Sorrento Therapeutics, Inc. announced the FDA clearance of a Phase 1 study of its oral main viral protease (Mpro) inhibitor, STI-1558, in patients with impaired renal and hepatic function.
A previously announced Phase 1 study of STI-1558 evaluating single ascending doses (SAD), multiple ascending doses (MAD) and food effect is proceeding in Australia, and the drug has been dosed in patients in the first 3 cohorts with doses of 300, 600 and 1,200 mg. The study is currently dosing the final cohort in the study at a dose of 2,000 mg per patient. STI-1558 has been well tolerated to date with only a few related adverse events, all of which have been transient, mild in severity and required no treatment.
To date, the PK profile has matched the predicted values based on the animal studies, confirming that STI-1558 is readily absorbed by humans with high bioavailability and indicating that there is no need for ritonavir, a potent cytochrome P450 3A4 inhibitor, to block metabolic clearance to maintain effective blood levels. Avoiding coadministration of ritonavir significantly reduces the potential for drug-drug interactions. PK modeling suggests that a dose of 600 mg twice daily will maintain blood levels well above the range necessary to effectively inhibit viral replication.
The Phase 1 study cleared by the FDA will examine the PK in patients with moderate renal and hepatic impairment. Two doses of STI-1558 (300 mg and 600 mg) will be studied in 12 subjects across 3 cohorts, 12 normal subjects, 12 renally-impaired subjects and 12 hepatically-impaired subjects, using a cross-over design. This is a required study in the approval process and is expected to enable Sorrento to proceed with the remaining studies that may be required to apply for an Emergency Use Authorization for STI-1558 for the treatment of COVID infections.
As soon as the SAD/MAD study is completed, Sorrento will prepare for a global Phase 2 study in subjects with acute onset of symptoms due to COVID-19. “STI-1558 has the potential to be a highly effective antiviral treatment for acute COVID-19 and we look forward to seeing how it performs in the Phase 1 study and the planned Phase 2/3 study,” stated Henry Ji, Ph.D., Chairman, President and CEO of Sorrento.