Search

Interleukin-2 (IL-2) expands the depleted T regulatory (Treg) cell population, and it has emerged as a potential therapy in systemic lupus erythematosus (SLE). However, IL-2 administration may involve the risk of expanding unwanted pro-inflammatory cells. We herein studied the effects of IL-2 on pro-inflammatory cytokine production by CD4 + and CD8 + T cells in parallel with Treg development following CD3/CD28 co-stimulation. While Treg cells are depleted in SLE patients, their CD4 + T cells were poised to receive and activate IL-2 signaling as evidenced by upregulation of CD25 and enhanced IL-2-incued STAT5 phosphorylation during Treg differentiation. In patients with SLE, however, IL-2 also expanded CD8 + T cells capable of producing interleukin-5, interkeukin-13 (IL-13), and interferon-γ (IFN-γ) that occurred with enhanced expression of GATA-3 and phosphorylation of STAT6 but not STAT5. Our data pinpoint a safety signal for systemic administration of IL-2 and challenges a long-held conceptual platform of type 1 and 2 cytokine antagonism by newly documenting the IL-2-dependent development of IL-13 and IFN-γ double-positive (IL-13 + IFNγ + ) CD8 + T cells in SLE., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Kato and Perl.)

While patient selection and clinical management have reduced high-dose IL-2 (HDIL2) immunotherapy toxicities, the immune mechanisms that underlie HDIL2-induced morbidity remain unclear. Here we show that dose-dependent morbidity and mortality of IL-2 immunotherapy can be modeled in human immune system (HIS) mice. Depletion of human T cell subsets during the HDIL2 treatment reduces toxicity, pointing to the central function of T cells. Preferential expansion of effector T cells secondary to defective suppressive capacity of regulatory T (T reg ) cells after HDIL2 therapy further underscores the importance of T reg in the maintenance of immune tolerance. IL-2 toxicity is induced by selective depletion or inhibition of T reg after LDIL2 therapy, and is ameliorated in HDIL2-treated HIS mice receiving the PIM-1 kinase inhibitor, Kaempferol. Modeling IL-2 pathophysiology in HIS mice offers a means to understand the functions of effector and regulatory T cells in immune-mediated toxicities associated with cancer immunotherapy.

Chemotherapy resistant leukemic stem cells (LSCs) are being targeted as a modern therapeutic approach to prevent disease relapse. LSCs isolated from methotrexate resistant side population (SP) of leukemic cell lines HL60 and MOLT4 exhibited high levels of CD25 and TRAIL R2/DR5 which are potential targets. Recombinant immunotoxin conjugating IL2α with TRAIL peptide mimetic was constructed for DR5 receptor specific targeting of LSCs and were tested in total cell population and LSCs. IL2-TRAIL peptide induced apoptosis in drug resistant SP cells from cell lines and showed potent cytotoxicity in PBMCs derived from leukemic patients with an efficacy of 81.25% in AML and 100% in CML, ALL and CLL. IL2-TRAIL peptide showed cytotoxicity in relapsed patient samples and was more effective than TRAIL or IL2-TRAIL proteins. Additionally, DR5 specific IL2-TRAIL peptide was effective in targeting and killing LSCs purified from cell lines [IC50: 952nM in HL60, 714nM in MOLT4] and relapsed patient blood samples with higher efficacy (85%) than IL2-TRAIL protein (46%). Hence, CD25 and DR5 specific targeting by IL2-TRAIL peptide may be an effective strategy for targeting drug resistant leukemic cells and LSCs., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

Recombinant interleukin-2 (rIL-2) administration in oncology indications is hampered by vascular toxicity, which presents as a vascular leak syndrome. We used this aspect of the toxicity of rIL-2 to evaluate candidate biomarkers of drug-induced vascular injury (DIVI) in rats given 0.36 mg/kg rIL-2 daily. Groups of rats were given either 2 or 5 doses of rIL-2 or 5 doses of rIL-2 followed by a 7-day recovery. The histomorphologic lexicon and grading scheme developed by the Vascular Injury Working Group of the Predictive Safety Testing Consortium of the Critical Path Institute were utilized to enable semiquantitative integration with circulating biomarker levels. The administration of rIL-2 was associated with time-dependent endothelial cell hyperplasia and hypertrophy and perivascular inflammation that correlated with increases in circulating angiopoietin-2, lipocalin-2, monocyte chemotactic protein-1, tissue inhibitor of metalloproteinase-1, vascular endothelial growth factor A, E-selectin, and chemokine (C-X-C motif) ligand-1, and the microRNAs miR-21, miR-132, and miR-155. The dose groups were differentially identified by panels comprising novel candidate biomarkers and traditional hematologic parameters. These results identify biomarkers of the early stages of DIVI prior to the onset of vascular smooth muscle necrosis., (© 2015 by The Author(s).)

Interleukin-2 (IL-2) is a multi-faceted cytokine, known for promoting proliferation, survival, and cell death depending on the cell type and state. For example, IL-2 facilitates cell death only in activated T cells when antigen and IL-2 are abundant. The availability of IL-2 clearly impacts this process. Our laboratory recently demonstrated that IL-2 is retained in blood vessels by heparan sulfate, and that biologically active IL-2 is released from vessel tissue by heparanase. We now demonstrate that heparanase digestion also releases a dimeric form of IL-2 that is highly cytotoxic to cells expressing the IL-2 receptor. These cells include "traditional" IL-2 receptor-bearing cells such as lymphocytes, as well as those less well known for IL-2 receptor expression, such as epithelial and smooth muscle cells. The morphologic changes and rapid cell death induced by dimeric IL-2 imply that cell death is mediated by disruption of membrane permeability and subsequent necrosis. These findings suggest that IL-2 has a direct and unexpectedly broad influence on cellular homeostatic mechanisms in both immune and non-immune systems.

The efficacy of donor lymphocyte infusion (DLI) for treatment of relapsed acute leukemia after allogeneic hematopoietic cell transplantation is limited. We hypothesized that interleukin-2 (IL-2) combined with DLI after chemotherapy might augment graft-versus-leukemia effects. To identify a safe and effective IL-2 regimen, a phase I/II study of DLI plus IL-2 therapy was performed for such patients. After chemotherapy, 17 patients received DLI (1 × 10(8) CD3/kg for patients with related donors, and 0.1 × 10(8) CD3/kg for those with unrelated donors) and an escalating dose of induction IL-2 (1.0, 2.0, or 3.0 × 10(6) IU/m(2)/day representing levels I [n = 7], Ia [n = 9], and II [n = 1]) for 5 days followed by maintenance (1.0 × 10(6) IU/m(2)/day) for 10 days as a continuous intravenous infusion. Unacceptable IL-2-related toxicities developed in 1 patient at level I, 2 at level Ia, and 1 at level II. Grades III-IV acute graft-versus-host disease (aGVHD) developed in 5 patients, and extensive chronic GVHD (cGVHD) developed in 8. Eight patients had a complete remission after chemotherapy prior to DLI, and 2 additional patients had a complete remission after DLI plus IL-2 therapy. In conclusion, the maximal tolerated induction dose of IL-2 combined with DLI appears to be 1.0 × 10(6) IU/m(2)/day. IL-2 administration after DLI might increase the incidence of cGVHD., (Copyright © 2011 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

There are several roadblocks that hinder systemic delivery of oncolytic viruses to the sites of metastatic disease. These include the tumor vasculature, which provides a physical barrier to tumor-specific virus extravasation. Although interleukin-2 (IL-2) has been used in antitumor therapy, it is associated with endothelial cell injury, leading to vascular leak syndrome (VLS). Here, we demonstrate that IL-2-mediated VLS, accentuated by depletion of regulatory T cells (Treg), facilitates localization of intravenously (i.v.) delivered oncolytic virus into established tumors in immune-competent mice. IL-2, in association with Treg depletion, generates "hyperactivated" natural killer (NK) cells, possessing antitumor activity and secreting factors that facilitate virus spread/replication throughout the tumor by disrupting the tumor architecture. As a result, the combination of Treg depletion/IL-2 and systemic oncolytic virotherapy was found to be significantly more therapeutic against established disease than either treatment alone. These data demonstrate that it is possible to combine biological therapy with oncolytic virotherapy to generate systemic therapy against established tumors.

Background: There is currently no chemotherapy or chemoimmunotherapy regimen that has shown impact on survival in patients with metastatic melanoma. Different biochemotherapy protocols showed promise with high response rates, but again without significant impact on survival., Methods: We report the results of a retrospective analysis of a regimen consisting of dacarbazine, cisplatin, vindesine, interleukin-2 and interferon-alpha2b in 25 consecutively treated patients with regard to toxicity, efficacy and practicability. The treatment was performed on a regular dermatological ward., Results: Grade III and IV toxicities were mainly haematological, with few cases of infection because of neutropenia seen. Best overall responses were CR 2/25, PR 2/25 and SD 9/25. The median progression free interval was 4 months (range 0-19) for all patients and the median survival time was 12 months (range 2-26). From a safety and practical point of view, there was no draw-back on treating patients in a non-intensive care unit. The median survival time is in the range of the one reported for monochemotherapy regimen. While there are some responding patients, the responses are short lived and go in parallel with high toxicity and impaired performance status., Conclusion: This complex and highly toxic chemoimmunotherapeutic regimen should not be considered as standard therapy in patients with metastatic malignant melanoma.

The recombinant duck interleukin-2 (rduIL-2) monomer was firstly isolated under nature condition, and refolded by oxidization procedure. Refolded rduIL-2 monomer induced in vitro proliferation of Con A-stimulated duck splenocytes in a sensitive and dose-dependent manner, and up-regulated in vivo the amounts of CD4+ T cells with low dose of administration. However, high doses intermittent administration resulted in sever side effects in vivo, with typical lymphocytic interstitial pneumonitis and nephritis, and lymphocytic depletion in splenic corpuscle. Our findings might be beneficial to studies of both mechanism and applications in vivo of avian IL-2.

As recently characterized, following s.c. implantation into syngeneic C57BL/6 mice, E0771 tumor invades locally into dermal layers and peritoneum, metastasizes to the lung, and induces a nonspecific immunosuppression in the host. Using this breast medullar adenocarcinoma model, a therapy consisting of a single moderate dose of doxorubicin followed by twice daily moderate doses of interleukin-2 for 30 days was examined for efficacy and mechanism of action when given to animals with established disease. This combination treatment, but not combinants alone, resulted in tumor-free long-term survival of 40% of the mice without significant toxicity and 83% of survivors had immune memory specific for E0771 cells. Treatment also decreased immune suppression induced by E0771 tumor. Full response to treatment required functional CD8(+) T cells, whereas depletion of natural killer cells caused only a reduction in response rate. A serum "biomarker" profile that correlated with, and seemed predictive of, response to treatment was identified by nuclear magnetic resonance-based metabonomic analysis. The efficacy of this nontoxic treatment and the potential to be able to predict which individual is responding to treatment are characteristics that make this chemoimmunotherapy attractive for clinical testing.

IL-2-induced vascular leak syndrome (VLS) is an important mechanism explaining the toxic effects of this cytokine and limiting its therapeutic use. We previously characterized a mouse model of IL-2-induced pulmonary VLS used to demonstrate that NK lymphocytes are involved in early/acute phase VLS (after one IL-2 injection). We also showed that NK cells and polymorphonuclear neutrophils (PMN) are involved in the late/chronic phase of the syndrome (after four daily IL-2 injections). In this study we use our mouse model to evaluate the role played by the IL-2 receptor (IL-2R) in VLS induction. Mouse and human IL-2R are different since the mouse IL-2Rbeta chain does not recognize IL-2. Here, we compare the acute and late VLS responses in human IL-2Rbeta transgenic and C57BL/6 wild type mice. Parameters linked to early phase VLS (bronchoconstriction and PMN mobilization) are enhanced in human IL-2Rbeta transgenic mice. By contrast, parameters used to measure late events (protein leakage and edema) are similar in human IL-2Rbeta transgenic mice and C57BL/6 wild type animals. However, after four IL-2 injections, the cellular content of the bronchoalveolar lavage fluids was different between the two types of animals. This study also characterizes a humanized animal model that could be further used to study human IL-2 activity and side effects in vivo.

Acute graft-versus-host disease (aGVHD) is partly mediated through activated T cells, and these cells are known to express the high-affinity receptor for interleukin 2 (IL-2R). Denileukin diftitox is composed of human IL-2 and diphtheria toxin that is cytotoxic to activated lymphocytes expressing the high-affinity IL-2R. We describe the results of a phase II study of denileukin diftitox in 22 patients with steroid-resistant aGVHD. Twenty patients were treated at dose level 1 (4.5 microg/kg daily on days 1-5 and then weekly on study days 8, 15, 22, and 29), and 2 patients were treated at dose level 2 (9.0 microg/kg delivered on the same schedule). Dose level 2 was associated with grade 3/4 renal and hepatic toxicity and vascular leak syndrome, and no further patients were treated at this level. Dose level 1 was generally well tolerated. The response of aGVHD was assessed at study days 36 and 100. Nine patients (41%) responded, all with a complete response at study day 36, and 6 patients (27%) responded at study day 100 (4 complete responses and 2 partial responses). Denileukin diftitox has promising activity in steroid-resistant aGVHD, and further study is warranted.

Denileukin diftitox (Ontak), a recombinant protein composed of human interleukin 2 (IL-2) fused to diphtheria toxin, has selective cytotoxicity against activated lymphocytes expressing the high-affinity IL-2 receptor. We conducted a phase 1 study of denileukin diftitox in 30 patients with steroid refractory acute graft-versus-host disease (GVHD). Seven patients received 9 microg/kg intravenously on days 1 and 15; 18 received 9 microg/kg intravenously on days 1, 3, 5, 15, 17, and 19; and 5 received 9 microg/kg intravenously on days 1 to 5 and 15 to 19. Hepatic transaminase elevation was the dose-limiting toxicity (DLT), and dose level 2 was the maximum tolerated dose (MTD). Overall, 71% of patients responded with complete resolution (12 of 24; 50%) or partial resolution (5 of 24; 21%) of GVHD. Eight of 24 patients (33%) are alive at 6.3 to 24.6 months (median, 7.2 months). Denileukin diftitox is tolerable and has promising activity in steroid-refractory acute GVHD.

Previous work suggested that interleukin (IL)-2 can be used for eradicating residual disease in autologous grafts and for preventing recurrence. We report a phase II study of autologous peripheral blood stem cell transplantation with in vitro IL-2 incubation of peripheral blood stem cells and posttransplantation IL-2 in patients with recurrent or refractory non-Hodgkin lymphoma. Salvage chemotherapy consisted of ifosfamide and etoposide. Responding patients underwent autologous peripheral blood stem cell transplantation. IL-2-incubated stem cells were infused on day 0. IL-2 1 mIU/m2 was given from day 1 until day 28. Four monthly maintenance cycles of IL-2 4 mIU/m2 subcutaneously twice daily days 1 to 5 and days 8 to 11 were administered thereafter. Eighty-four evaluable patients were enrolled, and 60 proceeded to transplantation, of which 56 received IL-2-incubated stem cells. The average received dose of posttransplantation IL-2 was 30% to 50% of planned. Only 42 patients received maintenance IL-2. The average received maintenance dose of IL-2 was also approximately 30% of planned. Most dose reductions were due to toxicity or patient refusal. Three-year survival and progression-free survival for all registered patients were 43% (95% confidence interval [CI], 33%-53%) and 31% (95% CI, 21%-41%), respectively. For the 60 patients undergoing transplantation, they were 59% (95% CI, 46%-72%) and 44% (95% CI, 31%-57%), respectively. There was no relation between the dose of IL-2 received and outcome. Survival and disease-free survival of the study group were similar to those of a previous study cohort that received unmanipulated stem cells and no systemic IL-2. Administration of IL-2-incubated peripheral blood stem cells and intensive posttransplantation IL-2 was associated with considerable but rapidly reversible toxicity. No effect on long-term outcome was observed., (Copyright 2004 American Society for Blood and Marrow Transplantation)

Because of its key role in immunity, interleukin-2 (IL-2) has been studied extensively for the adoptive immunotherapy of cancer. Although systemic administration of IL-2 has been shown to stimulate antitumor responses in vivo, its efficacy in the clinic has been limited by the development of serious side effects, including the induction of vascular leak syndrome. Previously, we have identified a small peptide fragment of IL-2 that was found to contain the entire vasopermeability activity of the cytokine. The identification of the location of this potentially undesirable property of IL-2 enabled us to focus on the generation of mutant derivatives that might be lacking vasopermeability activity but that retain cytokine functionality. In addition to this discovery, our laboratory has constructed monoclonal antibody/IL-2 fusion proteins that can target this potent cytokine directly to tumor for the immunotherapy of both solid and lymphoid malignancies. Using this fusion protein technology, we have constructed a series of point mutations in the newly identified vasopermeability region of IL-2 for the purpose of deleting this activity. Fusion proteins showing reduced or deleted vasopermeability activity were then tested for their cytokine potency by several methods, including their binding to IL-2 receptors, T-cell proliferation assays, the induction of secondary cytokines, dose-escalating toxicity, and finally their ability to treat established solid tumors in syngeneic immunocompetent mice. The results of these studies clearly show that the vasopermeability activity of IL-2 can be substantially deleted by single point mutations such as Arg38Trp without grossly affecting the immune function of the cytokine.

Interleukin-2 (IL-2) is used to treat metastatic renal cell carcinoma and malignant melanoma, but its use is limited by the severe hypotension it produces. We have shown here that M40403, a superoxide dismutase (SOD) mimetic, blocked IL-2-induced hypotension and allowed the dose of IL-2 to be increased in mice. The reversal of IL-2-mediated hypotension was associated with an increase in plasma catecholamines. In addition, M40403 increased lymphokine-activated killer (LAK) cell cytotoxicity in vitro and in vivo, through inhibition of macrophage superoxide production. Treatment of methylcholanthrene-induced (Meth A) ascites tumors with IL-2 and > or =3 mg per kg body weight M40403 induced 50% complete remissions lasting for more than 200 d, which was longer than those of untreated mice (15-d median survival) or mice treated with IL-2 alone (22-d median). Growth of subcutaneous implants of RENCA renal carcinoma was also inhibited by the combination of IL-2 and M40403. These results established that M40403 prevented IL-2 from causing dose-limiting hypotension, while enhancing its anticancer activity.

Interleukin 18 (IL-18) was discovered as an interferon-gamma (IFN-gamma)-inducing factor and plays important roles in natural killer (NK) cell activation. IL-18 also induces proinflammatory cytokines; chemokines; helper T-cell 2 (T(H)2) cytokines (eg, IL-4, IL-13); and immunoglobulin E (Ig-E) and IgG1 production. The combination of IL-18 plus IL-2 or IL-12 up-regulates IFN-gamma gene expression and NK cytotoxicity and has synergistic antitumor activity in vivo and in vitro. Here it is reported that daily administration of IL-18 with IL-2, but not of IL-18 or IL-2 alone, induces lethal lung injury in normal mice, but not in IL-18 receptor alpha (IL-1 receptor-related protein)-deficient (IL-18 receptor alpha(-/-)) mice. Marked interstitial infiltration of lymphocytes, composed mainly of NK cells, was found in the lungs of IL-18/IL-2-treated mice. Increased cytokine and chemokine levels were observed in the sera and lungs of IL-18/IL-2-treated mice. Administration of IL-18/IL-2 was also lethal to mice treated with a metalloproteinase inhibitor, which inhibited tumor necrosis factor-alpha and Fas-ligand release. While IFN-gamma(-/-) mice were partially resistant to the treatment, IL-4(-/-), IL-13(-/-), IL-4/IL-13(-/-), and Stat6(-/-) mice were sensitive to IL-18/IL-2, indicating that these genes were not involved in the host response. The lethal effect by IL-18/IL-2 was completely eliminated in severe combined immunodeficient mice pretreated with antiasialo-GM1 antibody and normal mice pretreated with anti-NK1.1 but not with anti-CD4 or anti-CD8, monoclonal antibody. These results suggest that specific cytokines, chemokines, and NK cells are involved in the pathogenesis of interstitial pneumonia. These results suggest that the clinical use of this interleukin may result in unexpected physiological consequences.

Interleukin 2 (IL-2) and interleukin 12 (IL-12) have potent anti-tumour activity as single agent therapy against several different murine and human tumours. Combining these cytokines may result in improved therapeutic effectiveness, however, the toxicity associated with simultaneous administration is prohibitive. This study was designed to determine the specific histopathologic changes associated with combination therapy. Mice were treated with 5 days of interleukin-2, interleukin-12, or both using standard doses and schedules. Histologic specimens were prepared from all internal organs on a daily basis to identify specific pathologic abnormalities. Treatment with interleukin-2, interleukin-12, or both resulted in pathologic insult to the liver and gastrointestinal tract. Mild lymphoplasmacytic infiltrates were seen in the liver. The most significant pathology was seen in the large bowel and consisted of apoptosis of colonic epithelial cells. While recovery of injured gastrointestinal mucosa occurred in mice treated with interleukin-2 or interleukin-12 alone, combination therapy resulted in death before recovery was possible. Combination interleukin-2 and interleukin-12 therapy results in irreversible injury of the colon as manifested by increased epithelial cell apoptosis and death in mice. Understanding the pathologic changes associated with combination cytokine therapy may lead to strategies that prevent toxicity while maintaining therapeutic effects., (Copyright 2002 Elsevier Science Ltd.)

We report the successful treatment of a patient with recurrent malignant glioma with adoptive cellular immunotherapy. The patient is a young adult with recurrent progressive disease refractory to aggressive multi-modality therapy including repetitive surgical resection, radiation, radiosurgery and chemotherapy. He received multiple courses of local administration of autologous lymphokine-activated killer (LAK) cells in combination with a low dose of interleukin-2 (IL-2) through an Ommaya reservoir-catheter system. The side-effects of this treatment were limited and manageable. The patient achieved a complete remission, as demonstrated by MRI and confirmed by glucose-positron emission tomography (PET) imaging 11 months after initiation of immune therapy. Twenty-six months later, the patient is still in remission with improving performance status. Adoptive cellular immunotherapy utilizing autologous LAK cells with low dose IL-2 appears to be a safe and effective therapy for a subset of patients with primary, recurrent or progressive malignant glioma following conventional therapy.

Unlabelled: The median survival for adults with recurrent primary malignant gliomas is 56 weeks following surgery, radiation, and chemotherapy. Generally, reoperation can extend the median survival an additional 26-32 weeks. We have developed an aggressive treatment program that utilizes low doses of interleukin-2 (IL-2) combined with ex vivo activated killer cells (LAK) infused via an indwelling catheter placed into the surgical resection cavity. Autologous leukocytes were collected during a standard 3-4 h, outpatient leukapheresis procedure, then activated ex vivo for 4-5 days with high doses of IL-2. The treatment protocol consisted of two 2-week cycles of therapy over a 6-week period. Patients with stable disease or objective response on follow-up MRI scans were retreated at 3-month intervals. Acute and cumulative IL-2-related toxicities were observed, but limited, and included fever, headache and transient neurologic irritation. Corticosteroid levels and usage were strictly controlled during immunotherapy, although higher doses were used intermittently to mitigate toxicity. Biologic changes included lymphocytic infiltration, regional eosinophilia, tumor necrosis, and the localized production of IL-2, IFN-gamma and IL-12, demonstrated by in situ hybridization and immunohistochemistry., Summary: IL-2 plus autogeneic LAK cells can be safely administered intracavitary to treat high grade primary brain tumors with limited toxicity within the central nervous system. Six out of 28 patients had long-term survival of greater than 2 years post-reoperation plus immunotherapy with 2 patients alive over 8 years. The presence of a marked regional eosinophilia appeared to correlate with increased survival and may be predictive of a biologic and therapeutic response. Regional adoptive immune therapy was well tolerated and should be considered an option for patients with high-grade tumors refractive to standard therapeutic approaches.

Human interleukin 2 (IL-2; Proleukin) is an approved therapeutic for advanced-stage metastatic cancer; however, its use is restricted because of severe systemic toxicity. Its function as a central mediator of T-cell activation may contribute to its efficacy for cancer therapy. However, activation of natural killer (NK) cells by therapeutically administered IL-2 may mediate toxicity. Here we have used targeted mutagenesis of human IL-2 to generate a mutein with approximately 3,000-fold in vitro selectivity for T cells over NK cells relative to wild-type IL-2. We compared the variant, termed BAY 50-4798, with human IL-2 (Proleukin) in a therapeutic dosing regimen in chimpanzees, and found that although the T-cell mobilization and activation properties of BAY 50-4798 were comparable to human IL-2, BAY 50-4798 was better tolerated in the chimpanzee. BAY 50-4798 was also shown to inhibit metastasis in a mouse tumor model. These results indicate that BAY 50-4798 may exhibit a greater therapeutic index than IL-2 in humans in the treatment of cancer and AIDS.

To evaluate the therapeutic effects and systemic toxicities of a capecitabine-based home therapy regimen in patients with metastatic renal cell carcinoma, 30 patients were enrolled in a phase II clinical trial. Treatment consisted of oral capecitabine combined with subcutaneous recombinant human interferon-alpha 2a, recombinant human interleukin-2 and oral 13-cis-retinoic acid. There were two (7%) complete responses (CRs) and eight (27%) partial remissions (PRs), for an overall objective response rate of 34% (95% CI 17-53%). Except one, all responses are ongoing, with a median duration of 9+ and 8+ months for CRs and PRs, respectively. Additionally, 12 patients (40%) reached stable disease. Eight patients (27%) showed continued disease progression despite treatment. Therapy was well tolerated and was given in the outpatient setting. Capecitabine-related World Health Organization (WHO) grade 2 and 3 toxicities were observed in five and two patients respectively, and were limited to fatigue, nausea/vomiting, diarrhoea, stomatitis, dermatitis and hand-and-foot syndrome. The substitution of capecitabine for 5-FU in the pre-existing biochemotherapy regimen did not result in a reduced therapeutic efficacy and showed significant anti-tumour activity in patients with advanced renal cell carcinoma., (Copyright 2000 Cancer Research Campaign.)

A hybrid human protein was produced in E. coli by fusing the genes encoding human pancreatic RNase1 (hpRNase1) and human IL-2 (hIL-2). The recombinant hpRNase1-hIL-2 inhibited protein synthesis in HTLV-1-infected, malignant T cells, which hyperproduce high affinity IL-2 receptors, with an IC(50)of 2x10(-8) M, whereas no inhibition was detectable in control cells with lower affinity receptors. HpRNase1 alone had an IC(50)of almost 10(-3) M. A molar excess of hIL-2 blocked the protein synthesis inhibition dose-dependently. In a human mixed lymphocyte culture, hpRNase1-hIL-2 inhibited the proliferation of responder cells with potency comparable to that of cyclosporine, while non-effective doses of FK506 importantly improved its potency. Despite its short half-life in animals, hpRNase1-hIL-2 rapidly enters cells in a few minutes and arrests the protein translation in less than 10 h. Thus, hpRNase1-hIL-2 may be useful to selectively eliminate activated lymphocytes hyperproducing high affinity IL-2 receptors, as in allograft rejection, graft-versus-host disease, autoimmune disorders, adult T cell leukaemia and other lymphoproliferative or retroviral malignancies including HIV infection, without inducing general immunosuppression. As an entirely human "immunotoxin analogue" it may alleviate the dose limiting toxicity and immunogenicity of conventional immunotoxins., (Copyright 2000 Academic Press.)

Replication-defective adenovirus (AdCMVmIL2) expressing murine interleukin-2 was directly injected into rat medullary thyroid carcinomas to examine antitumor activity. AdCMVmIL2 cured 42.9% of all treated tumor bearing animals. Most cured rats were protected against tumor growth after subsequent rechallenge with wild-type tumor cells, reflecting the immunity obtained from the original treatment. Studies of viral dissemination showed that the intratumoral inoculated viruses can enter the circulation, infect peripheral tissues, and express genes driven by the CMV promoter. Liver is the main target organ. In a toxicity study, AdCMVmIL2 was administered i.v. at a dose five times higher than that given directly into tumor. No detectable side effect was found. Histological studies showed variable degrees of lymphocyte infiltration in the livers of studied animals, and no functional change indicated by the normal serum level of glutamic oxalacetic transaminase and glutamic pyruvic transaminase was found in all animals studied. These data demonstrate that AdCMVmIL2 is an effective antitumor agent in this animal model, and that virus treatment can be given without significant toxicity to other organs.

The dose-limiting toxicity of interleukin-2 (IL-2) and immunotoxin (IT) therapy in humans is vascular leak syndrome (VLS). VLS has a complex etiology involving damage to vascular endothelial cells (ECs), extravasation of fluids and proteins, interstitial edema, and organ failure. IL-2 and ITs prepared with the catalytic A chain of the plant toxin, ricin (RTA), and other toxins, damage human ECs in vitro and in vivo. Damage to ECs may initiate VLS; if this damage could be avoided without losing the efficacy of ITs or IL-2, larger doses could be administered. In this paper, we provide evidence that a three amino acid sequence motif, (x)D(y), in toxins and IL-2 damages ECs. Thus, when peptides from RTA or IL-2 containing this sequence motif are coupled to mouse IgG, they bind to and damage ECs both in vitro and, in the case of RTA, in vivo. In contrast, the same peptides with a deleted or mutated sequence do not. Furthermore, the peptide from RTA attached to mouse IgG can block the binding of intact RTA to ECs in vitro and vice versa. In addition, RTA, a fragment of Pseudomonas exotoxin A (PE38-lys), and fibronectin also block the binding of the mouse IgG-RTA peptide to ECs, suggesting that an (x)D(y) motif is exposed on all three molecules. Our results suggest that deletions or mutations in this sequence or the use of nondamaging blocking peptides may increase the therapeutic index of both IL-2, as well as ITs prepared with a variety of plant or bacterial toxins.

Immune responses, including natural immunity (NI), potentiate the antitumor effects of chemotherapy. Since interferons and interleukin-2 (IL-2) augment NI, a pilot study was conducted to assess the tolerability and the effects on host immunity of adjuvant chemotherapy associated with IL-2 + interferon alpha (IFN) in breast cancer patients after surgery. Ten patients underwent alternating 28-day cycles of chemoimmunotherapy [cyclophosphamide + methotrexate + 5-fluorouracil (CMF, days 1, 8) + IL-2 (days 15 19) + IFN (day 22)] and chemotherapy alone (CMF). With this regimen each patient was considered to be a reasonable "control" of herself. Blood cell count and natural killer cell activity (NKA) were tested on days 1, 8, 15, 22, and 23. Preliminary in vitro studies indicated that IL-2 or IFN antagonized the severe inhibition of NKA induced by hydroxy-peroxy-cyclophosphamide (in vitro active derivative of cyclophosphamide), alone or associated with methotrexate + 5-fluorouracil. Nine patients completed all six alternating cycles, whereas one patient proved to have metastatic lesions after four cycles. The protocol was well tolerated, although leukopenia (CMF alone) and leukopenia with fever and moderate or minimal flu-like symptoms (CMF + IL-2 + IFN) were generally observed. Treatment with IL-2 facilitated complete recovery of white cell counts and NKA after the nadir on day 15. In conclusion, the present protocol appears to be well tolerated and amenable to administration on an outpatient basis. Therefore, further investigations should be performed to verify whether CMF + IL-2 + IFN would be superior to CMF alone for adjuvant treatment after surgery in breast cancer.

The use of interleukin 2 (IL-2) as an antineoplastic agent has been limited by the serious toxicities that accompany the doses necessary for a tumor response. Elevation of nitric oxide (NO) and tumor necrosis factor (TNF) both have been implicated in IL-2 toxicities. CNI-1493, a tetravalent guanylhydrazone, is an inhibitor of macrophage activation including the synthesis of TNF and other cytokines. Doses of CNI-1493 as low as 1 mg/kg/day conferred complete protection against fatal toxicity of IL-2 with IL-2 doses tenfold higher than the safely tolerated level in Sprague-Dawley rats. Moreover, typical pathologic changes in the lungs, kidneys, and the liver caused by IL-2 infusion were blocked by cotreatment with CNI-1493. When animals bearing established hepatomas were given IL-2 and CNI-1493 combination therapy, 10 of 10 hepatomas regressed from 1 cm3 to <1 mm3. Intracytoplasmic TNF levels were increased in normal tissues from IL-2 treated animals, and treatment with CNI-1493 maintained TNF at control levels. The degree of apoptosis measured by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling staining of tumors following IL-2 therapy was not reduced compared with IL-2 cotreated with CNI-1493. In contrast, apoptosis in the liver and lung parenchyma following IL-2 therapy was blocked completely by cotreatment with CNI-1493. Taken together, these data showed that low and infrequent doses of CNI-1493 markedly protected animals from IL-2 systemic toxicities whereas not affecting tumor response to IL-2 therapy. With the protection afforded by CNI-1493 treatment, IL-2 therapy dose levels could be increased to provide significant antitumor effects in animals with established hepatomas.

A high-dose bolus regimen for interleukin(IL)-2 administration to cancer patients frequently causes serious side-effects in which various organs are involved. In order to reveal the mechanism of toxicities associated with this regimen, we compared the augmenting effect of high-dose IL-2 on murine organ-associated lymphocytes between neoplastic and non-neoplastic states. Intraperitoneal administration of IL-2 at a dose of 10(5) JRU (Japanese Reference Units) twice daily for 3 days led to the death of all the syngeneic MH134-hepatoma- or X5563-myeloma-bearing mice, whereas it had no lethal effect on non-tumor-bearing mice. Histological and morphometric analyses demonstrated that tumor-bearing mice displayed more extensive infiltration of large granular lymphocytes and agranular lymphocytes in the liver and lungs than did the non-tumor-bearing mice. Large granular lymphocytes had the ultrastructural characteristics of lymphokine-activated killer cells. Lymphocytes often underwent extravasation into the interstitial space and exhibited local proliferation without causing any direct injury to apposed parenchymal cells. Flow-cytometric analysis of hepatic mononuclear cells demonstrated that IL-2-receptor-beta (IL-2R beta)-bearing lymphocytes, i.e., natural killer cells and intermediate CD3 cells, were increased in number in the neoplastic state before the IL-2 injection. The present study indicates that the tumor-bearing state increases the number of organ-associated IL-2R beta + lymphocytes, which are then greatly amplified by the challenge of high-dose IL-2, leading to the functional disturbance of organs. We have further demonstrated here that an intermittent low-dose IL-2 regimen has a potential therapeutic effect on tumor regression without causing lethal side-effects.

Interleukin 2 (IL-2) is a cytokine produced by activated T cells that plays a crucial role in the immune response and exerts multiple functions in different tissues including the nervous system. The present study was carried out to investigate the effect of recombinant human IL-2 (rhIL-2) on the survival of differnet glial cells type and of cortical neurons in culture. The results demonstrate that rhIL-2 is selectively cytotoxic to oligodendrocytes only if preincubated in aqueous solution (1200 U/ml) for at least two days before being added to the culture. Other glial and neuronal cells were unaffected. The cytotoxic effect was temperature- and concentration-dependent occurring only when rhIL-2 was reincubated at 37 degrees C and was dose-dependently neutralized by antibodies raised against IL-2 indicating that an immunoreactive IL-2 like compound is the active principle. Polyacrilamide gel electrophoresis under native (PAGE) and denaturing (SDS-PAGE) conditions and gel filtration analysis of the rhIL-2 incubated solution suggest that rhIL-2 is cytotoxic to oligodendrocytes only after association into soluble high weight molecular aggregates., (Copyright 1997 Academic Press Limited.)

We have constructed two fusion proteins, DAB389-mIL-3 and DAB389-(Gly4Ser)2-mIL-3, in which the receptor-binding domain of diphtheria toxin is replaced by mouse interleukin-3 (IL-3). Cytotoxic activity of the fusion toxins was observed on three out of six cell lines assayed. This toxicity was mediated through binding to the IL-3 receptor as it was inhibited in a dose-dependent manner with murine IL-3 or anti-IL-3 neutralizing antibodies. DAB389-(Gly4Ser)2-mIL-3 was up to 5 times more toxic than DAB389-mIL-3, depending on the cell line (0.8 x 10(-10) M < IC50 < 3 x 10(-10) M). These proteins can be used for the detection of IL-3 receptors on mouse cells and should allow for the selective elimination of IL-3 receptor-positive pluripotent hematopoietic stem cells prior to bone marrow transplantation.

Effective use of interleukin (IL)-2 as an antineoplastic agent may be hindered by severe side-effects, in particular vascular leak syndrome, which leads to generalized, especially pulmonary, edema. The oxygen-free-radical scavenger dimethylthiourea (DMTU) was shown to attenuate IL-2-induced vascular leak syndrome in sheep receiving a single IL-2 injection. However, in the clinical setting multiple injections are necessary to gain a therapeutic effect. The present study tests whether DMTU attenuates IL-2-induced vascular leak syndrome following multiple IL-2 injections without affecting IL-2-induced cytotoxicity in peritoneal mononuclear cells. Mice were treated intraperitoneally with 1 x 10(5) units IL-2 three times daily for four consecutive days. DMTU (10 mg/0.5 ml) was administered to the study group once daily, prior to the first IL-2 injection. Comparing the wet/dry weight ratio of lungs, liver, and spleen showed that IL-2 caused a significant (P < 0.05) wet/dry increase in all three organs. DMTU attenuated the wet/dry increase in the lungs (P < 0.05), in the spleen (P < 0.05), and not at all in the liver. IL-2 induced a marked increase in peritoneal mononuclear cell counts, which was not attenuated by DMTU. The cytotoxic effect of IL-2-activated peritoneal mononuclear cells on target B16 cells was also unchanged in animals pretreated with DMTU. In conclusion, we have shown that DMTU ameliorates pulmonary permeability and vascular leak syndrome associated with multiple-dose IL-2 therapy, without eliciting an inhibitory effect on IL-2 induced-cytotoxicity.

Interleukin-2 (IL-2) is reputed to cause a "vascular leak syndrome." We studied pulmonary hemodynamics and lymph dynamics in six sheep treated for 7 days with IL-2 (1.8 million IU/kg twice daily or 1.8 million IU/kg each day as a continuous infusion). Lung lymph flow increased from 4.8 +/- 2 ml/15 min pre-IL-2 to 14.4 +/- 6.8 ml/15 min on the seventh day of IL-2. The lymph-to-plasma protein concentration ratio was unchanged (0.70 +/- 0.06 vs. 0.63 +/- 0.13). The plasma-to-lymph equilibration half-time of radiolabeled albumin was 2.0 +/- 0.6 h pre-IL-2 and 1.0 +/- 0.7 h on day 7 of IL-2. Pulmonary arterial pressure was 24 +/- 7 cmH2O pre-IL-2, increased to 32 +/- 4 cmH2O on the fourth day of IL-2, and returned to 29 +/- 5 cmH2O on the seventh day of IL-2. Extravascular lung water was normal (4.07 +/- 0.25 g/g dry lung). To clearly determine whether the increase in lung lymph flow was due to hemodynamic changes or to increased leakiness of the microvascular barrier, we volume loaded six sheep with lactated Ringer solution before and after 3 days of IL-2 treatment (1.8 million IU/kg twice daily). Lung lymph flows increased fivefold during 4 h of crystalloid infusion compared with baseline and were higher after 3 days of IL-2. However, lymph-to-plasma protein concentration ratios decreased to the same low levels pre-and post IL-2 (0.39 +/- 0.06 vs. 0.41 +/- 0.10), indicating and intact microvascular barrier. Extravascular lung water was elevated (5.56 +/- 0.39 g/g dry lung) but was not different from lung water in three volume-loaded control sheep (4.87 +/- 0.53 g/G dry lung). We conclude that IL-2 causes minimal or no injury to the pulmonary microvascular barrier and that volume expansion during IL-2 treatment can cause hydrostatic pulmonary edema.

Subcutaneous injection of recombinant human interleukin-2 (rhuIL-2) at 10(2)-10(4) U/mouse induced delayed (48 h) accumulation of mononuclear leukocytes with diffuse granulocytes, including eosinophils. Subcutaneous local infusion of rhuIL-2 or recombinant murine IL-2 (10(2)-10(4) U/mouse) via implanted Alzet miniosmotic pumps in mice induced chronic inflammatory lesions characterized by infiltration of large vacuolated mononuclear leukocytes, lymphoid cells, and eosinophil foci; neovascularization, with high endothelial-like cells, was prominent, exhibiting intravascular trapping and migration of large mononuclear leukocytes. Leukocyte infiltrates comprised T lymphocytes (CD4+; CD8+), B lymphocytes, and macrophages. Control infusions of bovine serum albumin (BSA) induced weak fibrotic lesions with sparse macrophage infiltration and minimal accumulation of lymphocytes; VLA4+ and ICAM-1+ leukocyte infiltrates were significantly greater in IL-2-induced lesions compared with BSA-induced lesions. Quantitative image analysis showed significantly increased lesion size in the IL-2-induced lesions compared with those induced by BSA infusion. The vascularity of IL-2-induced lesions assessed by immunostaining for platelet-endothelial cell adhesion molecule was increased compared with control, BSA-induced lesions mainly due to neovascularization. ICAM-1 and VCAM-1 expression was significantly enhanced in IL-2 lesions. No systemic pathological changes were observed following IL-2 infusion. We conclude that local slow-release of IL-2 causes the evolution and maintenance of a specific chronic inflammatory lesion.

The high-affinity interleukin 2 (IL-2) receptor is a heterotrimer consisting of alpha, beta, and gamma subunits. We examined the concentration of subunit mRNA for each of the three protein subunits on human hematopoietic cell lines, human peripheral blood mononuclear cells, and murine fibroblasts transfected with cDNAs encoding the human IL-2 receptor subunits. In most cultured hematopoietic cells, there was abundant gamma subunit message. In contrast, there was variable expression of both alpha and beta subunit message. Sensitivity of cells to the diphtheria fusion toxin DAB389IL-2 was not related to expression of any single IL-2 receptor subunit mRNA. Rather, the greatest sensitivity was observed for cells possessing all three subunit mRNAs. Cells displaying beta and gamma subunit mRNA showed a reduced but significant sensitivity to the fusion toxin. In contrast, cells with alpha and gamma subunit mRNA, but missing the beta subunit mRNA, were insensitive to DAB389IL-2. The data correlate with the requirement for an intermediate or a high-affinity receptor for cell intoxication. A critical concentration of the beta subunit may be required for toxin internalization and killing.

Administration of interleukin 2 (IL-2) has been associated with potent in vitro antitumor effects. However, systemic in vivo toxicity has been problematic. Because local delivery and liposomal formulations of IL-2 may improve the therapeutic index, we used dogs to evaluate and compare immunological activation of inhaled free IL-2 and IL-2 liposomes. Twelve normal dogs were treated with nebulized IL-2 formulations and controls for 2 to 7 weeks. Cellular immune activation of peripheral blood mononuclear cells and bronchoalveolar lavage (BAL) effector leukocytes against tumor cell lines, changes in effector leukocyte populations, and toxicity were monitored. No toxicity was seen with either aerosolized free IL-2 or IL-2 liposomes. Free IL-2 given at 0.5 x 10(6) Biologic Response Modifier Program (BRMP) units twice daily to dogs resulted in increased peripheral blood mononuclear cell activation compared with saline control-treated dogs. IL-2 liposomes given at 0.5 x 10(6) BRMP units twice daily to dogs resulted in significantly increased BAL effector activation compared with IL-2 liposomes given at 1.0 x 10(6) BRMP units once daily (P = 0.018) and empty liposome controls (P = 0.016). The BAL leukocyte cell count was increased significantly after inhalation of IL-2 liposomes versus inhalation of free IL-2 (P = 0.011). BAL effector populations included a greater proportion and total number of lymphocytes and eosinophils after treatment with IL-2 liposomes. Nontoxic activation of pulmonary immune effectors for the treatment of cancer in the lung may be possible using nebulized IL-2 liposomes.

Interleukin (IL)-2-induced microvascular lung injury is an experimental paradigm commonly used to investigate the pathogenesis of the adult respiratory distress syndrome. Since tumor necrosis factor-alpha (TNF-alpha) is known to induce such an injury in vivo and since TNF-alpha is involved in other models of lung injury, we postulated that it might also mediate pulmonary toxicity after IL-2 administration. The present study tested this hypothesis by evaluating the effect of TNF-alpha inhibition on IL-2-induced lung injury in the rat. Recombinant human IL-2 (10(6) U IV per rat, n = 6) elevated lung water, myeloperoxidase activity, and protein accumulation in bronchoalveolar lavage fluid and induced tissue hypoxia. Also, IL-2 enhanced lung tissue TNF-alpha mRNA and peptide (1543 +/- 496 pg/g lung wet weight) localized to alveolar macrophages by in situ hybridization. In marked contrast, IL-2 failed to affect serum TNF-alpha, which remained at undetectable levels. Pretreatment with anti-TNF-alpha monoclonal antibody (25 mg/kg IV, n = 7) or the TNF-alpha synthesis inhibitor rolipram (200 micrograms/kg IV, n = 7) attenuated lung injury and reverted tissue hypoxia. Furthermore, TNF-alpha inhibition prevented the upregulation of lung tissue IL-1 beta, IL-6, cytokine-induced neutrophil chemoattractant, and E-selectin (ELAM-1) but not intercellular adhesion molecule-1 mRNAs in response to IL-2. These data imply that locally produced TNF-alpha mediates IL-2-induced lung inflammation and tissue injury and point to the potential utilization of TNF-alpha inhibitors in treating the pulmonary toxicity of IL-2 immunotherapy.

Interleukin 2 (IL-2) mediates the regression of metastatic cancer, but its clinical use is limited by associated toxicities including hepatic dysfunction. To determine the mechanism for IL-2-induced hepatic dysfunction, we hypothesized that IL-2 activation of Kupffer cells causes leukocyte-endothelial adhesion and decreases hepatic sinusoidal blood flow. C57BL/6 mice were given injections of latex particles and prepared for intravital hepatic microscopy 2 h after i.p. IL-2 administration. Liver tissue was also prepared to quantitate hepatic tumor necrosis factor (TNF) mRNA and processed for light and electron microscopy. Phagocytosing Kupffer cells and leukocytes adherent to the endothelium were counted, and surface sinusoidal blood flow was quantitated. Kupffer cell activity was quantitated as the ratio of phagocytosing Kupffer cells to sinusoidal blood flow. IL-2 significantly increased Kupffer cell activity (0.56 +/- 0.05 for controls versus 0.84 +/- 0.05 for IL-2), significantly caused leukocyte-endothelial adhesion (26.7 +/- 7.9 for controls versus 87.0 +/- 27.6 for IL-2, WBC/mm2 endothelial surface), and significantly decreased the number of sinusoids containing blood flow per microscopic field (6.66 +/- 0.15 for controls versus 5.79 +/- 0.13 for IL-2) without causing changes in systemic hemodynamic parameters. In IL-2 treated livers, light and electron microscopy showed the constriction of sinusoids associated with swollen or ruptured mitochondria, which was consistent with hypoxic deterioration near central venules. Adherent platelets, neutrophils, and lymphocytes within sinusoids and central venules were also observed. PCR revealed that IL-2 significantly induced TNF mRNA expression in the liver. These data suggest that IL-2 activates Kupffer cells in association with the release of monokines including TNF, which causes activation of circulating leukocytes as well as hepatic sinusoidal endothelial cells. The resultant leukocyte and platelet adhesion to the endothelium may then physically impede the sinusoidal microcirculation, resulting in microscopic areas of hepatic ischemia and explaining the mechanism of IL-2-induced hepatic dysfunction.

We tested whether NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, can prevent interleukin 2 (IL-2)-induced capillary leakage in tumour-bearing mice without compromising the therapeutic benefits of IL-2. C3H/HeJ female mice transplanted s.c. with 2.5 x 10(5) C3-L5 mammary carcinoma cells were treated with: nothing, IL-2 (ten injections of 15,000 Cetus units i.p. every 8 h), L-NAME (0.1, 0.5, or 1 mg ml-1 drinking water), IL-2 + L-NAME (0.1 or 0.5 or 1 mg ml-1 drinking water). Therapies were given in one round (IL-2, days 10-13; L-NAME, days 9-13) or in two rounds (IL-2, days 10-13 and 20-23; L-NAME, days 9-13 and days 19-23) after tumour transplantation. Capillary leakage was measured from the water contents of the pleural cavities, lungs, spleen and kidneys. Effects of the therapies on the primary tumour size and the number of spontaneous lung metastases were also recorded. NO production was measured as the nitrite + nitrate levels in the serum and in the pleural effusion. After the first round of therapies, addition of L-NAME significantly reduced IL-2-induced pulmonary oedema and water retention in the spleen in a dose-dependent manner. It also significantly reduced the IL-2-induced rise in NO levels in the serum and pleural fluid, but did not affect IL-2-induced pleural effusion or water retention in the kidney. At later stages of tumour growth (day 23), tumours themselves induced significant fluid retention in the lungs and the kidney, which was not aggravated further with the second round of IL-2 therapy. At this time, L-NAME therapy alone ameliorated tumour-induced pulmonary oedema. During both rounds of therapy different doses of L-NAME alone caused a reduction of primary tumour growth as well as spontaneous lung metastases, which improved further with the addition of IL-2. The combination therapy was at least as effective as IL-2 therapy. In summary, L-NAME had anti-tumour effects in vivo, reduced the severity of IL-2-induced capillary leakage in some organs and did not compromise anti-tumour efficacy of IL-2 therapy. Thus, L-NAME could be a valuable adjunct to IL-2-based cancer therapy.

Pulmonary vascular leak induced in mice by interleukin 2 (IL-2) was attenuated by pretreatment with single or multiple doses of oral methotrexate. Methotrexate also attenuated pulmonary vascular leak when either larger doses of IL-2 or when lymphokine-activated killer (LAK) cells or LAK cells plus IL-2 were administered. Lymphoid infiltrates in the lungs of mice treated with IL-2 and methotrexate were significantly lower. The number of mice surviving treatment with high doses of IL-2 was also significantly increased when these mice were treated with methotrexate. Methotrexate prevented the IL-2-induced increase in the number of splenocytes that were asialo GM1+ but had no effect on Lyt 2+ or L3T4+ cell content. A marginal but significant inhibition in the generation of effector splenocytes that were cytolytic to either YAC or MCA-205 tumor targets was observed in mice treated with methotrexate and IL-2. In vivo studies indicated that methotrexate did not compromise the anti-tumor efficacy of treatment regimens that contained IL-2, LAK cells, or IL-2 and LAK cells. These results demonstrate the potential clinical utility of methotrexate in attenuating pulmonary vascular leak induced by IL-2 without compromising its efficacy. One potential mechanism of action of methotrexate is related to its ability to stimulate the release of adenosine followed by the inhibition of the adhesion of leukocytes to the IL-2-activated endothelium.

Histologic, electron microscopic, and immunohistochemical studies were made to analyze the structural features and the cellular composition of the pulmonary lesions produced in rats by the administration of interleukin-2 (IL-2). This agent induced pulmonary edema; thickening of alveolar septa; damage to endothelial cells in capillaries and venules, marked interstitial infiltration by cytotoxic T lymphocytes, lymphokine-activated killer (LAK) cells, macrophages, and dendritic cells (as demonstrated by cell counting in preparations stained immunohistochemically with peroxidase- and fluorochrome-labeled antibodies); and injury to bronchiolar and alveolar epithelial cells. Granular and agranular lymphocytes often were closely apposed to endothelial cells in capillaries and venules. Contacts between lymphocytes and type II alveolar epithelial cells also were observed. Damaged type II alveolar epithelial cells showed nuclear and cytoplasmic features that are considered indicative of apoptosis (confirmed by nick end labeling). Phagocytosis of apoptotic bodies by macrophages was occasionally found. These results support the concept that IL-2 induces cytotoxic vascular and parenchymal cell damage that is mediated by LAK cells and cytotoxic T lymphocytes, which make contacts with endothelial cells and type II alveolar epithelial cells. This damage appears to be exacerbated by the secondary release of a variety of vasoactive agents and inflammatory mediators.

Interleukin-12 (IL-12) is a potent immunostimulatory cytokine and an inducer of type-1 T-helper cell activity and of cytotoxic T lymphocyte and natural killer cell function. We report here the paradoxical observation that a single injection of 4,900 IU of recombinant murine IL-12 inhibits acute graft-versus-host disease (GVHD) in a fully major histocompatibility complex (MHC) plus multiple minor antigen-mismatched bone marrow transplantation (BMT) model (A/J-->B10). The protective effect was enhanced by administration of T-cell-depleted host-type BM cells, and complete donor-type lymphohematopoietic reconstitution was observed in most animals. Treatment with a protective course of IL-12 led to increased serum interferon-gamma (IFN-gamma) levels as compared with those for GVHD controls at early time points, when IFN-gamma was produced predominantly by host-type natural killer cells, but led to almost complete inhibition of the later GVHD-associated increase in serum IFN-gamma levels, when IFN-gamma is produced predominantly by CD4+ T cells. Furthermore, IL-12 treatment was associated with marked alterations in the kinetics of donor T-cell expansion. Reductions in donor CD4+ and CD8+ T cells were observed in the spleen on day 4 post-BMT, but a marked increase in donor CD8+ cells was observed on day 7. Unlike broadly immunosuppressive methods for inhibiting GVHD, which are associated with loss of antileukemic effects, IL-12 has the potential to mediate antileukemic effects of its own; therefore, the GVHD-inhibitory effects of IL-12 described here suggest a potential application for this cytokine in clinical BMT.

Adoptive immunotherapy with tumor-infiltrating lymphocytes (TILs) causes regression of some human tumors. However, the sustained proliferation and antitumor activity of TILs requires the coadministration of potentially toxic amounts of interleukin-2 (IL-2). In an effort to overcome the requirement by T cells for IL-2, we have introduced alternative growth factor receptors that use the relatively nontoxic cytokine erythropoietin (Epo) as a ligand. In our model system, the coexpression of chimeric receptors consisting of the extracellular portion of the Epo receptor (EpoR) and the intracellular portions of the IL-2 receptor subunits, beta and gamma, conferred Epo responsiveness on a T-cell line. By contrast, cells expressing the wild-type EpoR did not proliferate in response to Epo. This suggested that Epo binding caused the activation of an IL-2 signal pathway mediated by the chimeric receptors. This approach can be used to minimize toxicity and potentially improve cancer immunotherapy with TILs.

Toxicity associated with high-dose recombinant interleukin 2 (rIL-2) therapy simulates a sepsis syndrome, but the mechanism remains unclear. We hypothesised that translocated gut-origin bacteria may be important. Fifty-one male rats were randomised to receive rIL-2 by intraperitoneal injection at doses (IU) of 10(5) (n = 15), 10(4) (n = 8), 10(3) (n = 8) or 10(2) (n = 8) twice daily, or a saline bolus (n = 12). After 5 days, ileal histomorphology was assessed and the mesenteric lymph node complex cultured. Results showed that colonisation of mesenteric lymph nodes with Escherichia coli occurred in all rats treated with 10(5) IU of rIL-2, and in 62%, 37% and 12% of rats treated with decreasing doses of rIL-2. No translocation was observed in control animals. An increase in submucosal lymphatics and occasional mucosal disruption was seen only in the group receiving 10(5) IU. These data show that rIL-2 promotes bacterial translocation and suggests a mechanism that may fuel high-dose rIL-2 toxicity in man.

Fifty-seven patients with metastatic melanoma were treated with interleukin 2 (IL-2) 7.8 MIU m-2 day-1 as a continuous infusion for 4 days combined with interferon alpha (IFN-alpha) 6 MIU m-2 day-1 subcutaneously on days 1 and 4. The cycle was repeated every 2 weeks for a maximum number of 13 cycles. Of the 51 evaluable patients, one (2%) achieved a complete and seven (14%) a partial response (total response rate 16%; CI 7-29%). Median time to progression and median survival were 2.5 and 11.3 months respectively. This regimen of IL-2 and IFN-alpha appeared to be only moderately active.

The role of interleukin-2 (IL-2) on tumor growth of B16F10 melanoma cells was assessed in two sets of mice with different immune status: normal (immunocompetent) mice and immunodeficient mice. The two sets of animals were treated with cyclophosphamide (CY) or IL-2 alone or with a combined therapy of CY+IL-2. On days 6 and 10 after tumor cell injection, we evaluated the incidence of hepatic B16 melanoma metastases and the percentage of hepatic volume occupied by metastatic tissue. We observed that the CY alone (300 mg/kg, days 3 and 8 post-tumoral inoculation) significantly reduced tumor growth in all treated mice; however, CY proved more effective in normal recipients than in immunodeficient hosts. On the other hand, whereas administration of IL-2 alone (10(5) IU daily, from day 3 to day 7) in immunocompetent mice significantly reduced tumor growth on days 6 and 10, in immunodeficient mice, no significant differences were observed in tumor growth either on the 6th or on the 10th day, in comparison to control groups. Finally, when the combined CY+IL-2 therapy was administered, an antisynergistic effect between these therapeutic agents was achieved both in normal and in immunodeficient mice. Thus, the addition of low-dose IL-2 (25 x 10(3) IU daily, from day 4 to day 7) to high-dose CY (300 mg/kg, days 3 and 8) significantly increased tumor growth in both the early and later periods, compared to the effect of CY alone. It is concluded that exogenous IL-2 can facilitate tumor growth of B16 melanoma cells in vivo.

Seven patients in second complete remission of acute myeloid leukemia (AML) aged 19-65 years were treated with polyethylene glycolated interleukin-2 (PEG IL-2), 1 x 10(6) U/M2 IV weekly as the sole postremission therapy. Second remission duration was in the range of 4-49+ months, and three patients had a second remission duration substantially longer than their first (6, 21+, and 42+ months). The results suggest that PEG IL-2 may prolong second remission duration in AML and that a prospective randomized study designed to test that idea is warranted.

Four normal adult dogs received two consecutive weekly cycles of human recombinant interleukin-2 (IL-2) by continuous infusion for 4 days/week. The dose of IL-2 given to each dog was 3 x 10(6) units m-2 day-1. Toxicities consisted of mild vomiting, diarrhea, and lethargy to varying degrees in all the dogs. These side-effects were reversed when the treatment was discontinued. Fever, tachypnea, and weight gain were not seen. A marked lymphocytosis and eosinophilia developed in all dogs after completion of each course of IL-2 (resulting in a more than sevenfold increase in each cell type) and persisted for more than 1 month in some. Fresh peripheral blood lymphocytes (PBL) obtained during this lymphocytosis mediated enhanced in vitro lysis of a natural-killer-cell-sensitive canine tumor cell line (CTAC). The in vitro proliferative responses of these same PBL to IL-2 could be detected earlier, progressed faster, and involved more cells than PBL tested prior to IL-2 infusion. Thus, a relatively well-tolerated regime of IL-2 in dogs can induce dramatic increases in lymphocyte numbers and activation, which is associated with augmentation of their in vitro antitumor reactivity. The clinical effectiveness of this immunotherapeutic approach remains to be tested in tumor-bearing dogs where it could serve as a relevant large-animal model for immunotherapy of cancer with IL-2.

Histological and ultrastructural changes were investigated in lung, liver, and heart of mice given interleukin-2 (IL-2), either alone or in combination with other cytokines. IL-2 induced a vascular leak syndrome (VLS) of a moderate degree with infiltration of lymphoid cells, moderate endothelial damage, mild hepatic parenchymal damage, and minimal myocardial alterations. Interferon-alpha (IFN-alpha) produced infiltration mainly of monocytes/macrophages in liver and heart; endothelial cell damage was absent in lung and heart and minimal in liver. Interleukin-1 alpha (IL-1 alpha) caused an increased number of neutrophils in liver and lung; VLS and parenchymal cell and endothelial damage were not found. The VLS and the cellular damage caused by the combination of IL-2 and IFN were much more severe than those produced by IL-2 alone. In animals treated with IL-2, IFN-alpha, and IL-1 alpha, VLS was minimal and parenchymal and endothelial cell damage were less severe than after IL-2 alone or IL-2 plus IFN-alpha. Taken together, these observations show that IL-1 alpha reduces ultrastructural changes produced by IL-2 and IFN-alpha. This reduction may be clinically useful in the treatment of neoplasms.

A double-institution phase II study was performed in patients with metastatic renal cell carcinoma treated subcutaneously (s.c.) with interleukin 2 (IL-2) and alpha-interferon (INF-alpha). Thirty-eight patients were treated over a course of 7 weeks. Initially (day 1 + 2) patients received s.c. IL-2 at 18 x 10(6) IU m-2. During the following 6 weeks, patients received s.c. IL-2 at 3.6 x 10(6) IU m-2 for 5 days per week and s.c. INF-alpha at 5 x 10(6) for 3 days per week. Thirty-eight patients were evaluated for response. An objective response was seen in seven patients (18.4 +/- 12.3%), with one complete response and six partial responses. Median duration of response was 6.7 months. Toxicity could be evaluated in 38 patients and was limited. Mild to moderate toxicity included fever (97%), fatigue or malaise (76%), nausea or vomiting (50%), anorexia (32%), hypotension (26%), neurological disturbances (26%) and hypercreatininaemia (39%). In addition, four grade IV haematological toxicities were noted. No cardiac side-effects were seen. IL-2 and INF-alpha given by this schedule can be safely administered in an outpatient setting. The objective response rate was similar to our previous treatments with high-dose IL-2 given as a continuous infusion.