The advanced understanding of the molecular biology and immunology of chronic myeloid leukemia (CML) has led to novel therapeutic strategies unique to this disease. CML responds to immune-mediated ...therapies, including stem cell transplantation, donor lymphocyte infusion (DLI), and interferon alfa. T cells and other immune effectors are implicated in the mechanisms of action of these immune therapies. Recently, clinical observations supported by laboratory data have demonstrated the presence of CML-specific T cells in patients. Several proteins may potentially act as leukemia-specific antigens for major histocompatibility complex (MHC)-restricted cytotoxicity in CML, and active specific therapies (vaccines) are in development. Antigens under investigation include bcr-abl, PR1, Wilms tumor protein (WT1), minor histocompatibility antigens (mH), CML-66, CML-28, and survivin. Other strategies target vascular endothelial growth factor (VEGF) and heat shock protein 90 (Hsp90) inhibitors or make use of CML-derived dendritic cells (DC).
MHC molecules carrying selected peptides will bind specifically to their cognate T cell receptor on individual clones of reactive T cells. Fluorescently labeled, tetrameric MHC-peptide complexes have ...been widely used to detect and quantitate antigen specific T cell populations via flow cytometry. We hypothesized that such MHC-peptide tetramers could also be used to selectively deplete unique reactive T cell populations, while leaving the remaining T cell repertoire and immune response intact. We show in an MHC-matched, minor antigen disparate, murine BMT model (BALB.B → C57BL/6), MHC-peptide-tetramers can be used to deplete the T cells responsible for Graft-Versus-Host-Disease (GVHD), while leaving the remaining immune response intact, as demonstrated by the retention of Graft-Versus-Tumor (GVT) activity. Using PE-labeled tetramers, anti-PE microbeads and an autoMACs separation system, we successfully depleted donor splenocytes of alloantigen specific T cells prior to transplantation. We demonstrated the specificity of the depletion by showing loss of the tetramer reactivity after depletion, whereas no changes were observed in the Vβ repertoire and the percentage of T cells, B cells, NK cells, monocyte/macrophages and granulocytes between pre- and post-depletion samples. When analyzed 6 days after transplantation, mice receiving specifically-depleted splenocytes had <0.5% of their CD8+ T cells reactive against the alloantigen (tetramer +) as compared to >8.5% of the CD8+ T cells in mice that received control-depleted splenocytes. A nearly 50% decrease in in vivo proliferation of donor splenocytes, assessed by CFSE dilution, was seen 3 days after transplant in recipients of specifically-depleted splenocytes, as compared to mice receiving control-depleted splenocytes. However, pre- and post-depletion splenocytes (specific and control) were equally capable of mounting an immune response against third party cells as demonstrated by mixed lymphocyte reaction. In a series of bone marrow transplants designed to assess GVHD and GVT, mice receiving specifically-depleted splenocytes had a nearly 4-fold increased median survival due to significant decreases in GVHD morbidity and mortality compared to recipients of control-depleted splenocytes. All mice receiving splenocytes (tetramer-depleted or not) showed equal GVT activity. Finally, we were able to demonstrate the simultaneous abrogation of GVHD and the retention of GVT in a single bone marrow transplant. In recipients of specifically-depleted splenocytes, there was a 33% long-term survival and significant increases in median survival, as compared to recipients of non-depleted splenocytes, control-depleted splenocytes or bone marrow only; all of these latter groups succumbed to GVHD or tumor. This method also provides the proof-of-concept for similar strategies to selectively remove other unwanted T cell clones, which could result in novel therapies for certain autoimmune disorders, T cell malignancies and solid organ graft rejection.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The BCR‐ABL translocation represents the first pathognomonic genetic event described in oncology. It is now known that a reciprocal translocation results in a fusion of the breakpoint cluster region ...(BCR) gene on chromosome 22 and the c‐Abl gene on chromosome 9. This fusion kinase (BCR‐ABL) provides antiapoptotic and proliferative signals that confer a competitive Darwinian advantage to the malignant clone. The advent of imatinib, a BCR‐ABL tyrosine kinase inhibitor, first provided proof‐of‐principle that molecularly targeted therapy could be an effective, non‐toxic treatment for many cancers. Here, we discuss the molecular pathology of BCR‐ABL in CML as it relates to oncogenesis, therapy, and drug resistance.
<span style="font-size: 12pt; font-family: ";Times New Roman";; mso-ansi-language: EN-US; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">A ...60-year-old woman with a medical history of diabetes mellitus, osteoporosis, peripheral vascular disease, and hypertension who was otherwise asymptomatic but continued showing elevated neutrophil levels sought a second opinion at our facility. Serum protein immunoelectrophoresis with immunofixation revealed an immunoglobulin A (IgA)-κ monoclonal gammopathy concentration of 1305 mg/dL (normal 80-350 mg/dL) but relatively normal concentrations of IgG of 840 mg/dL (620-1400 mg/dL) and IgM of 36 mg/dL (45-250 mg/dL). Clonal analysis revealed a polyclonal expression pattern in all cell types analyzed. We concluded that our patient’s neutrophilia may have been due to the underlying monoclonal gammopathy. This is the first case in the literature of a patient with monoclonal gammopathy of undetermined significance presenting with neutrophilia, suggestive of chronic neutrophilic leukemia (CNL). Patients with CNL have a poor prognosis; therefore, it is important to distinguish diagnostically between CNL and the less severe prognosis of monoclonal gammopathy of undetermined significance.
Abstract One limitation of reduced-intensity preparative regimens is potential for graft failure. We have developed a regimen that targets CD4+ lymphodepletion to ensure early and durable ...engraftment. The primary endpoint was achievement of ≥50% CD3+ donor chimerism by day +28. Forty-two patients (median age, 53 years; range, 29 to 73 years) received pentostatin 4 mg/m2 i.v. on days −28, −21, and −14 when the CD4+ cell count was >100 cells/μL and on days −4 and −3 regardless of CD4+ level. Rituximab 375 mg/m2 was administered to patients with CD20+ malignancies on days −21, −14, −7, +1, and +8. Busulfan 200 mg/m2 i.v. was administered on days −4 and −2 at a dose to target a cumulative AUC dose of 16,000 (±10%) μmol·min/L. Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus plus methotrexate in 86% of patients. Donors were matched-related (47%), matched unrelated (43%), or mismatched unrelated (10%). Chronic lymphocytic leukemia (45%) and follicular non-Hodgkin lymphoma (14%) were the most common diagnoses. Disease status at initiation of the preparative regimen was complete remission in 22%, partial response in 55%, and stable/progression in 24%. The median percent CD4+ cell count decrease from baseline (day −28) was 52% to day −21, 66% to day −14, 62% to day −7, and 91% to day 0. At day +28, all 42 patients (100%) had ≥50% CD3+ donor chimerism. No patient experienced graft failure. Overall response rate was 82% (complete remisson, 67%). The day +100 cumulative incidence of grade II-IV acute GVHD was 59% (grade III-IV acute GVHD, 19%), and the 2 year cumulative incidence of chronic GVHD was 69% (moderate/severe, 58%). Nonrelapse mortality was 2% at day +100 and 17% at 2 years. Two-year PFS was 55%, and OS was 68%. This regimen ensures durable engraftment, is effective against persistent disease, and results in relatively low mortality from causes other than relapse.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Monoclonal antibodies have become an important modality for cancer therapy. Genetically engineered chimeric and humanized antibodies have demonstrated activity against overt lymphoma and leukemia, as ...well as minimal residual disease. Radioimmunotherapy in both nonmyeloablative and myeloablative regimens has produced significant responses and also minimized radiation exposure to normal tissues. Targeted α-particle therapy offers the possibility of selective tumor cell kill. Antibody-drug conjugates have produced remissions in acute leukemia. Many proteins potentially act as leukemia or lymphoma-specific antigens for major histocompatibility complex–restricted T cell cytotoxicity. These include the idiotype proteins, breakpoint cluster region (bcr)-abl and other fusion oncoproteins, myeloid-specific differentiation antigens and minor histocompatibility antigens. Clinical trials exploiting the new understanding of the T cell immunology are underway.
PDF
