Abstract
Treatments for emerging and rare invasive fungal diseases (IFDs) represent a critical unmet medical need. For IFDs that occur less frequently than invasive aspergillosis, such as mucormycosis, hyalohyphomycosis, and phaeohyphomycosis, randomized controlled clinical trials are impractical and unlikely to meet urgent public health needs. Understanding regulatory approaches for approval of drugs for rare cancers and rare metabolic diseases could help meet the challenges of studying drugs for rare IFDs. A single-arm, controlled clinical trial with a high-quality external control(s), with confirmatory evidence from nonclinical studies, including pharmacokinetic/pharmacodynamic data in predictive animal models of the disease may support findings of effectiveness of new drugs and biologics. Control populations may include historical controls from published literature, patient registries, and/or contemporaneous external control groups. Continuous engagement among clinicians, industrial sponsors, and regulatory agencies to develop consensus on trial design and innovative development pathways for emergent and rare invasive fungal diseases is important.