Circulating monotypic B-cells in multiple myeloma: association with lambda paraproteins

Role of Immune Cells and Immunotherapy in Multiple Myeloma

The clinical signs of multiple myeloma, a plasma cell (PC) dyscrasia, include bone loss, renal damage, and paraproteinemia. It can be defined as the uncontrolled growth of malignant PCs within the bone marrow. The distinctive bone marrow milieu that regulates the progression of myeloma disease involves interactions between plasma and stromal cells, and myeloid and lymphoid cells. These cells affect the immune system independently or because of a complicated web of interconnections, which promotes disease development and immune evasion. Due to the importance of these factors in the onset of disease, various therapeutic strategies have been created that either target or improve the immunological processes that influence disease progression. The immune system has a role in the mechanism of action of multiple myeloma treatments. The main contributions of immune cells to the bone marrow microenvironment, as well as how they interact and how immune regulation might lead to therapeutic effects, are covered in this study.

Efficacy and Safety of CAR-Modified T Cell Therapy in Patients with Relapsed or Refractory Multiple Myeloma: A Meta-Analysis of Prospective Clinical Trials

Background: In recent years, chimeric antigen receptor-modified T (CAR-T) cell therapy for B-cell leukemia and lymphoma has shown high clinical efficacy. Similar CAR-T clinical trials have also been carried out in patients with refractory/relapsed multiple myeloma (RRMM). However, no systematic review has evaluated the efficacy and safety of CAR-T cell therapy in RRMM. The purpose of this study was to fill this literature gap. Methods: Eligible studies were searched in PUBMED, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), CNKI, and WanFang from data inception to December 2019. For efficacy assessment, the overall response rate (ORR), minimal residual disease (MRD) negativity rate, strict complete response (sCR), complete response (CR), very good partial response (VGPR), and partial response (PR) were calculated. The incidence of any grade cytokine release syndrome (CRS) and grade ≥3 adverse events (AEs) were calculated for safety analysis. The effect estimates were then pooled using an inverse variance method. Results: Overall, 27 studies involving 497 patients were included in this meta-analysis. The pooled ORR and MRD negativity rate were 89% (95% Cl: 83-94%) and 81% (95% Cl: 67-91%), respectively. The pooled sCR, CR, VGPR, and PR were 14% (95% Cl: 5-27%), 13% (95% Cl: 4-26%), 23% (95% Cl: 14-33%), and 15% (95% Cl: 10-21%), respectively. Subgroup analyses of ORR by age, proportion of previous autologous stem cell transplantation (ASCT), and target selection of CAR-T cells revealed that age ≤ 55 years (≤55 years vs. > 55 years, p = 0.0081), prior ASCT ≤70% (≤70% vs. > 70%, p = 0.035), and bispecific CAR-T cells (dual B-cell maturation antigen (BCMA)/BCMA + CD19 vs specific BCMA, p = 0.0329) associated with higher ORR in patients. Subgroup analyses of remission depth by target selection suggested that more patients achieved a better response than VGPR with dual BCMA/BCMA + CD19 CAR-T cells compared to specific BCMA targeting (p = 0.0061). In terms of safety, the pooled incidence of any grade and grade ≥ 3 CRS was 76% (95% CL: 63-87%) and 11% (95% CL: 6-17%). The most common grade ≥ 3 AEs were hematologic toxic effects. Conclusion: In heavily treated patients, CAR-T therapy associates with promising responses and tolerable AEs, as well as CRS in RRMM. However, additional information regarding the durability of CAR-T cell therapy, as well as further randomized controlled trials, is needed.

Anti-CD19 CAR T cells with high-dose melphalan and autologous stem cell transplantation for refractory multiple myeloma

BACKGROUND

Multiple myeloma is usually fatal due to serial relapses that become progressively refractory to therapy. CD19 is typically absent on the dominant multiple myeloma cell population but may be present on minor subsets with unique myeloma-propagating properties. To target myeloma-propagating cells, we clinically evaluated autologous T cells transduced with a chimeric antigen receptor (CAR) against CD19 (CTL019).

METHODS

Subjects received CTL019 following salvage high-dose melphalan and autologous stem cell transplantation (ASCT). All subjects had relapsed/refractory multiple myeloma and had previously undergone ASCT with less than 1 year progression-free survival (PFS).

RESULTS

ASCT + CTL019 was safe and feasible, with most toxicity attributable to ASCT and no severe cytokine release syndrome. Two of 10 subjects exhibited significantly longer PFS after ASCT + CTL019 compared with prior ASCT (479 vs. 181 days; 249 vs. 127 days). Correlates of favorable clinical outcome included peak CTL019 frequency in bone marrow and emergence of humoral and cellular immune responses against the stem-cell antigen Sox2. Ex vivo treatment of primary myeloma samples with a combination of CTL019 and CAR T cells against the plasma cell antigen BCMA reliably inhibited myeloma colony formation in vitro, whereas treatment with either CAR alone inhibited colony formation inconsistently.

CONCLUSION

CTL019 may improve duration of response to standard multiple myeloma therapies by targeting and precipitating secondary immune responses against myeloma-propagating cells.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT02135406.

FUNDING

Novartis, NIH, Conquer Cancer Foundation.

Effect of interferon-alpha on immunoglobulin production by peripheral blood mononuclear cells in multiple myeloma

To test a hypothesis that interferon-alpha (IFN) treatment might restore normal immunoglobulin (Ig) production in multiple myeloma (MM), the effect of IFN on Ig isotype (IgG and IgA) production by peripheral blood (PB) and bone marrow (BM) mononuclear cells (MNCs) in MM patients was analyzed by ELISA. IFN at a concentration of 1000 U/ml was found to enhance IgA production by PB MNCs in IgA-MM and had a trend to stimulate IgG production in IgG-MM. The effect of IFN on nonparaprotein Ig isotype production was more variable, with mostly neutral or inhibitory effects being seen in both the MM subtypes. In contrast to the influences observed in MM patients, IFN at the same concentration inhibited both IgG and IgA production by PB MNCs in healthy controls. In studying BM cells, IFN was found to reduce IgA production in IgA-MM, but had a neutral effect on IgG production in IgG-MM. In the controls, the production of both the IgG and the IgA isotypes by BM MNCs was decreased by IFN. On the basis of these results it seems that the disease itself somehow affects the Ig-producing cells in MM, when measured as different responses of the cells to exogenous IFN in vitro. The results do not support the hypothesis that IFN treatment could restore normal Ig production in MM patients.

Serial studies of peripheral blood myeloma cells in patients with multiple myeloma: when is the optimal time for stem cell harvest?

This study serially quantitated monoclonal plasma cells (PC) in the peripheral blood (PB) of 33 patients with multiple myeloma (MM) at diagnosis, after therapy, and at relapse using a sensitive immunofluorescence technique. The goal was to learn which disease phase is best for harvesting PB stem cells free of monoclonal PC. In 24 chemotherapy responders, 88% (21/24) had circulating PC at diagnosis; after therapy, 63% (15/24) had none, 33% (8/24) had < 3 x 10(6)/L, and only one had > or = 3 x 10(6)/L. In nine cases who failed to respond to initial chemotherapy, 89% (8/9) had high levels (> or = 3 x 10(6)/L) of circulating PC at diagnosis that remained high after therapy. In the relapse phase, 88% (21/24) had circulating PC and 63% (15/24) had high numbers. This study demonstrates that the PB is least likely to have circulating monoclonal PC during the period after successful chemotherapy. Patients who fail to respond to initial chemotherapy or are in relapse are likely to have tumor cells in the PB.

Evidence that the clonogenic cell in multiple myeloma originates from a pre-switched but somatically mutated B cell

There is still much controversy about the precursor cell type in multiple myeloma (MM). Some authors claim that it is a pre-B cell, others state that it is a memory B cell or plasmablast. We have recently shown that the VDJ region of the MM immunoglobulin heavy chain gene is somatically hypermutated and antigen selected, without intraclonal variation or evolution in time. By using a patient-specific PCR approach we have now obtained evidence that the premyeloma cell can be situated in the pre-switched B-cell compartment and that heavy chain switching can occur without further somatic mutation. Based on the MM immunoglobulin sequences derived from the bone marrow, patient-specific CDR2 and CDR3 oligonucleotides were designed. B lymphocytes were separated from plasma cells based on the expression of CD19 and HLA class II or surface bound IgM using immunomagnetic beads. The expressed Ig sequences were amplified by RT-PCR using patient specific CDR2 primers and isotype specific primers (C mu, C gamma, and C alpha). Myeloma-specific Ig sequences were detected by a myeloma-specific CDR3 probe and sequenced. In one out of five cases we found in the peripheral blood clonally related IgM and IgA sequences with the same somatic mutations as the MM-IgG sequence. In another case of an IgG MM we found in the bone marrow clonally related IgA sequences with the same somatic mutations. These findings, together with the fact that myeloma-Ig genes contain somatic mutations without intraclonal variation, suggest that the clonogenic cell in multiple myeloma can originate from a pre-switched but somatically mutated B cell.

Immunoglobulin gene rearrangement in plasma cell dyscrasias: detection of small clonal cell populations in peripheral blood and bone marrow

The bone marrow (BM) and peripheral blood (PB) samples of 71 patients with plasma cell dyscrasias were analysed by the Southern blot technique for the presence of clonal immunoglobulin (Ig) gene rearrangements. 53% of BM samples examined were archival material such as air dried BM slides or frozen trephine biopsies. The results were related to bone marrow plasmacytosis as determined by cytology and flow cytometry, and other clinical parameters. Clonal Ig gene rearrangements were found in BM samples of 45 (83%) of 54 MM patients and in 3 of 6 patients with monoclonal gammopathy of unknown significance (MGUS). Clonal cell populations in the PB were detected in 11 (30%) of 37 examined MM patients, but in none of the patients with MGUS or solitary plasmacytoma of bone. PB involvement was associated with progressive disease. Circulating monoclonal cells were significantly associated with higher M-protein levels (p < 0.05). Thus, circulating clonal precursor cells are encountered more frequently in active MM.

Detection of circulating monoclonal lymphocytes in multiple myeloma patients by analysis of gene rearrangements: correlation with progressive disease

Multiple myeloma is characterized by the proliferation of a monoclonal plasma cell population that essentially spreads in the bone marrow. However, immunological data and studies on clonal gene rearrangements have provided evidence for circulating malignant B-lymphocytes. Herein, we report on the detection and clinical significance of monoclonal lymphocytes in the peripheral blood of multiple myeloma patients. Applying the analysis of immunoglobulin gene rearrangements, clonal circulating lymphocytes were found in 8 out of 37 patients. In three of these eight patients, DNA from the bone marrow could be examined as well, and the same gene rearrangement as in peripheral blood was detected. This observation indicates that the monoclonal lymphocytes in the peripheral blood are part of the malignant plasma cell clone in the bone marrow. There was a strong correlation between progressive stage III disease and the detection of circulating tumour cells, whereas neither in stable stage III nor stage I disease could clonal gene rearrangements be detected. Our findings indicate the high incidence of monoclonal lymphocytes in the peripheral blood from patients with progressive multiple myeloma. This may be of importance with respect to cell harvesting strategies for autologous peripheral stem cell transplantation in multiple myeloma.

Histologic, biochemical, and clinical parameters for monitoring multiple myeloma

In a retrospective and prospective follow-up study from 1968 to 1989, bone marrow biopsy specimens, serum beta-2-microglobulin (SB2M) levels, and the clinical features of 251 patients with multiple myeloma (MM) and 28 patients with monoclonal gammopathy of undetermined significance (MGUS) were investigated. The main histologic variables (tumor cell type, tumor growth, tumor load, and fibrosis), SB2M level, serum thymidine kinase (STK) level, and various clinical parameters were analyzed to determine factors of value in monitoring the clinical phases of activity in MM. Our recently proposed prognostic strategy combining bone marrow histologic type, SB2M level, and signs of organ failure was tested for its ability to (1) diagnose the early and smoldering variants; (2) facilitate decisions on the time of initiation, the type and duration of initial induction therapy in the pretreatment phases (active and rapidly progressive phases); and (3) characterize variations in tumor regression and tumor-host interactions during chemotherapy (early treatment, plateau, relapse, transition, and refractory phases). The results indicate that this clinicopathologic monitoring combines information both on stage and aggressivity of MM and thus facilitates therapeutic decisions in the various clinical phases of MM.

Analysis of tumor-specific immunoglobulin gene rearrangement in peripheral blood B-cells of multiple myeloma patients

The search for bone marrow clone neoplastic precursors in the peripheral blood of multiple myeloma (MM) patients has been the subject of a number of studies which, using different methodological approaches, have led to conflicting results. With the aim of contributing toward resolving this controversy, immunoglobulin (Ig) gene rearrangement in the bone marrow mononuclear cells (BMMC) and B-lymphocyte enriched peripheral cells (BePBC) of 11 appropriately selected advanced MM patients was studied by means of Southern blotting. Peripheral mononuclear cells (PBMC) and BePBC were studied immunophenotypically by evaluating the presence of cytoplasmic Ig positive cells (CyIg+) and CD19/PCA-1 reactivity. A pattern of Ig gene rearrangement identical to that observed in the respective BMMC was found in only two patients who, moreover, had a significant number of CyIg+ cells. Ig gene rearrangement was not found in any of the remaining patients who showed no evidence of the presence of CyIg+ cells, although there were CD19/PCA-1 positive cells. Consequently, the significance of the presence of malignant pre-plasma cell peripheral B-lymphocytes needs to be reconsidered and, in any case, these cells should be looked for in cell populations greatly enriched in B-lymphocytes and, above all, completely lacking in plasma cells or CyIg+ cells.

Light chain restriction analysis of bone marrow plasma cells in patients with MGUS or 'solitary' plasmacytoma: diagnostic value and correlation with clinical course

Twenty-eight patients with a diagnosis of 'solitary' plasmacytoma or with gammopathy but with nondiagnostic morphologic examination of the bone marrow were investigated using a short-term bone marrow culture technique which enriched for the plasma cell fraction. The percentage of monotypic plasma cells in these plasma cell enriched cultures was correlated with the subsequent clinical course. The majority of patients with plasmacytoma and a significant number of those with gammopathy but with otherwise non-diagnostic investigations were found to have a monoclonal plasma cell component of greater than 20%. There was a significant correlation between the percentage of monoclonal plasma cells as detected by bone marrow culture and subsequent progression to disseminated myeloma. These results indicate that early bone marrow involvement can be detected by means of plasma cell culture prior to morphologic identification of marrow plasmacytosis and that short-term plasma cell culture distinguishes patients with early, low bulk myeloma from those with monoclonal gammopathy of uncertain significance (MGUS).