Treatment of Indian visceral leishmaniasis with single or daily infusions of low dose liposomal amphotericin B: randomised trial

Current treatment approaches to leishmaniasis

PURPOSE OF REVIEW

The leishmaniases consist of cutaneous, mucosal, and visceral syndromes. The classic treatment is with pentavalent antimonials. The disadvantages of the antimonials are their requirement for intramuscular or intravenous injection each day for 20-28 days, their toxicity, and the recent development of resistance in regions such as India. Amphotericin B is a potent secondary agent, but is also compromised by its parenteral nature and toxicity. Clinical investigation of treatment agents from January 2000 to January 2003 is reviewed to determine if there are new agents that can be used.

RECENT FINDINGS

A large number of pilot studies on visceral and cutaneous leishmaniasis have been performed. There can be more confidence in the visceral studies because visceral disease is incurable if untreated, and because large numbers of patients have been treated in highly endemic regions such as India. There is less confidence in pilot studies of the cutaneous disease, because most are uncontrolled, and there is a variable, and often high, cure rate without treatment.

SUMMARY

Liposomal amphotericin B, which is injected infrequently and is easily tolerated, is virtually 100% effective for Indian visceral disease at a total dose of 15 mg/kg and is 90% effective at a dose of 5-10 mg/kg. The oral agent, miltefosine, is more than 95% effective for Indian visceral disease. Fluconazole treatment for 6 weeks speeds up the already-rapid cure rate of cutaneous disease due to Leishmania major.

Single-dose liposomal amphotericin B in the treatment of visceral leishmaniasis in India: a multicenter study

Widespread antimony resistance renders conventional amphotericin B the only option for the treatment of visceral leishmaniasis (VL) in North Bihar, India. Because of its excellent safety profile, a large dose (7.5 mg/kg) of liposomal amphotericin B (L-AmB) was given to each of 203 patients with VL at 4 treatment centers, and the patients were discharged the next day. At initial clinical and parasitological follow-up, performed on day 30 after treatment, evidence of a cure was seen in 195 (96%) of 203 patients (95% CI, 92-98); 4 patients experienced treatment failure. Two patients were lost to follow-up, 2 died (one due to progressive disease and another, 5 months after treatment, due to an unrelated illness), and 12 experienced relapses during follow-up. Thus, 183 patients (90%; 95% CI, 85-94) had obtained final cure 6 months after treatment. Very few adverse events (fever with rigor, in 9.8% of patients) were seen. Single-dose L-AmB (7.5 mg/kg) treatment is safe and effective, and it may be used for the mass treatment of VL in India.

[Therapy of tropical diseases after returning from travel]

Most tropical diseases imported by travelers can be treated quite effectively. Human endoparasites belong to the protozoa and worms. Protozoa can be seen as microparasites, characterized by short generation periods and high rates of reproduction within a host--consequently the diseases mainly are of short duration. Effective drugs are available for malaria, amebiasis and other intestinal protozoa as well as for leishmaniasis. Resistance, however, sometimes is a problem. Worms are macroparasites that generally do not reproduce within a host--teleologically speaking because otherwise they would rapidly damage their own basis of living. Accordingly, severe worm disease is rarely found in travelers. Levels of anthelminthic resistances so far are low. The most important worm disease in travelers is schistosomiasis, a disease that also can be treated effectively if diagnosed early.

Liposomal amphotericin B in the treatment of visceral leishmaniasis in immunocompetent patients

The leishmaniases are protozoan diseases caused by Leishmania parasites. The first-line treatment of its visceral forms is pentavalent antimony (meglumine antimoniate or sodium stibogluconate), but toxicity is frequent with this drug. Moreover antimony unresponsiveness is increasing in Leishmania infantum and L. donovani foci, both in immunocompetent and in immunosuppressed patients. Amphotericin B is a polyene macrolide antibiotic that binds to sterols in cell membranes. It is the most active antileishmanial agent in use. Its infusion-related and renal toxicity may be reduced by lipid-based delivery. Liposomal amphotericin B (AmBisome); Gilead Science, Paris, France) seems to be less toxic than other amphotericin B lipid formulations (Amphocil); Liposome Technology Inc., Menlo Park, CA, USA, Amphotec); Ben Venue Laboratories Inc., Bedford, OH, USA). Optimal drug regimens of AmBisome) vary from one geographical area to another. In the Mediterranean Basin, a total dose of 18 mg/kg (3 mg/kg on days 1-5 and 3 mg/kg on day 10) could be used as first-line treatment of visceral leishmaniasis in immunocompetent patients. In immunocompromised patients, especially those co-infected with HIV, relapses are frequent with AmBisome), as with other drugs.

Two doses of a lipid formulation of amphotericin B for the treatment of Mediterranean visceral leishmaniasis

To evaluate the efficacy of a short course of a lipid formulation of amphotericin B (L-AmB) for the treatment of Mediterranean visceral leishmaniasis (VL), an open prospective study was conducted. Forty-one children with parasitologically confirmed leishmaniasis received L-AmB, 10 mg/kg daily for 2 days. The comparison groups were 30 children who, in a previous study, were treated with L-AmB, 4 mg/kg daily for 5 days, and 52 children who were treated with meglumine antimoniate. At 6 months after completion of treatment, overall treatment success was noted for 40 of 41 children treated with 2 doses of L-AmB, 27 of 30 children treated with 5 doses of L-AmB, and 47 of 52 children treated with meglumine antimoniate. Abatement of fever, reduction in spleen size, and correction of laboratory parameters occurred more quickly among the children who received 2 doses of L-AmB than among the comparison groups, and the total estimated cost of the 2-dose regimen was also lower than that of the other regimens. Two doses of L-AmB, 10 mg/kg each, is cost-effective therapy for Mediterranean VL in children.

Advances in the treatment of leishmaniasis

PURPOSE OF REVIEW

Treatment of leishmaniasis is far from satisfactory: all antileishmanial drugs are toxic and most have to be used parenterally for prolonged periods, especially for visceral leishmaniasis. In recent years, there has been a steady erosion in the efficacy of pentavalent antimony to cure visceral leishmaniasis in Bihar, India. In addition, several new antileishmanial formulations have become available.

RECENT FINDINGS

Through the publication of three studies from Africa, generic sodium stibogluconate, which is a fraction of the price of the branded drug Pentostam, has proven to be equivalent to Pentostam both in terms of safety and efficacy. The first oral drug, miltefosine, has been approved for treating visceral leishmaniasis in India, and preliminary reports of its efficacy against cutaneous leishmaniasis have been published. Interesting studies on successful low/single dose treatment of Indian visceral leishmaniasis with liposomal amphotericin B have been published. Several trials using different approaches towards treating cutaneous leishmaniasis are also reviewed. The results of clinical trials of two oral compounds are reported - fluconazole in treating cutaneous leishmaniasis was found to be safe and effective, whereas sitamaquine (WR6026) for visceral leishmaniasis was found to be toxic with poor efficacy.

SUMMARY

Generic stibogluconate enables the cost effective treatment of all forms of leishmaniasis as it remains the most important antileishmanial drug in most parts of the world. In India, successful single dose AmBisome for visceral leishmaniasis makes therapy simple and enables mass treatment, provided the drug cost is brought down. For cutaneous leishmaniasis, two new oral drugs, fluconazole and miltefosine, provide wider options to the clinician.

Oral miltefosine for Indian visceral leishmaniasis

BACKGROUND

There are 500,000 cases per year of visceral leishmaniasis, which occurs primarily in the Indian subcontinent. Almost all untreated patients die, and all the effective agents have been parenteral. Miltefosine is an oral agent that has been shown in small numbers of patients to have a favorable therapeutic index for Indian visceral leishmaniasis. We performed a clinical trial in India comparing miltefosine with the most effective standard treatment, amphotericin B.

METHODS

The study was a randomized, open-label comparison, in which 299 patients 12 years of age or older received orally administered miltefosine (50 or 100 mg [approximately 2.5 mg per kilogram of body weight] daily for 28 days) and 99 patients received intravenously administered amphotericin B (1 mg per kilogram every other day for a total of 15 injections).

RESULTS

The groups were well matched in terms of age, weight, proportion with previous failure of treatment for leishmaniasis, parasitologic grade of splenic aspirate, and splenomegaly. At the end of treatment, splenic aspirates were obtained from 293 patients in the miltefosine group and 98 patients in the amphotericin B group. No parasites were identified, for an initial cure rate of 100 percent. By six months after the completion of treatment, 282 of the 299 patients in the miltefosine group (94 percent [95 percent confidence interval, 91 to 97]) and 96 of the 99 patients in the amphotericin B group (97 percent) had not had a relapse; these patients were classified as cured. Vomiting and diarrhea, generally lasting one to two days, occurred in 38 percent and 20 percent of the patients in the miltefosine group, respectively.

CONCLUSIONS

Oral miltefosine is an effective and safe treatment for Indian visceral leishmaniasis. Miltefosine may be particularly advantageous because it can be administered orally. It may also be helpful in regions where parasites are resistant to current agents.

Recent developments in leishmaniasis

PURPOSE OF REVIEW

The leishmaniases, caused by protozoan parasites of the genus Leishmania, are a significant health problem in many regions of the world. This review highlights the recent advances in the study of leishmaniasis related to parasite biology, disease pathogenesis, clinical evaluation and treatment, and prevention.

RECENT FINDINGS

Genetic heterogeneity and clonal diversity is common among Leishmania strains. Gene knockout, overexpression, and re-introduction studies have identified a number of genes that play a role in parasite virulence. Surprisingly, the importance of the surface lipophosphoglycan in parasite virulence appears to differ among Leishmania spp. Studies in experimental animal models have further defined the roles of CD4 and CD8 T cells, IL-4, IL-10, and IL-12 in the control, maintenance, or progression of disease. The effect of Leishmania on dendritic cells and macrophage effector function has also been an important area of investigation. A number of new vaccine candidates have been identified through experimental animal studies. Clinical studies of leishmaniasis have focused on the host determinants of disease (most notably HIV co-infection), serological and DNA-based diagnostic assays, and treatment. Antimony-resistant cases of cutaneous and visceral leishmaniasis have become more common; liposomal amphotericin and oral miltefosine are promising alternative therapies.

SUMMARY

Significant advances have been made in the areas of pathogenesis, host defence, and treatment of leishmaniasis. A number of new vaccine candidates and potential targets of drug therapy have been identified, but progress from preclinical studies to clinical trials has been slow. Translational research, built upon the solid foundation of existing and ongoing basic investigation, is a high priority.

Noninvasive management of Indian visceral leishmaniasis: clinical application of diagnosis by K39 antigen strip testing at a kala-azar referral unit

Firm diagnosis of visceral leishmaniasis (kala-azar) requires organ aspiration and microscopic examination of tissue specimens. To determine the usefulness of noninvasive diagnosis by strip test detection of anti-K39 immunoglobulin (Ig) G antibody in blood specimens obtained by fingerstick, 143 Indian patients with suspected kala-azar (fever, splenomegaly, anemia) were studied. Of 120 strip test-positive subjects (subjects with presumed kala-azar [group A]), amphotericin B treatment induced clinical cure in 119. Of 23 strip test-negative subjects (subjects presumed to have other diseases [group B]), 16 had other disorders diagnosed at entry, 4 responded to empiric antimalarial therapy, 2 were proven to have kala-azar, and 1 died elsewhere after undergoing splenic aspiration. Six months after treatment ended, all 120 patients in group A and the 18 assessable patients in group B were healthy. In a region in India where visceral infection is prevalent, strip test detection of anti-K39 IgG is a clinically promising diagnostic guide in persons with suspected kala-azar.

Visceral leishmaniasis: current status of control, diagnosis, and treatment, and a proposed research and development agenda

Visceral leishmaniasis is common in less developed countries, with an estimated 500000 new cases each year. Because of the diversity of epidemiological situations, no single diagnosis, treatment, or control will be suitable for all. Control measures through case finding, treatment, and vector control are seldom used, even where they could be useful. There is a place for a vaccine, and new imaginative approaches are needed. HIV co-infection is changing the epidemiology and presents problems for diagnosis and case management. Field diagnosis is difficult; simpler, less invasive tests are needed. Current treatments require long courses and parenteral administration, and most are expensive. Resistance is making the mainstay of treatment, agents based on pentavalent antimony, useless in northeastern India, where disease incidence is highest. Second-line drugs (pentamidine and amphotericin B) are limited by toxicity and availability, and newer formulations of amphotericin B are not affordable. The first effective oral drug, miltefosine, has been licensed in India, but the development of other drugs in clinical phases (paromomycin and sitamaquine) is slow. No novel compound is in the pipeline. Drug combinations must be developed to prevent drug resistance. Despite these urgent needs, research and development has been neglected, because a disease that mainly affects the poor ranks as a low priority in the private sector, and the public sector currently struggles to undertake the development of drugs and diagnostics in the absence of adequate funds and infrastructure. This article reviews the current situation and perspectives for diagnosis, treatment, and control of visceral leishmaniasis, and lists some priorities for research and development.

Treatment of visceral leishmaniasis: a review of current treatment practices

Visceral leishmaniasis (VL) is a systemic protozoan infection that infects a million people living in subtropical and tropical areas. Once established, the clinical course of untreated disease leads to death. Recent, large-scale epidemics in east Africa and India and the emergence of a new epidemic in patients infected with HIV makes VL a priority for the World Health Organization. Pentavalent antimonials have been the mainstay of the treatment for > 60years. The progressive appearance of antimonial resistance, the developments of lipid formulations of amphotericin B and a new oral administered drug (miltefosine) have changed the pattern of VL treatment. The prohibitive cost of new therapies leads to different treatment practices according to the socioeconomic and cultural status of each region.

Visceral leishmaniasis in paediatrics

Visceral leishmaniasis is a vector-borne systemic infection, which affects half a million people each year in many areas of the world. Typical disease manifests with fever, hepatosplenomegaly, pancytopenia, and progressive deterioration of the host. Although molecular methods appear promising as a non-invasive diagnostic tool, definite diagnosis still relies on the demonstration of the parasite in tissue. Pentavalent antimonial compounds remain the mainstay of treatment worldwide, except in India. During the past decade, short courses of lipid formulations of amphotericin B were assessed and proved effective; however, their cost precludes their wide use in developing countries. Miltefosine, an oral active agent, was recently identified, and might fulfil our expectations for an effective, safe, easily administered and affordable antileishmanial treatment.