High-Dose Fluconazole for the Treatment of Cryptococcal Meningitis in HIV-Infected Individuals

CM is the most common central nervous system (CNS) complication of AIDS worldwide and accounts for up to a third of all deaths from AIDS in many developing countries. Current treatments for CM are lacking in both effectiveness and accessibility, particularly in limited-resources settings. Conventional therapies utilizing an amphotericin B deoxycholate (ampho B)-based regimen require maintaining intravenous access (IV) and monitoring and treating any associated complications. The price to acquire ampho B can also be prohibitive to successful treatment. Cumulatively, a treatment course with ampho B is neither cost effective nor administratively efficient, leaving patients either untreated or inadequately treated with low-dose regimens of fluconazole alone.

Fluconazole is widely available, inexpensive, can be given orally, has a demonstrated safety profile over a broad range of doses, and has proven activity against the fungus that causes CM, Cryptococcus neoformans. All of these factors make fluconazole a potential treatment option for a wide range of people. However, at its present recommended dosage, fluconazole is only expected to be successful in 34% to 42% of patients. This rate is lower than regimens combining fluconazole with other treatments including flucytosine or ampho B.

The purpose of this study was to evaluate whether high-dose fluconazole is safe and effective for the treatment of CM for up to 10 weeks. This study also collected information about treating CM with ampho B (either alone or with another drug, either flucytosine or fluconazole).

For this study, 168 HIV-infected people with CM participated for a duration of 24 weeks. This study proceeded with 2 stages and each stage consisted of up to 4 steps. Participants could take part in only one stage of the study. Stage 1 measured the maximum tolerated dose (MTD) of fluconazole in participants. Stage 2 consisted of dose validation and safety monitoring.

In Stage 1, participants were randomly assigned to receive either fluconazole only or an ampho B-based regimen (a regimen that is either ampho B alone or ampho B in combination with 5-fluorocytosine or fluconazole, according to the local standard of care).Three doses of fluconazole were tested, and the MTD was found to be 2000 mg/day. The two higher doses of fluconazole tested in Stage 1 (1600 mg/day and 2000 mg/day doses) were tested further in Stage 2 of the study.

Participants enrolled in Stage 2 were randomly assigned to receive treatment with either fluconazole only (at one of the 2 doses (1600 mg/day or 2000 mg/day) found to be safe in Stage 1) or an ampho B-based regimen.

After randomization in Step 1, participants in both Stage 1 and Stage 2 could be enrolled in up to three additional steps. In Step 2, participants who were randomly assigned to receive the ampho B-based regimen and who were intolerant to the regimen (experienced a treatment limiting toxicity [TLT]) received fluconazole (400-800mg daily). Participants who received study-provided fluconazole in Step 1 or in Step 2 could be enrolled in Step 3 if they had a negative cerebrospinal fluid (CSF) culture. Participants in Step 3 received fluconazole (400mg daily) until Week 10. At Week 10, all participants were enrolled in Step 4 and received a daily dose of fluconazole of 200mg until the end of the study (Week 24). Participants in both stages beginning treatment with ampho B received daily ampho B intravenously for up to 2 weeks.

Before entering the study, potential participants attended a screening visit where they had CSF collected via lumbar puncture. HIV testing was also conducted, along with clinical assessments, and a health and medical history questionnaire. Participants had blood collection, an electrocardiogram (ECG), and a pregnancy test (if applicable) at that visit. Once accepted into the study, participants again answered questions about their health and medication history; had a complete physical exam, blood collection, HIV testing, neurological exam, lumbar puncture, and ECG; and may have had a pregnancy test (if applicable).

Study visits occurred during Weeks 1 (at Days 1, 4, and 7), 2, 4, 6, 8, 10, and 24, and extra visits could occur for individualized reasons. Total study duration was 24 weeks. Plasma, urine, serum, and CSF samples were collected from all participants and stored for possible future use.

Note on efficacy population versus safety population: After entering the study, participants had their CM diagnosis confirmed by testing of the CSF collected via lumbar puncture. Confirmation could take up to 2 weeks after study entry. Due to the mortality rate of CM, participants received treatment before CM diagnosis confirmation. Post-entry 12 participants either reported non-confirmatory baseline results making them ineligible. An additional 2 participants were found to be ineligible for the study but died prior to being found ineligible (one had non-confirmatory baseline results, one was on a disallowed medication) All participants (n=168) are included in the safety population. Participants who were ineligible after study entry were excluded from the efficacy population (n=16). The efficacy population had 154 participants. Outcomes will specify if the efficacy population is used instead of the safety population.