Invasive esophageal aspergillosis associated with acute myelogenous leukemia: successful therapy with combination caspofungin and liposomal amphotericin B

Recent Progress in the Discovery of Antifungal Agents Targeting the Cell Wall

Due to the limit of available treatments and the emergence of drug resistance in the clinic, invasive fungal infections are an intractable problem with high morbidity and mortality. The cell wall, as a fungi-specific structure, is an appealing target for the discovery and development of novel and low-toxic antifungal agents. In an attempt to accelerate the discovery of novel cell wall targeted drugs, this Perspective will provide a comprehensive review of the progress made to date on the development of fungal cell wall inhibitors. Specifically, this review will focus on the targets, discovery process, chemical structures, antifungal activities, and structure-activity relationships. Although two types of cell wall antifungal agents are clinically available or in clinical trials, it is still a long way for the other cell wall targeted inhibitors to be translated into clinical applications. Future efforts should be focused on the identification of inhibitors against novel conserved cell wall targets.

Gastrointestinal manifestations of leukemia

Gastrointestinal (GI) manifestations of leukemia occur in up to 25% of patients at autopsy, generally during relapse. Its presence varies with the type of leukemia and has been decreasing over time due to improved chemotherapy. Gross leukemic lesions are most common in the stomach, ileum, and proximal colon. Leukemia in the esophagus and stomach includes hemorrhagic lesions from petechiae to ulcers, leukemic infiltrates, pseudomembranous esophagitis, and fungal esophagitis. Lesions in the small and large bowel are usually hemorrhagic or infiltrative. Infiltration of lymphoreticular organs, mainly spleen, liver, and lymph nodes, is more prominent in chronic than acute leukemia. Neutropenic enterocolitis, a necrotizing process involving the cecum, ascending colon, and terminal ileum, is increasing in incidence due to greater intensity of chemotherapy. Distension of bowel leads to mucosal breaches, permitting entry of organisms that grow profusely in the absence of neutrophils. Ischemic necrosis follows, leading to perforation and/or peritonitis. Patients present with fever, abdominal pain, diarrhea, nausea, vomiting, abdominal distension and tenderness. Ultrasound and computed tomography scans show thickening of the bowel wall. Treatment is supportive with surgery for necrosis and perforation. The main GI causes of death in leukemia are hemorrhage, infection, and necrotizing enterocolitis.

Invasive aspergillosis in developing countries

To review invasive aspergillosis (IA) in developing countries, we included those countries, which are mentioned in the document of the International Monetary Fund (IMF), called the Emerging and Developing Economies List, 2009. A PubMed/Medline literature search was performed for studies concerning IA reported during 1970 through March 2010 from these countries. IA is an important cause of morbidity and mortality of hospitalized patients of developing countries, though the exact frequency of the disease is not known due to inadequate reporting and facilities to diagnose. Only a handful of centers from India, China, Thailand, Pakistan, Bangladesh, Sri Lanka, Malaysia, Iran, Iraq, Saudi Arabia, Egypt, Sudan, South Africa, Turkey, Hungary, Brazil, Chile, Colombia, and Argentina had reported case series of IA. As sub-optimum hospital care practice, hospital renovation work in the vicinity of immunocompromised patients, overuse or misuse of steroids and broad-spectrum antibiotics, use of contaminated infusion sets/fluid, and increase in intravenous drug abusers have been reported from those countries, it is expected to find a high rate of IA among patients with high risk, though hard data is missing in most situations. Besides classical risk factors for IA, liver failure, chronic obstructive pulmonary disease, diabetes, and tuberculosis are the newly recognized underlying diseases associated with IA. In Asia, Africa and Middle East sino-orbital or cerebral aspergillosis, and Aspergillus endophthalmitis are emerging diseases and Aspergillus flavus is the predominant species isolated from these infections. The high frequency of A. flavus isolation from these patients may be due to higher prevalence of the fungus in the environment. Cerebral aspergillosis cases are largely due to an extension of the lesion from invasive Aspergillus sinusitis. The majority of the centers rely on conventional techniques including direct microscopy, histopathology, and culture to diagnose IA. Galactomannan, β-D glucan test, and DNA detection in IA are available only in a few centers. Mortality of the patients with IA is very high due to delays in diagnosis and therapy. Antifungal use is largely restricted to amphotericin B deoxycholate and itraconazole, though other anti-Aspergillus antifungal agents are available in those countries. Clinicians are aware of good outcome after use of voriconazole/liposomal amphotericin B/caspofungin, but they are forced to use amphotericin B deoxycholate or itraconazole in public-sector hospitals due to economic reasons.

The use of caspofungin in HIV-infected individuals

Fungal infections are a significant cause of HIV-related morbidity and mortality, particularly in the developing world, but also in countries with access to highly active antiretroviral therapy. New agents are essential to improve present efficacy rates, particularly in cases of drug resistance. Caspofungin is a new antifungal from the echinocandin class and is licensed for the treatment of candidal infections and as a second-line therapy for invasive aspergillosis. In this paper, the pharmacology, interaction and susceptibility data for this agent are reviewed and studies supporting the use of this agent in HIV-infected individuals are examined. Finally, evidence for the use of caspofungin for the treatment of Pneumocystis jiroveci pneumonia, an unlicensed indication, including a case series from our own unit is explored.