A 12-year-old previously healthy girl is brought to the emergency department in August with a sudden onset of severe headache, fever, and altered mental status. She has a history of swimming in a warm freshwater lake 5 days ago. A wet mount of her cerebrospinal fluid (CSF) shows motile amebae. In addition to intravenous amphotericin B and aggressive management of intracranial pressure, which novel agent is now a key component of the recommended combination therapy for primary amebic meningoencephalitis?