Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We previously showed that a peptide (PR1) derived from the primary granule enzyme proteinase 3 induced peptide specific cytotoxic T lymphocytes (CTL) in a normal HLA-A2.1+ individual. These CTL showed HLA-restricted cytotoxicity to myeloid leukemias (which overexpress proteinase 3). To further investigate their antileukemic potential, we studied the ability of PR1-specific CTL, derived from two HLA-A2.1+ normal individuals, to inhibit colony-forming unit granulocyte-macrophage (CFU-GM) from normal and leukemic individuals. CTL from 20 day PR1 peptide-pulsed lymphocyte cultures showed 89% to 98% HLA-A2.1-restricted colony inhibition of chronic myeloid leukemia targets. Colony formation in normal HLA-A2.1+ bone marrow or HLA-A2.1- CML cells was not inhibited. Sequencing of the exon encoding PR1 showed that colony inhibition was not caused by polymorphic differences in proteinase 3 between effectors and targets. Analysis by flow cytometry showed that proteinase 3 was overexpressed in the leukemia targets compared with normal marrow targets (median channel fluorescence 1,399 v 298, P = .009). These results show that PR1-specific allogeneic T cells preferentially inhibit leukemic CFU-GM based on overexpression of proteinase 3, and that proteinase 3-specific CTL could be used for leukemia-specific adoptive immunotherapy.
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PMID:Cytotoxic T lymphocytes specific for a nonpolymorphic proteinase 3 peptide preferentially inhibit chronic myeloid leukemia colony-forming units. 932 17

We previously showed (E. Clave et al., J. Immunother., 22: 1-6, 1999; J. Molldrem et al., Blood, 88: 2450-2457, 1996) that PR1, a human-lymphocyte-antigen (HLA)-A2.1-restricted peptide from proteinase 3, could be used to elicit CTLs from normal individuals. These CTLs showed HLA-restricted cytotoxicity and colony inhibition of myeloid leukemia cells that overexpress proteinase 3. In this study, we constructed a phycoerythrin-labeled PR1-HLA-A2 tetramer to identify PR1-specific CTLs by flow cytometry. No peripheral blood lymphocytes from three HLA-2.1+ donors stained with the tetramer, but, after 20 days in culture with weekly PR1 stimulation, 2-8% became tetramer+. Tetramer staining identified up to 40-fold more PR1-specific CTLs than were identified by limiting dilution analysis and correlated better with lysis of PR1-coated T2 cells (R2 = 0.95 versus R2 = 0.76). Tetramer+ CTLs were memory phenotype (91% CD45RO+), and most (58% CD95+) were activated. Tetramer-sorted allogeneic CTLs produced 83% lysis of HLA-A2.1+ chronic myelogenous leukemia (CML) blasts at an E:T ratio of 2.5:1, compared with 23% lysis by nonsorted CTLs, with no background lysis of HLA-A2.1+ normal cells. Cytoplasmic proteinase-3 expression was one log greater in CML blasts than in normal granulocytes. These results show that a PR1-HLA-A2 tetramer can be used to identify and select CTLs from normal donors that preferentially lyse CML cells, which could be used for leukemia-specific adoptive immunotherapy.
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PMID:A PR1-human leukocyte antigen-A2 tetramer can be used to isolate low-frequency cytotoxic T lymphocytes from healthy donors that selectively lyse chronic myelogenous leukemia. 1036 91

Although the immune system has long been implicated in the control of cancer, evidence for specific and efficacious immune responses in human cancer has been lacking. In the case of chronic myelogenous leukemia (CML), either allogeneic bone marrow transplant (BMT) or interferon-alpha2b (IFN-alpha2b) therapy can result in complete remission, but the mechanism for prolonged disease control is unknown and may involve immune anti-leukemic responses. We previously demonstrated that PR1, a peptide derived from proteinase 3, is a potential target for CML-specific T cells. Here we studied 38 CML patients treated with allogeneic BMT, IFN- alpha2b or chemotherapy to look for PR1-specific T cells using PR1/HLA-A*0201 tetrameric complexes. There was a strong correlation between the presence of PR1-specific T cells and clinical responses after IFN-alpha and allogeneic BMT. This provides for the first time direct evidence of a role for T-cell immunity in clearing malignant cells.
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PMID:Evidence that specific T lymphocytes may participate in the elimination of chronic myelogenous leukemia. 1097 22

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).
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PMID:Novel targeted and immunotherapeutic strategies in chronic myeloid leukemia. 1256 15

We have shown that cytotoxic T lymphocytes specific for PR1, an HLA-A2-restricted nonopeptide derived from proteinase 3, kill leukemia cells and may contribute to the elimination of chronic myelogenous leukemia (CML) after treatment with IFN or allogeneic bone marrow transplant. Some patients with persistent disease also have circulating PR1-specific T cells, however, suggesting the likelihood of immune tolerance. Here we show that both high- and low-avidity PR1-specific T cells from the peripheral blood of healthy donors can be identified and selectively expanded in vitro. Although high-avidity PR1-specific T cells killed CML more effectively than low-avidity T cells, only high-avidity T cells underwent apoptosis when stimulated with high PR1 peptide concentration or when exposed to leukemia that overexpressed proteinase 3. No high-avidity PR1-specific T cells could be identified or expanded from newly diagnosed leukemia patients, whereas low-avidity T cells were readily expanded. Circulating high-avidity PR1-specific T cells were identified in IFN-sensitive patients in cytogenetic remission, however. These results provide evidence that CML shapes the host immune response and that leukemia outgrowth may result in part from leukemia-induced selective deletion of high-avidity PR1-specific T cells.
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PMID:Chronic myelogenous leukemia shapes host immunity by selective deletion of high-avidity leukemia-specific T cells. 1261 11

Poor immune reconstitution after haploidentical stem cell transplantation results in a high mortality from viral infections and relapse. One approach to overcome this problem is to selectively deplete the graft of alloreactive cells using an immunotoxin directed against the activation marker CD25. However, the degree of depletion of alloreactive cells is variable following stimulation with recipient peripheral blood mononuclear cells (PBMCs), and this can result in graft versus host disease (GVHD). We have refined this approach using recipient Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) as stimulators to activate donor alloreactive T cells. Our studies demonstrate that allodepletion with an anti-CD25 immunotoxin following stimulation with HLA-mismatched host LCLs more consistently depleted in vitro alloreactivity than stimulation with host PBMCs, as assessed in primary mixed lymphocyte reactions (MLRs). Allodepletion using this approach specifically abrogates cytotoxic T-cell responses against host LCLs. In interferon-gamma (IFN-gamma) enzyme-linked immunospot (ELISPOT) assays, antiviral responses to adenovirus and cytomegalovirus (CMV) were preserved following allodepletion. Likewise, using HLA-A2-pp65 tetramers, we have shown that the frequency of CMV-specific T cells is unaffected by allodepletion. Moreover, the donor anti-EBV response is partially retained by recognition of EBV antigens through the nonshared haplotype. Finally, we studied whether allodepletion affects the response to candidate tumor antigens in myeloid malignancies. Using HLA-A2-PR1 tetramer analysis, we found that the frequency of T cells recognizing the PR1 epitope of proteinase 3 was not significantly different in allodepleted and unmanipulated PBMCs from patients with chronic myeloid leukemia (CML) undergoing transplantation. Based on these data, we have embarked on a phase 1 clinical trial of addback of allo-LCL-depleted donor T cells in the haplo-identical setting.
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PMID:Selective depletion of donor alloreactive T cells without loss of antiviral or antileukemic responses. 1276 37

Antigens implicated in the graft-versus-leukemia (GVL) effect in chronic myeloid leukemia (CML) include WT1, PR1, and BCR-ABL. To detect very low frequencies of these antigen-specific CD8+ T cells, we used quantitative polymerase chain reaction (qPCR) to measure interferon-gamma (IFN-gamma) mRNA production by peptide-pulsed CD8+ T cells from HLA-A*0201+ healthy volunteers and from patients with CML before and after allogeneic stem cell transplantation (SCT). Parallel assays using cytomegalovirus (CMV) pp65 tetramers demonstrated the IFN-gamma copy number to be linearly related to the frequency of tetramer-binding T cells, sensitive to frequencies of 1 responding CD8+ T cell/100 000 CD8+ T cells. Responses to WT1 and PR1 but not BCR-ABL were detected in 10 of 18 healthy donors. Responses to WT1, PR1, or BCR-ABL were observed in 9 of 14 patients with CML before SCT and 5 of 6 after SCT, often to multiple epitopes. Responses were higher in patients with CML compared with healthy donors and highest after SCT. These antigen-specific CD8+ T cells comprised central memory (CD45RO+CD27+CD57-) and effector memory (CD45RO-CD27-CD57+) T cells. In conclusion, leukemia-reactive CD8+ T cells derive from memory T cells and occur at low frequencies in healthy individuals and at higher frequencies in patients with CML. The increased response in patients after SCT suggests a quantitative explanation for the greater effect of allogeneic SCT.
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PMID:Functional leukemia-associated antigen-specific memory CD8+ T cells exist in healthy individuals and in patients with chronic myelogenous leukemia before and after stem cell transplantation. 1507 Jul 13

Human neutrophil elastase (HNE) and proteinase 3 (PRO3) are myeloid tissue-restricted serine proteases, aberrantly expressed by myeloid leukemia cells. PRO3 and HNE share the PR1 peptide sequence that induces HLA-A*0201-restricted cytotoxic T cells (CTLs) with antileukemia reactivity. We studied the entire HNE protein for its ability to induce CTLs. In an 18-hour culture, HNE-loaded monocytes stimulated significant intracellular interferon gamma (IFN-gamma) production by CD4+ and CD8+ T cells in 12 of 20 and 8 of 20 healthy individuals, respectively. Lymphocytes from 2 HNE responders were pulsed weekly for 4 weeks to generate HNE-specific CTLs. One of 2 HLA-A*0201-negative individuals inhibited the colony formation of HLA-identical chronic myelogenous leukemia progenitor cells (73% inhibition at 50:1 effector-target [E/T] ratio), indicating that peptides other than PR1 can induce leukemia-reactive CTLs. Repetitive stimulations with HNE in 2 of 5 HLA-A*0201+ individuals increased PR1 tetramer-positive CD8+ T-cell frequencies from 0.1% to 0.29% and 0.02% to 0.55%, respectively. These CTLs recognized PR1 peptide or killed HNE-loaded targets. These results indicate that exogenously processed HNE is a source of PR1 peptide as well as other peptide sequences capable of inducing leukemia-specific CD8+ and CD4+ T cells. HNE could, therefore, be used in an HLA-unrestricted manner to induce leukemia-reactive CTLs for adoptive immunotherapy.
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PMID:Identification and in vitro expansion of CD4+ and CD8+ T cells specific for human neutrophil elastase. 1507 Jun 88

Identification of tumor-associated Ags is a prerequisite for vaccine-based and adoptive immune therapies. Some tumor-associated Ags elicit specific CD8 T cells in patients with chronic myeloid leukemia (CML). Here, we characterized ex vivo responses of CD8 T cells from CML patients to extrajunction bcr-abl peptides and telomerase 540-548 hTert, PR1, and WT1 peptides. CML-specific CD8 T cells were present in most treated patients and were usually multiepitopic: WT1, hTert, PR1, and bcr74 tetramer(+) cells were detected in 85, 82, 67, and 61% of patients, respectively. The breadth and magnitude of these responses did not differ significantly according to treatment or disease status. CML-specific tetramer(+) CD8 T cells had a predominantly memory phenotype, an intermediate perforin content, and low intracellular IFN-gamma accumulation in the presence of the relevant peptide. However, in short-term culture with HLA-matched leukemia cells, the patients' memory T cells were specifically reactivated to become IFN-gamma-producing effector cells, suggesting that CD8 T cell precursors with lytic potential are present in vivo and can be activated by appropriate stimulation. In conclusion, this study shows that multiepitopic tumor-specific CD8 T cell responses occur naturally in most CML patients, opening the way to new strategies for enhancing anti-CML immunity, in particular in patients with minimal residual disease.
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PMID:Ex vivo characterization of multiepitopic tumor-specific CD8 T cells in patients with chronic myeloid leukemia: implications for vaccine development and adoptive cellular immunotherapy. 1594 30

Donor-derived cytotoxic T lymphocytes (CTL) that respond to tumor antigens emerge after hematopoietic stem cell transplantation (HSCT), particularly in association with the status of immune recovery. To analyze the frequency of CTL against PR1, PRAME and WT1 after HSCT, a tetramer-based analysis was performed in 97 samples taken from 35 patients (9 AML, 11 MDS, 2 CML, 4 ALL, 7 lymphoma and 2 renal cell carcinoma [RCC]) with the HLA-A02 phenotype. Regarding PR1, only 1 sample showed the presence of tetramer-positive cells (0.04%/lymphocyte). Similarly, in PRAME, only 10 of 97 samples were sporadically positive with low titers. For WT1, positive results were detected in 39 of 97 samples and 7 (2 CML, 1 ALL, 2 lymphoma and 2 RCC) patients clearly showed positive results more than once. On the basis of these results, we performed serial analyses of WT1-specific CTL during the clinical course in 2 patients with RCC, who underwent HSCT with a reduced-intensity regimen, to examine the precise correlation between the kinetics of CTL, the occurrence of GVHD and the observed clinical response. A higher positive rate for WT1-specific CTL and a correlation with the clinical response suggest that WT1 may be a useful antigen for a wider monitoring application.
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PMID:Monitoring of WT1-specific cytotoxic T lymphocytes after allogeneic hematopoietic stem cell transplantation. 1659 44


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