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Abstract: This article reported the identification of heat shock protein 90 (hsp90) homologues by immunoblot in Cryptococcus neoformans. Mycograb®, a genetically recombinant antibody against hsp90, was evaluated against 8 clinical isolates and the National External Quality Assessment Service for Microbiology strain of C. neoformans alone and in combination with amphotericin B, caspofungin, and fluconazole by checkerboard assay. At the end point of an optically clear well, the minimum inhibitory concentration (MIC) 0''s ranged from 256 to 1024 μg/mL for Mycograb®, from 0.5 to 1 μg/mL for amphotericin B, and from 16 to 32 μg/mL for caspofungin. The combination of Mycograb® and amphotericin B produced a fractional inhibitory concentration index from 0.27 to 0.56, indicating a mainly synergistic effect, whereas for caspofungin, it varied from 0.5 to 2. At an end point of ≥50% inhibition, the MIC-2s varied from 16 to 128 μg/mL for Mycograb® and from 0.125 to 16 μg/mL for fluconazole. The fractional inhibitory concentration index classified the combination as indifferent for 5 isolates, additive for 3 more isolates, and synergistic in a single isolate. Time-kill analysis on 2 isolates (F/7844 and F/10156), which had synergistic and additive results with amphotericin B, respectively, on checkerboard was performed with 4–16 μg/mL of Mycograb®, 2–8 μg/mL of fluconazole, and 0.0625–2 μg/mL of amphotericin B. This demonstrated an increasingly static effect with augmenting concentrations of fluconazole and an initial static effect with amphotericin B at lower concentrations, which became fungicidal as the level of drug increased. The addition of either 4 or 8 μg/mL of Mycograb® to 0.5 μg/mL of amphotericin B with C. neoformans F/7844 changed a static effect to a fungicidal effect at 8 h with an increased killing of 1.2 logs at 48 h. With C. neoformans F/10156, the addition of 16 μg/mL of Mycograb® to 0.25 μg/mL of amphotericin B produced a difference in killing from 1 logarithm after 4 h to 1.5 logarithms after 48 h. These data suggest that the combination of amphotericin B and Mycograb® would be worth exploring in the treatment of infection due to C. neoformans. [Copyright &y& Elsevier]

A letter to the editor is presented in response to comments made on the author's article by Herbrecht and colleages regarding the double-blind trial comparing combination therapy with Mycograb plus lipid-associated amphotericin B with amphotericin B monotherapy.

Background. Mycograb (NeuTec Pharma) is a human recombinant monoclonal antibody against heat shock protein 90 that, in laboratory studies, was revealed to have synergy with amphotericin B against a broad spectrum of Candida species. Methods. A double-blind, randomized study was conducted to determine whether lipid-associated amphotericin B plus Mycograb was superior to amphotericin B plus placebo in patients with culture-confirmed invasive candidiasis. Patients received a lipid-associated formulation of amphotericin B plus a 5-day course of Mycograb or placebo, having been stratified on the basis of Candida species (Candida albicans vs. non-albicans species of Candida). Inclusion criteria included clinical evidence of active infection at trial entry plus growth of Candida species on culture of a specimen from a clinically significant site within 3 days after initiation of study treatment. The primary efficacy variable was overall response to treatment (clinical and mycological resolution) by day 10. Results. Of the 139 patients enrolled from Europe and the United States, 117 were included in the modified intention-to-treat population. A complete overall response by day 10 was obtained for 29 (48%) of 61 patients in the amphotericin B group, compared with 47 (84%) of 56 patients in the Mycograb combination therapy group (odds ratio [OR], 5.8; 95% confidence interval [CI], 2.41–13.79; P<.001). The following efficacy criteria were also met: clinical response (52% vs. 86%; OR, 5.4; 95% CI, 2.21–13.39; P<.001), mycological response (54% vs. 89%; OR, 7.1; 95% CI, 2.64–18.94; P<.001), Candida-attributable mortality (18% vs. 4%; OR, 0.2; 95% CI, 0.04–0.80; P = .025), and rate of culture-confirmed clearance of the infection (hazard ratio, 2.3; 95% CI, 1.4–3.8; P = .001). Mycograb was well tolerated. Conclusions. Mycograb plus lipid-associated amphotericin B produced significant clinical and culture-confirmed improvement in outcome for patients with invasive candidiasis. [ABSTRACT FROM AUTHOR]