Rex’s company, F2G, is in the final stages of clinical trials for an antifungal drug called olorofim. This drug prevents fungi from making pyrimidines, a type of building block for DNA and RNA. Interfering in that process prevents fungi from replicating and can kill some dangerous fungi, including Aspergillus species. If the drug is approved by the U.S. Food and Drug Administration, it will have been about a 25-year journey.