High proportions of VLA-5- immature myeloma cells correlated well with poor response to treatment in multiple myeloma

The clinical significance of CD49e and CD56 for multiple myeloma in the novel agents era

Multiple myeloma (MM) is a hematological malignancy characterized by the proliferation of abnormal plasma cells in bone marrow. Flow cytometry distinguishes between normal and abnormal plasma cells by evaluating cluster of differentiation (CD) 56 and CD19 expression patterns. Moreover, immunophenotyping of mature plasma cell 1 (MPC-1) and very late antigen-5 (CD49e) identifies the maturity of MM as mature (MPC-1⁺, CD49e⁺), intermediate (MPC-1⁺, CD49e^-), or immature (MPC-1^-, CD49e^-). We retrospectively examined the effects of surface marker expression and maturity subtype on overall survival (OS) and time to next treatment (TNT) among 55 patients (25 males, 30 females) with symptomatic MM. All patients were treated with regimens containing bortezomib (BOR) (n = 39) or lenalidomide (LEN) (n = 16) as the initial treatment. Median age at diagnosis was 72 years (range: 36-88). The lack of CD56, an aberrant marker, was associated with significantly worse prognosis compared with CD56⁺ MM (median OS: 24 vs. 60 months, respectively; p = 0.0050). In CD49e⁺ MM, defined as mature type, no significant difference was seen in TNT of the initial treatment, regardless of whether it was a BOR-based regimen or LEN + dexamethasone (Ld) therapy. On the other hand, in CD49e^- MM, defined as immature/intermediate type, TNT of Ld therapy was significantly longer than that of BOR-based regimens (median TNT: undefined vs. 12 months, respectively; p = 0.0043). These results suggest that Ld therapy is more effective than BOR-based therapy for CD49e^- MM and thus may aid regimen-related decisions in the novel agents era.

Therapeutic outcome of cyclic VAD (vincristine, doxorubicin and dexamethasone) therapy in primary systemic AL amyloidosis patients

OBJECTIVE

Intensive chemotherapy targeting plasma cell dyscrasia has been recently employed for the treatment of primary systemic AL amyloidosis. We prospectively studied the clinical usefulness of cyclic VAD (vincristine, doxorubicin and dexamethasone) in patients with primary systemic AL amyloidosis who were ineligible for high-dose melphalan with autologous stem cell support.

PATIENTS AND METHODS

Eight patients (mean age, 60.4+/-8.8 years) were treated with cyclic VAD until the disappearance of M-protein from both serum and urine. Of these, seven showed nephrotic syndrome before the start of VAD irrespective of a decrease in creatinine clearance. Serial follow-up studies after VAD evaluated hematological status and organ function.

RESULTS

Four patients (50%) showed a marked decrease in abnormal plasma cells in the bone marrow and normalized kappa/lambda ratios of serum free light chain in conjunction with disappearance of M-protein after 1 to 3 courses of VAD. There were no serious adverse events, and nephrotic syndrome gradually improved with no hematological relapse in the follow-up period of 3 to 5 years. The remaining 4 patients showed worsening of congestive heart failure and/or systemic edema ascribable to dexamethasone, resulting in cessation of cyclic VAD before disappearance of M-protein. All of these patients died of multiple organ failure or required permanent hemodialysis within 1 year after the start of cyclic VAD.

CONCLUSION

Cyclic VAD is a potent therapeutic option in primary systemic AL amyloidosis, but in patients with renal or cardiac dysfunction careful management for adverse events, especially body fluid retention, is necessary.

Long-term follow-up of plasma cells in bone marrow and serum free light chains in primary systemic AL amyloidosis

OBJECTIVE

Primary systemic AL amyloidosis arises from immunoglobulin light chains produced by plasma cell dyscrasia. To prospectively investigate the production of M-protein and plasma cells in bone marrow before and after chemotherapy, we performed flow cytometry and analysis of serum free light chains (FLCs).

PATIENTS AND METHODS

Fifty-nine patients with primary systemic AL amyloidosis (mean age, 59.9+/-8.8 years) were enrolled in this study, and of these 31 were serially studied before and after chemotherapy. Complete hematological remission was defined as normalization of the FLC kappa/lambda ratio.

RESULTS

MPC-1(-)CD45(-) (p<0.05) and MPC-1(+)CD45(-)CD49e(-) (p<0.005) were significantly higher, and MPC-1(-)-CD45(+) (p<0.05), MPC-1(+)CD45(+)CD49e(-) (p<0.0001) and MPC-1(+)CD45(+)CD49e(+) (p<0.0005) were significantly lower in the patients with AL amyloidosis than in controls. There was a significantly positive correlation between the serum predominant FLC/serum creatinine ratio and MPC-1(+)CD45(-)CD49e(-) (p<0.05). After chemotherapies, such as high-dose melphalan with autologous stem cell support, 20 of 31 patients with AL amyloidosis achieved complete hematological remission. There were no significant differences in any subtype of plasma cells before treatment between the remission and non-remission groups, but in the former group MPC-1(+)CD45(-)CD49e(-) and MPC-1(-)CD45(+) were significantly decreased and increased after chemotherapy compared with before, respectively.

CONCLUSION

Abnormal plasma cells in the bone marrow, particularly the MPC-1(+)CD45(-)CD49e(-) subset, may be important as a follow-up marker before and after chemotherapy in primary systemic AL amyloidosis. These cells maintain low levels as long as no relapse occurs.

An increase in MPC-1- and MPC-1-CD45+ immature myeloma cells in the progressive states of bone marrow plasmacytosis: the revised phenotypic classification of monoclonal marrow plasmacytosis (MOMP-2005)

The heterogeneity of bone marrow plasmacytosis is clearly analyzed by multicolor staining with anti-CD38 antibody. To date, at least 5 subpopulations of plasma cells have been identified in the bone marrow of multiple myeloma (MM) patients with regard to the expression of MPC-1, CD49e (VLA-5), and CD45: MPC-1(-)CD49e(-)CD45(+) proliferative immature cells, MPC-1(-)CD49e(-)CD45(-) immature myeloma cells, MPC-1(+)CD49e(-)CD45(-) and MPC-1(+)CD49e(-)CD45(+) intermediate myeloma cells, and MPC-1(+)CD49e(+)CD45(+) mature myeloma cells. We performed phenotypic analyses in 75 cases of monoclonal bone marrow plasmacytosis, including 46 cases of MM and 29 cases of monoclonal gammopathy of undetermined significance (MGUS). In 31 cases of progressive MM disease, MPC-1(-) immature and MPC-1(-)CD45(+) proliferative immature myeloma cells were significantly increased up to >25% and >10%, respectively, of the plasma cell fractions (CD38(++) cells), whereas there were no increases in MPC-1(-) or MPC-1(-)CD45(+) proliferative immature myeloma cells in 15 cases of stable disease. Interestingly, the proportions of MPC-1(-) and MPC-1(-)CD45(+) immature monoclonal plasma cells also increased in the 7 progressive cases of MGUS. Finally, we present the revised (2005) phenotypic classification of monoclonal marrow plasmacytosis (MOMP-2005).

Correlation between serum levels of free light chain and phenotype of plasma cells in bone marrow in primary AL amyloidosis

To investigate whether there is a correlation between subtypes of plasma cells in the bone marrow and the production of M-protein, flow cytometry and serum free light chain (FLC) analyses were carried out in 17 patients with primary systemic AL amyloidosis (mean age, 59.9+/-8.8 years) and controls with M-protein (MGUS controls, n=6) and without it (negative controls, n=9). The patients showed a significantly higher value in the serum predominant FLC:serum creatinine ratio (43.8+/-63.2) and CD38++ CD19- CD56+ subpopulation (monoclonal plasma cells) (2.57+/-5.35%) than either the negative (p<0.0005 and p<0.001, respectively) or MGUS controls (p<0.05). With respect to maturation of plasma cells in the bone marrow, the intermediate (MPC-1+ CD45- CD49e-) and mature (MPC-1+ CD45+ CD49e-) subtypes were significantly higher (49.2+/-23.2%, p<0.005) and lower (27.6+/-21.3%, p<0.005) in the patients than in the negative controls, respectively. The serum predominant FLC:serum creatinine ratio was elevated in parallel with an increase in CD38++ CD19- CD56+ and MPC-1+ CD45- CD49e- cells and a decrease in mature subtypes (MPC-1+ CD45+ CD49e- and MPC-1+ CD45+ CD49e+ cells), There was a significantly positive correlation between the serum predominant FLC:serum creatinine ratio and either CD38++ CD19- CD56+ (r=0.510, p<0.05) or MPC-1+ CD45- CD49e- cells (r=0.481, p<0.05). In primary AL amyloidosis M-protein is probably produced by increased monoclonal plasma cells in the bone marrow, particularly by the intermediate subpopulation with a phenotype of MPC-1+ CD45- CD49e-.

Prognostic significance of surface markers expressed in multiple myeloma: CD56 and other antigens

Multiple myeloma (MM) is characterized by increased numbers of malignant plasma cells. Plasma cells, that represent the terminal differentiation of B lymphocytes, have considerable heterogeneity of surface markers expressed on them. Some studies showed the prognostic significance of several immunophenotypic molecules on MM cells. Here, we review several surface markers related to their prognostic significance in MM patients. We also report that CD56-negative MM is the unique entity characterized by poor prognosis with high incidence of extramedullary disease, Bence Jones protein, renal insufficiency, thrombocytopenia and plasmablastic morphology.

Evaluation of intensive chemotherapy in AL amyloidosis: usefulness of flow cytometric analysis of plasma cells in bone marrow

To investigate whether monoclonal plasma cells in the bone marrow are useful as a therapeutic marker in AL amyloidosis, serial flow cytometry was performed in five patients with this disorder before and after chemotherapy. Four patients were treated with 2 or 3 courses of VAD (vincristine, doxorubicin and dexamethazone) and subsequently with high-dose melphalan followed by auto-PBSCT. The remaining one patient was treated with two courses of VAD alone. Before treatment all patients exhibited a CD19- CD56+ subpopulation, which indicated monoclonal plasma cells, in varying degrees. After treatment all patients showed a decrease in monoclonal plasma cells in accordance with the disappearance of M-protein in serum and/or urine. In two patients treated with VAD followed by auto-PBSCT, polyclonal (CD19+ CD56-) and total plasma cells gradually increased in the follow-up study, while monoclonal plasma cells stayed at less than 0.3% nine months after treatment. No apparent correlation was found between altered maturation of plasma cells and disappearance of M-protein. With respect to easy detection of monoclonal plasma cells producing amyloidogenic M-protein, flow cytometry of bone marrow aspirates is useful and reliable in the follow-up of patients with AL amyloidosis and in the evaluation of the effects of chemotherapy.

Phenotypic analysis of plasma cells in bone marrow using flow cytometry in AL amyloidosis

AL amyloidosis is an intractable disease resulting from a plasma cell dyscrasia which has a wide clinical spectrum. To investigate the phenotype of plasma cells in the bone marrow, a flow cytometric analysis was carried out in 10 patients with this disease (mean age, 57.8 +/- 7.9 years) and controls with M-protein (positive controls, n = 4) and without it (negative controls, n = 8). All patients were shown to have either A kappa- or A lambda-immunoreactive amyloid deposits on the biopsied tissues. On flow cytometry CD38++CD19+CD56- cells (polyclonal plasma cells) showed no significant difference between patients (0.59 +/- 0.37%) and either negative (2.25 +/- 2.84%) or positive controls (0.38 +/- 0.20%), while CD38++CD19-CD56+ cells (monoclonal plasma cells) showed a significantly higher level in the patients (1.34 +/- 1.54%) than in either negative (0.041 +/- 0.004%, p < 0.005) or positive controls (0.11 +/- 0.09%, p < 0.05). With respect to maturation of plasma cells, five of the patients (50%), three of the positive controls (75%) and all of the negative controls showed a dominant proliferation of mature subtype (CD45+MPC-1+CD49e- or CD45+MPC-1+CD49e+). Immature (CD45+MPC-1- or CD45-MPC-1-) and intermediate (CD45-MPC-1+CD49e-) subtypes were dominantly present in the bone marrow in 2 and 3 patients, respectively. In AL amyloidosis monoclonal plasma cells producing M-protein can be easily and reliably detected in the bone marrow by flow cytometry. This analysis might provide plasma cell phenotypic markers useful for assessing the prognosis and for monitoring the response to treatment.

Determination of plasma cell secreting potential as an index of maturity of myelomatous cells and a strong prognostic factor

According to the widely accepted myeloma staging system, the bulk of paraprotein is the main determinant of disease stage. However, myelomatous plasma cells differ considerably in their ability to synthesize and secrete monoclonal paraprotein. We determined plasma cell secreting potential (PCSP) as the amount of M-component, divided by the percentage of marrow plasmacytic infiltration, in 240 patients with myeloma, and correlated our results with chain isotype, plasma cell morphology, severity of bone disease, well-recognized prognostic factors, such as serum LDH, CRP, albumin and beta2-microglobulin, treatment response and overall survival. PCSP was higher in IgG than in other myeloma types, and was an almost constant parameter for each individual patient, in 134/166 cases. A > 10% decrease of PCSP in 26 patients was associated with disease aggressiveness and treatment failure. Patients with MGUS had significantly higher PCSP than those with myeloma of the same chain type. Higher PCSP was associated with stage I, absence of Bence-Jones proteinuria and indolent forms of disease with lower proliferating cell nuclear antigen (PCNA) positivity, serum LDH, alpha2-globulins, CRP and beta2-microglobulin and higher albumin levels. Conversely, patients with immature/plasmablastic morphology and those with severe bone disease had lower PCSP. Good responders to treatment had significantly higher PCSP than moderate and poor responders and PCSP was strongly correlated with overall survival in IgG and IgA myeloma. In conclusion, PCSP reflects the maturation status of myelomatous cells and therefore can be used as a prognostic factor, since patients with high secreting potential represent a lower malignancy group, in comparison to those with a low secreting potential.

In multiple myeloma, only a single stage of neoplastic plasma cell differentiation can be identified by VLA-5 and CD45 expression

The nature of the proliferating fraction in myeloma is still not known and understanding the characteristics of this fraction is central to the development of effective novel therapies. However, myeloma plasma cells typically show a very low rate of proliferation and this complicates accurate analysis. Although the level of CD45 and/or VLA-5 has been reported to identify proliferating 'precursor' plasma cells, there are discrepancies between these studies. We have therefore used a rigorous sequential gating strategy to simultaneously analyse cycle status and immunophenotype with respect to CD45, VLA-5 and a range of other integrin molecules. In 11 presentation myeloma patients, the proliferative fraction was distributed evenly between CD45+ and CD45- cells, however, cycling plasma cells were consistently VLA-5-. There was close correlation between the expression of VLA-5 and a range of other integrin molecules (CD11a, CD11c, CD103), as well as the immunoglobulin-associated molecules CD79a/b (Spearman, n = 10, P < 0.0001). In short-term culture, cells that were initially VLA-5-showed increasing VLA-5 expression with time. However, simultaneous analysis of the DNA-binding dye 7-amino-actinomycin D demonstrated that this was not as a result of differentiation, as VLA-5+ plasma cells were all non-viable. This was confirmed in freshly explanted plasma cells from nine patients. Discrete stages of plasma cell differentiation could not be distinguished by the level of CD45 or VLA-5 expression. The results indicate that there is a single stage of plasma cell differentiation, with the phenotype CD38+CD138+VLA-5-. These findings support the hypothesis that neoplastic bone marrow plasma cells represent an independent, self-replenishing population.

The interleukin-6 receptor alpha-chain (CD126) is expressed by neoplastic but not normal plasma cells

Interleukin-6 (IL-6) is reported to be central to the pathogenesis of myeloma, inducing proliferation and inhibiting apoptosis in neoplastic plasma cells. Therefore, abrogating IL-6 signaling is of therapeutic interest, particularly with the development of humanized anti–IL-6 receptor (IL-6R) antibodies. The use of such antibodies clinically requires an understanding of IL-6R expression on neoplastic cells, particularly in the cycling fraction. IL-6R expression levels were determined on plasma cells from patients with myeloma (n = 93) and with monoclonal gammopathy of undetermined significance (MGUS) or plasmacytoma (n = 66) and compared with the levels found on normal plasma cells (n = 11). In addition, 4-color flow cytometry was used to assess the differential expression by stage of differentiation and cell cycle status of the neoplastic plasma cells. IL-6R alpha chain (CD126) was not detectable in normal plasma cells, but was expressed in approximately 90% of patients with myeloma. In all groups, the expression levels showed a normal distribution. In patients with MGUS or plasmacytoma, neoplastic plasma cells expressed significantly higher levels of CD126 compared with phenotypically normal plasma cells from the same marrow. VLA-5− “immature” plasma cells showed the highest levels of CD126 expression, but “mature” VLA-5+ myeloma plasma cells also overexpressed CD126 when compared with normal subjects. This study demonstrates that CD126 expression is restricted to neoplastic plasma cells, with little or no detectable expression by normal cells. Stromal cells in the bone marrow microenvironment do not induce the overexpression because neoplastic cells express higher levels of CD126 than normal plasma cells from the same bone marrow in individuals with MGUS.

The interleukin-6 receptor alpha-chain (CD126) is expressed by neoplastic but not normal plasma cells

Interleukin-6 (IL-6) is reported to be central to the pathogenesis of myeloma, inducing proliferation and inhibiting apoptosis in neoplastic plasma cells. Therefore, abrogating IL-6 signaling is of therapeutic interest, particularly with the development of humanized anti–IL-6 receptor (IL-6R) antibodies. The use of such antibodies clinically requires an understanding of IL-6R expression on neoplastic cells, particularly in the cycling fraction. IL-6R expression levels were determined on plasma cells from patients with myeloma (n = 93) and with monoclonal gammopathy of undetermined significance (MGUS) or plasmacytoma (n = 66) and compared with the levels found on normal plasma cells (n = 11). In addition, 4-color flow cytometry was used to assess the differential expression by stage of differentiation and cell cycle status of the neoplastic plasma cells. IL-6R alpha chain (CD126) was not detectable in normal plasma cells, but was expressed in approximately 90% of patients with myeloma. In all groups, the expression levels showed a normal distribution. In patients with MGUS or plasmacytoma, neoplastic plasma cells expressed significantly higher levels of CD126 compared with phenotypically normal plasma cells from the same marrow. VLA-5− “immature” plasma cells showed the highest levels of CD126 expression, but “mature” VLA-5+ myeloma plasma cells also overexpressed CD126 when compared with normal subjects. This study demonstrates that CD126 expression is restricted to neoplastic plasma cells, with little or no detectable expression by normal cells. Stromal cells in the bone marrow microenvironment do not induce the overexpression because neoplastic cells express higher levels of CD126 than normal plasma cells from the same bone marrow in individuals with MGUS.

Immunophenotypic Aberrations, DNA Content, and Cell Cycle Analysis of Plasma Cells in Patients with Myeloma and Monoclonal Gammopathies

We describe the immunophenotypic and gross DNA defects in 55 patients with myeloma and 50 patients with monoclonal gammopathy and review the literature on this subject (MedLine, 1994-2000). Our data confirmed previous reports indicating that in myeloma nearly all marrow plasma cells are abnormal (98.7 +/- 8.1%). In monoclonal gammopathy the fraction of abnormal plasma cells was 35.0 +/- 32.8%. In both myeloma and monoclonal gammopathy, the most frequent aberrant phenotypic features consisted of absence of expression of CD19, strong expression of CD56, and decreased intensity of expression of CD38; aberrant expression of CD10, CD20, CD22, or CD28 was observed in less than one-third of myeloma cases. The vast majority of cases had two or more phenotypic aberrations. In the DNA studies, 7% of myeloma cases were biclonal and 93% of cases were monoclonal. In those studies with only one plasma cell mitotic cycle, 37% had normal DNA content and 63% were aneuploid (hyperploid, 61%; hypoploid, 2%). The mean percentages of plasma cells in S- and G2M phases were 4.9 +/- 8.5 and 4.4 +/- 6.9%, respectively. Thirty-eight percent of cases had more than 3% of plasma cells in S phase. In monoclonal gammopathy, the DNA index of abnormal plasma cells ranged from 0.89 to 1.30 and the percentage of diploid (31%) and aneuploid (69%) cases was not different from the results found in myeloma. The differences in percentage of abnormal plasma cells in S- (7.4 +/- 8.6%) and G2M-phases (2.4 +/- 1.7%) in patients with monoclonal gammopathy were not statistically significant.

The role of adhesion receptors in the pathogenesis of multiple myeloma

There is now an improved understanding of the types of adhesion receptors present on normal and malignant plasma cells. This knowledge has been helpful in identifying plasma cells and in beginning to understand the pathogenesis of myeloma. Future research is needed to delineate the signaling pathways used by the plasma cell after the adhesion receptor binds to its ligands. This information should help in designing more effective therapy for this fatal disease.

cCD79a expression in a case of plasma cell leukemia

In the present report we analyzed the immunophenotype of the neoplastic cells in a case of primary plasma cell leukemia (PCL). We performed simultaneous analysis of bone marrow and peripheral blood samples to investigate minor phenotypic variations that could explain the tendency of a population to leave medullary compartments. No major differences were observed between the two populations. The phenotype of the malignant clone was: CD38+, CD138+, CD19-, CD56+, CD117-, CD33+, CD44 , CD49e , cCD79a+ with positive cytoplasmic stain for kappa and IgG. Our findings expands the potential uses of cCD79a to cases of PCL with atypical morphology.

Diagnosis, prognosis, and standard treatment of multiple myeloma

The diagnosis of multiple myeloma (MM) is often difficult; most patients present with asymptomatic gammopathy. The only findings that confirm a diagnosis of MM are an elevation in the M-component or extension of the lytic bone lesions that are the hallmark of the disease. Tests that delineate plasma cell biology, such as plasma cell proliferation rate, are helpful; magnetic resonance imaging can disclose bone marrow lesions leading to subsequent osteolytic disease. After the diagnosis of MM has been established and prognostic factors identified, the appropriate therapy can be determined. Melphalan and prednisone are no longer considered to be the "gold standard" of therapy. In fact, this approach is suitable for less than half of patients with myeloma. This article presents guidelines for standard treatment options and examines the efficacy of new high-dose chemotherapy approaches.

Myeloma stem cell phenotype. Implications for treatment

The phenotypic heterogeneity of myeloma cells in fact delineates a differentiation process that appears to be an integral part of the disease process. Immature myeloma cells interact with their microenvironment differently than do the more mature cells. As a result of this interaction, the immature cells display different responses to chemotherapy than do the mature cells. Addressing this issue by tailoring treatment to target immature as well as mature myeloma cells may change dramatically the outcome of treatment. The ability to define the myeloma clone by molecular genetic techniques has markedly increased the ability to detect clonal cells. This technique provides a most sensitive tool for monitoring elimination of tumor cells; however, the role of the early clonal B cells identified through the use of ASO-PCR in the disease process needs to be clarified. Currently, a great deal of effort is directed towards development of treatment protocol that will eliminate all clonal cells, and a method of purging clonal cells from harvested mobilized peripheral stem cells. Understanding the biologic significance of early clonal B cells in myeloma will allow for a more rational approach to curative treatment.