The general immunopharmacology of levamisole

The safety, tolerability and pharmacokinetics of levamisole alone, levamisole plus ivermectin, and levamisole plus albendazole, and their efficacy against Onchocerca volvulus

Two randomized, double-blind, placebo-controlled trials, in which levamisole (2.5 mg/kg) was given alone or co-administered with ivermectin (200 microg/kg) or albendazole (400 mg), were conducted. In Trial 1, safety and drug-drug interaction were explored in 42 healthy male volunteers. During Trial 2, the safety of the same treatment regimens and their efficacy against the adult worms and microfilariae of Onchocerca volvulus were investigated in 66 infected subjects of both sexes. Safety was determined from the results of detailed clinical and laboratory examinations before treatment, during hospitalization and on day 30. The pharmacokinetic parameters for levamisole alone and the combinations were determined in Trial 1 and then compared with historical data for ivermectin and albendazole, given as single agents, to determine if drug-drug interaction had occurred. The level of efficacy against the adult worms was determined by the examination of histology sections of nodules excised 6 months posttreatment and from the changes seen in the levels of microfilaridermia within a year of treatment. Microfilaricidal efficacy was estimated from the reductions in the levels of microfilaridermia between day 0 (1 day pre-treatment) and day 30. Although the regimens were generally well tolerated, there were unexpected adverse effects in both healthy volunteers and infected subjects. Clinically significant drug-drug interactions resulted in an increase in the bio-availability of ivermectin but a reduction in that of albendazole when these drugs were co-administered with levamisole. Levamisole given alone or with albendazole had little effect on O. volvulus. The combination of levamisole with ivermectin was neither macrofilaricidal nor more effective against the microfilariae and the adult worms than ivermectin alone. The pathogenesis of the adverse events and the drug-drug interactions are discussed.

Long-term effects of levamisole treatment in childhood nephrotic syndrome

The effects of levamisole treatment on long-term outcome were evaluated in a retrospective study of frequently-relapsing (FRNS, n=15), steroid-dependent (SDNS, n=13), and steroid-resistant (SRNS, n=6) nephrotic syndrome in 34 children (21 boys, 13 girls, mean age 5.0+/-3.4 years) during a 60-month follow-up period. The definition of frequent relapses was > or = 4 relapses per year. The current relapse was treated with prednisolone 60 mg/m2 per day for 4 weeks, then with 40 mg/m2 every other day for 4 weeks, after which the dose was tapered by 10 mg weekly. From the beginning of the 5th week, levamisole was introduced at a dose of 2 mg/kg per day. The duration of levamisole treatment was 17+/-7 months. Before starting levamisole treatment the mean level of proteinuria was 2.17+/-1.34 g/day and the relapse rate was 4.41/year. By the end of levamisole therapy, proteinuria had fallen to 0.142+/-0.211 g/day and the relapse rate to 0.41/year. No relapse occurred in 23 of the 34 patients during levamisole treatment. In the 24-month follow-up period after the discontinuation of levamisole, 28 children remained in total remission, while 6 had relapses. The cumulative steroid dose before levamisole therapy was 7,564.4+/-3,497.1 mg/year and following the introduction of levamisole 1,472.9+/-1,729.9 mg/year (P<0.0001). We observed reversible neutropenia in 5 patients, but no other side effects were seen. Our findings suggest that in FRNS and SDNS levamisole significantly reduces both the relapse rate and the cumulative steroid dose; therefore, it could be recommended for these patients. In SRNS patients it has also some benefit because proteinuria and the cumulative steroid dose could be reduced significantly.

Age-dependent differences in the efficacy of cancer immunotherapy in C57BL and AKR mouse strains

While tumor incidence increases with age, tumor growth and metastasis often proceed at a slower rate in aged organisms. The mechanisms underlying this age-related reduced tumor development may suggest therapeutic modalities appropriate for the aged. Decreased tumor aggressiveness in the old was shown to be related to altered immune response. Consequently, the aim of the present study was to assess whether cancer immunotherapy has an age-dependent effect. Only a few studies have compared cancer immunotherapy efficiency as a function of age, most showing lower inhibition in older animals. In the present study, we tested the effect of two immunomodulators, levamisole and BCG, on two tumors, B16 melanoma and AKR lymphoma, in mice of different ages. We demonstrated a higher efficiency of immunotherapy in aged as compared to young mice, particularly at low immunomodulator doses. While decreased T cell function during aging is apparently established, nonspecific immunity is more preserved or even enhanced in later life. We found an increased number of macrophages in tumors of old compared to young mice and an increase in MAC-1+ cells in old levamisole-treated compared to non-treated mice. The stronger therapeutic effect of this immunomodulator in old mice might thus be due to an increased macrophage-mediated anti-tumoral effect.

Levamisole in dermatology : a review

Levamisole, an anthelmintic agent with a wide range of immunomodulatory actions, has been used successfully as monotherapy and an adjunct to treatment in a variety of diseases. Since 1990, combination therapy of levamisole and fluorouracil has played an important role in the treatment of resected Dukes stage C adenocarcinoma of the colon. Because of its immunomodulating effects levamisole has been used in a wide range of diseases with and without success. In dermatologic disease levamisole has been successfully used in the treatment of parasitic, viral and bacterial infections including leprosy, collagen vascular diseases, inflammatory skin diseases and children with impaired immune a variety of reasons. It has also been used in combination with other drugs for treating a number of dermatologic disorders, e.g. in combination with cimetidine for treating recalcitrant warts, with prednisolone for treating lichen planus, erythema multiforme and aphthous ulcers of the mouth. Adverse affects of levamisole are mild and infrequent and include rash, nausea, abdominal cramps, taste alteration, alopecia, arthralgia, and a flu-like syndrome. It can rarely cause agranulocytosis. More studies need to be undertaken to study the full potential of levamisole in dermatologic diseases.

Treatment of pediculosis capitis with thiabendazole: a pilot study

BACKGROUND

Despite the improvement of health standards, head lice infestation remains a problem worldwide. In addition, there is increasing evidence that head lice are becoming resistant to common pediculocides.

AIM

To test the potential effectiveness of thiabendazole, a potent and broad-spectrum antiparasitic and scabicidal agent, for the treatment of pediculosis capitis.

METHODS

Twenty-three female patients, aged 7-12 years, who had active head lice infestation, were treated with oral thiabendazole, 20 mg/kg twice daily for 1 day, with repeat treatment after 10 days.

RESULTS

On the 11th day, meticulous hair examination showed that 21 patients had responded to treatment [91%; 95% confidence interval (CI), 71-98%], with 14 showing complete responsiveness (61%; 95% CI, 40-78%). The only adverse reactions observed were nausea and mild dizziness, which occurred in four patients, three of whom took the drug on an empty stomach.

CONCLUSIONS

Thiabendazole may be a promising treatment for head lice infestation. The primary action of this drug seems to be the inhibition of parasite microtubule polymerization by binding to beta-tubulin. In addition, thiabendazole may interfere with the synaptic transmission of lice through its probable cholinergic effect. As pediculosis capitis is a very communicable disease, the unresponsiveness to thiabendazole could largely be attributed to new infestations during the drug-free interval. Therefore, massive and simultaneous rather than individual and isolated treatments should be used to achieve the epidemiologic control of this ectoparasitosis. As this is a preliminary study, the performance of double-blind, randomized controlled trials on this subject is warranted. Thiabendazole, either alone or in combination with other agents, may prove to be of particular use in areas in which head lice show resistance to common pediculocides.

Levamisole is a potent enhancer of gilthead seabream natural cytotoxic activity

Gilthead seabream (Sparus aurata L.) head-kidney (HK) leucocytes were incubated with 10(3) to 10(-4) ng levamisole/ml for 4, 24 or 48 h and then assayed for their natural cytotoxic activity against xenogeneic tumor cells. This activity was slightly increased after 24 h of incubation. In a second experiment, fish specimens were fed 0, 75, 150 or 300 mg levamisole/kg diet for 10 consecutive days. The fish were then fed a commercial non-supplemented diet and sampled 0, 1, 2, 3, 4 and 6 weeks post-administration of levamisole. The cytotoxic activity was found increased along the experiment and remained greatly enhanced at the end. In conclusion, levamisole enhanced seabream natural cytotoxic cell activity both in vitro and in vivo and had a great and lasting action when administered by feeding.

Adjuvant therapy of cancers of the colon and rectum

Important advances have been made in our understanding of the role of adjuvant therapy for colorectal cancer. Current standard 5FU-based regimens have been convincingly shown to reduce the incidence of recurrences and to prolong overall survival in patients with resected stage III colon cancer. Colon cancer patients with stage II disease have a better-overall prognosis than those with stage III; however, the relative merits of adjuvant treatment in these patients remains controversial. Combined chemotherapy plus radiation therapy is currently the standard adjuvant approach for stage II and III rectal cancer patients. Despite the advances that have been made, far too many patients with resectable colorectal cancer ultimately relapse and die of their disease. There remains a pressing need for continued development of improved adjuvant treatments. Participation of eligible patients in clinical trials must continue to be actively encouraged. Only in this way will we be able to continue to build and expand on the progress that has been made thus far.

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.

Anticancer agents suppressive for adult parasites of filariasis in Mongolian jirds

Eight chemical structures not previously reported to possess antifilarial activity have been identified. A total of 79 compounds with anticancer properties were evaluated for possible macrofilaricidal activity against Brugia pahangi and Acanthocheilonema viteae transplanted into male Mongolian jirds (Meriones unguiculatus). All eight active compounds were suppressive for the onchocerciasis type (Acanthocheilonema viteae) of the disease. None was macrofilaricidal for the lymphatic form (Brugia pahangi). These new structures may represent a nucleus around which effective drugs can be synthesized.

Synthesis of new pyrrolo[1,2-d][1,2,4]triazines and thiazolo[3,4-d][1,2,4]triazines as immunostimulating agents

Four pyrrolo[1,2-d][1,2,4]triazines and four thiazolo[3,4-d][1,2,4]triazines were synthesized from trans-4-hydroxy-L-proline and L-thiaproline, respectively. The synthetic route involved formation of hydrazides followed by cyclization with orthoesters. The proliferative response to human lymphocyte mitogen (phytohemagglutinin) revealed significant immunostimulant activity for all test drugs. Furthermore, some triazine derivatives were effective to activate production of free oxygen radical by phagocytes in response to stimulation by opsonized zymosan.

A randomized trial comparing cisplatin plus 5-fluorouracil with or without levamisole in operable gastric cancer

OBJECTIVES

To determine the effectiveness and toxicity when levamisole was added to the adjuvant combination chemotherapy in patients with operable gastric cancer.

METHODS

After en bloc resection of gastric cancer without gross or microscopic evidence of residual disease from April 1991 to December 1992, 100 patients were randomized to 6 months of 5-fluorouracil 1,000 mg/m2/day administered as continuous infusion for 5 days, cisplatin 60 mg/m2/day as intravenous infusion for 1 day with or without levamisole (50 mg every eight hours P.O for a period of three days every 2 weeks for 6 months). This chemotherapy treatment was begun within 2 to 4 weeks after the surgery. The chemotherapy consisted of discrete 5-day courses administered at 4-weeks intervals. All 100 patients are assessable.

RESULTS

The fifty patients were assigned to each treatment group. There was no statistical difference and no bias in the distribution of characteristics of the 100 evaluable patients between the two groups. A total of 274 courses of treatment were given in the levamisole group and 260 courses of treatment in non-levamisole group. Eleven patients in each group did not finish planned 6 courses of treatment mainly due to non-compliance. At median follow up of 39 months, 32 patients relapsed 19 in the levamisole group and 13 in the non-levamisole group (p = 0.284). Twenty five patients died of relapsed diseases, 15 in the levamisole group and 10 in the non-levamisole group. The levamisole group tended to show more risk of overall death rate and recurrence than the non-levamisole group. However, this result was not statistically significant at 3 years. The treatment was well tolerated in both treatment groups. The grade 2-3 toxicities were nausea/ vomiting (levamisole, non-levamisole group; 31.7%, 29.3% of treatment courses respectively), diarrhea (7.6%, 8.4%), mucositis (11.6%, 12.3%), and leukopenia (9.8%, 9.6%).

CONCLUSION

Levamisole had negative effects on disease-free survival and overall survival when added to adjuvant combination chemotherapy of cisplatin and 5-fluorouracil in patients with operable gastric cancer. Both treatment arms were generally well tolerated and the toxicity profile was similar with or without levamisole.

beta-Sitosterol and beta-sitosterol glucoside stimulate human peripheral blood lymphocyte proliferation: implications for their use as an immunomodulatory vitamin combination

The phytosterols, beta-sitosterol (BSS), and its glucoside (BSSG) enhance the in vitro proliferative response of T-cells stimulated by sub-optimal concentrations of phytohaemagglutinin (PHA) several fold at extremely low concentrations (femtogram level). A 100:1 (mass:mass) ratio of BSS:BSSG (termed essential sterolin formulation, ESF) showed higher stimulation than the individual sterols at the same concentration. In vivo activity of ESF was also demonstrated when volunteers ingested ESF for 4 weeks. Proliferation of their T-cells, stimulated maximally with PHA, was significantly enhanced (20-920%) when compared to baseline values. In vitro, ESF (1 microgram.ml) was able to significantly enhance the expression of CD25 and HLA-Dr activation antigens on T-cells and increased the secretion, into the medium, of IL-2 and gamma interferon. NK-cell activity was also increased by BSS and BSSG alone, but with EST a higher activity was always found at different effector:target ratios (100:1 12:1).

Therapy for chronic hepatitis B infection

Interferon-alpha is currently the only therapy approved for treatment of chronic HBV in the United States and Europe. Interferon-alpha therapy causes loss of HBeAg and HBV DNA in approximately a third of treated patients, and the loss of these markers of active viral replication is associated with improvements in hepatic histology and ALT levels. However, the long-term effects of interferon-alpha on morbidity and mortality, and especially on the incidence of the complications of chronic HBV infection, remain to be defined. The currently available treatment for chronic HBV is far from perfect. Interferon therapy is usually associated with significant side effects and requires subcutaneous administration. Additionally, there are a large number of patients who either fail to meet criteria for treatment, or who, with therapy, fail to respond (at least 60% of all patients). Moreover, interferon treatment is expensive (approximately $5,000 for a 16 week course of 5MU daily). Hence the search continues for effective, orally-available and cost-efficacious therapy. Of the agents available, the nucleoside analogues appear to have the greatest promise. The availability of cell culture systems and animal models for studying potential anti-HBV drugs will aid in the future development of these agents. Therapeutic vaccines, and combination therapies (given either concurrently or sequentially) may also play a future role in the management of chronic HBV infection. While prevention of disease must be a primary goal in the war against this common infection, a continued focus must be maintained on the treatment of the approximately 300 million individuals world-wide with established chronic HBV infection.

The combination 5-fluorouracil/levamisole induces enhanced rat Kupffer cell-mediated cytotoxicity in vitro against the syngeneic colon adenocarcinoma cell line CC531

The mode of action of the combination treatment 5-fluorouracil (5-FU) and levamisole in colorectal cancer patients is unknown. It is postulated that the beneficial effect may be explained by an immunomodulatory effect on Kupffer cell (KC) cytotoxicity. We evaluated the effect of levamisole (200 micrograms/ml) and 5-FU (10 microM) on rat KC cytotoxicity against syngeneic CC531 tumor cells. Viability of KCs was unaffected by 5-FU and/or levamisole. The combination did not enhance growth inhibition of CC531 compared to 5-FU alone. A significant increase in KC cytotoxicity was observed after 24-hr incubation with 5-FU/levamisole especially at an effector/target ratio of 10 (P < 0.05). 5-FU alone had no effect on KC cytotoxicity, while levamisole induced only a slight increase. Our in vitro data suggest that the additive effect of the combination 5-FU/levamisole on KC cytotoxicity may attribute to the beneficial effect of the adjuvant treatment in colorectal cancer patients.

The immunomodulatory effect of levamisole is influenced by postoperative changes and type of lymphocyte stimulant

The results of both laboratory and clinical research into the immunomodulatory activity of levamisole have shown a considerable degree of inconsistency and sometimes contradiction. This is probably a reflection of the lack of understanding of the mechanism(s) of action of levamisole and it is therefore necessary to base conclusions about its immunomodulatory efficacy in the treatment of disease on experimental assays that take into consideration the in vivo conditions. This investigation was designed to compare the immunomodulatory activity of levamisole under clinically achievable and non-achievable conditions as judged by changes in the perioperative proliferative response of lymphocytes from 30 patients with colorectal cancer. The results obtained showed that proliferation in antigen (purified protein derivative, PPD)-stimulated, but not phytohaemagglutinin(PHA)- or staphylococcal-enterotoxin-B(SEB)-stimulated, lymphocyte cultures was consistently and significantly augmented by levamisole in concentrations of 25 ng-25 micrograms/ml. High concentrations of levamisole (25 micrograms/ml and 100 micrograms/ml) were inhibitory to PHA- and SEB-stimulated, but not PPD-stimulated, lymphocyte cultures, especially in the postoperative period. Of particular interest was the observation that, although levamisole temporarily lost its stimulatory activity in the postoperative period (third postoperative day), it did enhance antigen-stimulated lymphocytes at the time of the nadir of the postoperative suppression of lymphocyte proliferation (first postoperative day). Clinically achievable concentrations of levamisole are therefore effective both before and after operation in enhancing the response of lymphocytes to antigens.

Role of adjuvant therapy in surgically resected colorectal carcinoma

An important advance in cancer treatment has been made in recent years with the finding that adjuvant therapy can significantly improve the survival of patients with colorectal cancer. In patients with resected lymph node-positive colon carcinomas (TNM stage 3), adjuvant 5-fluorouracil and levamisole produced an unequivocal survival advantage that established this combination as the standard of clinical practice. Given that biochemical modulation of fluorouracil by leucovorin can increase response rates in advanced disease, this combination is undergoing evaluation as an adjuvant treatment. Preliminary results indicate that 5-fluorouracil and leucovorin are effective in reducing disease relapse; however, the effect of this regimen on patient survival rates awaits extended follow-up. In the treatment of stages 2 and 3 rectal cancer, significant reductions in local recurrence and death rates have been achieved with the combination of 5-fluorouracil and radiation therapy. Immunologic approaches and newer chemotherapeutic agents may further improve patient outcome and are under investigation, as are efforts to reduce the toxic effects of cancer chemotherapy. Increased understanding of the biology of these diseases is likely to yield prognostic markers capable of identifying subgroups of earlier stage patients at high risk of disease relapse who may also benefit from adjuvant therapy.

Treatment of chronic hepatitis B

Chronic infection with the hepatitis B virus (HBV) is a major cause of worldwide morbidity and mortality. A large number of therapeutic approaches has been tried, including interferon (IFN), nucleoside analogues and immunomodulators. To date controlled clinical trials have shown that only IFN is of long-term value but many patients fail to respond to treatment. New approaches to treating patients with IFN-resistant hepatitis B are currently undergoing clinical and experimental evaluation, and it seems likely that new therapeutic agents will be available in the near future.

T-cell adjuvants

T-cell adjuvancy involves the use of agents to stimulate preferentially delayed type hypersensitivity (DTH). Traditional adjuvants like Alum, Freunds, muramyl peptides, and endotoxins are not selective. Natural infection (e.g. vaccinia) may yield selective DTH. Low dose cyclophosphamide (CY) with mycobacteria was the first experimental T-cell adjuvant. New adjuvant formulations (ISCOMS, MAPS, etc.) with synthetic T-cell epitopes offer improved formulations. Upregulation of TH-1 helper cells and their actions with interleukins like IL-2, IL-12, and gamma IFN or antibodies to IL-4 and IL-10 may augment potently pathogen and tumor resistance. Similarly, transfection of tumor target cells with genes for IL-2, IL-12, gamma IFN, etc., offers novel vaccine treatment approaches. Finally, "thymomimetic" peptides like thymosin alpha 1 or drugs like levamisole or isoprinosine alone or in conjunction with interleukins may augment TH-1 and DTH responses. These approaches are seeing increasing emphasis in new treatment strategies for cancer and infections like HIV.

Folinic acid and 5-fluorouracil as adjuvant chemotherapy in colon cancer

BACKGROUND/AIMS

Colon cancer is one of the major health problems in industrialized countries, and its incidence appears to be increasing. Surgical resectability is the most important prognostic determinant, although despite apparently curative surgery, recurrent tumors are common. Metastatic disease cannot be cured, and thus, there is a need for better adjuvant therapies.

METHODS

Two hundred and thirty-nine patients with surgically resected colon cancer in Dukes' stage B2 or C were randomly assigned to chemotherapy or observation alone to determine whether adjuvant chemotherapy could effectively reduce the rate of cancer recurrence. One hundred and twenty-one patients in stage B2 and 118 patients in stage C were enrolled in the study. Adjuvant treatment consisted of folinic acid 200 mg/m2, intravenously, plus 5-fluorouracil 400 mg/m2, intravenously, on days 1-5 every 4 weeks for 12 cycles.

RESULTS

In stage B2, no significant difference between the adjuvant arm and the observation arm was noted. In stage C, adjuvant chemotherapy produced an advantage over observation in terms of a reduction in cancer recurrence rate with prolongation of a disease-free interval (P = 0.0016) and an improvement in overall survival (P = 0.0025).

CONCLUSIONS

This study shows that folinic acid plus 5-fluorouracil adjuvant chemotherapy is effective in patients with surgically resected Dukes' stage C colon carcinoma.

Immunomodulation by levamisole in patients with recurrent aphthous ulcers or oral lichen planus

The purpose of this study was to evaluate the effect of levamisole on the immune system of patients with recurrent aphthous ulcers (RAU) or oral lichen planus (OLP) in an open trial. Lymphocyte subsets, serum immunoglobulins, and circulating immune complexes (CIC) in patients with RAU or OLP and in normal control subjects were determined by an indirect immunofluorescence (IIF) technique with monoclonal anti-lymphocyte antibodies, by single radial immunodiffusion, and by precipitation with 3% polyethylene glycol, respectively. In addition, the anti-nuclear antibodies (ANA) and anti-basal cell antibodies (anti-BCA) in sera were detected by an IIF technique. We found a significant improvement in clinical symptoms and normalization of the decreased CD4/CD8 ratio in RAU patients after levamisole treatment. Moreover, the decreased CD4/CD8 ratio, which persisted until the remission stage in the untreated RAU patients, reverted to normal in the active late stage in the levamisole-treated patients. This reversion of aberrant cellular immunity in an earlier stage of the ulcer cycle may explain why RAU patients experience symptom improvement after levamisole treatment. Although RAU patients treated with levamisole for 1 to 3 or 4 months still had higher than normal levels of CIC and serum immunoglobulins, the levels of their IgA and IgM returned to normal values after 4 months of levamisole treatment. The serum ANA detected in 6 patients with RAU and 3 patients with erosive OLP disappeared after 1-22 months of levamisole treatment. The disappearance of serum anti-BCA was also observed in 50% of the anti-BCA-positive patients with erosive OLP after 3-13 months of levamisole treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody-targeted drugs for the therapy of cancer

The advent of monoclonal antibodies has revitalised the concept of magic bullets and various agents (eg. drugs, toxins and isotopes) have been conjugated to monoclonal antibodies for selective delivery to tumours. Preclinical studies in mouse tumour models have been impressive and have lead to several clinical trials. These phase I trials have been less impressive. However, keeping in mind the aim of Phase I trials, the safety of using these conjugates in humans have been established. Several, major problems still remain to be overcome before these agents may be useful for the treatment of cancer. These problems stem from the nature of tumour vasculature, cytotoxic activity of the moiety linked to antibody and the targeted tumour antigen expressed on the cell surface. This review will deal with these various aspects described above and possible approaches to overcome these obstacles with a definite bias towards drug-monoclonal antibody conjugates. However, these concepts are equally applicable for improved targeting of other agents.

Treatment of chronic hepatitis B with recombinant interferon alpha versus recombinant interferon alpha plus levamisole

To compare the efficacy and tolerance of the simultaneous administration of levamisole plus IFN versus treatment with IFN alone in chronic hepatitis B, 39 patients were randomly assigned into two groups. Nineteen patients received 15 million units of recombinant alpha interferon 2b (rIFN-alpha 2b) 3 times a week for 4 months. The other 20 patients were treated with the same dose and schedule of rIFN-alpha 2b and 150 mg of levamisole simultaneously given during the first 6 weeks of treatment. At the end of the study (thirteenth month), serum HBV-DNA was negative in 59% of patients treated with interferon alone and in 37% of those treated with interferon and levamisole. HBeAg was negative in a similar percentage in the two groups (41% vs. 37%). Serum alanine aminotransferase levels decreased in patients who lost viral DNA. These data demonstrate that the combination of alpha interferon and levamisole, at the doses and under the schedule used in this study, does not achieve better results than the treatment with alpha interferon alone. Although tolerance to the simultaneous administration of alpha interferon and levamisole is good, secondary effects may be hazardous.

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.

Effect of levamisole on major histocompatibility complex class I expression in colorectal and breast carcinoma cell lines

BACKGROUND

The antihelminthic drug levamisole (LMS) is used in conjunction with 5-fluorouracil (5-FU) as adjuvant therapy to reduce the incidence of colon cancer relapse following surgical resection. Clinical trials in patients with breast cancer have yielded conflicting results as to its efficacy in the treatment of this malignancy. LMS is thought to act as an immunostimulant, yet its precise mechanism remains unclear. In this study, the effect of LMS on major histocompatibility complex (MHC) class I (MHC I) and MHC class II (MHC II) expressions in human colorectal and breast carcinoma cell lines was examined.

METHODS

The colon cancer cell line CaCo-2 and the breast cancer cell line MDA-MB-435 were cultured for 24-68 hours in the presence or absence of 10-microns LMS followed by staining with antibodies directed against either MHC I or MHC II: After staining, cells were visualized by fluorescent microscopy.

RESULTS

When cultured in the presence of LMS, cells from both cell lines exhibited a decreased fluorescent intensity with antibodies directed against MHC I protein. The most significant difference from cells cultured without LMS was apparent after 48 hours of incubation. Neither cell line exhibited fluorescent intensities above background when stained with anti-MHC II antibody.

CONCLUSIONS

LMS decreases the expression of MHC I on CaCo-2 and MDA-MB-435 tumor cell lines. Prior studies have indicated that natural killer (NK) cells are more efficient in attacking cells with lowered or no MHC I expression. An MHC I deficiency induced by LMS would augment NK-mediated immune surveillance. One mechanism contributing to levamisole's anti-tumor activity in vivo may be reduction of MHC I expression on tumor cells.

Immunotherapy of colorectal cancer

Specific and nonspecific stimulation of the host immune system to reject cancer is an attractive concept that is just beginning to mature. Results with crude extracts and nonspecific immune stimulation have been variable. However, the recent observations of improved survival after administration of levamisole plus 5-fluorouracil in the adjuvant setting have made an impact on the treatment of colorectal cancer. Animal studies consistently show that immune therapies are most effective for disease that is not advanced. Thus, the small benefit seen with levamisole, a low toxicity immunomodulator, suggests that much more impressive results can be anticipated with more potent and specific agents. Postsurgical autologous tumor cell vaccine has been effective in some prospective randomized trials; in others, no benefit was found. The identification and purification of allogeneic tumor-associated antigens has lead to enhanced antigen-specific host cell-mediated immunity; this may result in more consistent antitumor effects. The current development of chemically defined immune adjuvants of low toxicity allows tumor-specific immune stimulation to be tested in high-risk apparently healthy patients after resection of colorectal cancer (Stages II and III). The influx of information regarding immune cell populations, cell-surface markers, and cytokines has fostered extensive exploration of lymphocyte stimulation, in vitro cell growth and expansion, and in vivo evaluation in patients with advanced cancer. Modest tumor response rates have been documented with adoptive transfer of lymphokine-activated killer cells and interleukin-2. Improved results are anticipated with the more potent tumor-infiltrating lymphocytes and specific in vitro sensitization of draining lymph node cells to autologous and allogeneic tumor antigens. Murine monoclonal antibodies specific for cell-surface markers, such as carcinoembryonic antigen, have been tested for their value in the diagnosis and therapy of colorectal cancer. A small response rate has been seen with single and multiple injections of C017-1A, a monoclonal antibody specific for colonic and pancreatic cancer. The development of antiidiotypic antibodies in these patients may have been important in those that responded to this type of therapy. However, laboratory evidence suggests that monoclonal antibody conjugated to a cytotoxic agent (i.e., radionuclide, drug, or toxin) should be much more effective. Radioimmunotherapy trials in the nude mouse model bearing human colon cancer xenografts showed good tumor incorporation of the radionuclide (yttrium 90 or iodine 131), inhibition of tumor growth, and long-term survival.(ABSTRACT TRUNCATED AT 400 WORDS)

Levamisole augments roxatidine's immune modulatory effects in the graft-versus-host reaction (GVHR)

Levamisole is known to have anti-anergic properties in immune compromised, but no or only marginal effects in immunologically competent subjects. In this study the possibility that levamisole would act as an 'immunoadjuvant' with roxatidine, a histamine H2 receptor blocker, is explored in healthy animals. Sixteen female, inbred Sprague-Dawley rats acted as lymphocyte donors and were treated for 8 days with either a roxatidine-levamisole combination, or levamisole alone, or roxatidine alone or placebo. Five randomly bred guinea pigs and eight inbred BD IX rats acted as lymphocyte acceptors. The in vivo effects of the four treatment modalities on transferred lymphocytes were expressed as the sizes of the allogeneic and xenogeneic graft-versus-host reactions as well as the radioactivity in each AGVHR. The combination of levamisole and roxatidine significantly augmented the cell mediated immune response in vivo and resulted in the most reactive lymphocytes as indicated by the AGVHR's and XGVHR's. These cells mediated reactions with significantly larger wheals as well as more lymphocyte proliferation in each reaction site than those caused by either levamisole or placebo treatment.

Levamisole plus 5-fluorouracil inhibits the growth of human colorectal xenografts in nude mice

Fragments of human colorectal adenocarcinomas were inserted under the renal capsule of nude mice. The growth of these tumour grafts was significantly inhibited by the combination of 5-fluorouracil (5-FU) and levamisole. An alternating regimen of levamisole 2.5 mg/kg and 5-FU 20 mg/kg decreased the size of tumour implants by 33-59% and/or increased the number of macroscopically disappeared fragments in the combined group compared with ineffective monotherapy with saline, levamisole or 5-FU. This model could be valuable for investigating the mechanism of action of levamisole and to evaluate the effects of this adjuvant therapy in other oncological settings.

Augmentation of the immune response of the murine liver by levamisole

Murine hepatic nonparenchymal cells (NPC) were studied following in vivo treatment with levamisole. This agent was found to increase the cytolytic action of these cells against YAC-1 and P815 target cells. An increase in the cytostatic activity against liver-derived murine colon adenocarcinoma 38 tumor cells was also observed. Treatment with levamisole also augmented the proliferation of the hepatic NPC. Supernatants generated by these cells contained an agent capable of stimulating the proliferation of bone marrow cells from the same mice. The effect of levamisole on different subsets of NPC derived from the liver in this model is discussed.

Diethylcarbamazine (DEC): immunopharmacological interactions of an anti-filarial drug

Anti-parasitic drugs may achieve their therapeutic effect either by direct activity against the pathogenic organism, or by altering host factors which lead to parasite killing. In this review, we discuss the evidence for an indirect mode of action for one major anti-filarial drug, diethylcarbamazine (DEC). The interpretation most consistent with existing data is that DEC alters arachidonic acid metabolism in microfilariae and in host endothelial cells. These changes may result in vasoconstriction and amplified endothelial adhesion leading to immobilization of microfilarial parasites, enhanced adherence and cytotoxic activity by host platelets and granulocytes. These events would represent activation of the innate, non-specific immune system, independent of the adaptive, antigen-specific, immune response. This model explains the paradox between rapid clearance in vivo and the lack of an in vitro effect, as well as the efficacy of DEC in non-immune animals. It may also account for the inconsistencies in the effects of DEC against different filariae in different host species. In addition, we discuss the significant side-effects often associated with treatment of heavily infected patients, and the longer-term changes in T-cell reactivity and the host-parasite relationship which follow successful treatment with DEC.

Chemotherapy and immunotherapy of colorectal cancer

More than 50% of the patients with large bowel cancer develop disseminated disease and invariably succumb. Adjuvant chemotherapy with 5-FU and levamisole have been shown to be more efficient than 5-FU alone or in combination with cytostatics. The combination of 5-FU, leukovorin and methotrexate induces prolonged survival with a good quality of life in metastatic colorectal cancer (CRC). During the last decade tumor immunotherapy has been an alternative facilitated by isolation and large scale production of cytokines and monoclonal antibodies. The mouse monoclonal antibody (MAb) 17-1A recognizes a tumor-associated antigen (TAA), present in high concentrations on the surface of gastrointestinal tumor cells. Injections of MAb 17-1A in patients with metastatic CRC induced generation of anti-idiotypic (ab2) in 90% and anti-anti-idiotypic (ab3) antibodies in 47% of the treated patients. The development of ab3 correlated significantly with survival (mean 80 weeks) while ab3- patients survive only 38 weeks. One of 52 patients treated with MAb 17-1A is a complete remission after 66 months, 3 had minor regression and 6 had a stable disease (19% RR). Based on in vitro findings showing increased antibody-dependent cellular cytotoxicity (ADCC) by the combination of granulocyte-macrophage colony stimulating factor (GM-CSF) and MAb 17-1A, 16 CRC patients have been treated with subcutaneously injections of GM-CSF for 10 days and intravenous infusions of MAb 17-1A at day 3. Two of 16 are in CR, 1 in MR and 3 in SD (37.5% RR). Minor side-effects were registered. A further development of immunotherapy of CRC might imply vaccination by injection of specific human anti-idiotypic antibodies (ab2) which mimics the nominal antigen, in order to induce a specific immunity.

Metabolism of levamisole, an anti-colon cancer drug, by human intestinal bacteria

1. Anaerobic incubation of levamisole with human intestinal flora resulted in the formation of three thiazole ring-opened metabolites, namely, levametabol-I, II and III. These new hydroxamic lactam-type metabolites were isolated and characterized by various spectroscopic methods. 2. Various pure cultures of human intestinal bacterial strains were shown, by quantitative h.p.l.c. analysis, to have ring-opening ability. Strong metabolizers include Bacteroides and Clostridium spp. Bacterial mixtures prepared from human faeces showed much greater ability to transform levamisole (74% in 48 h) than any pure strain culture. 3. Greatly decreased levamisole-transforming activity was observed with autoclaved bacterial cultures, and no activity was found with broth medium alone. This indicates that metabolism requires the presence of anaerobic bacteria and involves, at least in part, a non-enzymic process.

Interference of levamisole with cerebral edema

The anthelmintic and immunomodulator drug levamisole is also a thromboxane synthetase inhibitor. The effect of levamisole on cerebral edema in Mongolian gerbils and in rat models of stroke was evaluated. Cerebral ischemia was produced in gerbils by right carotid ligation and in rats by right carotid ligation and anoxia. Mortality and right hemisphere edema were evaluated 24 hours after induction of cerebral anoxia in levamisole treated animals. Levamisole failed to protect gerbils from death or cerebral edema but decreased dose-dependently the cerebral edema in rats. The fact that levamisole inhibits thromboxane synthetase and decrease cerebral swelling in rats supports further tests against human stroke.

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.

Modulation of experimental autoimmune uveitis with formosanin-C in guinea pigs

Formosanin-C, a diosgenin saponin, was isolated from a perennial herb, Paris formosana Hayata (Liliaceae) which has been used as a folk remedy for snake bite and as an anti-inflammatory or anti-neoplastic agent. Its effect on the development of S-antigen-induced experimental autoimmune uveitis (EAU) in guinea pigs was studied. Guinea pigs treated with formosanin-C (1.5 mg/kg/2 days and 0.5 mg/kg/2 days) were compared with untreated guinea pigs in regard to the development of EAU, lymphocytic proliferative responses, and anti-S-antigen serum antibodies. The higher dosage of formosanin-C (1.5 mg/kg) obviously delayed the onset of EAU. Treatment of this drug, 1.5 mg/kg and 0.5 mg/kg doses, significantly inhibited the specific lymphocytic response of lymph node and spleen cells to S-antigen. On the contrary, treatment in 1.5 mg/kg dose significantly increased the response of lymph node and spleen cells to the polyclonal T cell mitogen, phytohemagglutinin (PHA). Treatment with formosanin-C in both the 1.5 mg/kg and 0.5 mg/kg doses had a minimal effect on the lymphocytic response of lymph node to concanavalin-A (ConA), while a noticeable suppressive effect on the response of spleen cells to ConA was observed in the 1.5 mg/kg dose. This agent in 1.5 mg/kg and 0.5 mg/kg doses significantly inhibited the anti-S-antigen antibody production by days 14 and 18 postimmunization. This study suggests that formosanin-C, an immunomodulator, may offer a new approach to modulate the development of EAU.

Levamisole inhibits in vivo rat platelet aggregation by a release of prostacyclin-like factor

1. The anti-thrombotic effect of levamisole (LMS) and acetylsalicylic acid (ASA) were examined in vitro and in vivo models. 2. LMS inhibits rat platelet aggregation induced by either adenosine 5'-diphosphate (ADP) or collagen (CLG) in vitro and in vivo. 3. LMS is more active in vivo than in vitro while acetylsalicylic acid (ASA) is more active in vitro than in vivo. It seems that in vivo LMS does not act by blocking thromboxane A2 formation only, but via participation of an endogenous factor. 4. The release of LMS-induced anti-thrombotic factor is inhibited by ASA pretreatment, indicating to be a cyclooxygenase metabolite of arachidonic acid. 5. The LMS-induced anti-thrombotic factor has a t1/2 of 3.6 +/- 0.8 min that is similar to the t1/2 of synthetic prostacyclin (PGI2) tested in our system (3.9 +/- 0.5 min; P = NS). 6. The release of PGI2-like substance from vascular tissue is LMS dose-dependent.

Immune stimulation. A new approach in the treatment of glomerulonephritis

We discuss here a new approach to the treatment of idiopathic membranous glomerulonephritis (IMGN). Steroids and cytotoxic drugs have been used during the last years for the treatment of this disease, but the results are controversial. We develop here the hypothesis that the pathogenesis of IMGN is a relative incompetence of the immune system in clearing foreign antigens. Therefore, most patients should benefit from immune stimulation in the direction of a greater and more avid immune response.