CD44 isoforms are differentially regulated in plasma cell dyscrasias and CD44v9 represents a new independent prognostic parameter in multiple myeloma

To evaluate the role of CD44 variant isoforms (CD44v) in plasma cell dyscrasias, CD44v expression was analysed in bone marrow (BM) biopsies of multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS) patients, in biopsies of soft tissue infiltration by MM and in extramedullary plasmacytoma samples. Expression of CD44 isoforms containing the 3v, 4v, 6v or 10v domain was observed in 15, 7, 13 and 5% of 87 samples from 49 consecutive MM cases, but could not be detected in ten normal persons or 11 MGUS patients. In contrast, CD44v9 revealed a broader pattern of expression and was observed in plasma cells in three out of ten normal persons and in three out of 11 MGUS cases. In MM, CD44v9 was detected in 32 out of 87 samples (37%) of BM infiltrates and was associated with an advanced Durie and Salmon stage (P<0.03), a progressive disease (P<0.01) and an IgA subtype (P<0.01). Furthermore, CD44v9 expression was observed in three out of five cases of MM soft tissue infiltrates, was often upregulated during disease progression, was significantly correlated with a shorter overall survival (P<0.03) and emerged as an independent prognostic factor in multivariate analysis (stage: relative risk 1.36, P<0.02; CD44v9 expression: relative risk 1.45, P<0.04). These results substantiate the clinical relevance of CD44v domains in plasma cell disorders and establish CD44v9 as a new independent prognostic parameter in MM.     

Analysis of the efficacy and toxicity of bortezomib for treatment of relapsed or refractory multiple myeloma in community practice

The clinical data on the efficacy and toxicity of bortezomib as treatment for multiple myeloma patients are restricted to prospective phase II studies in expert myeloma centers. Here we report a multi-institutional analysis of the efficacy and toxicity of bortezomib in patients with relapsed or refractory multiple myeloma who were treated in community centers in a compassionate need program.     

Toward targeting B cell cancers with CD4+ CTLs: identification of a CD19-encoded minor histocompatibility antigen using a novel genome-wide analysis

Some minor histocompatibility antigens (mHags) are expressed exclusively on patient hematopoietic and malignant cells, and this unique set of antigens enables specific targeting of hematological malignancies after human histocompatability leucocyte antigen (HLA)–matched allogeneic stem cell transplantation (allo-SCT). We report the first hematopoietic mHag presented by HLA class II (HLA-DQA1*05/B1*02) molecules to CD4⁺ T cells. This antigen is encoded by a single-nucleotide polymorphism (SNP) in the B cell lineage-specific CD19 gene, which is an important target antigen for immunotherapy of most B cell malignancies. The CD19^L-encoded antigen was identified using a novel and powerful genetic strategy in which zygosity-genotype correlation scanning was used as the key step for fine mapping the genetic locus defined by pairwise linkage analysis. This strategy was also applicable for genome-wide identification of a wide range of mHags. CD19^L-specific CD4⁺ T cells provided antigen-specific help for maturation of dendritic cells and for expansion of CD8⁺ mHag-specific T cells. They also lysed CD19^L-positive malignant cells, illustrating the potential therapeutic advantages of targeting this novel CD19^L-derived HLA class II–restricted mHag. The currently available immunotherapy strategies enable the exploitation of these therapeutic effects within and beyond allo-SCT settings.Leukemia, lymphoma, and myeloma together account for ∼500,000 deaths per year worldwide (1). HLA-matched allogeneic stem cell transplantation (allo-SCT) is a widely applied immunotherapeutic approach for several of these hematological malignancies. The therapeutic effect of allo-SCT is largely mediated by alloreactive donor T cells directed at polymorphic peptides presented by HLA molecules on the recipient''s malignant cells (2). These polymorphic peptides, also known as minor histocompatibility antigens (mHags), are frequently derived from cellular proteins encoded by allelic genes on autosomal chromosomes. Although several mHags are expressed ubiquitously, some mHags are exclusively expressed on hematopoietic cells and their malignant counterparts (2–4). Hence, targeting donor T cells toward such hematopoietic mHags is considered an ideal strategy to establish specific antitumor effects after allo-SCT (2, 4). Because CD8⁺ T cells are traditionally considered as the effector cells of antitumor responses, over the past years the major focus was to identify hematopoietic mHags presented to CD8⁺ CTLs (5–12). Nonetheless, several reports, including ours, indicate that not only CD8⁺ CTLs but also CD4⁺ T cells may possess immunotherapeutic potential (13–15). Yet no hematopoietic mHag presented by HLA class II has been identified, partly because the available techniques are not well suited for identification of such antigens. More importantly, several of the apparently hematopoietic mHags recognized by CD4⁺ T cells are not derived from genuine hematopoietic antigens. For instance, the recently identified autosomal mHag presented to CD4⁺ T cells is derived from the broadly expressed phosphatidylinositol 4-kinase type II β gene (16).We previously isolated an HLA-DQA1*05/B1*02–restricted mHag-specific CD4⁺ T cell (clone 21) from the PBMC of a multiple myeloma patient after HLA-identical allo-SCT. This clone recognized recipient-derived EBV-transformed B cells (EBV-transformed lymphoblastoid cell lines [EBV-LCLs]) but not the nonhematopoietic fibroblasts and stromal cells, suggesting that its target antigen was encoded by a hematopoietic gene (unpublished data). To identify the mHag recognized by clone 21, we developed a nonlaborious but powerful genetic strategy in which a zygosity-genotype correlation analysis was used for fine mapping of the genomic locus mHag identified by classical pair-wise two-point linkage analysis. The new gene-mapping method was also genomewide applicable for a broad range of mHags. Further investigation on the identified locus revealed that the antigen recognized by clone 21 was encoded by a single-nucleotide polymorphism (SNP) in the B cell lineage-specific CD19 gene, which is a highly important target antigen for immunotherapy of almost all B cell malignancies. The CD19^L-specific CD4⁺ T cells not only mediated antigen-specific help for the induction and expansion of CD8⁺ mHag-specific T cells but also displayed antigen-specific and HLA-restricted lysis of CD19^L-positive malignant cells, illustrating the potential therapeutic advantages of targeting this CD19^L-derived HLA class II–restricted mHag.     

A class II-restricted cytotoxic T-cell clone recognizes a human minor histocompatibility antigen with a restricted tissue distribution

Following a human leucocyte antigen (HLA)-identical allogeneic stem cell transplantation (allo-SCT), minor histocompatibility antigens (mHags) play an important role in the induction of graft-versus-leukaemia (GvL) and graft-versus-myeloma (GvM). Many mHags show ubiquitous tissue expression and are associated with GvL and graft-versus-host disease. Here we describe a cytotoxic CD4(+) T lymphocyte line and a cytotoxic, CD4(+) T cell clone (CTC), 3AB11, which recognized a tissue-restricted mHag. This CTC was isolated from a multiple myeloma patient with clinical GvM following an HLA-matched allo-SCT. CTC 3AB11 was activated in a HLA-DP*0401 restricted fashion and the antigen was expressed by 27% of HLA-DP*0401 positive Epstein-Barr virus (EBV)-transformed B-cell lines (EBV-B). Tissue distribution analysis of antigen 3AB11 showed it to be expressed by patient-derived EBV-transformed B cell lines (EBVp), the myeloma plasma cell-line UM9 and monocytes. It was weakly expressed by peripheral blood-derived phytohaemagglutinin-induced T-cell blasts and absent on CD40L stimulated peripheral B (CD40L B) cells and stromal cells. The relatively high prevalence of the HLA class II-restricted 3AB11 antigen, together with its apparent haematopoietic-restricted expression, makes it an antigen of interest for cellular immunotherapy.     

Chimaeric anti-interleukin 6 monoclonal antibodies in the treatment of advanced multiple myeloma: a phase I dose-escalating study

Interleukin 6 plays a key role in the pathogenesis of multiple myeloma (MM). Therefore we conducted a phase I dose-escalating study with chimaeric monoclonal anti-IL6 antibodies (cMab) in MM patients resistant to second-line chemotherapy. The cMab (CLB IL6/8; K _d 6.25 × 10⁻¹²  M ) was given in two cycles of 14 daily infusions, starting on day 1 and day 28, repectively, with a daily dose of 5 mg in patients 1–3, 10 mg in patients 4–6, 20 mg in patients 7–9 and 40 mg in patients 10–12 (total dose 140 mg, 280 mg, 560 mg and 1120 mg of anti-IL6, respectively). 11/12 patients had elevated pretreatment IL6 levels.
Except for transient thrombocytopenia in two patients there was no toxicity. There were no changes in haemoglobin levels, granulocyte count, liver enzymes or renal function. No human anti-chimaeric antibodies were induced. This was also reflected in a long half-life time of the cMab (median 17.8 d), resulting in accumulation of the anti-IL6 cMab and high levels of circulating IL6. However, this was in the form of biologically inactive IL6/cMab complexes and did not result in acceleration of the disease. Although C-reactive protein (CRP) levels were decreased to below detection level in 11/12 patients, indicating effective IL6 blocking, none of the patients achieved a response according to the standard criteria. We conclude that this chimaeric anti-IL6 Mab has a low toxicity, low immunogenicity and a long T _1/2. A dose of 40 mg/d for 14 d can safely be used in future phase II studies.     

Cyclosporin for thrombotic thrombocytopenic purpura after autologous bone marrow transplantation

Thrombotic thrombocytopenic purpura (TTP) after bone marrow transplantation (BMT) is a serious complication that, in contrast to classic TTP, is generally not responsive to therapeutic plasma exchange. We describe the remission of TTP after autologous BMT by administration of cyclosporin in four patients, either after failure of plasmapheresis (two patients) or as primary treatment modality (two patients). Cyclosporin may be an attractive drug for post autologous BMT-TTP.     

Interleukin-6, a new target for therapy in multiple myeloma?

Summary During the past few years much insight has been gained into the immunobiology of multiple myeloma. It has become evident that the growth of myeloma cells is regulated by cytokines, notably interleukin-6. In this paper a brief review is given of the evidence derived from in vitro as well as in vivo observations that interleukin-6 is involved in the pathogenesis of multiple myeloma, and the implications of these findings for the development of new therapeutic strategies are discussed.