Subcutaneous IL-2 Research Articles

Effects of nitric oxide (NO) synthesis inhibition on antitumor responses during interleukin-2 (IL-2) treatment of mice.

ObjectivesTo evaluate if L-arginine: NO pathway is activated in tumor tissues during IL-2 therapy and to evaluate whether IL-2 induced NO synthesis represents an antitumor effector muchanism or an inhibitory factor against therapeutic effects of IL-2.MethodsFour groups[untreated control, NG-monomethyl-L-arginine(MLA) therapy only, IL-2 therapy only, IL-2/MLA therapy groups] of BALB/c mice were injected intraperitoneally with 2×106 Meth A tumor cells on day 0. MLA was administered subcutaneously with Alzet continuous infusion pumps on day 2. IL-2 therapy (180,000 IU s.c. every 12h for 5 days) was started on day 3. NO production within ascites tumors was assessed by measuring nitrite concentrations in cultures of ascites cells harvested on day 8. Survival and the rate of body weight increment of the mice were measured to evaluate therapeutic responses. Daily urinary nitrate excretion was monitored to demonstrate the effectiveness of MLA in inhibiting NO synthesis.ResultsNitrite production in supernatants of Meth A ascites cell cultures was 63±14 μM in IL-2 treated mice and 3.2±1.5 μM in untreated controls (p < 0.001). MLA prevented the IL-2 therapy induced increase in nitrite production. IL-2 therapy did not decrease the rate of body weight increment and marginally prolonged mean survival to 18.2 days, compared to 16.6 days in control mice (p=0.255). MLA administration decreased the rate of body weight increment and prolonged mean survival of IL-2 treated mice (21.8 days, p=0.001 versus IL-2 alone). Interestingly, the MLA treatment increased the rate of body weight increment and diminished the survival of control mice to 11.6 days (p=0,003). MLA administration via Alzet continuous infusion pumps achieved appoximately 60% suppression of urinary nitrate excretion by control mice. Subcutaneous IL-2 treatment strongly induced nitric oxide synthesis (up to 3.5 μmoles of urinary nitrate/mouse/day). MLA also effectively suppressed IL-2 induced NO production.ConclusionL-arginine: NO pathway can be activated in malignant ascites, by IL-2 therapy and NO synthesis functions as an inhibitory mechanism against IL-2 induced anti-tumor effects.

Nitric oxide synthesis contributes to IL-2-induced antitumor responses against intraperitoneal Meth A tumor.

IL-2 therapy is a potent inductive stimulus for nitric oxide (NO.) synthesis in mice and humans. It is not yet clear whether NO. can contribute to IL-2-induced therapeutic responses. The murine skin cancer Meth A is relatively resistant to lymphokine-activated killer (LAK) cell killing, allowing evaluation of the role of IL-2-induced NO. synthesis in vivo, without contribution by LAK cells. Subcutaneous IL-2 treatment of mice bearing i.p. Meth A tumor increased nitrite production by cells derived from ascites (63 +/- 14 microM vs 3.2 +/- 1.5 microM in untreated controls). N omega-monomethyl-L-arginine (MLA), NO. synthase inhibitor, prevented this increase. NO. production correlated in an inverse fashion with tumor cell proliferation in vitro. Evidence for IL-2-induced heme nitrosylation was demonstrated in tumor cells by electron paramagnetic resonance spectroscopy. By immunomagnetic depletion experiments, macrophages were implicated as a major source of NO. synthesis. Cytologic and flow-cytometric evaluation revealed that IL-2 treatment resulted in enhanced lymphocyte and macrophage recruitment into malignant ascites, and decreases in tumor cell recovery. MLA administration further increased host cell recovery. Subcutaneous IL-2 therapy increased urinary nitrate excretion up to eightfold in mice, and appeared to produce a significant survival advantage that was prevented by MLA administration.

Long-term Subcutaneous Recombinant Interleukin-2 as Maintenance Therapy: Biological Effects and Clinical Implications

Several trials have evaluated the therapeutic efficacy of rIL-2 combined with more traditional treatments such as chemotherapy and radiotherapy, but the use of IL-2 as adjuvant therapy for minimal residual disease or to maintain clinical response obtained with other standard treatments has yet to be investigated. The aim of the present trial was to study the biological effects of maintenance long-term treatment (6 months) with subcutaneous low-dose IL-2 in 16 patients with different neoplasms previously treated with chemo-immuno therapeutic regimens or with surgery (7 metastatic renal cancers, 5 locally advanced renal cancers previously subjected to radical nephrectomy, 2 metastatic breast cancers, 1 small cell lung cancer, and 1 metastatic melanoma). Clinical tolerability, feasibility and therapeutic implications are also discussed. The IL-2 schedule was as follows: 4.5 million IU/day, 3 times weekly for 6 months. A total of 14 patients completed therapy without requiring dose modifications and are free of progression after a median duration of 8+ months (range: 7+ to 34+) while two patients progressed during therapy (one inflammatory breast cancer and one renal cancer). Important and persistent hemato-immunostimulating effects in both soluble (IL-2, sIL-2R, IL-6) and cellular (lymphocyte subsets, monocytes, eosinophils) parameters were noted during the entire treatment. The IL-2 related toxicity was quite low. Moreover, this long-term IL-2 therapy could control neoplastic growth and thus prolong clinical response obtained with standard treatments. Prospective randomized studies regarding the clinical efficacy have been initiated.

A CLINICAL-STUDY OF IMMUNOTHERAPY VERSUS ENDOCRINE THERAPY VERSUS CHEMOTHERAPY IN THE TREATMENT OF ADVANCED PANCREATIC ADENOCARCINOMA

The advanced carcinoma of pancreas still remains an untreatable disease. Both chemotherapy and hormono-therapy seem not to prolong the survival time. Also immunotherapy with IL-2 has been shown to have no efficacy. Our experimental studies suggested the possibility of enhancing the antitumor activity of IL-2 by the administration of immunomodulating neurohormones, such as melatonin (MLT). This study was carried out to evaluate the efficacy of IL-2 plus MLT in advanced cancer of the pancreas. Fifty patients, with advanced adenocarcinoma of the pancreas, were randomized to receive chemotherapy consisting of 5-FU plus folates, endocrine therapy with LHRH and somatostatin analogues, supportive care alone or immunotherapy with subcutaneous low-dose IL-2 plus MLT. A partial response was obtained in 1/13 patients treated with chemotherapy and in 2/12 patients receiving immunotherapy; no tumor regression was seen in the other groups. The percent of survival at 1 year achieved in patients treated with immunotherapy was significantly higher than in the other groups tested (3/12 vs 1/38; p<0.02). This preliminary study would suggest that the immunotherapy with IL-2 plus MLT may represent a new promising treatment of advanced pancreatic adenocarcinoma.

Lymphocytosis decline is not responsible for tumor progression in cancer patients chronically treated with interleukin-2.

The antitumor activity of IL-2 is mediated by an increase in lymphocyte number. Moreover, our previous studies have shown that therapy for 1 week/month with low-dose subcutaneous IL-2 is sufficient to maintain high levels of lymphocytes in cancer patient who have had tumor regression or stable disease (SD) in response to IL-2 immunotherapeutic cycles. This study was performed to establish whether tumor progression in cancer patients chronically treated with IL-2 may be associated with lymphocyte number decline. The study included 53 metastatic renal cell cancer patients, who were treated with 2 induction cycles of IL-2 subcutaneous immunotherapy (6 million IU/day for 5 days/week for 6 weeks, corresponding to one cycle). Tumor regression occurred in 15/53 patients, 20 patients had a SD, and the remaining 18 cases progressed. Non progressed patients (n = 35) underwent a maintenance therapy consisting of one week of therapy every month. After a median follow-up of 18 months, 26/35 patients with response or SD had progressed. The immune investigation consisted of lymphocyte, T lymphocyte, NK cell number determination and sCD25 level detection. The mean number of lymphocytes, T lymphocytes and NK cells observed on IL-2 maintenance therapy was significantly higher than that seen before beginning the immunotherapy. Moreover, mean number of lymphocytes and mean levels of sCD25 observed at the time of tumor progression were respectively lower and higher than those seen on maintenance therapy in the same patients, without, however, significant differences. Despite the importance of lymphocytes in mediating the antitumor activity of IL-2, this study shows that tumor progression in cancer patients chronically treated with low-dose IL-2 after response or SD during IL-2 induction cycles is not associated with a significant decline in lymphocyte, T lymphocyte or NK cell numbers. Further studies, carried out to analyze the functional status of immune cells at the time of tumor progression, will be necessary to define the role of immunity in cancer patients progressing under IL-2 chronic therapy.

Phase [formula omitted] study of low-dose intravenous OKT3 and subcutaneous interleukin-2 in metastatic cancer

In a phase I II study the safety, immunostimulatory and antitumour effects of a combined OKT3/interleukin 2 (IL-2) treatment was studied in 15 cancer patients who failed IL-2 treatment. OKT3 was given as a 2-h intravenous infusion. Doses of 50, 100, 200 and 400 μg OKT3 were studied. Within 24 h, subcutaneous IL-2 was started 5 days/week for 4 weeks, at a dose of 9–18 × 10 6 U daily. Maximum tolerated dose was 400 μg OKT3 with neurotoxicity as dose-limiting toxicity. Toxicity of subcutaneous IL-2 was acceptable. At the maximum tolerated dose, 9 patients with renal cell carcinoma with measurable disease were treated in a phase II testing. 8 patients were evaluable for response. 4 patients had stable disease and 4 had progressive disease. An increase of activated lymphocyte subpopulations could not be found, although OKT3 was detectable on lymphocytes in vivo. Only if laboratory studies shed light on methods of improving immunostimulating effects of OKT3 will further clinical studies be warranted.