patients with negative c-maf expression had higher remission rates upon the treatment of non-bortezomib-based regimens although no effect of c-maf expression on progression-free survival or overall survival was observed.

CONCLUSION

Patients with negative c-maf expression had higher remission rates upon the treatment of non-bortezomib-based regimens although no effect of c-maf expression on survival was observed. A further large-scale prospective study is required to verify these findings.

Phenotypic and functional characterization of a bortezomib-resistant multiple myeloma cell line by flow and mass cytometry

Multiple myeloma (MM) is an incurable malignant plasma cell neoplasm. Proteasome inhibitors including Bortezomib (Bz) are used to treat MM, and treatment failure due to drug resistance occurs. Bz-sensitive and -resistant MM cells have distinct immunophenotypic signatures that correlate with clinical outcome. These changes can be identified by fluorescence-based cytometry (FBC), however, FBC is rarely used in predicting Bz resistance. Mass cytometry (MC) is a recently developed variation of flow cytometry that detects heavy metal-ion tagged antibodies using time-of-flight mass spectrometry allowing for detection of up to 38 epitopes simultaneously in a single cell, without significant overlap, exceeding the dimensionality of FBC 3-4-fold. Here, we compared FBC and MC in the immunophenotypic characterization of Bz-sensitive and -resistant human MM cell line U266. We show that Bz-resistant cells are associated with the loss of CD56 and CD66a adhesion molecules as well as an activation signature.

Towards Stratified Medicine in Plasma Cell Myeloma

Plasma cell myeloma is a clinically heterogeneous malignancy accounting for approximately one to 2% of newly diagnosed cases of cancer worldwide. Treatment options, in addition to long-established cytotoxic drugs, include autologous stem cell transplant, immune modulators, proteasome inhibitors and monoclonal antibodies, plus further targeted therapies currently in clinical trials. Whilst treatment decisions are mostly based on a patient’s age, fitness, including the presence of co-morbidities, and tumour burden, significant scope exists for better risk stratification, sub-classification of disease, and predictors of response to specific therapies. Clinical staging, recurring acquired cytogenetic aberrations, and serum biomarkers such as β-2 microglobulin, and free light chains are in widespread use but often fail to predict the disease progression or inform treatment decision making. Recent scientific advances have provided considerable insight into the biology of myeloma. For example, gene expression profiling is already making a contribution to enhanced understanding of the biology of the disease whilst Next Generation Sequencing has revealed great genomic complexity and heterogeneity. Pathways involved in the oncogenesis, proliferation of the tumour and its resistance to apoptosis are being unravelled. Furthermore, knowledge of the tumour cell surface and its interactions with bystander cells and the bone marrow stroma enhance this understanding and provide novel targets for cell and antibody-based therapies. This review will discuss the development in understanding of the biology of the tumour cell and its environment in the bone marrow, the implementation of new therapeutic options contributing to significantly improved outcomes, and the progression towards more personalised medicine in this disorder.

High expression of endoplasmic reticulum chaperone grp94 is a novel molecular hallmark of malignant plasma cells in multiple myeloma

BACKGROUND

Multiple myeloma (MM) is a hematologic malignancy that is characterized by the proliferation of abnormal bone marrow plasma cells (BMPC) and overproduction of immunoglobulin or light chains with evidence of end-organ damage such as bone damage, anemia, hypercalcemia, and renal dysfunction. The pathogenesis of MM is closely linked to dysregulated unfolded protein response (UPR) in the endoplasmic reticulum (ER). Constitutive activation of UPR in mice, as demonstrated by transgenic expression of a master UPR transcription factor XBP1s (a UPR-specific splice variant of X-box binding protein 1), causes myeloma. grp94 (gp96) is a key downstream chaperone in the ER that mediates the UPR as a part of the protein quality control mechanism in the secretory pathway. Our recent study has shown that the persistence of plasma cells as well as the development of myeloma in XBP1s-transgenic mice is critically dependent on grp94. However, the role of grp94 in the initiation and progression of human MM is still unknown.

METHODS

The expression level of grp94 in BMPCs was measured by flow cytometry, real-time RT-PCR, and Western blot analysis. We compared the expression levels of grp94 in BMPCs in a spectrum of patients including MM, monoclonal gammopathy of undetermined significance (MGUS), smoldering MM (SMM), as well as non-plasma cell disorders (NPC).

RESULTS

We found that grp94 was highly expressed in malignant plasma cells in patients with MM, but not in BMPCs in patients with MGUS/SMM and NPC. The expression level of grp94 correlated significantly with CD138 expression level. We also found that the grp94 expression level in BMPCs from International Staging System (ISS) stage III MM patients is higher than those in ISS stage I/II MM patients.

CONCLUSIONS

grp94 is highly expressed in BMPCs in MM, which correlates with the advanced stage of this disease. Our data demonstrated that grp94 is a novel diagnostic and prognostic biomarker. It also positioned grp94 as a promising therapeutic target for MM.

Incidence and clinical features of extramedullary multiple myeloma in patients who underwent stem cell transplantation

Extramedullary disease (EMD), defined as an infiltrate of clonal plasma cells at an anatomic site distant from the bone marrow, is an uncommon manifestation of multiple myeloma. Six hundred and sixty-three consecutive patients with multiple myeloma who underwent stem cell transplantation between January 2005 and December 2011 were assessed for the presence of EMD. A cohort of 55 patients with biopsy-proven EMD was identified, comprising 8·3% of the total study population. EMD was present at the time of diagnosis in 14·5% of cases and at the time of relapse in 76% of patients. The most common EMD presentations at relapse were liver involvement and pleural effusions. EMD specimens had high expression of CD44 (92%) and moderate expression of CXCR4. The median overall survival from time of myeloma diagnosis was 4·1 years (95% CI: 3·1, 5·1) and the median overall survival from time of EMD diagnosis was 1·3 years (95% CI: 0·8, 2·3). This report demonstrates that the incidence of EMD has not increased with the introduction of novel agents and stem cell transplantation. The most common EMD presentations in the relapsed setting were liver and pleural fluid. The presence of CD44 and CXCR4 expression may represent new markers of EMD that warrant further investigation.

The oncogenic transcription factor IRF4 is regulated by a novel CD30/NF-κB positive feedback loop in peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCLs) are generally aggressive non-Hodgkin lymphomas with poor overall survival rates following standard therapy. One-third of PTCLs express interferon regulatory factor-4 (IRF4), a tightly regulated transcription factor involved in lymphocyte growth and differentiation. IRF4 drives tumor growth in several lymphoid malignancies and has been proposed as a candidate therapeutic target. Because direct IRF4 inhibitors are not clinically available, we sought to characterize the mechanism by which IRF4 expression is regulated in PTCLs. We demonstrated that IRF4 is constitutively expressed in PTCL cells and drives Myc expression and proliferation. Using an inhibitor screen, we identified nuclear factor κB (NF-κB) as a candidate regulator of IRF4 expression and cell proliferation. We then demonstrated that the NF-κB subunits p52 and RelB were transcriptional activators of IRF4. Further analysis showed that activation of CD30 promotes p52 and RelB activity and subsequent IRF4 expression. Finally, we showed that IRF4 transcriptionally regulates CD30 expression. Taken together, these data demonstrate a novel positive feedback loop involving CD30, NF-κB, and IRF4; further evidence for this mechanism was demonstrated in human PTCL tissue samples. Accordingly, NF-κB inhibitors may represent a clinical means to disrupt this feedback loop in IRF4-positive PTCLs.

CD30 expression in acute lymphoblastic leukemia as assessed by flow cytometry analysis

We assessed CD30 expression in patients with acute lymphoblastic leukemia (ALL) of either T-cell or B-cell lineage to examine the potential benefit of anti-CD30-targeted therapy in this group of patients. Bone marrow specimens of 34 patients with T- and 44 with B-ALL were assessed for CD30 expression by multicolor flow cytometry immunophenotyping analysis. Of these 78 patients, 75 (96%) were adults; and 63 (81%) had refractory/relapsed disease. Using an arbitrary 20% cut-off, 13/34 (38%) cases of T-ALL and 6/44 (13%) cases of B-ALL were considered to express CD30. In five patients with T-ALL with sequential bone marrow tested, increased CD30 expression was observed during the course of high-dose chemotherapy (p = 0.025). Philadelphia chromosome/BCR-ABL1 fusion was positive in 14/44 cases of B-ALL and 2/32 cases of T-ALL, which showed no significant correlation with CD30 expression. In summary, we detected CD30 expression in approximately one-third of patients with T-ALL, and less frequently in B-ALL (p = 0.017). In T-ALL, CD30 expression is up-regulated during high-dose chemotherapy. These data indicate that anti-CD30-targeted therapy may be a potential option for patients with T-ALL with refractory/relapsed disease.