Faculty Bibliography

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. (Blood. 2000;96:3880-3886)

PURPOSE/OBJECTIVE:To determine the effect of polymorphic variations in the tumor necrosis factor alpha (TNFalpha) and lymphotoxin alpha (LTalpha) genes on the predisposition to myeloma and the effect of these polymorphisms on response to treatment and overall survival. PATIENTS AND METHODS/METHODS:Genotype distribution was determined in 63 patients with monoclonal gammopathy of uncertain significance (MGUS) and 198 patients with myeloma and compared with that in 250 age- and sex-matched population-based controls. The effect on treatment response and survival was determined in 171 myeloma patients treated with either conventional or high-dose chemotherapy. RESULTS:Comparison of the extended TNFalpha/LTalpha haplotype in the myeloma cases and controls showed a significant excess of high-producer alleles in the cases. The double heterozygotes TNF1/2 and LT10.5/5.5 were present in 35.8% of cases but in only 18% of the controls; this presence was associated with a significant increased risk of myeloma (odds ratio, 2.05; 95% confidence interval, 1.26 to 3.35). A similar odds ratio was seen in the MGUS cases, suggesting that this genotype is associated with the initiation of plasma-cell disorders rather than the progression of MGUS to myeloma. The median overall survival time of myeloma patients was 53.8 months and showed no difference with regard to TNFalpha/LTalpha polymorphic status. A trend toward an improved progression-free survival was apparent in cases with a high-producer haplotype, although this effect was seen only in patients receiving high-dose chemotherapy. CONCLUSION/CONCLUSIONS:Individuals with polymorphisms associated with a high production of TNFalpha/LTalpha are at a significantly increased risk of developing MGUS and myeloma. The impact of polymorphic status on overall survival is minimal, although there is a trend toward an increased progression-free survival in the high-producer group.

There is a wide variation in the degree of marrow and blood involvement between patients with multiple myeloma. Both of these parameters are known to be highly significant prognostic factors, and the differences between patients may be due to variable expression of adhesion molecules. To test this we used three-colour flow cytometry to study three adhesion molecules associated with myeloma, namely CD38, CD56 and CD138. The level of expression of these molecules was compared with the distribution of myeloma plasma cells in bone marrow (n=59) and peripheral blood (n=26) in patients at presentation or relapse. The extent of marrow infiltration on the trephine biopsy correlated inversely with CD56 expression (Mann-Whitney U Test, P=0.022); there was no difference in CD38 or in CD138 expression. CD56 expression also correlated inversely with the number of circulating plasma cells (linear regression, R2=0.4268, slope=-0.58, P=0.0003). Peripheral blood plasma cell numbers correlated weakly with bone marrow plasmacytosis, and inversely with CD38 expression. The level of CD56 expression by neoplastic plasma cells was assessed in 37 patients over a median of 11 months (range 6-25). There was no significant change in expression (Wilcoxon Signed Rank, P=0.6271). We conclude that plasma cell CD56 expression is constant over the course of the disease; unlike CD138 expression, it is significantly linked to the degree of both bone marrow and peripheral blood involvement.

Studies utilizing flow cytometry and PCR have shown that the B-cell compartment in myeloma contains cells which are clonally related to the myelomatous plasma cells. Current data, however, remains inconclusive regarding the extent of this involvement. By combining fluorescent immunophenotyping, tyramine signal amplification and fluorescence in-situ hybridization (FICTION-TSA), we have used the presence of numerical chromosomal abnormalities within plasma cells as a clonal marker to examine the CD20+ B-cell compartment for the presence of aneuploidy. A series of 54 cases of myeloma were screened for the presence of numerical abnormalities of chromosomes 3 and 11. FICTION-TSA was performed on 13 cases with either trisomy 3 or 11 and on a control group of six cases known to be disomic for the two chromosomes. B-cell numbers were reduced in the myeloma cases compared to the normal controls (median 1.8% v 3.0%, P = 0.05). In the cases with a chromosomal marker, three signals were seen in a median of 1.88% of CD20+ B cells compared to 2.58% within the control group. Comparison of the two groups using a Wilcoxon-Mann-Whitney U test showed no statistical significant difference. Using this data set, it was possible to exclude a 3.03% expansion of clonally related B cells (95% confidence level). We conclude that the B-cell compartment in myeloma does not represent the major site of clonal expansion, and if clonally related cells are present then the numbers are few.

In order to delineate the specific morphological and immunophenotypic features of B-cell lymphoproliferative disorders associated with trisomy 12, 172 sequential unselected cases of CD19+CD5+ B-cell disorders, primarily affecting the peripheral blood and bone marrow, were studied. Trisomy 12 was found in 24 cases (13.9%), with all cases morphologically classified as either CLL-PL or CLL-mixed by FAB criteria. Trisomy 12 was not found in any cases of typical CLL. Trisomy 12 cases demonstrated a significant higher expression of CD11a (P<0.0001) and CD20 (P<0.0006) when compared to cases with the equivalent morphology and immunophenotype, but without the chromosomal abnormality. Trisomy 12 cases also demonstrated a higher frequency of FMC7, CD38 expression and moderate to strong surface immunoglobulin staining. However, no correlation was detected between the percentages of trisomy 12 cells and cells expressing CD11a, CD38, FMC7 or sIg mean fluorescent intensity. Cells from trisomy 12 positive cases were sorted according to their CD11a expression using fluorescent activated cell sorting. There was a significant increase in the percentage of trisomy 12 cells within the CD11a+ sorted fraction compared to the unsorted population (P < 0.05), implying that trisomy 12 is associated with increased expression of CD11a. With the highly specific morphological and immunophenotypic features demonstrated by trisomy 12 cases in this study, it is highly likely that these cases constitute a specific group of B-cell lymphoproliferative disorders.

Liposomal encapsulation of anthracyclines is a potential method of drug targeting, altering both the antitumour activity and side-effect profile of anthracyclines. Liposomal daunorubicin (daunoxome) shows both altered pharmacokinetics and a potential for reducing dose-limiting cardiotoxicity compared to conventional daunorubicin. Anthracyclines have a common role in the treatment of multiple myeloma, a prevalent and fatal haematological malignancy. Avoiding cumulative anthracycline toxicity in these patients is important. There is also a need for more effective relapse schedules given that many patients have chemosensitive disease at relapse. We have analysed daunoxome in vitro in myeloma cell lines using a thymidine-based cytotoxicity assay and show superior efficacy compared to a pegylated liposomal doxorubicin derivative. Subsequently we have treated seven relapsed myeloma patients with a regime consisting of oral CCNU 25-50 mg/m2 on day 1, 4 days of oral dexamethasone 10 mg/m2 and intravenous daunoxome (liposomal daunorubicin) given for 4 days (total 100 mg/m2). The main toxicity was myelosuppression but non-haematological toxicity was minimal and the regime was well tolerated. Four out of seven of these heavily pretreated patients responded. Together with the in vitro data on its cytotoxicity in myeloma and its favourable pharmacokinetic profile further studies of liposomal daunorubicin in myeloma would be warranted.

The reduced levels of normal immunoglobulin in patients with myeloma may be due to suppression of normal B-cell differentiation. However, reports on the numbers of B cells vary, with some finding decreases consistent with immunoparesis, and others reporting expansions of phenotypically aberrant cells. We have therefore assessed the phenotype and levels of B lymphocytes in patients at presentation (n = 23), in plateau or complete remission (PB n = 42, BM n = 18), and in relapse (PB n = 17, BM n = 14), in comparison to normal individuals (n = 10). Phenotypic analysis was performed using five-parameter flow cytometry, with CD14 used to exclude monocytes where necessary. We found no evidence of a phenotypically distinctive blood or marrow B-cell population in patients with myeloma, nor of an increase in the levels of any B-cell subset. Numbers of blood CD19+ 38+ normal plasma cell precursors were significantly reduced in presentation/relapse patients, but not in patients in plateau/remission. Total CD19+ cells were significantly reduced only in patients with circulating myeloma cells, detected by IgH-PCR. In the marrow, CD19+ B cells expressing CD5, CD10, CD34, CD38, CD45(low) and Syndecan-1 were significantly decreased at presentation/relapse, but not in patients in plateau/remission. The majority of these antigens are expressed by normal B-cell progenitors, indicating that myeloma also affects the early stages of B-cell development. The suppression of progenitor cells was not restricted to B-lymphoid differentiation, as total CD34+ cells were also significantly reduced in the marrow of myeloma patients at presentation. These results indicate that, if neoplastic B cells are present in myeloma, they are low in number and have a phenotype similar to their normal counterparts. Furthermore, there is a reversible suppression of CD19+ B lymphocytes that correlates inversely with disease stage, and specifically affects the early and late stages of normal B-cell differentiation.

We have developed a competitor-based RT-PCR technique which will detect and quantitate the CBFbeta/MYH11 transcripts associated with inv(16)(q22;p13) and have used it to study presentation and follow-up samples of acute myeloid leukaemia (AML). The levels of the leukaemia-specific transcripts are expressed as a ratio to a ubiquitously expressed mRNA species (Abl) which controls for RNA degradation. This technique has been applied to 75 consecutive patients presenting with either de novo AML or tMDS; 6/75 patients analysed were positive for the inv(16), all were confirmed by conventional cytogenetics. The inv(16) has a strong association with M4Eo, but we found only 2/6-positive patients to have this diagnosis (two patients with M2, one patient M1 and one patient had MDS). At presentation the levels of CBFbeta/MYH11 transcripts were 0.1-10/Abl transcript (mean 3.3/Abl transcript). Seventeen follow-up samples were available on 5/6 of these patients, and on two further patients in whom stored material was available. Following the first cycle of chemotherapy the level of transcripts was at least 10(-2) lower (0.1-10 x 10(-2)/abl transcript) than their presentation sample. Subsequent samples on these patients when in remission gave transcript levels in the range (1.0 x 10(-4) - 2 x 10(-3)/abl transcript), and three long-term follow-up samples were negative. We have developed a quantitative test which opens the possibility of predicting relapse by detecting changes in the numbers of leukaemia-specific transcripts.