Sorrento Therapeutics has reported positive data from a Phase Ib clinical trial of ovydso (STI-1558), an oral main viral protease (Mpro) inhibitor for Covid-19.
Conducted in China, the placebo-controlled, randomised, double-blind study was designed for evaluating the pharmacokinetics (PK), efficacy, tolerability, and safety of single and multiple STI-1558 oral doses in healthy volunteers, as well as Covid-19 patients.
Four dose-escalation cohorts, including single oral dose of 300mg, 600mg, 1200mg, and 2000mg STI-1558 or a placebo, were conducted, with eight participants in each cohort in the study’s single ascending dose (SAD) portion.
In the multiple ascending dose (MAD) portion, three dose-escalation cohorts with 300mg BID, 600mg BID, or 800mg BID daily for 7.5 days were conducted, with eight Covid-19 patients in each dose cohort.
The findings showed that STI-1558 was well-tolerated at these doses and no adverse events (AEs) were reported by most of the participants in the SAD and MAD portions of the trial.
There were no deaths, no premature discontinuations of STI-1558 due to an AE, and no severe or serious AEs were observed.
In the study’s MAD portion, Covid-19 patients treated with STI-1558 compared to a placebo were found to have significant viral RNA load reductions on days two, four, and six after treatment.
This indicated the strong antiviral activity of STI-1558 in Covid-19 patients.
At the therapeutic dose of 600mg BID, a significant reduction of viral RNA was observed on day two post-treatment that indicates STI-1558’s early antiviral activity in patients.
A 600mg twice-daily dose for five days has been chosen as a recommended dose for Phase III studies, based on the PK profiles, safety, and significant antiviral efficacy in the patients.
The company has submitted a Phase III protocol to the China National Medical Products Administration (NMPA), following communication with the Chinese regulatory agency.
Sorrento chairman and CEO Henry Ji said: “We are excited to see the similarities of PK in the China study and the Australian study. The significant antiviral effectiveness and tolerability of ovydso in Covid patients suggests this compound will significantly benefit patients and will require no boosting with Ritonavir.
“We expect to initiate the Phase III trial very soon in China, and meanwhile, we are engaging with regulatory agencies on a global Phase II/III trial design in order to initiate ovydso Phase II/III trials in Mexico and the US as soon as possible.”