Targeting paraprotein biosynthesis for non-invasive characterization of myeloma biology

Purpose

Multiple myeloma is a hematologic malignancy originating from clonal plasma cells. Despite effective therapies, outcomes are highly variable suggesting marked disease heterogeneity. The role of functional imaging for therapeutic management of myeloma, such as positron emission tomography with 2-deoxy-2-[¹⁸F]fluoro-D-glucose (¹⁸F-FDG-PET), remains to be determined. Although some studies already suggested a prognostic value of ¹⁸F-FDG-PET, more specific tracers addressing hallmarks of myeloma biology, e.g. paraprotein biosynthesis, are needed. This study evaluated the amino acid tracers L-methyl-[¹¹C]-methionine (¹¹C-MET) and [¹⁸F]-fluoroethyl-L-tyrosine (¹⁸F-Fet) for their potential to image myeloma and to characterize tumor heterogeneity.

Experimental Design

To study the utility of ¹¹C-MET, ¹⁸F-Fet and ¹⁸F-FDG for myeloma imaging, time activity curves were compared in various human myeloma cell lines (INA-6, MM1.S, OPM-2) and correlated to cell-biological characteristics, such as marker gene expression and immunoglobulin levels. Likewise, patient-derived CD138⁺ plasma cells were characterized regarding uptake and biomedical features.

Results

Using myeloma cell lines and patient-derived CD138⁺ plasma cells, we found that the relative uptake of ¹¹C-MET exceeds that of ¹⁸F-FDG 1.5- to 5-fold and that of ¹⁸F-Fet 7- to 20-fold. Importantly, ¹¹C-MET uptake significantly differed between cell types associated with worse prognosis (e.g. t(4;14) in OPM-2 cells) and indolent ones and correlated with intracellular immunoglobulin light chain and cell surface CD138 and CXCR4 levels. Direct comparison of radiotracer uptake in primary samples further validated the superiority of ¹¹C-MET.

Conclusion

These data suggest that ¹¹C-MET might be a versatile biomarker for myeloma superior to routine functional imaging with ¹⁸F-FDG regarding diagnosis, risk stratification, prognosis and discrimination of tumor subtypes.

A SCID-hu in vivo model of human Waldenström macroglobulinemia

The preclinical evaluation of investigational agents for Waldenström macroglobulinemia (WM) has been limited by the lack of in vivo models that enable the use of explanted patient cells. We describe here a novel in vivo model of human WM in severe combined immunodeficient (SCID) mice implanted with human fetal bone chips (SCID-hu mice) into which WM cells from patient bone marrow are engrafted directly into the human bone marrow (huBM) microenvironment. WM cells in SCID-hu mice produced human monoclonal paraprotein (immunoglobulin M [IgM] and/or kappa or lambda chain) detectable in mice sera. Immunohistochemical analysis of human bone retrieved from SCID-hu mice showed infiltration with CD20+, IgM+, and monotypic light chain+ lymphoplasmacytic cells. Mast cells were observed to be associated with the infiltrate in these sections. Treatment of SCID-hu mice bearing WM with rituximab induced tumor regression, associated with a decrease in serum paraprotein. This model, therefore, recapitulates the in vivo biology of WM and allows the study of novel investigational drugs targeting WM cells in the huBM milieu.

Monoclonal immunoglobulin production is a frequent event in patients with mucosa-associated lymphoid tissue lymphoma

PURPOSE

Mucosa-associated lymphoid tissue (MALT) lymphoma comprises 7% of all newly diagnosed non-Hodgkin's lymphomas and is therefore among the most common lymphoma entities. Monoclonal gammopathy due to production of a monoclonal immunoglobulin by lymphoma cells is a well-known phenomenon associated with various types of B-cell non-Hodgkin's lymphomas. The objective of the present study was to evaluate the incidence and clinical relevance of paraprotein (PP) production in patients with MALT lymphoma.

EXPERIMENTAL DESIGN

Fifty two patients were prospectively evaluated with regard to differentiation of the MALT lymphoma cells, t(11;18) translocation, monoclonal immunoglobulin production, Helicobacter pylori (HP) status, stage, treatment, and clinical outcome.

RESULTS

Nineteen of 52 MALT lymphoma patients (36%) had PP (8 IgMkappa, 6 IgGkappa, 4 IgMlambda, and 1 IgAkappa). The histologic feature of plasmacytic differentiation correlated significantly with the production of PP (P = 0.001). No correlation was found between PP and clinical stage, HP status, and t(11;18) status. PP was, however, negatively associated with response to eradication of HP in gastric MALT lymphoma, and PP levels declined significantly in patients responding to chemotherapy or radiation. Importantly, both immunofixation and serum electrophoresis have to be performed to detect low PP levels.

CONCLUSIONS

In conclusion, PP levels may probably be used as a potential prognostic tool for response to HP eradication, and serial measurements may also allow for noninvasive assessment of response to radiation or chemotherapy in patients with MALT lymphoma.

Monoclonal gammopathy of undetermined significance (MGUS) in patients with solid tumors: effects of chemotherapy on the monoclonal protein

The aim of this study was to assess the effect of systemic chemotherapy on the monoclonal protein levels of patients with solid tumors who also have a monoclonal gammopathy of undetermined significance (MGUS). All patients with solid tumors who were referred to our department for consideration of systemic chemotherapy were evaluated with serum protein electrophoresis (SPEP) for the presence of MGUS. When MGUS was confirmed with immunofixation, serial SPEP was performed during and after completion of chemotherapy. Over a 6-year period, 21 patients with solid tumors and MGUS were prospectively identified and assessed. At least 50% reduction of serum monoclonal protein was noted in 4 of 11 patients treated with paclitaxel or docetaxel with a platinum analogue and in 5 of 7 patients who received an irinotecan-containing regimen. Our data indicate that in MGUS patients treated with irinotecan-containing chemotherapy regimens, a high incidence of reduction in their monoclonal protein levels is observed. Since topotecan, another topoisomerase I inhibitor, has some activity in multiple myeloma, further evaluation of irinotecan may be warranted. Evaluation of larger numbers of MGUS patients treated with chemotherapy for their underlying malignancy may help identify "in vivo" potentially active agents and regimens for patients with overt myeloma.

The role of adhesion molecules in multiple myeloma

The neoplastic plasma cells of multiple myeloma differ from normal plasma cells and other B-cell malignancies by an almost exclusive homing to the bone marrow microenvironment which clearly provides the appropriate support, both physical and cytokine, to mediate clonal proliferation and terminal differentiation. Cellular adhesion molecules are involved in the homing of malignant plasma cells to the bone marrow, the production of growth factors and the recirculation of these tumour cells in the advanced stages of disease. Neoplastic plasma cells express H-CAM (CD44), VLA-4 (CD49d/CD29), ICAM-1 (CD54), N-CAM (CD56) and LFA-3 (CD58). In addition VLA-5 (CD49e/CD29) expression seems to be related to cells with less proliferative potential and more potential for paraprotein production. In addition there are fundamental changes in the bone marrow stroma of patients with multiple myeloma including altered composition of the extracellular matrix, increased growth capability of the cellular elements and increased synthesis of interleukin-6 and interleukin-3, which are features postulated to localise and promote growth of the circulating neoplastic progenitors in the bone marrow. However, the evidence to date does not fully explain the inter-relationship of the clonal B cells and the bone marrow stroma in patients with myeloma, including factors which trigger and facilitate the extravasation and recirculation of neoplastic plasma cells as seen in advanced disease.

Increased incidence of paraproteinemia and autoantibodies in patients with normal-pressure glaucoma

We assessed the incidence of paraproteins and autoantibodies in 44 patients (mean age, 65.3 +/- 1.9 years) with normal-pressure glaucoma and 41 patients (mean age, 68.8 +/- 1.8 years) monoclonal proteins occurred more often (P = .0047) in patients with normal-pressure glaucoma (eight of 44, 18%) than in control subjects with primary open-angle glaucoma (zero of 41, 0%). Autoantibodies to extractable nuclear antigens, most often Sjögren's syndrome A antigen (SSA[Ro]), were also found more frequently (P = .0022) in patients with normal-pressure glaucoma (13 of 44, 30%) than in control subjects (one of 41, 2%). Paraproteins and autoantibodies to extractable nuclear antigens generally occurred in different patients with an overall incidence of 20 of 44 (45%) patients with normal-pressure glaucoma. In contrast, no significant difference in the incidence of antinuclear antibodies existed between the groups. These findings suggest that humoral immune mechanisms may have a role in the pathogenesis of optic neuropathy in patients with normal-pressure glaucoma.

Paraproteins and primary lymphoma in SJL mice. II. Primary lymphomas do not produce paraprotein

The incidences of Ig paraprotein (PP) and reticulum cell sarcomas (lymphomas) were studied in a group of 75 SJL mice, 9-11 months of age. PP and lymphoma were observed in 52% of the mice. PP alone was observed in an additional 27% and lymphoma alone in an additional 11% of mice. In attempts to establish a causal relationship between lymphomas and PP, three approaches were used: (a) Serum PP levels were followed during lymphoma growth in primary lymphoma bearing mice and found to decrease rather than to increase. (b) Recipients of primary transplants were examined for appearance of PP-related idiotypes (Id) in their sera and for lymphoma growth. The Id appeared early (Day 10-11) and then disappeared, while lymphoma growth usually was detectable by greater than or equal to 1 month. (c) One of the primary lymphomas was propagated as a tissue culture line and found not to produce any PP or intact Ig. It is concluded that the PP of SJL mice are not produced by their lymphomas. Other possible relationships are discussed, including the role of the PP as a symptom of a prelymphomatous stage that develops in a very high percentage of SJL mice.

Human long-term bone marrow cultures (HLTBMCs) in myelomatous disorders

Human long-term bone marrow cultures (HLTBMCs) were established with bone marrow (BM) collected from five patients with myelomatous disorders (four with multiple myeloma, one with plasma cell leukemia). In all cases, up to at least 6 weeks of culture, there was a persistence of the monoclonal plasma cell population in the adherent layer of the culture. In some cultures proliferating plasma cells could be demonstrated by the Ki-67 monoclonal antibody. In all instances a paraprotein could be shown in the conditioned medium. This study demonstrates that malignant plasma cells, in analogy to their normal counterparts, have an affinity for the BM stroma and suggests that their long-term survival might be enhanced by their interaction with it.

Effect of interferon on the in vitro synthesis of paraprotein by plasma cells in myeloma

The aim of this study was to determine the effects of interferon on in vitro immunoglobulin synthesis by the plasma cells of patients with multiple myeloma. Bone marrow cultures were set up in the presence of media alone or alpha-interferon. Supernatants were harvested over a 24-hour period and assayed for paraprotein immunoglobulin synthesis using radio-immunoassays developed in this department. The 24-hour paraprotein synthesis ranged from 9 to 493 micrograms/10(6) plasma cells in patients with IgG myeloma (n = 11), and from 0.3 to 8.3 micrograms/10(6) plasma cells in those with IgA (n = 4). Alpha-Interferon had variable effects on paraprotein synthesis in IgG myelomas, causing an inhibition of synthesis (up to 61%) in 3 patients and an enhancement of synthesis (up to 95%) in 5 cases. In IgA myelomas, on the other hand, alpha-interferon caused inhibition of synthesis in 1 case. In the 2 patients studied during alpha-interferon administration, IgG synthesis was significantly reduced. More cases are currently being investigated. Clearly, immunoglobulin synthesis by plasma cells shows variable modulation by alpha-interferon in vitro.

Failure of human myeloma cells to heterotransplant into the brain of athymic rats

Sixty-four separate intracranial inoculations of bone marrow cells obtained from 26 patients with human myeloma were performed and the animals were kept under observation for 9-10 months. Samples were obtained from a heterogenous group of patients with diverse types of paraprotein production, clinical status, and response to treatment. Inocula size ranged from 3.5 x 10(5) nucleated cells to about 2 x 10(7), while the percentage of plasma cells varied from nondetectable to 90%. Only one animal (of 2) injected with an aliquot of the bone marrow aspirate from a patient developed a small, clinically undetectable tumor, noticed at the end of the observation period. No other animal developed tumors. Thus, our studies indicate that the intracerebral inoculation of human myeloma cells may not be a profitable means of establishing additional human myeloma cell lines.

Appearance of multiple benign paraproteins during early engraftment of soy lectin T cell-depleted haploidentical bone marrow cells in severe combined immunodeficiency

Recent advances in the prevention of graft-versus-host disease through postthymic T-cell depletion have allowed the use of haploidentical bone marrow cells for immunologic reconstitution of severe combined immunodeficiency disease. We report a male infant with severe combined immunodeficiency (with normal adenosine deaminase) who developed two IgG kappa and one IgA lambda paraproteins 7 weeks following the administration of 1.4 X 10(9) maternal bone marrow cells depleted of postthymic T cells by soy lectin agglutination and sheep erythrocyte rosetting. Serum IgG rose from 128 to 820 mg/dl, and IgA from 0 to 2400 mg/dl, peaking at 10 weeks postgrafting. By 14 weeks posttransplantation T-cell numbers and function had risen to normal (all dividing T cells had the donor karyotype) and paraprotein concentrations began to decline. These observations strongly suggest that the later-appearing T cells regulated the B-cell clones from which the paraproteins were derived. Failure of such function to appear could account for the increased incidence of B-cell lymphomas in severe combined immunodeficiency.

Biosynthesis of immunoglobulin in human immunoproliferative diseases. II. Comparison of tumour cell mass in multiple myeloma measured by synthetic rate studies with that calculated from clinical staging systems

Tumour cell mass (TCM) in patients with multiple myeloma has been measured by synthetic rate studies of bone-marrow tumor cells in culture. From the measurements of Salmon and co-workers, a simple clinical staging system in which TCM is calculated by a programmable pocket calculator has been developed. We have compared the measurement and calculation of TCM in patients with IgG and IgA multiple myeloma by these methods in our own laboratory. There was correlation between synthetic rate and serum IgG paraprotein concentration but not the serum IgA paraprotein concentration. In patients with IgG myeloma there was correlation between measured and calculated TCM as well as measured TCM and serum IgG paraprotein concentration, urine Bence-Jones protein excretion, and serum albumin concentration. Measured TCM also inversely correlated with haemoglobin concentration. In patients with IgA myeloma, however, there was no correlation between measured TCM and calculated TCM or any other individual clinical laboratory parameter. A number of problems have contributed to the overall failure of this method to measure and calculate TCM including methodological differences, definition of myeloma cells, proteolysis of newly synthesized paraprotein in culture, changes in synthetic rates with time and assessment of the degree of bone lesions by skeletal roentgenograms. We cannot recommend these methods as they stand to measure and calculate TCM in patients with multiple myeloma.

Multiple myeloma: current concepts in diagnosis and management

The basic pathologic process in multiple myeloma is the neoplastic proliferation of a single clone of plasma cells. Although the events which trigger autonomous cell growth are not well understood, the secretion of an M component, a serum or urinary immunoglobulin molecule or a light chain fragment by the vast majority of myeloma cells has provided a biologic marker which has greatly facilitated the study of this disease Some of the more recent clinical concepts which have evolved from studies on the plasma cell and the immunoglobulin molecule are discussed.

Temporary disappearance ("eclipse") of LPC-1 plasmacytoma M component synthesis following tumor cell transfer

The early phase of LPC-1 plasmacytoma development was studied by in vivo labeling with [6-14C]arginine using its M component (immunoglobulin G 2a,kappa) as marker. At a time when M component was not detected or faint by protein staining of electrophoretograms, significant labeling of M component was detectable by autoradiography. Labeling of the M component was fairly constant for the first 10 hr but was markedly decreased from Days 1 to 7. Nadir (0 to 3% of initial 30-min value) was observed on Day 3. Recovery of M component labeling to the 30-min level was complete by Day 13. This period of marked reduction or "eclipse" in newly synthesized M component was shortened by 2 days when mice were pretreated with pristane or cyclophosphamide prior to tumor cell transfer. The eclipse period was also 2 days shorter in athymic BALB/c-nu/nu mice than in normal BALB/c mice. The eclipse period corresponds to the classical "lag" following tumor cell transfer before tumor growth can be detected by conventional methods. The sensitivity of the [6-14C]arginine pulse permits the in vivo detection of small numbers of tumor cells (as few as 10(6) cells) over the early time periods after cell transfer. Modification of eclipse by manipulating host and/or tumor cells may elucidate the accompanying cellular and biochemical events.

[Immunology and oncology of paraproteins]

Since the first description by Apitz paraproteins were for a long time regarded as biologically abnormal proteins which normally do not appear in the human plasma. According to the modern biochemical knowledge this determination of the notion can no more be acknowledged, since analyses of amino acids did not reveal any differences in the composition of the complete paraproteins and the immune globulins. Apart from the complete paraproteins which consist either of gamma, my, delta, alpha or epsilon heavy chains on the one hand and of kappa or lambda easy chains on the other hand, also molecule fragments and isolated heavy or easy chains, respectively, appear. Like immune proteins paraproteins are formed by B-lymphocytes and their transformation forms, respectively, in which case the monoclonality represents their specific characteristic. Thus exist close relations to malignant changes of the B-lymphocyte system, in particular to the non-Hodgkin-lymphomas. Several functional peculiarities of the paraproteins, such as autoantibody effect, lymphocytotoxicity, aggregation ability and binding affinity to blood cells lead to multiform clinical phenomena. To this belong immune defects, nephropathies, haemocytopenias, amyloidoses and haemorrhagic diatheses. As evoking cause of the alteration of B-lymphocyte system with activation of one or several cell clones (e.g. in double paraproteinaemia) tumour viruses are taken into consideration. After an infection with oncogenic herpes viruses irreversible cell transformations in the lymphatic system have been proved. Thus it is doubtful, whether there are indeed true benign paraproteinaemias. One has rather to speak only of relatively benign forms of the course.

Idiopathic paraproteinemia. II. Transplantation of the paraprotein-producing clone from old to young C57BL/KaLwRij mice

Transplantation experiments in the C57BL/KaLwRij mouse model of idiopathic paraproteinemia (IP) showed that an IP-producing clone can be further propagated in young, lethally irradiated mice and also equally as well in nonirradiated recipients by a bone marrow and/or spleen cell transfer. The latency period before the original paraprotein was detected in the sera of recipients varied in different experiments between 1 and 9 months after transplantation. With subsequent transplantations, the "take" frequency gradually decreased. Propagation of IP for three to four generations seems to be the final limit. In comparison to age-matched seems to be the final limit. In comparison to age-matched control groups, no substantial influence of the transplanted IP on the survival of the recipients was observed. In contrast, transplantation of cells from mice with a B cell lymphoma or a myeloma led to continuous propagation of the malignancy, with a high "take" frequency, progressive development of the paraproteinemia, and a shortened survival time of the recipients. These findings indicate that IP represents in its final stage in the aging C57BL mice an intrinsic cellular defect within the affected B cell clone, which is, however, different from that found in B cell malignancies.

Asynchronous development of two monoclonal proteins (IgM lambda and delta 1 chains) in a patient with abdominal lymphoma

An IgM paraprotein was detected in a patient with abdominal lymphoma. Due to some doubts about the malignant nature of the situation, no cytostatic drugs were administered. When seen two years later the patient had considerably deteriorated in clinical status, with evidence of extra-abdominal involvement. At this time he presented a second paraprotein of low of molecular weight (74,000 to 80,000), consisting of two covalently linked delta1-chain fragments.

Plane xanthomata associated with multiple myeloma and hyperlipoproteinaemia

A case of plane xanthomatosis associated with multiple myeloma and hyperlipoproteinaemia in a 62-year-old woman is reported. The patient had IgG type lambda paraproteinaemia and type II A hyperlipoproteinaemia. The IgG paraprotein showed binding activity against high-density lipoprotein. It could not be demonstrated that these paraprotein-lipoprotein complexes were responsible for the hyperlipidaemia. Microchemical analysis of pathological skin demonstrated a high content of triglycerides, similar to that in eruptive xanthomata. No correlation was found between the lipid composition of the xanthomatous skin and the serum lipid composition. The results obtained with an in vitro culture method showed that the paraprotein present in the patient's serum was synthesized in the bone marrow but not in the normal or pathological skin.