A recent phase 2 clinical trial found MicuRx Pharmaceuticals’ contezolid acefosamil (MRX-4) to be effective in treating acute bacterial skin and skin structure infections (ABSSSI) with dosing regimens that appeared to be safe and well-tolerated.

In the randomized, double-bind clinical trial, contezolid acefosamil met all primary and secondary efficacy endpoints, The study compared contezolid acefosamil with linezolid for treating ABSSSI, including MRSA infections. The drug was found to be effective with both IV and oral formulations, according to MicuRX.
The biopharmaceutical company said, in a prepared statement, that it plans to advance contezolid acefosamil into phase 3 development next year.

The phase 2 trial enrolled 196 patients with ABSSSI in a 2:1 ratio (131 participants used contezolid acefosamil, 65 used linezolid) at 7 centers in the United States. The study evaluated the safety and efficacy of the intravenous (IV) and oral formulations of contezolid acefosamil for 10-14 days of therapy compared to linezolid.
Study participants using contezolid acefosamil started with a loading dose of 1500 mg IV followed by twice daily 1000 mg IV doses with the option after at least 3 IV doses to switch to 1300 mg oral doses twice daily. Participants using linezolid started with 600 mg IV twice daily for at least 3 doses, after which they could switch to oral 600 mg twice daily.

For the primary efficacy endpoint, the percentages of participants in the intent-to-treat (ITT) population with favorable early clinical responses at the early assessment (EA) visit (48-72 hours after the start of study drug) were 77.9% in the contezolid acefosamil group and 78.5% in the linezolid group. Outcomes were also similar in the ITT population at the post-therapy evaluation (PTE) visit (7-14 days after end of therapy [EOT]), with favorable responses of 76.3% in the contezolid acefosamil group and 73.8% in the linezolid group. Similar results between the study groups were observed in other secondary efficacy outcomes in clinically evaluable and microbiological populations at the EA, EOT, and PTE visits.

Methicillin-resistant Staphylococcus aureus (MRSA) was the most commonly identified pathogen, and efficacy outcomes were similar in subjects between the 2 study arms with MRSA infections.

The overall incidence of treatment-emergent adverse events (TEAEs) was similar between the study arms, including TEAEs considered to be related to contezolid acefosamil 16.3%, and linezolid 14.1%. Nausea and vomiting were the most common TEAEs, and most were mild or moderate in severity. There were no drug-related TEAEs considered to be serious.



MicuRx Pharmaceuticals Reports Positive Top-Line Results From a US Phase 2 ABSSSI Clinical Trial of Novel Antibiotic Contezolid Acefosamil [news release]. Forest City, CA and Shanghai; September 9, 2019: MicuRX Pharmaceuticals. http://micurxchina.com/1652.html. Accessed September 10, 2019.