Treatment of Infections in Immunocompromised Children with Cancer, HIV and other Immunodeficiencies.Our studies of infections complicating children with neoplastic disease, HIV infection, and other immunodeficiencies focus on development of new approaches to treatment and prevention of invasive fungal infections, rapid molecular detection, and augmentation of host defenses. In developing new approaches for treatment of invasive fungal infections in immunocompromised children, we have previously demonstrated through a translational research program that lipid formulations of amphotericin B (e.g. amphotericin B lipid complex (ABLC) and liposomal amphotericin B) were more effective and less toxic than conventional antifungal therapy in experimental disseminated candidiasis and invasive pulmonary aspergillosis, providing a rational foundation for clinical trials. We then conducted phase I-II studies in immunocompromised patients, leading to approval for the first lipid formulations of amphotericin B in the U. S. in children and adults. We also completed a pivotal phase III randomized double-blind controlled trial of empirical liposomal amphotericin B versus conventional amphotericin B in persistently febrile neutropenic patients, which led to the first approval of any compound for empirical antifungal therapy. We developed a similar experimental foundation and clinical research program for development and application of the extended spectrum triazoles (itraconazole, voriconazole, posaconazole, and ravuconazole) for empirical antifungal therapy and definitive therapy of invasive filamentous fungal infections in children and adult patients with cancer, HSCT, HIV, and other immunodeficiencies. We have further characterized the antifungal properties of advanced spectrum triazoles, demonstrating in experimental models their superior activity against resistant fungal pathogens. These findings led to the recent completion of a multicenter phase III trial comparing voriconazole and liposomal amphotericin B, demonstrating that voriconazole was comparable to liposomal amphotericin but superior in preventing breakthrough invasive fungal infections, including invasive aspergillosis. We are currently investigating the novel class of cell wall active agents, the echinocandins, the spectrum of which includes Candida spp., Aspergillus spp., and Pneumocystis carinii. Having demonstrated concentration dependent and dosage dependent fungicidal activity in vitro and in vivo, we completed phase I-II clinical trials of these compounds. Based upon the data from these trials, we conducted and have now completed the first phase III trial comparing echinocandin and fluconazole for prevention of invasive fungal infections in bone marrow/stem cell transplant recipients. This study demonstrated that the echinocandin was superior to fluconazole in prevention of invasive fungal infections during the neutropenic phase of hematopoietic stem cell transplantation. These laboratory and early clinical trials laid the foundation for the recently published multicenter, international double blind randomized trial demonstrating that an echinocandin was comparable to liposomal amphotericin B for empirical antifungal therapy in high risk leukemia patients and was superior in primary treatment of baseline invasive mycoses, in safety profile, and in conferring a significant improvement in survival. These data now provide patients with leukemia and other hematological malignancies a safer and effective alternative for empirical antifungal therapy during their highest risk periods of neutropenia. Arising from our earlier Laboraotry and clinical trials and as an expanding effort to treat life-threatening infections in immunocompromised children of all ages, we recently reported the successful treatment of refractory invasive candidiasis in newborn infants, including those with persistent candidemia, Candida meningitis, and renal candidiasis. All infants cleared their infection and all but one are alive and well nearly one year after successful treatment of their infection. These laboratory and clinical trials of monotherapy have now laid the foundation for addressing the critical scientific questions of combination therapy. Based upon extensive drug interaction studies in vitro and in vivo, we are now preparing a definitive protocol for a multicenter, international double-blind randomized controlled trial of an antifungal triazole plus echinocandin versus triazole alone in the primary treatment of invasive aspergillosis in children and adults performed in collaboration with the NIAID. We also are developing with the NIAID a multicenter program that will designate 50 institutions to conduct leading edge clinical trials of treatment of zygomycosis, an uncommon but highly lethal infection with an overall mortality of approximately 60% for which therapy and survival has not appreciably changed in the last 40 years. With new reports of increasing frequency of this emerging infection, new treatment paradigms are needed for zygomycosis, which infects not only patients with cancer and BMT recipients, but also patients with diabetes mellitus, solid organ transplantation, renal failure, burns, and trauma. During the past decade, the Section's work on the epidemiology, pathogenesis, host defenses, and treatment of zygomycosis are now providing key contributions to the understanding of this often lethal and emerging infection. Returning to a more basic level in collaboration with the USDA, we have found novel water-soluble molecules with potent antimicrobial activity from the native host defense systems of plants. We are characterizing their unique cellular and molecular mechanisms of action against microbial pathogens and their safety profile in human cell culture lines. Complementing these therapeutic interventions, we are characterizing the molecular epidemiology of nosocomial aspergillosis and fusariosis in order to develop strategies for environmental control as an adjunctive approach for reducing exposure and respiratory acquisition of these human pathogens. In creating new methods for improving the early diagnosis and therapeutic monitoring of disseminated candidiasis and aspergillosis, we are currently developing rapid PCR diagnostic systems for measuring early infection and for assessing therapeutic response. Following more than a decade of collaborative investigation with galactomannan as a marker for invasive asperigillosis, the enzyme immunoassay was approved for use in detection of this infection in patients in the United States. We are further characterizing the use of combined galactomannan expression and PCR signal in BAL fluid in our animal models and in patients for enhanced sensitivity and specificity for detection of pulmonary infiltrates. We are further characterizing the proteomic expression in vitro and in vivo of pulmonary aspergillosis in collaboration with the CCMD as a new initiative for detection and prognosis of this often-lethal opportunistic infection. In developing new approaches for augmenting host defenses, we have demonstrated that MCSF augments pulmonary host defenses against experimental invasive aspergillosis, that neutralization of IL-4 and IL-10 improves host response against aspergillosis, and that IL-15 is a potent activator of superoxide production (not through upregualtion of NADPH-oxidase genes) and of antifungal activity against Candida in elutriated monocytes.
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