Denileukin Diftitox Research Articles

Abstract 1608: CD122-selective IL-2/anti-IL-2 complexes reduce regulatory T cell function and promote CD8+ T cell polyfunctionality for durable ovarian cancer immunotherapy

Abstract The IL-2 receptor (IL-2R) is an attractive target for cancer immunotherapy as it controls both immune-suppressive regulatory T cells (Tregs) and anti-tumor T cells. We tested depleting Tregs as immunotherapy using anti-CD25 (high-affinity IL-2R subunit) antibodies (αCD25) in ID8agg mouse ovarian cancer (OC). αCD25 reduced ascites and Treg numbers but failed to reduce tumor burden, possibly because it depleted newly activated anti-tumor T cells in tumor-draining lymph nodes. Thus, αCD25 could be novel malignant ascites palliation, but has limited stand-alone efficacy. We then tested IL-2/anti-IL-2 complexes (IL-2c) that selectively stimulate medium-affinity (CD122/CD132) IL-2R thought to expand anti-tumor T cells preferentially, but with little Treg effects. In contrast to several single agents we tested that failed to treat ID8agg (e.g., αCD25, αPD-L1, IL-2 fusion toxin denileukin diftitox), IL-2c alone durably reduced ID8agg tumor burden despite lowering the tumor microenvironmental CD8+/Treg ratio. Thus, we hypothesized that IL-2c improved CD8+ function, reduced Treg function, or both. IL-2c increased polyfunctional IFN-γ+TNF-α+ anti-tumor T cells as expected, an effect that persists weeks after drug clearance. IL-2c also increased anti-tumor T cell CD25 expression that increased IL-2 sensitivity and STAT5 phosphorylation, a likely mechanism for increased polyfunctionality. Unexpectedly, IL-2c reduced the Treg functional mediators CD25, TIGIT and granzyme B, and reduced Treg suppressive function. Thus, favorable Treg modifications are a novel IL-2c mechanism of action. Adding αCD25 to IL-2c to deplete Tregs further unexpectedly worsened IL-2c efficacy in ID8agg and reduced effector memory T cells and polyfunctional T cells in the tumor microenvironment, suggesting a previously unappreciated role for CD25 in IL-2c therapy. Similar data were seen in B16 melanoma, suggesting αCD25 reduction of IL-2c efficacy is not tumor or compartment-specific (ID8agg is peritoneal and B16 is subcutaneous). αPD-L1, an ineffective monotherapy in ID8agg, combined with IL-2c to promote complete responses, suggesting potential for potent, novel combinatorial approaches. Our data suggest that antagonizing high affinity IL-2R (such as to deplete Tregs with αCD25) has limited cancer immunotherapy utility without more specific Treg targeting. In contrast, stimulating medium-affinity IL-2R with CD122-selective IL-2c has great translational promise by simultaneously improving beneficial anti-tumor T cells and reducing detrimental Treg function. Citation Format: Justin M. Drerup, Sri Lakshmi Pandeswara, Aijie Liu, Curtis A. Clark, Alvaro S. Padron, Wanjiao Chen, Vincent Hurez, Tyler J. Curiel. CD122-selective IL-2/anti-IL-2 complexes reduce regulatory T cell function and promote CD8+ T cell polyfunctionality for durable ovarian cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1608. doi:10.1158/1538-7445.AM2017-1608

Suppressor Cell-Depleting Immunotherapy With Denileukin Diftitox is an Effective Host-Directed Therapy for Tuberculosis.

Host-directed therapies that augment host immune effector mechanisms may serve as important adjunctive therapies for tuberculosis treatment. We evaluated the activity of denileukin diftitox in an acute mouse model of tuberculosis (TB) infection and analyzed the cellular composition and bacterial burden in lungs and spleens. These in vivo studies show that denileukin diftitox potentiates standard TB treatment in the mouse model, an effect which may be due to depletion of T-regulatory and myeloid-derived suppressor cells during TB infection. Our results indicate that denileukin diftitox and other suppressor cell-depleting therapies may be useful adjunctive, host-directed therapies for TB.

Biphasic Rapamycin Effects in Lymphoma and Carcinoma Treatment.

mTOR drives tumor growth but also supports T-cell function, rendering the applications of mTOR inhibitors complex especially in T-cell malignancies. Here, we studied the effects of the mTOR inhibitor rapamycin in mouse EL4 T-cell lymphoma. Typical pharmacologic rapamycin (1-8 mg/kg) significantly reduced tumor burden via direct suppression of tumor cell proliferation and improved survival in EL4 challenge independent of antitumor immunity. Denileukin diftitox (DD)-mediated depletion of regulatory T cells significantly slowed EL4 growth in vivo in a T-cell-dependent fashion. However, typical rapamycin inhibited T-cell activation and tumor infiltration in vivo and failed to boost DD treatment effects. Low-dose (LD) rapamycin (75 μg/kg) increased potentially beneficial CD44hiCD62L+ CD8+ central memory T cells in EL4 challenge, but without clinical benefit. LD rapamycin significantly enhanced DD treatment efficacy, but DD plus LD rapamycin treatment effects were independent of antitumor immunity. Instead, rapamycin upregulated EL4 IL2 receptor in vitro and in vivo, facilitating direct DD tumor cell killing. LD rapamycin augmented DD efficacy against B16 melanoma and a human B-cell lymphoma, but not against human Jurkat T-cell lymphoma or ID8agg ovarian cancer cells. Treatment effects correlated with IL2R expression, but mechanisms in some tumors were not fully defined. Overall, our data define a distinct, biphasic mechanisms of action of mTOR inhibition at doses that are clinically exploitable, including in T-cell lymphomas. Cancer Res; 77(2); 520-31. ©2016 AACR.

Cutting Edge: T Regulatory Cell Depletion Reactivates Latent Simian Immunodeficiency Virus (SIV) in Controller Macaques While Boosting SIV-Specific T Lymphocytes

T regulatory cells (Tregs) are critical in shaping the latent HIV/SIV reservoir, as they are preferentially infected, reverse CD4+ T cell activation status, and suppress CTL responses. To reactivate latent virus and boost cell-mediated immune responses, we performed in vivo Treg depletion with Ontak (denileukin diftitox) in two SIVsab-infected controller macaques. Ontak induced significant (>75%) Treg depletion and major CD4+ T cell activation, and only minimally depleted CD8+ T cells. The overall ability of Tregs to control immune responses was significantly impaired despite their incomplete depletion, resulting in both reactivation of latent virus (virus rebound to 103 viral RNA copies/ml plasma in the absence of antiretroviral therapy) and a significant boost of SIV-specific CD8+ T cell frequency, with rapid clearance of reactivated virus. As none of the latency-reversing agents in development have such dual activity, our strategy holds great promise for cure research.

Haploidentical Natural Killer Cell Infusion Induces Remission in Non-Hodgkin Lymphoma and Overcomes Resistance to Rituximab

Patients with chemotherapy refractory non-Hodgkin lymphoma (NHL) have poor prognosis. We report the results of a phase 2 clinical trial testing the efficacy of haploidentical donor NK cell infusion with rituximab for refractory NHL. Sixteen patients were enrolled, and 14 were evaluable.Treatment included IV lymphodepleting chemotherapy (pentostatin 3.75mg x 2 days; n=6 or fludarabine 25mg/m2 x 4 days; n=10) with cyclophosphamide (60mg/kg IV day -5; n=14). To enhance NK cell function and deplete regulatory T cells(Treg), we used the IL-2 receptor-targeting agent denileukin diftitox (18 μg/kg/day IV day -1; n=5) or methylprednisolone (1 mg/kg day -2 through day +9; n=9). Donor lymphocytes were CD3- and CD19-depleted and overnight stimulated with 1000 U/ml IL-2. The cellular product at a dose of 1.5-8 x 107 NK cells/kg was infused IV on day 0 followed by subcutaneous infusion of IL-2 at 9 million IU x 6 doses. Peripheral blood (PB) donor NK cells were evaluated by short tandem repeats and/or flow cytometry analyzing donor-specific HLA alleles.Patients characteristics included median age of 52 years (range 48-67); diffuse large B cell lymphoma was the most common diagnosis (n=11); all patients were rituximab and chemotherapy refractory.Of 14 evaluable patients at 2 months post-infusion, 4 achieved remissions (2 complete, 2 partial; 28%). Three patients in continuous remission proceeded to allogeneic donor transplantation at 2,3 and 9 months after NK cell therapy.Compared to healthy controls, NK cells in patients prior to therapy had reduced function (CD107a, INFγ and TNFα production), lower expression of natural cytotoxic receptors NKp46, NKp44 and DNAM (but higher NKp30) and reduced expression of suppressor receptors TIGIT, PD1 and TIM3.In all evaluable patients (n=9), donor NK cells persisted in the PB for at least 7 days after infusion with median 18% (range 0.5-97%) of the NK cells were of donor origin. In one responding patient, donor NK cells sustained beyond day 28. Responding patients (R) had significantly lower levels of absolute number of Treg (Foxp3+CD25+CD127-) at baselineand 14 days after therapy (Figure) as compared to non-responders (NR), however neither denileukin diftitox nor methylprednisolone resulted in PB Treg depletion. Expectedly, lower PB Tregs correlated with low serum levels of IL-10 (R2=0.7; p<0.001; n=12), suggestive of attenuated immuno-suppressive milieu. In addition, frequencies of PB myeloid derived suppressor cells (MDSC) were remarkably low in responders as compared to non-responders at baseline (4.5%±0.05% vs. 11%±6%) and after therapy (day 14: 3.8%±1%; vs. 9.4%±5%).Endogenous Inteleukin-15 (IL-15) serum levels peaked at the day of NK cell infusion (range 11-33pg/dl). Responders had higher IL-15 levels compared to non-responders at day 0 (Figure). IL-15 levels also correlated with functional NK cell killing at day 14 as measured by expression of CD107a (R2=0.8; p=0.008; n=5), suggesting that higher endogenous IL-15 improved NK cell cytotoxic capacity.We observed expected, but transient hematologic toxicity. Therapy was associated with grade 3 adverse effects (tumor lysis syndrome, Pneumocystis pneumonia; Clostridium difficile colitis, neutropenic fever; thrombotic microangiopathy). One unevaluable patient developed sepsis prior to NK cell infusion, and the second died of sepsis a week after therapy.In summary, our observation supports further investigation of donor NK cellular therapies for advanced NHL as a strategy to overcome chemoresistance. NK cell expansion and therapeutic efficacy might be further improved by administration of IL-15. [Display omitted] DisclosuresCooley:Fate Therapeutics: Research Funding. Miller:Oxis Biotech Scientific Advisory Board: Membership on an entity's Board of Directors or advisory committees.

Data from the First CD20-Targeted Immunotoxin, MT-3724, in a Phase I/Ib Study in Relapsed/Refractory (R/R) Non-Hodgkin's B-Cell Lymphoma (NHL)

BackgroundNovel mechanisms of action (MOA) are needed for the treatment of NHL. Because of the ubiquity and persistence of CD20 expression in B-cell malignancies, there is strong rationale to develop novel MOAs targeting CD20. However, CD20's non-internalizing nature has impeded the development of novel MOAs against this target.. MT-3724 is a recombinant fusion protein consisting of a CD20 binding variable fragment (scFv) fused to the ribosomal inhibitory protein Shiga-like toxin-I A1 subunit (SLT-I A1). Upon scFv binding to surface CD20, SLT-I A1 forces MT-3724 internalization and irreversibly inactivates cell ribosomes triggering cell death. MT-3724 has been shown to specifically bind and kill CD20+ malignant human B-cells in vitro and in in vivo animal models. Data from the first eighteen subjects evaluable for efficacy in the on-going Phase I/Ib monotherapy dose-escalation study of MT-3724 are presented.MethodsMT-3724 is being tested in a first-in-human, open label, ascending dose study (3 + 3 design) in cohorts of 5, 10, 20, 50, 100, and 75 mcg/kg/dose. Eligible subjects who previously responded to a CD20 MAb containing therapy followed by relapse/recurrence of NHL receive 6 infusions over 2 hours in the first 12 days of a 28 day cycle (first cycle). With continued safety, tolerability and lack of tumor progression, subjects may receive 4 additional 6-dose cycles (21 days) with tumor assessments after cycles 2, 4 and 5. Dose escalation is based on < 33% dose limiting toxicities (DLTs) observed during the first 28 day cycle.ResultsTo date, 18 R/R NHL subjects (mean number of prior therapies >4) have enrolled and completed at least one cycle in either the 5, 10, 20, 50, 100, or 75 mcg/kg/dose cohort. Two DLTs were identified in the 100 mcg/kg cohort considered possibly consistent with early signs/symptoms of capillary leak syndrome, a known side effect of immunotoxins. These adverse events (AEs) were non-life threatening and reversible upon drug withdrawal. The most common non-DLT AEs have been reversible hypoproteinemia (≤ Grade 2) with or without transient peripheral edema (≤ Grade 2). A summary of AEs and pharmacodynamic results will be presented. Anti-drug antibodies (ADA) have been observed with MT-3724 but the advent of ADA in subjects has not precluded deepening tumor responses. These data are consistent with the clinical experience of denileukin diftitox, the only approved toxin-based oncology therapeutic. Consistent signs of efficacy including responses were seen in subjects without recent exposure to CD20 antibodies (see table). Conversely, progression by cycle 2 was seen in all subjects who had recent CD20 antibody exposure. CD20 antibodies compete with MT-3724 for target binding and high tissue levels of CD20 antibodies likely inhibit MT-3724 activity.ConclusionsTargeting CD20 with antibodies has substantially improved survival in NHL, but unmet need remains and there is strong rationale for agents with new MOAs. MT-3724 is the first CD20 targeted immunotoxin to enter clinic trials. Encouraging clinical activity has been seen; safety, efficacy, PK, and ADA data will be presented. Ribosome inhibition represents a novel mechanism of action for the treatment of R/R NHL and continued development of MT-3724 is warranted.*both Drs. Hamlin and Fanale contributed equally to this work [Display omitted] DisclosuresHamlin:Molecular Templates: Research Funding; Novartis: Research Funding; Xencor: Membership on an entity's Board of Directors or advisory committees; Portola: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Research Funding. Fanale:molecular templates: Research Funding. Valacer:Molecular Templates: Employment, Equity Ownership. Higgins:Molecular Templates: Employment, Equity Ownership. Younes:Molecular Templates: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Single dose denileukin diftitox does not enhance vaccine-induced T cell responses or effectively deplete Tregs in advanced melanoma: immune monitoring and clinical results of a randomized phase II trial

BackgroundDepletion of CD25+ Tregs improves anti-tumor immunity in preclinical models. Denileukin diftitox is a recombinant fusion protein of human IL-2 and diptheria toxin fragment that also can kill CD25+ T...

Age and sex affect αCTLA-4 efficacy alone and combined with αB7-H1 or regulatory T cell depletion in a melanoma model.

Abstract Background Most cancer patients are aged but most preclinical studies are in young hosts. We tested age effects on immunotherapy to further our understanding and identify strategies. Methods Young (3 mos) and aged (~26 mos) BL6 mice were injected subcutaneously with syngeneic B16 melanoma cells. 7 days later, mice got 2 μg denileukin diftitox (DD), an FDA-approved IL-2/diphtheria toxin or 200 μg αCD25 (both to deplete Tregs) ± 50 μg αCTLA-4 or 100 μg αB7-H1. 5 days later mice got a 2nd treatment. Results αCTLA-4 depleted intra-tumor Tregs in young but not aged males, a major age effect. In young BL6 males or females αCTLA-4 + αB7-H1 rejected B16 tumors better than either single agent. In aged males, αCTLA4 + αB7-H1 treated B16, but surprisingly accelerated tumors in aged females. Individual agents were effective in young hosts but had negligible effects in the aged. αCTLA-4 + either DD or αCD25 to deplete Tregs significantly reduced tumor growth in young mice but DD was better than αCD25. Neither combo treated B16 in aged mice. This DD dose did not deplete Tregs in aged mice as well as young, but higher DD doses were equally effective. In support, in Foxp3DTR mice, in which we deplete ~100% Treg (versus 20–50% with DD or αCD25), aged mice potently rejected B16. Conclusions Cancer immunotherapy studies in young give an incomplete understanding of clinical effects and mechanisms in the aged most at risk for cancer. We identify major Treg effects and differential Treg depletion efficacy of αCTLA4 and DD contributing to treatment failures in the aged and means to mitigate effects. With appropriate treatments, even very old mice can mount effective anti-tumor immunity. Novel sex differences in aged are unlikely estrogen-related and require further study.

Rapamycin directly inhibits T cell lymphoma proliferation at high doses and facilitates immune-independent toxin-mediated killing at a low dose in vivo.

Abstract Hyperactive mammalian target of rapamycin (mTOR) signaling that drives tumor growth makes mTOR inhibition an attractive cancer therapeutic strategy. mTOR inhibitors are approved to treat certain carcinomas, but effects on T cell hematologic malignancies, which also express hyper-activated mTOR, are less reported. We studied effects of the mTOR inhibitor rapamycin (Rapa) in mouse EL4 T cell lymphoma. Typical pharmacologic Rapa doses (1–8 mg/kg) significantly reduced tumor burden and improved survival in subcutaneous EL4 challenge independent of interferon (IFN)-γ or host T cells which we showed was by direct suppression of tumor cell proliferation. Though we found EL4 refractory to many anti-cancer immunotherapies, its growth was significantly slowed by regulatory T cell depletion with denileukin diftitox (DD) in vivo in a T cell-dependent fashion. However, typical Rapa doses inhibited T cell activation and tumor infiltration in vivo and failed to boost DD treatment effects as expected. Low dose (LD, 75 μg/kg) Rapa reportedly improves anti-tumor immunity and we found it increased potentially beneficial CD8+ T cells with a central memory phenotype (CD44hiCD62L+) in EL4 challenge, but without clinical effect. LD Rapa significantly enhanced DD treatment efficacy, but surprisingly, DD + LD Rapa treatment effects were independent of T cells, IFN-γ or perforin. Instead, Rapa up-regulated EL4 IL-2 receptor expression (DD binding site) in vitro and in vivo, apparently facilitating direct DD tumor cell killing. We thus show an unexpected mechanism for mTOR inhibitor in cancer immunotherapy and show distinct, biphasic mechanisms of action at typical pharmacologic doses versus LD Rapa that can be exploited clinically.

Age effects on tumor B7-H1 and related immune therapies in an aggressive model of ovarian cancer.

Abstract Age is the greatest cancer risk factor, but contributions of aging to tumor intrinsic properties and immunotherapy responses are poorly understood as most preclinical studies are in young hosts. We assessed age effects on tumor properties, progression, immunity and response to immunotherapies in an aggressive ID8 ovarian cancer line (ID8agg) that is poorly immunogenic and fatal in ~5 weeks. Young (3 mos) and aged (24 mos) BL6 females were injected intraperitoneally with 4×106 syngeneic ID8agg cells. In young mice, ID8agg ascites had more regulatory T cells (Tregs) and myeloid suppressor cells (MDSCs). Young mice gained 30% weight from ascites ~30 days after ID8agg challenge and formed 1–2 large, discrete peritoneal tumor masses. Aged mice tended to lose weight although ascites volumes were comparable to young, suggesting cachexia, and formed multiple small peritoneal nodules. Aged ascites had more tumor cells, Tregs, monocytic MDSCs and PD-1+ T cells versus young. Strikingly, tumor cells and MDSCs in aged ascites upregulated the immune checkpoint molecule B7-H1 greater than in young ascites. The combination of depleting Tregs and MDSCs with denileukin diftitox (DD), an FDA-approved IL-2/diphtheria toxin + αGr-1 temporarily slowed tumor progression in aged mice with increased IFNγ+ CD8 T cells, consistent with our prior B16 data. Treg depletion with either DD or αCD25 alone, or plus αCTLA4 did not significantly prevent ID8agg progression in young or aged mice. In young hosts, αB7-H1 slowed tumor growth and increased survival, with both clinical outcomes potentiated by adding αCTLA4. αCTLA4 + αB7-H1 effects in aged hosts are under study. Thus, we identified major age effects on tumor progression, and immune and immunotherapy responses.

Research progress of peripheral T-cell lymphoma: reports from the 57th American Society of Hematology annual meeting

Peripheral T-cell lymphoma (PTCL) accounting for 10% to 15% of non-Hodgkin lymphoma (NHL) is characterized highly heterogeneous and aggressive clinical course. PTCL patients are prone to suffer from chemotherapy refractory and disease progression. Reports on research progress of PTCL in the 57th American Society of Hematology annual meeting covered multiple respects of PTCL. In basic research, the novel partner genes further improve the pathogenesis mechanism of ALK+ anaplastic large cell lymphoma (ALCL). For prognostic indicators, GATA-3 expression detected by immunochemical assay provide a novel tool to monitor PTCL prognosis. Belinostat-CHOP, brentuximab vedotin-CHP, romidepsin-ICE regimens and stem cell transplantation provide more options for patients with PTCL, and the novel drugs such as alisertib, darinaparsin and denileukin diftitox offer new hope for PTCL patients in preclinical trials. Key words: Lymphoma, T-cell, peripheral; Diagnosis; American Society of Hematology annual meeting

Abstract B034: Preclinical immune antitumor activity of myeloid-targeting E7046 and Treg depleting E7777

Abstract Purpose: To assess the combined activity of E7046 and E7777 against multiple murine syngeneic tumor models. Background: Both regulatory T cells (Tregs)and myeloid cells are significant constituents in the tumor microenvironment in many types of cancer, where they help to maintain an immunosuppressive milieu that inhibits cytotoxic T cell function, which favors tumor persistence. Prostaglandin E2 (PGE2) engages the EP4 receptor on monocytes to direct myeloid cell activities away from antigen presentation and toward immunosuppression (wound healing). PGE2-driven myeloid responses have been reported to enhance Treg immunosuppressive activity, while Tregs with high expression of the FoxP3 transcription factor have been reported to up-regulate cyclooxygenase expression and PGE2 secretion. E7046 is a highly selective small molecule that potently competes with PGE2 binding to EP4. Single agent E7046 slows the growth of multiple syngeneic murine tumor types, in a mechanism dependent upon the presence of T cells. Denileukin diftitox (ONTAK®), an IL-2/diphtheria toxin fusion protein, was originally approved by the US FDA for treating patients with relapsed/refractory cutaneous T cell lymphoma. E7777 is a new version of denileukin diftitox developed using an improved manufacturing process. We and others have shown that denileukin diftitox selectively depletes Tregs. Neither E7046 nor E7777 affects tumor cell viability in vitro. Here we assessed their combined activity against syngeneic tumor models and the mechanisms driving their activity. Methods: Tumors were implanted subcutaneously in groups of 5-10 female BALB/c mice. When tumors were &amp;gt; 50 mm3, mice were treated with E7046 (150 mg/kg, QD x 21, p.o.) and/or E7777 (2.5 or 3 μg/head, Q7D x 2 or 3, i.v). Tumors, spleens, and tumor-draining lymph nodes were excised and analyzed by flow cytometry for immune cell composition and function. Results: As single agents, both E7046 and E7777 delayed the growth of established tumors. When combined, their anti-tumor activities were significantly enhanced, with up to 20% of animals rendered stably tumor-free. Activity was significantly reduced if animals were treated with antibody to deplete CD8+ T cells. In the tumors, the combination treatment dramatically increased the ratio of CD8 T cells to CD4+CD25+Foxp3+ Tregs, and also decreased the frequency of immunosuppressive myeloid cells. Importantly, the CD8+ T cells in the treated tumors, but not in the control tumors, were found to express granzyme B. Spleens from the treated animals also showed an increased ratio of CD8+ T cells vs the highly active CD4+CD25+Foxp3+ ICOS+ Tregs. Conclusions: The combination of E7046 and E7777 showed promising preclinical anti-tumor activity via an immune-mediated mechanism. Citation Format: Diana I. Albu, Kuan-Chun Huang, Jiayi Wu, Xingfeng Bao, Kenichi Nomoto, Mary Woodall-Jappe. Preclinical immune antitumor activity of myeloid-targeting E7046 and Treg depleting E7777. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B034.

Denileukin diftitox

Denileukin diftitox

Phase I Study of E7777, a Diphtheria Toxin Fragment-Interleukin-2 Fusion Protein, in Japanese Patients with Relapsed or Refractory Peripheral and Cutaneous T-Cell Lymphoma

Phase I Study of E7777, a Diphtheria Toxin Fragment-Interleukin-2 Fusion Protein, in Japanese Patients with Relapsed or Refractory Peripheral and Cutaneous T-Cell Lymphoma

The thyroid adverse effects of novel anti-neoplastic agents

Novel anti-neoplastic agents, including targeted therapies and immunotherapies, show promising results in managing both solid and hematological malignancies: their mechanisms of action include direct effect on signaling of tumor cells, anti-angiogenetic effects and host's immune system activation leading to enhanced anti-tumor response. However new typical side effects have emerged including thyroid dysfunction, which can manifest as development of thyroid auto-immunity, primary hypothyroidism, and thyrotoxicosis. Immune checkpoint inhibitors (monoclonal antibodies targeting different ligands on T-cells and tumor cells), have shown striking results in improving prognosis of patients with metastatic melanoma and are now under investigation for several malignancies. These drugs lead to T-cell reactivation against tumor cells and host cells, causing both anti-neoplastic response and autoimmune adverse events. Autoimmune thyroid disease includes primary hypothyroidism, thyrotoxicosis and euthyroid Graves’ ophtalmopathy. In this setting, hypothyroidism may be a consequence of autoimmune hypophysitis as well. Tyrosine-kinase inhibitors, currently used for gastrointestinal stromal tumors, renal carcinoma and other malignancies, frequently lead to thyroid dysfunction and many mechanisms have been advocated, including capillary regression within the thyroid gland, direct toxic effects on thyrocytes and peripheral effects on thyroid hormone metabolism. Other immunotherapies, such as denileukin diftitox, alemtuzumab and lenalidomide can cause thyroid adverse effect as well. Thyroid dysfunction can be associated with non specific signs and symptoms which can overlap with the effects of either anti-cancer therapies or the underlying disease. Therefore clinicians should be aware of thyroid adverse effects of novel anti-neoplastic agents, in order not to overlook a condition that potentially affects patients’ morbidity and mortality.

Repeated Injections of IL-2 Break Renal Allograft Tolerance Induced via Mixed Hematopoietic Chimerism in Monkeys.

Tolerance of allografts achieved in mice via stable mixed hematopoietic chimerism relies essentially on continuous elimination of developing alloreactive T cells in the thymus (central deletion). Conversely, while only transient mixed chimerism is observed in nonhuman primates and patients, it is sufficient to ensure tolerance of kidney allografts. In this setting, it is likely that tolerance depends on peripheral regulatory mechanisms rather than thymic deletion. This implies that, in primates, upsetting the balance between inflammatory and regulatory alloimmunity could abolish tolerance and trigger the rejection of previously accepted renal allografts. In this study, six monkeys that were treated with a mixed chimerism protocol and had accepted a kidney allograft for periods of 1-10 years after withdrawal of immunosuppression received subcutaneous injections of IL-2 cytokine (0.6-3 × 10(6) IU/m(2) ). This resulted in rapid rejection of previously tolerated renal transplants and was associated with an expansion and reactivation of alloreactive pro-inflammatory memory T cells in the host's lymphoid organs and in the graft. This phenomenon was prevented by anti-CD8 antibody treatment. Finally, this process was reversible in that cessation of IL-2 administration aborted the rejection process and restored normal kidney graft function.

Effect of denileukin diftitox (DD) on vaccine-induced T-cell responses and depletion of Tregs in melanoma.

3046 Background: Depletion of CD25+ Tregs improves anti-tumor immunity in preclinical models. DD is a recombinant fusion protein of hIL-2 and diptheria toxin fragment that also kills CD25+ T cells....

Anti-CD25 antibody and denileukin diftitox deplete regulatory T cells in ID8 ovarian cancer equally, but αCD25 promotes more T cell cytotoxicity that correlates with better survival (VAC12P.1112)

Abstract In ovarian cancer (OC) regulatory T cells (Tregs) block anticancer immunity, suggesting Treg depletion could be beneficial. In our phase 2 denileukin diftitox (DDT) trial we found no clinical efficacy in 19 OC patients despite Treg depletion. αCD25 depletes Tregs but reportedly only works as cancer prophylaxis. We found that αCD25 did not treat subcutaneous B16 mouse melanoma whereas DDT did, and both reduced Tregs equally. We further show that in intraperitoneal ID8 challenge, αCD25 depletes Tregs in ascites and strikingly extends survival better than DDT, the first demonstration that αCD25 is effective cancer treatment (vs prophylaxis). Treg suppression of T cell proliferation in vitro from ID8-bearing mice was equal after DDT or αCD25. DDT and αCD25 could thus target or modulate Treg subsets or other immune cells differentially, as neither is Treg-specific. Despite reduced clinical efficacy, DDT increased beneficial IFN-γ+CD4+ and ID8-specific CD8+ T cells and NK cells in ascites better than αCD25, but also increased pro-tumorigenic IL-17+ and TNF-α+ CD4+ T cells, whereas αCD25 did not. αCD25 increased numbers of ascites GzB+CD107a+CD8+ T cells whereas DDT did not, suggesting increased cytotoxicity that could explain better clinical efficacy. These observations show that Treg depletion agents available for clinical use have distinct effects on antitumor immunity, help define clinical indications for αCD25 versus DDT and identify responsive cancers or anatomic compartments.

Denileukin diftitox reduces EL4 lymphoma growth by depleting regulatory T cells, which can be improved by αICOS (VAC12P.1116)

Abstract Immunotherapy shows promise in carcinoma treatments. As less is known about effects on lymphomas, we tested EL4 T cell lymphoma. We found that EL4 cells were CD25-CTLA4-B7H1loPD1hi by flow cytometry. Immune checkpoint blockade with αCTLA4, αB7H1, or αPD1 antibodies had no effect on tumor growth in EL4-challenged mice. αCD25 worked as prophylaxis (before EL4 challenge) but not therapy, despite depleting regulatory T cells (Tregs). In Foxp3DTR mice, specific Treg depletion reduced EL4 tumor growth, suggesting Treg depletion as a good treatment strategy. Denileukin diftitox (DD) is a relatively-specific Treg depletion drug with clinical benefits in mouse and human cancer. DD (5 μg/4 days starting 4 days after EL4 challenge) significantly delayed EL4 tumor growth and increased survival (P=.002) in WT mice. DD protection was lost in βδ TCR KO mice lacking all T cells, suggesting a T cell dependent treatment mechanism. In EL4-challenged WT, DD depleted Tregs &amp;gt; αCD25 but significantly increased ICOS by 2-fold on remaining Tregs &amp;gt; than on CD4+ or CD8+ T cells in tumor draining lymph nodes. Nearly all Tregs within tumors were ICOS+. ICOS+ Tregs were mostly CD44+ with hi Ki-67, suggesting activation that reduced DD treatment effects. In support, αICOS (100 μg/4 days starting 1 day after DD) enhanced DD-mediated EL4 tumor growth inhibition, but did not improve overall survival. DD-mediated Treg depletion plus αICOS and/or other adjuncts could lead to effective lymphoma immunotherapy.

Denileukin Diftitox (Ontak) as Maintenance Therapy for Peripheral T-Cell Lymphomas: Three Cases with Sustained Remission.

Peripheral T-cell lymphomas (PTCL) are rare but markedly aggressive forms of non-Hodgkin's lymphoma (NHL). They carry a poor prognosis, with current therapeutic approach being generally ineffective. The most employed first-line treatment is CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone), which still results in high rates of relapses. Denileukin diftitox is a fusion protein combining the cytotoxic portion of the diphtheria toxin and the receptor-binding domain of the interleukin-2 (IL-2) molecule, thereby targeting cells expressing the IL-2 receptor, including both T-cell and B-cell lymphomas. It has been approved for the treatment of cutaneous T-cell lymphomas, and it has documented activity in PTCL both as a single agent and as part of combination therapy. This report documents three cases of PTCL where denileukin diftitox has been used as long-term maintenance therapy after complete remission was achieved. While the overall survival rate of patients with advanced stage, refractory PTCL is generally poor (with median overall survival of 5.5 months), the three patients described in this report are all experiencing an ongoing complete remission for more than four years.