Short term treatment of visceral leishmaniasis of the Old World with low dose interferon gamma and pentavalent antimony

Three decades of clinical trials on immunotherapy for human leishmaniases: a systematic review and meta-analysis

Aim: Current treatments for leishmaniases are not satisfactory, thus alternatives are needed. We searched for clinical trials with immunotherapeutic approaches for patients with leishmaniasis. Materials & methods: Out of 205 articles, 24 clinical trials were selected, and eight submitted to meta-analysis. Results: A reduction in healing time was observed in patients with tegumentary leishmaniasis treated with pentavalent antimony plus granulocyte-macrophage colony-stimulating factor, and therapeutic vaccines. Overall meta-analysis indicated that immunotherapy associated with the standard chemotherapy generated a significantly reduced risk of treatment failure than the pentavalent antimony alone (p = 0.03). Conclusion: Our review confirmed the efficacy of immunotherapies for the treatment of cutaneous and visceral leishmaniasis and highlighted the importance of clinical trials using immunotherapies for leishmaniases.

Drug combinations for visceral leishmaniasis

PURPOSE OF REVIEW

Several attempts have been made to combine drugs for treating visceral leishmaniasis, but only recently have effective drugs become available and combinations been tested systematically.

RECENT FINDINGS

Sequential treatments with liposomal amphotericin B followed by miltefosine or paromomycin (as short as 7 days), as well as the concomitant administration of miltefosine and paromomycin (for 10 days) are very effective in India (>95%). Sodium stibogluconate plus paromomycin for 17 days is more than 90% effective in East Africa. The shortened combination regimens are cost-effective in India. No combination has been tested so far in Brazil, Nepal and Bangladesh, although studies may be expected in the near future. No cost-effectiveness analysis has been done as yet outside India.

SUMMARY

There is evidence of high efficacy and benefits with sequential and co-administration treatments in India. More studies are needed in other endemic areas. Introducing combinations and scaling up their use will be challenging. Experience acquired with malaria may be useful. Proper monitoring of use and effects (efficacy and safety) will be required. Currently there are no options for fixed-dose combination treatments for leishmaniasis.

Treatment of visceral leishmaniasis (kala-azar): a decade of progress and future approaches

In 1990, there was essentially one treatment regimen in use for visceral leishmaniasis (kala-azar) around the world: 20 to 28 days of daily injections of pentavalent antimony (Sb). During the past 10 years, however, new agents have been tested alone or in combination, in more than 50 studies carried out worldwide. This renewed clinical effort was spurred by a variety of factors, including the emergence of large-scale Sb unresponsiveness in India, where up to one-half of the world's cases of kala-azar now are found. As this new decade opens, the success of this clinical research effort is tangible: three additional, highly effective parenteral regimens now are available (amphotericin B, lipid formulations of amphotericin B, aminosidine), and an active oral agent, a long sought after objective in kala-azar, has been identified (miltefosine). This report reviews the evolution of treatment of visceral leishmaniasis, considers the interaction of the immune response and chemotherapy, highlights therapeutic successes and failures, examines advantages and disadvantages of current treatments, and looks at future therapeutic approaches to the management of this disseminated intracellular protozoal infection.

Successful therapy of chronic, nonhealing murine cutaneous leishmaniasis with sodium stibogluconate and gamma interferon depends on continued interleukin-12 production

Treatment of nonhealing forms of human leishmaniasis with antimonial drugs in combination with gamma interferon (IFN-gamma) may promote healing more effectively than conventional drug therapy. Although the natures of immune responses in patients prior to treatment are often unclear, it is generally assumed that such therapy also promotes a switch from a Th2-type response to a dominant Th1-type response. We have examined the efficacy of IFN-gamma therapy, in combination with drug therapy, to promote healing and a Th2-to-Th1 switch in highly susceptible BALB/c mice infected with Leishmania major. Short-term treatment with the antileishmanial drug sodium stibogluconate failed to significantly alter the course of disease or the immune response when it was given during the third and fourth weeks of infection. IFN-gamma therapy, administered over the same time period, also failed to induce cure or a Th1 dominant response. In contrast, mice treated with a combination of drug and IFN-gamma therapy resolved their infections and developed Th1-type responses. However, administration of an antibody to interleukin 12 (IL-12) reversed the therapeutic effects of therapy with drug plus IFN-gamma, suggesting that IFN-gamma promotes cure through an IL-12-dependent mechanism. Analysis of mRNA levels within parasitized lesions suggests that drug treatment plus IFN-gamma treatment, in addition to reducing parasite numbers, results in reduced levels of IL-4, IL-10, and transforming growth factor beta transcripts but increased levels of transcripts of the p40 chain of IL-12 and inducible nitric oxide synthase, which catalyzes the production of nitric oxide. Together, these results suggest that such immunotherapy may promote the development of a protective Th1-type response in susceptible mice by a mechanism which involves both suppression of regulatory cytokines and enhancement of IL-12 and nitric oxide production.

Interferon-gamma and host antimicrobial defense: current and future clinical applications

In the 1980s, substantive experimental data and emerging clinical results suggested that interferon-gamma (IFN-gamma), a T-cell-derived lymphokine with broad macrophage-activating effects, had considerable potential in the treatment of nonviral infections as a host defense-enhancing antimicrobial agent. During the past 6 years, the breadth of the experimental activity with IFN-gamma against nonviral pathogens has been expanded still further, and pilot studies and formal clinical trials using IFN-gamma have been undertaken in the treatment of patients both at risk for and with active infections. Thus far, IFN-gamma has been approved for use as prophylaxis in patients with chronic granulomatous disease. However, IFN-gamma also appears effective as adjunctive therapy for at least one disseminated intracellular infection (visceral leishmaniasis), and in conjunction with conventional therapy, may benefit patients with certain forms of cutaneous leishmaniasis, disseminated Mycobacterium avium complex infection, and lepromatous leprosy. Despite a rationale for its use, IFN-gamma has not yet been tested in tuberculosis or fungal or common bacterial infections nor sufficiently examined in the prevention and/or treatment of the opportunistic infections related to acquired immunodeficiency syndrome. IFN-gamma remains a promising host defense-enhancing cytokine with still unexplored clinical potential.