Potentiation of interleukin-2 activity by levamisole and imidazole

Influence of levamisole and other angiogenesis inhibitors on angiogenesis and endothelial cell morphology in vitro

Angiogenesis, the formation of new blood vessels from existing vessels is required for many physiological processes and for growth of solid tumors. Initiated by hypoxia, angiogenesis involves binding of angiogenic factors to endothelial cell (EC) receptors and activation of cellular signaling, differentiation, migration, proliferation, interconnection and canalization of ECs, remodeling of the extracellular matrix and stabilization of newly formed vessels. Experimentally, these processes can be studied by several in vitro and in vivo assays focusing on different steps in the process. In vitro, ECs form networks of capillary-like tubes when propagated for three days in coculture with fibroblasts. The tube formation is dependent on vascular endothelial growth factor (VEGF) and omission of VEGF from the culture medium results in the formation of clusters of undifferentiated ECs. Addition of angiogenesis inhibitors to the coculture system disrupts endothelial network formation and influences EC morphology in two distinct ways. Treatment with antibodies to VEGF, soluble VEGF receptor, the VEGF receptor tyrosine kinase inhibitor SU5614, protein tyrosine phosphatase inhibitor (PTPI) IV or levamisole results in the formation of EC clusters of variable size. This cluster morphology is a result of inhibited EC differentiation and levamisole can be inferred to influence and block VEGF signaling. Treatment with platelet factor 4, thrombospondin, rapamycin, suramin, TNP-470, salubrinal, PTPI I, PTPI II, clodronate, NSC87877 or non-steriodal anti-inflammatory drugs (NSAIDs) results in the formation of short cords of ECs, which suggests that these inhibitors have an influence on later steps in the angiogenic process, such as EC proliferation and migration. A humanized antibody to VEGF is one of a few angiogenesis inhibitors used clinically for treatment of cancer. Levamisole is approved for clinical treatment of cancer and is interesting with respect to anti-angiogenic activity in vivo since it inhibits ECs in vitro with a morphology resembling that obtained with antibodies to VEGF.

Levamisole monotherapy for oral lichen planus

BACKGROUND

Several different kinds of drugs have been used to treat chronic oral lichen planus (OLP). During the last decade, there have been several reports demonstrating success with levamisole and low dose prednisolone therapy for treating OLP. However, some OLP patients who have underlying diseases such as diabetes, hypertension and malignancy are unable to take steroids.

OBJECTIVE

The aim of this study was to evaluate levamisole monotherapy for treating OLP.

METHODS

Eleven patients who had OLP were treated with levamisole between 2005 and 2007. The levamisole was administered at a dose 50 mg thrice daily for three consecutive days, but then it was not administered on the following four days.

RESULTS

After 2 weeks of treatment, 8 patients reported a partial response, 3 patients reported no response and no patients reported clearance of lesion. After 4 weeks of treatment, 6 patients reported a partial response, 3 patients reported no response and 2 patients reported clearance of lesion. Furthermore, after 3 months of treatment, 3 patients reported a partial response, 3 patients reported no response and 5 patients reported complete clearance of lesion. Clinical improvement was shown in 2 weeks, whilst the mean duration to achieve clearance of lesion was 6.2 weeks. Although 1 patient had mild itching, there were no significant adverse effects.

CONCLUSION

Levamisole monotherapy could be a successful and safe treatment option for patients with chronic OLP and who cannot take steroids.

Levamisole-induced multifocal inflammatory leukoencephalopathy: clinical characteristics, outcome, and impact of treatment in 31 patients

Levamisole (LEV) has been used as an immunomodulating medication in patients with recurrent aphthous ulcers and as an adjuvant for chemotherapy. LEV, with or without 5-fluorouracil (5-FU), induces multifocal inflammatory leukoencephalopathy (MIL). We identified 31 patients with LEV-induced MIL: 7 from our institution and 24 from a MEDLINE search. Twenty-one patients (67.7%) had been treated with a combination of LEV and 5-FU, while 10 patients had been treated with LEV alone. The onset of MIL was delayed in patients who took LEV and 5-FU in combination compared with the patients treated with LEV alone (11.7 +/- 3.7 vs. 4 +/- 2.5 wk, p < 0.001). Colon cancer (67.7%) was the most common indication for LEV administration. Gait ataxia occurred in 20 (64.5%) patients, and dysphagia was noted in 16 (51.6%) patients. Imaging studies revealed periventricular enhancement in 17 (54.8%) patients and supratentorial lesions in 16 (51.6%) patients. Cerebrospinal fluid studies showed lymphocytic pleocytosis in 10 of 21 (47.6%) patients. Early diagnosis of MIL and discontinuation of LEV is essential, yielding good recovery in most cases. Treatment with corticosteroids and/or intravenous immunoglobulin may be needed for this serious inflammatory encephalopathy. Twenty-nine patients exhibited improved clinical status and imaging findings after initial steroid or immunoglobulin treatment. Plasmapheresis may be an alternative regimen for patients with steroid resistance.

Levamisole Inhibits Angiogenesis in vitro and Tumor Growth in vivo

The synthetic anthelmintic compound Levamisole has previously been used in cancer treatment as an adjuvant in combination with 5-fluorouracil. Its mode of action remains unclear, but an immune-stimulatory effect has been suggested. Here, we show that Levamisole inhibits angiogenesis in vitro and tumor growth in vivo. In vitro, Levamisole specifically inhibits proliferation and differentiation of endothelial cells propagated in co-culture with fibroblasts. In vivo, Levamisole inhibits the growth in nude mice of a transplanted human tumor. The use of nude mice as tumor hosts permits the discrimination between the angiogenesis inhibitory effect of Levamisole and its assumed immune-stimulatory effect. Our findings support a possible therapeutic effect of angiogenesis inhibitors in the treatment of cancer and call for further investigations of the mechanism(s) underlying the anti-angiogenic effect of Levamisole.

Levamisole: might it be used in treatment and prevention of atopic diseases?

As an antihelmintic and Th1-biased immunostimulant, levamisole has been used to restore impaired cell mediated immunity. We sought to explore whether the Th1 driving effect of levamisole may also have an influence on the course of allergic diseases, by shifting the Th2 dominant immunity more toward Th1-mediated response. BALB/c mice were sensitized intraperitoneally on days 0, 7, and 15 with ovalbumin (OVA). After the sensitization, they were challenged intranasally with OVA once a day for 6 consecutive days. Levamisole (2.5 mg/kg) was administered orally three times a week during sensitization and challenge. After the last challenge, differential cell counts were performed, and IL-4 and IFNgamma levels were measured in the bronchoalveolar lavage fluids (BALF). Serum total IgE level was determined, and lungs were examined histologically. The present study establishes that mice administered with oral levamisole gave significantly lower IL-4 levels on sensitization with OVA; however, IFNgamma production, eosinophil infiltration, and serum IgE levels remained unaffected. In conclusion, use of levamisole may have important implications in the management of the allergic inflammation.

Antitumor effects of 5-fluorouracil on human colon cancer cell lines: antagonism by levamisole

BACKGROUND

The addition of levamisole (Lev) to 5-fluorouracil (5-FU) for the adjuvant treatment of stage III colon cancer has been shown to improve 5-year survival in patients. The mechanism of action of Lev remains unknown. Because we showed little in vitro immunological effect of Lev, we asked whether Lev, alone or in combination with 5-FU, had antitumor activity in vitro.

METHODS

Proliferation of COLO-205 and HT-29 colon cancer cells incubated for 2 to 3 days in Lev and 5-FU was measured in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium colorimetric assays. Cell cycle analysis was performed by treating tumor cells for 6, 24, and 48 h with Lev and 5-FU, staining cells with propidium iodide, and measuring DNA content by flow cytometry.

RESULTS

The addition of Lev to 5-FU did not reduce proliferation below that of 5-FU alone. The inhibitory concentration 50% (IC(50)) for 5-FU was 3.2 x 10(-6) M for COLO-205 and 1.3 x 10(-5) M for HT-29. An IC(50) was not reached for Lev, even at millimolar doses. DNA analysis of cells treated for 48 h revealed significant S-phase accumulation of both HT-29 (from 17% in control cells to 36% in treated cells) and COLO-205 (from 35% in control cells to 59% in treated cells) cell lines at micromolar 5-FU concentrations. In contrast, Lev alone did not affect cell cycle distribution for either cell line. The addition of Lev to 5-FU not only did not augment, but inhibited, the effects of 5-FU.

CONCLUSIONS

Levamisole has no direct cytotoxic effect and no additive or synergistic cytotoxic effect when combined with 5-FU on two colon cancer cell lines. Either the observed clinical effects of Lev treatment occur through an as yet unknown mechanism, require longer treatment periods in vitro to become evident, or the results of clinical trials showing its effectiveness should be carefully reexamined.

Combined interferon alpha with levamisole in patients with metastatic renal cell carcinoma

To evaluate the efficacy and toxicity of interferon alpha-2b (IFN-alpha2b) and levamisole treatment regimen in patients with metastatic renal cell carcinoma (RCC). Seventeen patients with metastatic RCC were treated using recombinant IFN-alpha2b at a dose of 10 MU/m2 body surface subcutaneously three times in a week, for 3 months, with levamisole 50 mg t.d.s orally on days 1-3 on alternate weeks. The mean follow-up period was 10.7 (range 2-23) months. We achieved 1 complete response (lasting for 12+ months) and 1 partial response (lasting for 15 months), for an objective response rate of 11.7%. A further 7 patients (41%) had a stabilization of disease. The overall toxicity was moderate, with mainly grade I or II side effects. Grade III toxicities reported among 3 patients including vomiting (2 patients) and anorexia (1 patient). There was no treatment related death. Although additions of levamisole to IFN-alpha do not result in any significant increase in treatment toxicity, the response rate appears to be no better than IFN-alpha monotherapy reported in the literature.

Levamisole treatment enhances protective antibody response to hepatitis B vaccination in hemodialysis patients

Hemodialysis shows a high risk for hepatitis B infection, and hepatitis B virus (HBV) vaccination has now become a routine procedure. Unfortunately, 40% to 50% of hemodialysis patients do not have adequate protective antibodies against the HBV vaccination which is thought to be due to depressed cell mediated immunity. Levamisole has been reported to stimulate depressed T-cell activity and enhance B lymphocyte function and restore delayed hypersensitivity reactions in immune-depressed patients. We studied the effects of levamisole, an immunomodulatory agent, on the protective antibody response of hemodialysis patients to the HBV vaccination. Our hemodialysis patients with negative anti-HBs antibody routinely received 40 microg doses of recombinant HBV vaccine intramuscularly at 0, 1, and 6 months, and we followed serum anti-HBs levels. Patients with a serum antibody level of >10 mIU/ml were considered as responders. Study groups were classified as follows. Group 1 was comprised of 96 chronic hemodialysis patients with negative anti-HBs and HBV core antibody (52 male, 44 female, mean age of 45 +/- 15 years and mean hemodialysis duration of 46 +/- 40 months) who received HBV vaccination; 55 patients (57%) were found to be responders. Group 2 was comprised of 19 randomly selected patients who had never received hepatitis B vaccine (13 male, 6 female, mean age of 42 +/- 14 years, mean duration of hemodialysis 31 +/- 27 months) and who were started on an HBV vaccination protocol with levamisole per os 80 mg after each hemodialysis session for 4 months and followed up on serum anti-HBs levels. Seventeen of the patients completed this levamisole treatment. Fourteen of the 17 patients had the levels of the protective serum antibody indicating a higher response rate when compared with patients who did not receive levamisole (82% versus 57%, respectively, p < 0.05). Group 3 was comprised of 19 patients randomly selected from persons who did not respond to previous vaccination programs (10 male, 9 female, mean age of 51 +/- 14 years, mean duration of hemodialysis 41 +/- 31 months). A second HBV vaccination program was started with the same levamisole protocol. In this group, 18 patients completed this treatment model. Fourteen of them responded to the vaccination model. In Group 4, a second HBV vaccination program was applied without levamisole to 20 randomly selected persons who did not respond to the previous routine vaccination program (12 male, 8 female, mean age of 53 +/- 17 years, mean duration of dialysis 51 +/- 38 months). Only 3 of them responded to a second vaccination program. Comparing Group 3 with Group 4, there was a higher responder rate to HBV vaccination (77% versus 15%, respectively, p < 0.0001). These results show that levamisole treatment increases the response rate to the first HBV vaccination and of the previously unresponsive cases by modulating possible cellular immune response.

Reticuloendothelial stimulation: levamisole compared

PURPOSE

Levamisole in combination with 5-fluorouracil is an effective adjuvant for the treatment of resected Dukes stage C colon cancer. Since the mechanism of action of levamisole is not known, we have investigated its effects on hepatic and splenic reticuloendothelial system (RES) activity in the rat and compared the effect of levamisole with other known RES stimulators.

METHODS

The hepatic and splenic uptake of an intravenous dose of technetium-99m-sulfur colloid has been used to measure RES activity in rats treated with levamisole, glucan, zymosan, chlormethiazole, octreotide, and saline.

RESULTS

Levamisole significantly increased the hepatic uptake of technetium-99m-sulfur colloid and is comparable in its effect to the other RES stimulators. In contrast, levamisole has no effect on splenic RES activity.

CONCLUSION

RES function is considered to be a potentially important factor in the development of liver metastases, and the stimulatory effect of levamisole on the hepatic RES may partly explain its efficacy as an adjuvant treatment in colon cancer.

Clinical response to levamisole in thirty-nine patients with erythema multiforme. An open prospective study

Patients with erythema multiforme (EM) often have chronic or recurring oral lesions that cause intense pain and interfere with a variety of functions including eating and speech. Previous studies suggest that levamisole restores to normal the function of phagocytes and T lymphocytes, and activates the inflammatory response. In our previous double-blind study 8 of 13 patients with EM had a decrease in severity and frequency of attacks. The purpose of this open prospective study was to evaluate short-term and long-term clinical efficacy of levamisole in patients with mucocutaneous EM. Thirty-nine patients with mucocutaneous EM seen in the Oral Medicine Clinic, School of Dentistry, University of California-San Francisco, comprised our study group. Levamisole was used alone in 17 patients or in combination with prednisone in 22 patients and was given as a single dose of 150 mg/day for 3 consecutive days. Thirty-one patients showed a complete response from levamisole (alone in 13 and in combination with prednisone in 18). Four showed a partial response of signs and symptoms, and four others had no benefits from levamisole whether alone or in combination. The most common side effects from levamisole were skin rash, tiredness, weakness, myalgia, taste change, and insomnia.

Influence of levamisole on pancreatic infection in acute pancreatitis

We investigated the effect of levamisole on pancreatic infection in a model of acute pancreatitis (AP) in cats. Animals with and without AP received Escherichia coli intravenously. Blood was then taken at intervals for culture. AP reduced phagocytic function by 28% as measured by the rate of bacterial disappearance from the blood (p less than 0.03). In other cats, AP was induced, and E. coli were placed into the pancreatic duct. Levamisole was given orally in some cats; the remainder were untreated. Control cats (neither AP nor levamisole) also received E. coli. Seven days later, pancreases from all control cats were sterile. In AP cats, the pancreatic infection rate was 73%. Levamisole reduced the rate of infection to 22% (p less than 0.03). We concluded that phagocytic function was impaired in cats with AP. Levamisole reduced the rate of pancreatic infection.

Immunomodulatory action of levamisole--I. Structural analysis and immunomodulating activity of levamisole degradation products

In our laboratory we observed that solutions of levamisole (LMS) stored at 4 degrees C consistently enhanced the lymphocyte proliferation response to concanavalin A (Con A) more than freshly prepared solutions did. To determine if the increased immunopotentiation observed with the stored solutions of LMS was due to products formed from LMS, we assessed the stability of LMS when stored at 4 or 37 degrees C at pH 6, 7, 7.5 and 8. Analysis of the various solutions by high pressure liquid chromatography demonstrated that LMS decomposes during storage in neutral and alkaline conditions to form three products. The formation of the products was accelerated by increasing the temperature from 4 to 37 degrees C. The three degradation products were purified by preparative high pressure liquid chromatography and their structures determined by mass spectrometry, infrared spectrometry and homo- and heteronuclear two dimensional nuclear magnetic resonance spectroscopy. The degradation products, denoted as No. 1, No. 2 and No. 3, based on their high pressure liquid chromatography retention times, were identified as: No. 1, 3-(2-mercaptoethyl)-5-phenylimidazolidine-2-one; No. 2, 6-phenyl-2,3-dihydroimidazo (2,1-b) thiazole and No. 3, bis [3-(2-oxo-5-phenylimidazolidin-1-yl) ethyl] disulfide. Product 2 significantly enhanced murine lymphocyte proliferation responses to concanavalin A (Con A) at concentrations between 0.5 and 10.0 micrograms/ml (whereas the optimum concentration of LMS is 10-100 fold higher (50-100 micrograms/ml)). Products 1, 2 and 3 significantly inhibited the lymphocyte proliferative response at concentrations greater than 2.2, 10.0 and 10.0 micrograms/ml, respectively. These studies indicate that under relatively mild conditions, including physiological conditions, LMS may decompose to products which inhibit or enhance lymphocyte responses to Con A.

Levamisole in the treatment of advanced breast cancer. A ten-year follow-up of a randomized study

A total of 101 patients with advanced breast cancer were treated during the years 1976 to 1978 with doxorubicin, vincristine and cyclophosphamide, and randomized to receive either levamisole or placebo in a double-blind fashion. The chemotherapy cycles were repeated every four weeks, and levamisole, 2.5 mg/kg, was given on two consecutive days every week except on the days chemotherapy was given. The patients treated with levamisole exhibited higher response rates (63%) than patients given placebo (47%). The survival rate was also significantly higher in the levamisole group. The results correlated with potentiation of intracutaneous PPD test. In the lymphocyte blast transformation tests, the suppression of T-cell response to mitogens two weeks after the start of chemotherapy was markedly diminished by levamisole. In contrast to some negative reports, the results of the present study are encouraging for further evaluation of levamisole and other biological response modifiers in breast cancer.

Levamisole and fluorouracil for adjuvant therapy of resected colon carcinoma

Twelve hundred ninety-six patients with resected colon cancer that either was locally invasive (Stage B2) or had regional nodal involvement (Stage C) were randomly assigned to observation or to treatment for one year with levamisole combined with fluorouracil. Patients with Stage C disease could also be randomly assigned to treatment with levamisole alone. The median follow-up time at this writing is 3 years (range, 2 to 5 1/2). Among the patients with Stage C disease, therapy with levamisole plus fluorouracil reduced the risk of cancer recurrence by 41 percent (P less than 0.0001). The overall death rate was reduced by 33 percent (P approximately 0.006). Treatment with levamisole alone had no detectable effect. The results in the patients with Stage B2 disease were equivocal and too preliminary to allow firm conclusions. Toxic effects of levamisole alone were infrequent, usually consisting of mild nausea with occasional dermatitis or leukopenia, and those of levamisole plus fluorouracil were essentially the same as those of fluorouracil alone--i.e., nausea, vomiting, stomatitis, diarrhea, dermatitis, and leukopenia. These reactions were usually not severe and did not greatly impede patients' compliance with their regimen. We conclude that adjuvant therapy with levamisole and fluorouracil should be standard treatment for Stage C colon carcinoma. Since most patients in our study were treated by community oncologists, this approach should be readily adaptable to conventional medical practice.

Potential immunomodulatory activity of phenylphosphonothioates

In the course of immunotoxicological studies of several organophosphorous compounds, it was noted that some phenylphosphonothioates enhanced the activation of rat splenocytes by concanavalin A. In the present study some of these compounds were compared to the well-characterized immunomodulatory thiol, 2-mercaptoethanol (2-ME). Two of the compounds are able to substitute for 2-ME and allow near maximal growth of a strictly 2-ME-dependent lymphocyte cell line (CTLL-2). These compounds exhibit essentially additive effects with 2-ME on CTLL-2 cells and rat splenocytes. In agreement with previous results with 2-ME, the phosphonothioates have essentially no effect on interleukin-2 production in mitogen-stimulated splenocyte cultures. One phosphonothioate, as well as its possible thiol hydrolysis product, supports cell survival and enhanced cystine incorporation by CTLL-2 cells. However, 2-ME was more effective in stimulation of enhanced generation of extracellular thiols than were the other agents. These results suggest very similar modes of action for phosphonothionates and 2-ME. Finally, a phosphonothioate selected for low neurotoxic potential was examined and found to effectively support lymphocyte growth in vitro and to exhibit relatively low acute toxicity in mice.