Sorrento Therapeutics, Inc. announced positive topline results of a pivotal Phase 3 study of Sorrento?s oral Mpro inhibitor, Ovydso (Olgotrelvir, STI-1558), in mild or moderate symptomatic adults infected with SARS-CoV-2, or COVID-19, irrespective of risk factors for severe complications. Ovydso is an Oral Mpro Inhibitor as a standalone treatment for COVID-19 meaning it does not require co-administration with other agents. The Phase 3 study results met the primary endpoint of time to sustained recovery of 11 COVID-19 symptoms, as well as the key second endpoint of the viral RNA copy load reduction at Day 4 (after three-day treatment).

In this phase 3 trial, 1,212 patients were enrolled in China between February 2023 and June 2023, and 98.7% of the patients were vaccinated or previously infected with SARS-CoV-2. All patients were treated in an out-patient setting and received 600 mg BID of Ovydso for 5 days as a standalone treatment or placebo. The median time to sustained recovery of 11 COVID symptoms was 8.6 days in comparison with 11.0 days in the placebo group (HR 1.29/95% CI, p=0.0001). Ovydso also demonstrated profound antiviral activity in COVID-19 patients at Day 4 (three days after treatment), reducing the viral RNA copy load by -0.8 log10 (p< 0.0001) compared with placebo group.

Results of subgroup analyses were largely consistent with these overall results. In patients with risk factors for severe COVID-19, Ovydso improved recovery time by 2.3 days (7.6 days vs 9.9 days, HR 1.36/95% CI, p= 0.026) and reduced viral RNA copy load by -1.10 log10 (p<0.0001) at Day 4, compared with the placebo group. A total of 327 Treatment?Emergent Adverse Events (TEAEs) were reported in 1,212 patients (27.0%).

Among them, 188 of 606 (31.0%) were in the Ovydso group and 139 of 606 (22.9%) were in the placebo group. Most TEAEs were mild and balanced between the Ovydso group and the placebo group. Nausea (1.5 % vs 0.2%) and skin rash (3.3% vs 0.3%) were the only two AEs that occurred with >1.0% with higher incidence in the Ovydso group than in the placebo group.

No metallic taste was reported in the Ovydso group. Very few serious AEs were reported (4 in placebo and 3 in Ovydso), which were not related to the drug. The Phase 3 study was conducted at 25 sites in China, led by Dr. Hongzhou Lu, Fellow of the American Society for Microbiology, Professor and Dean of Shenzhen Third Hospital and co-led by Dr. Ronmeng Jiang, Professor and Deputy Dean of Beijing DiTan Hospital.

Sorrento has initiated communications with the NMPA for an NDA submission and potential approval in China. Sorrento plans to open discussions with other regulatory authorities worldwide to discuss the potential path required for each particular authority for a full approval of Ovydso.