Promising Results of Olorofim Phase IIb Trial for Difficult-to-Treat Invasive Fungal Infections

Researchers from KU Leuven, the University of California Davis Medical Center, the University of Cologne, and more than 20 other institutions report encouraging findings from a Phase IIb clinical trial investigating olorofim, a novel antifungal medication. The study involved patients with invasive fungal diseases who had exhausted existing treatment options, demonstrating that olorofim was both effective and well-tolerated.

Invasive fungal infections, often caused by mold pathogens, pose serious health risks, especially when standard antifungal treatments like polyenes, triazoles, and echinocandins fail due to resistance or toxicity. Certain fungi such as Aspergillus species resistant to triazoles and other molds like Lomentospora prolificans and Scedosporium are particularly challenging because they resist most available antifungal agents. Although these infections usually affect immunocompromised individuals, they are increasingly found in healthy hosts.

Olorofim belongs to the orotomide class of antifungals and operates by inhibiting fungal pyrimidine biosynthesis, leading to fungal cell death. Laboratory studies had previously shown its potency against resistant fungi.

The phase IIb study, published in The Lancet Infectious Diseases, evaluated oral olorofim in 203 patients aged 16 and above across 22 centers in 11 countries. Patients received an initial loading dose—either 180-300 mg divided doses or a simplified regimen of 150 mg twice on the first day—followed by a maintenance dose of 90 mg twice daily. Results showed that a successful global response—indicating improvements in clinical, radiological, and microbiological assessments—was observed in approximately 28.7% and 27.2% of patients at days 42 and 84, respectively. When including stable disease (no progression but no measurable improvement), success rates increased to over 63% at day 84.

The all-cause mortality rate was 11.9% at day 42 and 16.3% at day 84. Adverse events included drug-induced liver injury in 10% of patients, which resolved with dose adjustments, and gastrointestinal issues in 10%, mostly mild or moderate. No deaths were attributed directly to the treatment.

These findings suggest that olorofim offers a promising new option for patients with limited alternatives for invasive fungal infections. A Phase III trial is underway to further assess its efficacy specifically for invasive aspergillosis.

Source: https://medicalxpress.com/news/2025-07-olorofim-phase-iib-trial-efficacy.html