Studies on IgA and IgA monoclonal proteins derived from a single patient. Evidence for identical light chains and variable regions of the heavy chain

Response comparison of multiple myeloma and monoclonal gammopathy of undetermined significance to the same anti-myeloma therapy: a retrospective cohort study

BACKGROUND

Multiple myeloma is consistently preceded by monoclonal gammopathy of undetermined significance (MGUS), which is usually only treated by a form of anti-multiple myeloma therapy if it is causing substantial disease through deposition of secreted M proteins. However, studies comparing how MGUS and multiple myeloma plasma cell clones respond to these therapies are scarce. Biclonal gammopathy multiple myeloma is characterised by the coexistence of an active multiple myeloma clone and a benign MGUS clone, and thus provides a unique model to assess the responses of separate clones to the same anti-multiple myeloma therapy, in the same patient, at the same time. We aimed to identify how MGUS and multiple myeloma plasma cell clones responded to anti-multiple myeloma therapy in patients newly diagnosed with biclonal gammopathy multiple myeloma.

METHODS

In this retrospective cohort study, we identified patients with biclonal gammopathy multiple myeloma by central laboratory analysis of 6399 newly diagnosed patients with multiple myeloma enrolled in three UK clinical trials (Myeloma IX, Myeloma XI, and TEAMM) between July 7, 2004, and June 2, 2015. In addition to the inclusion criteria of these trials, our study necessitated at trial entry the presence of two distinct M proteins in immunofixation electrophoresis. The primary endpoint was difference in response achieved with anti-multiple myeloma therapy on MGUS (which we defined as M2) and multiple myeloma (M1) clones-overall, within patients, and between therapy types-with international therapy response criteria assessed with χ² analyses. We analysed by intention to treat.

FINDINGS

44 patients with biclonal gammopathy multiple myeloma with IgG or IgA MGUS clones were subsequently identified from the three trials and then longitudinally monitored. 41 (93%) of M1 clones had a response to therapy (either complete response, very good partial response, partial response, or minor response) compared with only 28 (64%) of M2 clones (p=0·0010). For the 20 patients who received intensive therapy, there was no difference between the proportion of responding clones in M1 (19 [95%]) and M2 (15 [75%], p=0·13). However, for the 17 patients who received non-intensive therapy, 16 (94%) of M1 clones had a response compared with ten [59%] of M2 clones (p=0·031). When examining clones within the same patient, 30 (68%) of 44 individual patients had different levels of responses within the M1 and M2 clones. One patient exhibited M2 progression to myeloma and subsequently died.

INTERPRETATION

These results show that, in patients with biclonal gammopathy multiple myeloma, anti-multiple myeloma therapies exert a greater depth of response against multiple myeloma plasma cell clones than MGUS plasma cell clones. Although some MGUS clones exhibited a complete response, many did not respond, which suggests that the underlying features that render multiple myeloma plasma cells susceptible to therapy are present in only some MGUS plasma cell clones. To determine MGUS clone susceptibly to therapy, future studies might seek to identify, with biclonal gammopathy multiple myeloma as an investigative model, the genetic and epigenetic alterations that affect whether MGUS plasma cell clones are responsive to anti-multiple myeloma therapy.

FUNDING

National Institute of Health Research, Medical Research Council, and Cancer Research UK.

Molecular analysis of immunoglobulin genes reveals frequent clonal relatedness in double monoclonal gammopathies

Monoclonal gammopathies (MGs) are hematological diseases characterized by high levels of a monoclonal immunoglobulin (Ig) or M-protein. Within this group are patients with more than one M-protein, referred to as double MGs (DMGs). The M-proteins in DMG patients may have different heavy chain (HC) isotypes that are associated with different light chains (LCs), or different HCs that are LC matched. In this study, we examined the clonal relatedness of the M-proteins in the latter type in a cohort of 14 DMG patients. By using PCR, we identified 7/14 DMG patients that expressed two Ig HC isotypes with identical Ig HC variable (IGHV), diversity (IGHD), joining (IGHJ), and complementarity determining region (HCDR3) sequences. Two additional DMG patients had two Ig transcripts using the same IGHV, IGHD and IGHJ genes but with slight differences in variable region or HCDR3 mutations. LC analysis confirmed that a single LC was expressed in 3/7 DMG patients with identical HC transcripts and in the two DMGs with highly similar transcripts. The PCR findings were confirmed by immunofluorescence for HC and LC expression. Clonally related HC-dissimilar/LC-matched DMGs may occur often and defines a new subtype of MG that may serve as a tool for studies of disease pathogenesis.

IgG1-kappa biclonal gammopathy associated with multiple myeloma suggests a regulatory mechanism

Multiclonal gammopathies associated with multiple myeloma may result either from a neoplastic transformation of a cell clone undergoing immunoglobulin class switching or from independent transforming events yielding proliferation of unrelated plasma cell clones. The simultaneous presence of more than one neoplastic clone may possess regulatory implications in terms of cell proliferation, clonal expansion, secretion of M-components or response to chemotherapy. We report a patient, diagnosed with multiple myeloma stage IIIa, who presented with two well-defined homogeneous IgG1-kappa components in the serum (designated WER-1 and WER-2) with striking differences in their plasma concentration and response to the classic melphalan/prednisone treatment. Immunochemical characterization and amino terminal sequence analysis of both the heavy and light chains of each M-component undoubtedly determined their biclonal origin. WER-1 was identified as IgG1(VHII)-kappaI while WER-2 was classified as IgG1(VHIII)-kappaIII. The plateau phase was characterized by very low or undetectable levels of WER-2, a high, almost constant, concentration of WER-1 and the absence of Bence Jones proteinuria, whereas these parameters were completely reversed during the escape phase with levels resembling those observed at the time of diagnosis. The statistically significant negative correlation between the biclonal components and the different susceptibility to the treatment clearly suggests regulatory interactions between the clones WER-1 and WER-2.

Prothrombinase components can accelerate tissue plasminogen activator-catalyzed plasminogen activation

The enzymatic and cofactor subunits of human prothrombinase, factor Xa (FXa) and factor Va (FVa), respectively, were evaluated as modulators of Glu- and Lys-plasminogen (Pg) activation by tissue plasminogen activator (tPA). The data revealed that both FXa and FVa could accelerate tPA activity by as much as 60-fold for Lys-Pg and > 150-fold for Glu-Pg. This function of FVa depended on pretreatment with plasmin (Pn), whereas the FXa fibrinolytic cofactor activity was endogenous. In the native state, FVa was observed to inhibit the acceleration of Pn generation by FXa. These effects were dependent on Ca2+ and procoagulant phospholipid. Interactions between plasminogen and prothrombinase components were quantified. The apparent Kd for binding to FXa was 35 nM. Strikingly, the affinity between FVa and Pg was increased by approximately 2 orders of magnitude when the FVa was Pn-pretreated (Kd = 0.1 microM). These data cumulatively suggest a mechanism by which Pn production is coordinated with coagulation and localized to sites where procoagulant phospholipid is exposed on a cell surface.

Lymphoplasmacytic lymphoma. Report of a case with three monoclonal proteins derived from a single neoplastic clone

The unique case of a 60-year-old patient with a non-Hodgkin's B-cell lymphoma of the lymphoplasmacytic type and three associated monoclonal proteins, is described. The patient also exhibited various autoimmune phenomena that were consistent with the diagnoses of Sjögren's syndrome and autoimmune thyroiditis. The evolution from production of a single monoclonal protein (IgM-kappa) to three monoclonal proteins (IgG-kappa, IgA-kappa, and IgM-kappa) suggested that the lymphoplasmacytic cells were at different stages of terminal differentiation within a single neoplastic clone. The chronic antigenic stress imposed on the immune system by the autoimmune disorder may have played a role in the development of lymphoma and in the heavy chain immunoglobulin switching that occurred during the patients' clinical course.

The clinical aspects of biclonal gammopathies. Review of 57 cases

Between 1966 and 1979, biclonal gammopathy was recognized in 57 patients. Clinical and laboratory features differentiated three groups: biclonal gammopathy of undetermined significance, 37 cases (65 percent); multiple myeloma, nine cases (16 percent); and lymphoproliferative disease--including lymphoma, macroglobulinemia, chronic lymphocytic leukemia and unclassified lymphoproliferative disorders--11 cases (19 percent). With biclonal gammopathy of undetermined significance, symptomatic multiple myeloma developed after two years in one patient; the others remained stable. One patient with multiple myeloma had osteosclerotic myeloma and a severe sensorimotor peripheral neuropathy, and another presented with plasma cell leukemia. In the remainder response to therapy and survival were much the same as in patients with multiple myeloma with a monoclonal protein. Patients with lymphoproliferative disease responded to chemotherapy like that for monoclonal gammopathy. Of the 57 patients, 30 (53 percent) had IgG and IgA components, 15 (26 percent) had IgG and IgM, six had two IgG components, three had IgA and IgM, one had IgA proteins, one had IgA and IgE and 1 had triclonal gammopathy. Of the 115 light chains, 70 percent were kappa; the chains were both kappa and lambda in 63 percent of biclonal pairs. In many cases, serum electrophoresis produced only a single band on the acetate strip, and the biclonal gammopathy was not recognized until immunoelectrophoresis was done. Although the clinical features of biclonal gammopathy and its response to therapy are similar to those of monoclonal gammopathy, this subject is of importance because of the lack of clinical data in the literature.

Temporal relationship between primary injection and cyclophosphamide administration necessary for the inhibition of the priming for a secondary response

Using the mouse PFC anti-SRBC response, the temporal relationship between primary antigen dose and cyclophosphamide (CP) administration necessary for the inhibition of priming for the secondary IgG response was studied. The administration of CP 1 h after the primary or secondary antigen injection inhibits the responses in both cases. The administration of CP 1 h after the primary antigen injection does not inhibit priming for the secondary response; this priming is inhibited if CP is administered at 12 h or more, and the maximal degree of inhibition is induced when CP is administered 7 or 9 days after the primary antigen injection. Therefore, the proliferation stage of mature B cells to IgM secretion is not necessary for this priming. It is suggested that the switch from IgM to IgG takes place in a proliferative stage of B-cell precursors in presence of the antigen.

Antibody differentiation: apparent sequence identity between variable regions shared by IgA and IgG immunoglobulins

We have analyzed a pair of human myeloma immunoglobulins (biclonal proteins) of the IgG and IgA classes from a single patient, GR. The light chains are identical in amino-acid sequence over 40 residues at their NH2-terminus, hwereas the heavy chains are identical throughout 45 residues of their NH2-terminus. Additional chemical and serological studies suggest the light chains and variable regions of the heavy chains (VH) are very similar, if not identical. The implications of these and of other published studies are discussed with regard to (i) the association of one VH region with multiple constant regions of the heavy chain (CH regions), (ii) two alternative types of V-C joining mechanisms, (iii) the differentiation of antibody-producing cells, and (iv) three categories of biclonal immunoglobulins.