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Journal of Immunology (Baltimore, Md. :... Nov 2008Chronically SIVagm-infected African green monkeys (AGMs) have a remarkably stable nonpathogenic disease course, with levels of immune activation in chronic SIVagm...
Cutting edge: Experimentally induced immune activation in natural hosts of simian immunodeficiency virus induces significant increases in viral replication and CD4+ T cell depletion.
Chronically SIVagm-infected African green monkeys (AGMs) have a remarkably stable nonpathogenic disease course, with levels of immune activation in chronic SIVagm infection similar to those observed in uninfected monkeys and with stable viral loads for long periods of time. In vivo administration of LPS or an IL-2/diphtheria toxin fusion protein (Ontak) to chronically SIVagm-infected AGMs triggered increases in immune activation and subsequently of viral replication and depletion of intestinal CD4(+) T cells. Our study indicates that circulating microbial products can increase viral replication by inducing immune activation and increasing the number of viral target cells, thus demonstrating that immune activation and T cell proliferation are key factors in AIDS pathogenesis.
Topics: Adjuvants, Immunologic; Animals; CD4-Positive T-Lymphocytes; Chlorocebus aethiops; Chronic Disease; Diphtheria Toxin; Flow Cytometry; Interleukin-2; Lipopolysaccharides; Lymphocyte Activation; Recombinant Fusion Proteins; Simian Acquired Immunodeficiency Syndrome; Simian Immunodeficiency Virus; Viral Load; Virus Replication
PubMed: 18981083
DOI: 10.4049/jimmunol.181.10.6687 -
Annals of Oncology : Official Journal... Sep 2008
Topics: Antigens, CD; CTLA-4 Antigen; Diphtheria Toxin; Humans; Immunotherapy; Interleukin-2; Neoplasms; Receptors, Interleukin-2; Recombinant Fusion Proteins; T-Lymphocytes, Regulatory
PubMed: 18790959
DOI: 10.1093/annonc/mdn459 -
Blood Oct 2008The role of FoxP3(+)CD4(+) regulatory T (Treg) cells in HIV-1 disease in vivo is poorly understood due to the lack of a robust model. We report here that CD4(+)FoxP3(+)...
The role of FoxP3(+)CD4(+) regulatory T (Treg) cells in HIV-1 disease in vivo is poorly understood due to the lack of a robust model. We report here that CD4(+)FoxP3(+) T cells are developed in all lymphoid organs in humanized Rag2(-/-)gammaC(-/-) (DKO-hu HSC) mice and they display both Treg phenotype and Treg function. These FoxP3(+) Treg cells are preferentially infected and depleted by a pathogenic HIV-1 isolate in HIV-infected DKO-hu HSC mice; and depletion of Treg cells is correlated with induction of their apoptosis in vivo. When CD4(+)CD25(+/hi) Treg cells are depleted with the IL-2-toxin fusion protein (denileukin diftitox), HIV-1 infection is significantly impaired. This is demonstrated by reduced levels of productively infected cells in lymphoid organs and lower plasma viremia. Therefore, FoxP3(+) Treg cells are productively infected and play an important role in acute HIV-1 infection in vivo. The DKO-hu HSC mouse will be a valuable model to study human Treg functions and their role in HIV-1 pathogenesis in vivo.
Topics: Animals; Apoptosis; DNA-Binding Proteins; Diphtheria Toxin; Forkhead Transcription Factors; HIV Infections; HIV-1; Humans; Immunoglobulin gamma-Chains; Interleukin-2; Interleukin-2 Receptor alpha Subunit; Lymphocyte Depletion; Mice; Mice, Knockout; Recombinant Fusion Proteins; T-Lymphocytes, Regulatory; Virus Replication
PubMed: 18544681
DOI: 10.1182/blood-2008-03-145946 -
Blood Aug 2008CD4(+)CD25(high)FoxP3(+) regulatory T (Treg) cells limit antigen-specific immune responses and are a cause of suppressed anticancer immunity. In preclinical and clinical... (Clinical Trial)
Clinical Trial
CD4(+)CD25(high)FoxP3(+) regulatory T (Treg) cells limit antigen-specific immune responses and are a cause of suppressed anticancer immunity. In preclinical and clinical studies, we assessed the immune consequences of FoxP3(+) Treg-cell depletion in patients with advanced malignancies. We demonstrated that a CD25(high) targeting immunotoxin (denileukin diftitox) depleted FoxP3(+) Treg cells, decreased Treg-cell function, and enhanced antigen-specific T-cell responses in vitro. We then attempted to enhance antitumor immune responses in patients with carcinoembryonic antigen (CEA)-expressing malignancies by Treg-cell depletion. In a pilot study (n = 15), denileukin diftitox, given as a single dose or repeated dosing, was followed by immunizations with dendritic cells modified with the fowlpox vector rF-CEA(6D)-TRICOM. By flow cytometric analysis, we report the first direct evidence that circulating CD4(+)CD25(high)FoxP3(+) Treg cells are depleted after multiple doses of denileukin diftitox. Earlier induction of, and overall greater exposure to, the T-cell response to CEA was observed in the multiple-dose group, but not the single-dose group. These results indicate the potential for combining Treg-cell depletion with anticancer vaccines to enhance tumor antigen-specific immune responses and the need to explore dose and schedule of Treg depletion strategies in optimizing vaccine efforts.
Topics: Antigens, Neoplasm; Cancer Vaccines; Carcinoembryonic Antigen; Dendritic Cells; Diphtheria Toxin; Humans; Immunity; Immunotherapy, Adoptive; Interleukin-2; Lymphocyte Depletion; Pilot Projects; Recombinant Fusion Proteins; T-Lymphocytes, Regulatory; Treatment Outcome
PubMed: 18519811
DOI: 10.1182/blood-2008-01-135319 -
American Journal of Hematology Jul 2008Peripheral T-cell lymphoma (PTCL) is an aggressive form of non-Hodgkin's lymphoma (NHL), associated with poor prognosis and without standard approach to treatment....
Peripheral T-cell lymphoma (PTCL) is an aggressive form of non-Hodgkin's lymphoma (NHL), associated with poor prognosis and without standard approach to treatment. Denileukin diftitox (Ontak) is a synthetic fusion protein combining the receptor-binding domain of interleukin-2 to the enzymatically active portion of diphtheria toxin. While approved for the treatment of cutaneous T-cell lymphoma, it has demonstrated activity in non-Hodgkin's lymphomas of both T-cell and B-cell origin. This report documents the first case of de novo maintenance therapy with denileukin diftitox sustaining an ongoing complete response at the molecular level for 2 years in a patient with PTCL.
Topics: Diphtheria Toxin; Humans; Interleukin-2; Lymphoma, T-Cell, Peripheral; Male; Middle Aged; Recombinant Fusion Proteins; Remission Induction
PubMed: 18383317
DOI: 10.1002/ajh.21177 -
American Journal of Hematology Jul 2008Denileukin diftitox (Ontak) is an immunotoxin used in the treatment of cutaneous T-cell lymphomas. Vascular leak syndrome is a known complication of this therapy,...
Denileukin diftitox (Ontak) is an immunotoxin used in the treatment of cutaneous T-cell lymphomas. Vascular leak syndrome is a known complication of this therapy, although the syndrome is most often self-limited. We report the case of a patient with cutaneous gamma/delta (gammadelta) T-cell lymphoma and previous undiagnosed liver disease treated with denileukin diftitox. Just 4 days after initiating drug therapy, the patient developed profound vascular leak syndrome characterized by a rapid fall in his previously normal serum albumin to levels below the limit of detection. The patient then quickly deteriorated into rhabdomyolysis and eventual death. To our knowledge, this is the first report of a death directly related to denileukin diftitox therapy. The purpose of this case is to increase awareness and improve management of patients who are treated with denileukin diftitox with resulting vascular leak syndrome leading to hypoalbuminemia.
Topics: Diphtheria Toxin; Fatal Outcome; Fibrosis; Humans; Interleukin-2; Lymphoma, T-Cell, Cutaneous; Male; Middle Aged; Recombinant Fusion Proteins; Syndrome; Treatment Failure; Vascular Diseases
PubMed: 18335564
DOI: 10.1002/ajh.21180 -
Journal of Translational Medicine Mar 2008Cognate immunity against neoplastic cells depends on a balance between effector T cells and regulatory T (Treg) cells. Treg cells prevent immune attack against normal...
BACKGROUND
Cognate immunity against neoplastic cells depends on a balance between effector T cells and regulatory T (Treg) cells. Treg cells prevent immune attack against normal and neoplastic cells by directly suppressing the activation of effector CD4+ and CD8+ T cells. We postulated that a recombinant interleukin 2/diphtheria toxin conjugate (DAB/IL2; Denileukin Diftitox; Ontak) may serve as a useful strategy to deplete Treg cells and break tolerance against neoplastic tumors in humans.
METHODS
We administered DAB/IL2 (12 microg/kg; four daily doses; 21 day cycles) to 16 patients with metastatic melanoma and measured the effects on the peripheral blood concentration of several T cell subsets and on tumor burden.
RESULTS
We found that DAB/IL2 caused a transient depletion of Treg cells as well as total CD4+ and CD8+ T cells (< 21 days). T cell repopulation coincided with the de novo appearance of melanoma antigen-specific CD8+ T cells in several patients as determined by flow cytometry using tetrameric MART-1, tyrosinase and gp100 peptide/MHC conjugates. Sixteen patients received at least one cycle of DAB/IL2 and five of these patients experienced regressions of melanoma metastases as measured by CT and/or PET imaging. One patient experienced a near complete response with the regression of several hepatic and pulmonary metastases coupled to the de novo appearance of MART-1-specific CD8+ T cells. A single metastatic tumor remained in this patient and, after surgical resection, immunohistochemical analysis revealed MART1+ melanoma cells surrounded by CD8+ T cells.
CONCLUSION
Taken together, these data indicate that transient depletion of T cells in cancer patients may disrupt the homeostatic control of cognate immunity and allow for the expansion of effector T cells with specificity against neoplastic cells. Several T cell depleting agents are clinically available and this study provides strong rationale for an examination of their efficacy in cancer patients.
TRIAL REGISTRATION
NCT00299689 (ClinicalTrials.gov Identifier).
Topics: Adult; Aged; Antigens, Neoplasm; Antineoplastic Agents; Cell Line, Tumor; Diphtheria Toxin; Female; Humans; Immunoglobulin G; Interleukin-2; Leukocyte Count; Male; Melanoma; Middle Aged; Neoplasm Metastasis; Recombinant Fusion Proteins; Remission Induction; Skin Neoplasms; T-Lymphocyte Subsets; T-Lymphocytes, Regulatory; Time Factors; Treatment Outcome; Tumor Burden
PubMed: 18334033
DOI: 10.1186/1479-5876-6-12 -
Journal of Immunological Methods Apr 2008There has been recent interest in the depletion of regulatory T cells (Tregs) as part of a multi-faceted approach to the immunotherapy of melanoma patients. This is in... (Comparative Study)
Comparative Study
There has been recent interest in the depletion of regulatory T cells (Tregs) as part of a multi-faceted approach to the immunotherapy of melanoma patients. This is in part due recent findings that convincingly show that Tregs are an integral part of regulating and even suppressing an immune response to growing tumor cells. We therefore compared three methods of Treg depletion and/or elimination, utilizing low dose cyclophosphamide (CY), a specific antibody directed against the IL-2 receptor found on Tregs (PC61) and the use of denileukin diftitox (DD), which is a fusion protein designed to have a direct cytocidal action on cells which express the IL-2 receptor. We show that CY administration resulted in the highest reduction in Tregs among the three reagents. However, the reduction in Tregs with CY was also associated with the concomitant reduction of CD8(+) T cells and a lack of tumor antigen priming. Utilization of DD resulted in a >50% Treg cell reduction without parallel cytocidal effects upon other T cell subsets but did not enhance anti-tumor immunity against B16 melanoma. Lastly, the PC61 showed a moderate reduction of Tregs that lasted longer than the other reagents, without a reduction in the total number of CD8(+) T cells. Furthermore, PC61 treatment did not abrogate tumor antigen-specific immunity elicited by dendritic cells (DC). We therefore conclude that PC61 administration was the most effective method of reducing Tregs in a murine melanoma model in addition to providing evidence of a synergistic effect when combined with DC-based immunotherapy.
Topics: Animals; Cell Line, Tumor; Cyclophosphamide; Diphtheria Toxin; Disease Models, Animal; Female; Flow Cytometry; Immunotherapy; Interleukin-2; Lymphocyte Depletion; Melanoma, Experimental; Mice; Mice, Inbred C57BL; Receptors, Interleukin-2; Recombinant Fusion Proteins; Survival Analysis; T-Lymphocytes, Regulatory
PubMed: 18295790
DOI: 10.1016/j.jim.2008.01.012 -
American Journal of Hematology Dec 2007
Clinical Trial
Topics: Adult; Aged; Bone Marrow Cells; Diphtheria Toxin; Humans; Interleukin-2; Mastocytosis, Systemic; Middle Aged; Recombinant Fusion Proteins
PubMed: 17665501
DOI: 10.1002/ajh.21013 -
Blood Nov 2007CD4+CD25+Foxp3+ regulatory T (Treg) cells have been implicated in the lack of effective antitumor immunity. Denileukin diftitox (DAB(389)IL-2), a fusion protein of... (Comparative Study)
Comparative Study
CD4+CD25+Foxp3+ regulatory T (Treg) cells have been implicated in the lack of effective antitumor immunity. Denileukin diftitox (DAB(389)IL-2), a fusion protein of interleukin 2 (IL-2) and diphtheria toxin, provides a means of targeting Treg cells. In this study, we examined (1) the effect of denileukin diftitox on the deletion of Treg cells in various lymphoid compartments and (2) the dose scheduling of denileukin diftitox in combination with a recombinant poxviral vaccine to enhance antigen-specific immune responses. Treg cells in spleen, peripheral blood, and bone marrow of normal C57BL/6 mice were variously reduced after a single intraperitoneal injection of denileukin diftitox; the reduction was evident within 24 hours and lasted approximately 10 days. Injection of denileukin diftitox 1 day before vaccination enhanced antigen-specific T-cell responses above levels induced by vaccination alone. These studies show for the first time in a murine model (1) the differential effects of denileukin diftitox on Treg cells in different cellular compartments, (2) the advantage of combining denileukin diftitox with a vaccine to enhance antigen-specific T-cell immune responses, (3) the lack of inhibition by denileukin diftitox of host immune responses directed against a live viral vector, and (4) the importance of dose scheduling of denileukin diftitox when used in combination with a vaccine.
Topics: Animals; Cells, Cultured; Combined Modality Therapy; Diphtheria Toxin; Drug Administration Schedule; Female; Immunity, Cellular; Immunotoxins; Influenza A virus; Interleukin-2; Lymphocyte Count; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Transgenic; Poxviridae; Recombinant Fusion Proteins; T-Lymphocytes, Regulatory; Viral Vaccines
PubMed: 17616639
DOI: 10.1182/blood-2007-06-094615