Longitudinal analysis and prognostic effect of cancer-testis antigen expression in multiple myeloma.

PURPOSE: Reliable data on the persistence of tumor expression of cancer-testis (CT) antigens over time and consequent analyses of the effect of CT antigen expression on the clinical course of malignancies are crucial for their evaluation as diagnostic markers and immunotherapeutic targets. EXPERIMENTAL DESIGN: Applying conventional reverse transcription-PCR, real-time PCR, and Western blot, we did the first longitudinal study of CT antigen expression in multiple myeloma analyzing 330 bone marrow samples from 129 patients for the expression of four CT antigens (MAGE-C1/CT7, MAGE-C2/CT10, MAGE-A3, and SSX-2). RESULTS: CT antigens were frequently and surprisingly persistently expressed, indicating that down-regulation of these immunogenic targets does not represent a common tumor escape mechanism in myeloma. We observed strong correlations of CT antigen expression levels with the clinical course of myeloma patients as indicated by the number of bone marrow-residing plasma cells and peripheral paraprotein levels, suggesting a role for CT antigens as independent tumor markers. Investigating the prognostic value of CT antigen expression in myeloma patients after allogeneic stem cell transplantation, we found that expression of genes, such as MAGE-C1, represents an important indicator of early relapse and dramatically reduced survival. CONCLUSIONS: Our findings suggest that CT antigens might promote the progression of multiple myeloma and especially MAGE-C1/CT7, which seems to play the role of a "gatekeeper" gene for other CT antigens, might characterize a more malignant phenotype. Importantly, our study also strongly supports the usefulness of CT antigens as diagnostic and prognostic markers as well as therapeutic targets in myeloma.

CD4+CD25+FOXP3+ T regulatory cells reconstitute and accumulate in the bone marrow of patients with multiple myeloma following allogeneic stem cell transplantation.

BACKGROUND: Very little is known about the number and function of immunosuppressive CD4(+)CD25(+)FOXP3(+) T regulatory cells (Treg) in the human bone marrow and it is unclear whether bone marrow-residing Treg are capable of regenerating following allogeneic stem cell transplantation. This is particularly surprising since the bone marrow represents a major priming site for T-cell responses and Treg play important roles in the prevention of T-cell-mediated graft-versus-host disease and in promoting tumor escape from T-cell-dependent immunosurveillance. DESIGN AND METHODS: Applying flow cytometry, real-time polymerase chain reaction, and functional assays, we performed the first study on bone marrow and peripheral blood Treg in healthy donors as well as multiple myeloma patients before and after allogeneic stem cell transplantation. RESULTS: We found that, following the allogeneic transplantation, donor-derived CD4(+)CD25(+)FOXP3(+) Treg expanded faster than conventional CD4(+) T cells, leading to an accumulation of Treg in the bone marrow of transplanted patients who lack relevant thymic function. The reconstituted bone marrow-residing CD4(+)CD25(+)FOXP3(+) Treg of myeloma patients after allogeneic stem cell transplantation consisted preferably of CD45RA(-)CCR7(-) memory T-cells and contained low numbers of T-cell receptor excision cycles, indicating that Treg had indeed expanded outside the thymus. Importantly, bone marrow-residing Treg of newly diagnosed and myeloma patients after allogeneic stem cell transplantation expressed high levels of transforming growth factor beta and cytotoxic T-lymphocyte antigen 4, and showed a strong inhibitory function. CONCLUSIONS: We suggest that allogeneic stem cell transplantation provides a short but significant window of opportunity for CD8(+) T cells before an exuberant regeneration of immunosuppressive Treg sets in. Later after transplantation, bone marrow-residing Treg probably contribute to suppressing graft-versus-host disease but may also undermine persistent immune control of multiple myeloma.

Cancer-testis antigens are commonly expressed in multiple myeloma and induce systemic immunity following allogeneic stem cell transplantation.

Immunotherapies using cancer-testis (CT) antigens as targets represent a potentially useful treatment in patients with multiple myeloma (MM) who commonly show recurrent disease following chemotherapy. We analyzed the expression of 11 CT antigens in bone marrow samples from patients with MM (n=55) and healthy donors (n=32) using reverse transcriptase-polymerase chain reaction (RT-PCR). CT antigens were frequently expressed in MM with 56% (MAGEC2), 55% (MAGEA3), 35% (SSX1), 20% (SSX4, SSX5), 16% (SSX2), 15% (BAGE), 7% (NY-ESO-1), and 6% (ADAM2, LIPI) expressing the given antigen. Importantly, CT antigens were not expressed in healthy bone marrow. Analyzing patients with MM (n=66) for antibody responses against MAGEA3, SSX2, and NY-ESO-1, we found strong antibody responses against CT antigens preferentially in patients who had received allogeneic stem cell transplantation (alloSCT). Antibody responses against NY-ESO-1 correlated with NY-ESO-1-specific CD4+ and CD8+ T-cell responses against peptide NY-ESO-1(51-62) and CD4+ responses against NY-ESO-1(121-140) in 1 of these patients. These allogeneic immune responses were not detectable in pretransplantation samples and in the patients' stem cell donors, indicating that CT antigens might indeed represent natural targets for graft-versus-myeloma effects. Immune responses induced by alloSCT could be boosted by active CT antigen-specific immunotherapy, which might help to achieve long-lasting remissions in patients with MM.