Optimal regimes for local IL-2 tumour therapy

Bovine ocular squamous cell carcinoma

Ocular squamous cell carcinoma (OSCC) in animals is a primary neoplasm of epithelial origin. OSCC or "cancer eye" is the most common malignant tumor affecting cattle in North America and is responsible for significant economic losses. In the United States, the prevalence of OSCC varies geographically and is higher in the southwestern region and in lower latitudes with higher levels of sunlight. Control of this disease would be of considerable significance to the economics and profitability of the beef and dairy cattle industries. This article reviews the characteristics of the most commonly affected animals, the factors that are believed to contribute to the development of OSCC, and the treatment options that have been proposed.

The novel chelator lipid 3(nitrilotriacetic acid)-ditetradecylamine (NTA3-DTDA) promotes stable binding of His-tagged proteins to liposomal membranes: Potent anti-tumor responses induced by simultaneously targeting antigen, cytokine and costimulatory signals to T cells

Recent studies indicate that the chelator lipid nitrilotriacetic acid ditetradecylamine (NTA-DTDA) can be used to engraft T cell costimulatory molecules onto tumor cell membranes, potentially circumventing the need for genetic manipulation of the cells for development of cell- or membrane-based tumor vaccines. Here, we show that a related lipid 3(nitrilotriacetic acid)-ditetradecylamine (NTA(3)-DTDA, which has three NTA moieties in its headgroup instead of one) is several-fold more effective than NTA-DTDA at promoting stable His-tagged protein engraftment. IAsys biosensor studies show that binding of His-tagged B7.1 (B7.1-6H) to NTA(3)-DTDA-containing membranes, exhibit a faster on-rate and a slower off-rate, compared to membranes containing NTA-DTDA. Also, NTA(3)-DTDA-containing liposomes and plasma membrane vesicles (PMV) engrafted with B7.1-6H and CD40-6H exhibit greater binding to T cells, in vitro and in vivo. Engrafted NTA(3)-DTDA-containing PMV encapsulated cytokines such as IL-2, IL-12, GM-CSF and IFN-gamma, allowing targeted delivery of both antigen and cytokine to T cells, and stimulation of antigen-specific T cell proliferation and cytotoxicity. Importantly, use of B7.1-CD40-engrafted PMV containing IL-2 and IL-12 as a vaccine in DBA/2J mice induced protection against challenge with syngeneic tumor cells (P815 mammary mastocytoma), and regression of established tumors. The results show that stable protein engraftment onto liposomal membranes using NTA(3)-DTDA can be used to simultaneously target associated antigen, costimulatory molecules and cytokines to T cells in vivo, inducing strong anti-tumor responses and immunotherapeutic effect.

Locoregional IL-2 low dose applications for gastrointestinal tumors

AIM: To explore the feasibility of local interleukin 2 (IL-2) in patients with different forms of abdominal cancer. This required experimentation with the time interval between IL-2 applications and the methods of application.

METHODS: Sixteen patients with stages III and IV of gastrointestinal malignancies (primary or metastatic) who were admitted to our Department of Gastroenterology were treated with locoregionally applied IL-2 in low doses.

RESULTS: No major problems applying locoregional IL-2 were encountered. In 6 out of 16 patients, a modest but clinically worthwhile improvement was obtained. Adverse effects were minimal. The therapeutic scheme was well tolerated, even in patients in a poor condition.

CONCLUSION: This study demonstrates the feasibility of low dose locoregional IL-2 application in advanced abdominal cancer. Local IL-2 therapy gives only negligible adverse effects. The results suggest that it is important to apply intratumorally. Local IL-2 may be given adjunct to standard therapeutic regimes and does not imply complex surgical interventions. These initial results are encouraging.

Synergistic antitumor response of interleukin 2 with melphalan in isolated limb perfusion in soft tissue sarcoma-bearing rats

The cytokine interleukin 2 (IL-2) is a mediator of immune cell activation with some antitumor activity, mainly in renal cell cancer and melanoma. We have previously shown that tumor necrosis factor (TNF)-alpha has strong synergistic antitumor activity in combination with chemotherapeutics in the isolated limb perfusion (ILP) setting based on a TNF-mediated enhanced tumor-selective uptake of the chemotherapeutic drug followed by a selective destruction of the tumor vasculature. IL-2 can cause vascular leakage and edema and for this reason we examined the antitumor activity of a combined treatment with IL-2 and melphalan in our well-established ILP in soft tissue sarcoma-bearing rats (BN175). ILP with either IL-2 or melphalan alone has no antitumor effect, but the combination of IL-2 and melphalan resulted in a strong synergistic tumor response, without any local or systemic toxicity. IL-2 enhanced significantly melphalan uptake in tumor tissue. No signs of significant vascular damage were detected to account for this observation, although the tumor sections of the IL-2- and IL-2 plus melphalan-treated animals revealed scattered extravasation of erythrocytes compared with the untreated animals. Clear differences were seen in the localization of ED-1 cells, with an even distribution in the sham, IL-2 and melphalan treatments, whereas in the IL-2 plus melphalan-treated tumors clustered ED-1 cells were found. Additionally, increased levels of TNF mRNA were found in tumors treated with IL-2 and IL-2 plus melphalan. These observations indicate a potentially important role for macrophages in the IL-2-based perfusion. The results in our study indicate that the novel combination of IL-2 and melphalan in ILP has synergistic antitumor activity and may be an alternative for ILP with TNF and melphalan.

In situ crosslinked biodegradable hydrogels loaded with IL-2 are effective tools for local IL-2 therapy

We investigated the therapeutic efficacy of recombinant human interleukin-2 (rhIL-2)-loaded, in situ gelling, physically crosslinked dextran hydrogels, locally applied to SL2 lymphoma in mice. The physical crosslinking was established by stereocomplex formation between d-lactic acid oligomers and l-lactic acid oligomers grafted separately to dextrans. The stereocomplex hydrogel as described in our manuscript has several favourable characteristics, which enables its use as system for the controlled release of pharmaceutically active proteins. Firstly, the hydrogel system is a physically crosslinked system. In physically crosslinked gels, the use of chemical crosslinking agents is avoided. Such agents can potentially inactivate the protein and can covalently link the protein to the hydrogel network. Secondly, the hydrogel formation takes place at room temperature and physiological pH, and, importantly, in an all-aqueous environment. All factors are important to preserve the three-dimensional structure, and thus the biological activity, of the protein to be entrapped and released from the gels. Thirdly, the gel formation does not occur instantaneously. This means that a liquid formulation can be injected which solidifies after injection (in situ gel formation is possible). Fourthly, no pH drop during degradation is expected during degradation. As a control, free rhIL-2 was administered locally in either a single injection or at five consecutive days. All mice received the same total dose of rhIL-2. The rhIL-2-loaded hydrogels released most IL-2 over a period of about 5 days. The biocompatibility and biodegradability of the gels were excellent, as there were no acute or chronic inflammatory reaction and as the gels were replaced completely by fibroblasts after 15 days. The therapeutic efficacy of rhIL-2-loaded in situ gelled hydrogels is very good, as was demonstrated in DBA/2 mice bearing SL2. The therapeutic effect of a single application of gels loaded with 1 x 10(6) IU rhIL-2 is at least comparable to the therapeutic effect of injection of an equal dose of free rhIL-2. All mice cured with rhIL-2-loaded hydrogels survived a subsequent challenge, rejecting 10(6) intraperitoneal (i.p.) injected SL2 cells. In conclusion, this study demonstrates that in situ gelling, physically crosslinked dextran hydrogels slowly release encapsulated rhIL-2 in such a way that it is intact and biologically and therapeutically active. These hydrogels may greatly enhance the clinical applicability of rhIL-2 immunotherapy as only a single treatment is required and as these hydrogels are completely biodegradable.

Presence of Cytotoxic B220+CD3+CD4−CD8− Cells Correlates with the Therapeutic Efficacy of Lymphoma Treatment with IL-2 and/or IL-12

Cancer treatment with IL-2 and IL-12 is thought to work via enhancement of proliferation and activity of T cells and NK cells. Incubation of cytotoxic T lymphocytes (CTLs) and NK cells with IL-2 and/or IL-12 results in propagation of a distinct cell type called lymphokine-activated killers (LAK) characterized by increased lytic activity against many tumor types. Here we address the question whether cytokine therapy may be efficient in treatment of a LAK-insensitive tumor and, if so, which cell type, other than classic LAK cells, is responsible for tumor cell killing. We used DBA/2 mice bearing metastasized SL2 lymphoma and treated them with locally applied IL-2 and /or IL-12 injections. We showed that IL-12 treatment is efficient, though there is a rather narrow range of effective doses because of toxicity. This toxicity may be alleviated by a single injection of IL-12 before treatment. Next, we showed that IL-12 synergistically enhances the efficacy of local IL-2 treatment. Moreover, our results indicate that the IL-2/IL-12-mediated therapeutic effect is greatest when it is given after establishment of an immune response to a tumor. Finally, we showed the existence of a unique population of lymphoid cells, namely B220+CD3+CD4-CD8-, at the site of tumor growth. These cells become highly cytotoxic to SL2 cells in mice treated with cytokines late (day 10-14) in the course of the immune response, but not in mice treated early (day 3-7), and cytotoxicity of this unique cell population correlates with the success of therapy.

IL-2 loaded dextran microspheres with attractive histocompatibility properties for local IL-2 cancer therapy

Biodegradable dextran microspheres (MS) were developed as a slow-release system for interleukin-2 (IL-2) to apply them for local IL-2 therapy of cancer. We describe the tissue reactions induced by these MS without or with IL-2 in rats. Dextran MS stain bright red-purple with the periodic acid Schiff (PAS), visualising the exact spot of IL-2 release and its relation to the histological reaction pattern. Subcutaneously injected MS always form a well-circumscribed deposit. In the first 2 days there is a PMN inflammation within the MS-deposit, but the surroundings show only a scanty inflammatory reaction. The PMN reaction is replaced by an abundant macrophage reaction in particular in the MS-deposit. At day 21 a fibrous capsule of about 50 mum surrounds the deposit. The effect of IL-2 administered in its free form is mainly vascular, with vascular dilatation, vascular leakage and oedema. It is remarkable that lymphocytes are present in the injection area already at day 2. When IL-2 releasing MS were used, the various reactions induced by IL-2 and MS were amplified leading to local necrosis. We conclude that neither placebo MS nor IL-2 leads to necrosis after subcutaneous injection in rats. In contrast, when IL-2 was released from MS, then massive necrosis was induced. This might be due to increased phagocytosis or changes in the micro-niche due to the release of humoral factors by the infiltrating cells. This is probably fortuitous for local IL-2 therapy of cancer, as massive necrosis of tumour cells can be expected to lead to an increased antitumour reaction.

Therapeutic efficacy of IL-2-loaded hydrogels in a mouse tumor model

Interleukin-2 (IL-2) is a highly effective anticancer drug if it is applied locally for 5 consecutive days. In most cases this requires 5 invasive treatments, which is not usually acceptable for either the patient or the clinician. For this reason we have developed dextran-based hydrogels from which the required amount of encapsulated IL-2 (1-4 x 10(6) IU of IL-2) is gradually released during 5-10 days. Initially IL-2-containing macroscopic cylinder-shaped gels (implants), and later IL-2-containing injectable microspheres, were developed. These preparations were characterized in vitro, and the therapeutic activity was tested in DBA/2 mice with SL2 lymphosarcoma. The therapy was given to mice with a large and extensively metastasized tumor load (at least 5% of the body weight). If 1-4 x 10(6) IU of IL-2 was slowly released from the hydrogels over a period of 5-10 days, the therapeutic effects were very good and comparable to the effects of free IL-2 injections for 5 consecutive days. In conclusion, dextran-based hydrogels are promising systems for the controlled release of IL-2.

A novel approach for modifying tumor cell-derived plasma membrane vesicles to contain encapsulated IL-2 and engrafted costimulatory molecules for use in tumor immunotherapy

The genetic modification of tumor cells and delivery of cytokines have been proposed as useful strategies in the development of anti-tumor vaccines; however, a number of factors limit their use in clinical settings. To facilitate vaccine development, we explored the possibility of modifying plasma membrane vesicles (PMV) by using a novel chelator lipid, nitrilotriacetic acid ditetradecylamine (NTA-DTDA). Our analyses by flow cytometry show that NTA-DTDA can be incorporated into PMV prepared from murine P815 mastocytoma and that the incorporated NTA-DTDA permits anchoring or "engraftment" onto the vesicle surface of hexahistidine-tagged proteins such as recombinant forms of the costimulatory molecules B7.1 and CD40. The engrafted PMV also can incorporate and deliver the immunostimulatory cytokine Interleukin-2 (IL-2). Our results show that modified PMV derived from P815 cells bind the murine T cell clone D10 in a receptor-ligand dependent manner, inducing cell adhesion and promoting cell survival in vitro. The modified PMV can bind syngeneic T cells, stimulating T cell proliferation and cytotoxic T cell responses. Moreover, when used as vaccines in syngeneic animals, the modified vesicles induce significant protection against challenge with the native P815 tumor. The results indicate that PMV modified by engraftment of recombinant forms of B7.1 and CD40 and incorporation of IL-2 can be used to modulate immune responses, which provides a novel approach for the development of anti-tumor vaccines and cancer immunotherapies.

Locoregional immunotherapy in cancer patients: review of clinical studies

Many patients with invasive cancer have a compromised immune system. This immune dysfunction does appear to start at the site of the tumor. Locoregional immunotherapy is given to stimulate the immune system in order to kill tumor cells either indirectly via a specific or a non-specific way or directly via cell transfer therapy. Advantages to give this immunotherapy locoregionally in stead of systemically are a higher concentration of the immunomodulator at the site of the tumor, to attract or activate effector cells, and diminished toxicity. In this review we have summarised the clinical studies using loco-regional immunotherapy in patients with cancer. Only phase I and II studies were performed. Clinical responses were seen. No single locoregional treatment has become a standard therapy. Relatively few investigations were performed to estimate the influence on the locally effector mechanisms or immune dysfunction. In future clinical trials it is essential to get a better insight in these mechanisms.

Generation of a systemic antitumor response with regional intratumoral injections of interferon gamma retroviral vector

The generation of a lasting systemic immune response is a primary goal for cancer immunotherapy. Here we examine the ability of high-titer IFN-gamma retroviral vector injected into an accessible tumor to generate significant antitumor responses at a distal untreated site. CT26 or B16F10 murine tumors were inoculated subcutaneously to form solid tumors in BALB/c or C57BL/6 mice. Seven to 10 days postinoculation, high-titer IFN-gamma retroviral vector was directly injected into the subcutaneous tumor nodule, and optimal dose and course of therapy were determined. As a model for disseminated disease, mice were inoculated intravenously with CT26 cells to form pulmonary lesions, at the same time as the subcutaneous injections. Regression of subcutaneous tumor correlated with a systemic response at the distal lung metastases in the IFN-gamma-treated group (p < 0.0005). Splenocytes from mice with completely regressed tumors had a twofold increase in percent specific cytotoxicity in a standard CTL assay as compared with nonresponding mice. CD8+ T cells were shown to be essential for the regional and systemic antitumor response, as determined by in vivo cell depletion experiments. These data demonstrate that IFN-gamma retroviral vector gene therapy delivered intralesionally can generate significant inhibition of pulmonary tumor formation distal to the treatment site. The data from these preclinical studies suggest the potential clinical value of retroviral vector-mediated cytokine gene therapy for systemic cancer.

Development of a routine analysis method for liposome encapsulated recombinant interleukin-2

This paper describes the development of an isocratic reversed-phase high-performance liquid chromatographic method for the routine analysis of recombinant interleukin-2 (rIL-2) in liposome samples. The chromatographic system employed a C4 column maintained at 30 degrees C eluted with 52.5% (w/w) acetonitrile in water, containing 100 mM NaClO4 and 10 mM HClO4. To remove phospholipid interference the chromatographic method was combined with a lipid-extraction procedure. No significant loss of rIL-2 was noted upon inclusion of this extraction step. The protein eluted from the column with a capacity factor (k') of 5.8. The method was validated for robustness, linearity, precision and reproducibility. It was shown that the method was linear over a sample concentration range of 1-100 microg/ml. Upon assessment of the intra-day and inter-day precision, the relative standard deviations (RSD) were within the range of the methodical error (approximately 5%), except at the lower concentration of 10 microg/ml, where the intra-day RSD was relatively high (17.8%). The recovery of rIL-2 upon liposome preparation and subsequent analysis of the samples was in the range 94+/-9%. The results indicate that the method is suitable for routine quantitation of rIL-2 in liposomal samples.

Intravesical interleukin-2 in T1 papillary bladder carcinoma: regression of marker lesion in 8 of 10 patients

PURPOSE

We evaluate the therapeutic effect of intravesical interleukin-2 (IL-2) on T1 papillary bladder carcinoma after incomplete transurethral resection.

MATERIALS AND METHODS

After incomplete transurethral resection we treated 10 patients in whom the marker lesion was left in place with 3 x 10(6) Chiron units IL-2 in 50 ml. saline plus 0.1% human serum albumin. The solution remained in the bladder for 2 hours and it was instilled on 5 consecutive days. The effect of IL-2 treatment on the marker lesion was evaluated by cystoscopy and repeat biopsy of the marker site 2 months after treatment. In addition, the effect on the recurrence of bladder tumors was studied.

RESULTS

At 2 months 8 of the 10 marker lesions (80%) had completely regressed and there were no tumor cells on repeat biopsy. Four patients remained tumor-free after 30 to 54 months. We noted no toxic effects. In 1 patient with a 7-year history of bladder cancer the marker was only partially regressed after 2 months. After removal of the marker this patient remained tumor-free at a followup of 54 months.

CONCLUSIONS

To our knowledge this report represents the first study of the effect of IL-2 on marker lesions left in place after transurethral resection. The results indicate that IL-2 instillations are feasible, and the combination of transurethral resection and IL-2 instillation may have a powerful antitumor effect. The therapeutic effects may not simply be due to intravesical IL-2, because previous transurethral resection probably caused some influx of infiltrating cells and the marker may have had tumor associated antigens. Consequently these effects may be due to the interaction of tumor associated antigens, infiltrating cells and IL-2.

Anti-tumor effects of local irradiation in combination with peritumoral administration of low doses of recombinant interleukin-2 (rIL-2)

The aim of this work was to improve radiotherapy results by immune stimulation. We tested the effects of a combination of radio- and immunotherapy, i.e., local low dose recombinant interleukin-2 (rIL-2) treatment, in two murine tumor models. Syngeneic tumors (SL2 lymphoma or M8013 mammary carcinoma) were induced subcutaneously on one or both flanks of mice. Irradiation was given either as a single dose (20 Gy) or fractionated (25 Gy) in 2 weeks. One or two cycles of rIL-2 were given concurrent with or subsequent to radiotherapy. One cycle of rIL-2 consisted of peritumoral injections administered on 5 consecutive days. Treatment effects were measured in terms of local tumor response and disease-free survival (DFS). The combined treatment modality was significantly better than treatment with either irradiation alone or rIL-2 alone. When tumors were inoculated on both flanks of the mice, combined radioimmunotherapy of one of the tumors also resulted in regression of the contralateral untreated tumor, indicating that a systemic anti-tumor immune reaction was induced. Additional rIL-2 injections did not enhance radiation toxicity. In conclusion supplementing irradiation with locally administered low doses of rIL-2 results in better local anti-tumor responses and DFS rates than either treatment alone without enhanced treatment toxicity. Furthermore, the local treatment induces a systemic anti-tumor reaction, influencing the growth patterns of a second, untreated tumor.