MicuRx Pharmaceuticals, Inc., today announced positive top-line results from the pivotal Phase 3 clinical trial in China for its lead antibacterial drug candidate contezolid (MRX-I) in adult patients with complicated skin and soft tissue infection (cSSTI). Contezolid met the primary endpoint of noninferiority compared to linezolid for the clinical cure rate at the test-of-cure visit (TOC visit, 7-14 days after the last dose of study drug), and was associated with fewer drug-related hematologic laboratory adverse events.
"We are very pleased with the favorable results of this Phase 3 clinical trial which established that contezolid is an effective and safer antibacterial drug," said Dr. Zhengyu Yuan, President and CEO of MicuRx. "We plan to file a New Drug Application with the National Medical Products Administration (NMPA) of China in the 4th quarter of 2019 for this exciting new drug," continued Dr. Yuan.
In this double-blind study conducted at 50 sites in China, patients with cSSTI were randomized to receive oral contezolid 800 mg or oral linezolid 600 mg twice daily for a period of 7 to 14 days. Of the 719 patients enrolled, 589 patients were clinically evaluable (CE) at the TOC visit. For the CE patients, the clinical cure rates at the TOC visit were comparable for contezolid (93.0%) and linezolid (93.4%) (treatment difference -0.4% [95% confidence interval (CI) -4.4%, 3.7%]), meeting the noninferiority margin of -10%. In addition, all lower boundaries of the 95% CI were above -10% margin for all secondary efficacy endpoints, including the clinical cure rates at the end-of-therapy (EOT) visit, microbiological clearance rates at the TOC visit, and overall response rates at the TOC visit, indicating similar treatment outcomes between contezolid and linezolid.
The overall rates of treatment-emergent adverse events (TEAEs) were comparable between contezolid and linezolid, as were the TEAEs considered by investigators to be related to study drug (contezolid 23.4%, linezolid 26.8%), and most were mild or moderate in severity. However, study drug-related TEAEs reported for hematologic tests below normal were fewer for contezolid than linezolid: white blood cells, contezolid 0.28% and linezolid 3.42% (p=0.002); neutrophils, contezolid 0.28% and linezolid 1.71% (p=0.068); reticulocytes, contezolid 0.28% and linezolid 1.42% (p=0.123); and platelets, contezolid 0% and linezolid 2.28% (p=0.004). Of the 405 patients that received more than 10 days of therapy, 25.4% linezolid patients experienced more than a 30% reduction in platelets counts at the end of therapy (EOT) visit relative to baseline visit, while only 2.5% contezolid patients had a similar decrease.
"The oxazolidinone class of antibacterial drugs has excellent efficacy in treating infections caused by multidrug resistant Gram-positive bacteria but with usage limitations due to myelosuppression," commented Dr. Yingyuan Zhang, director of the Institute of Antibiotics at Fudan University and the Principle Investigator of this study. "However, data from this Phase 3 study demonstrated that contezolid can offer the efficacy of the oxazolidinone class without the bone marrow suppression associated toxicity," Dr. Zhang continued.
Contezolid is an oral oxazolidinone antibiotic designed to treat drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), while offering physicians and patients a safer and better tolerated therapeutic option than currently available oxazolidinone agents. The development of contezolid in China has been designated as a "Significant New Drugs Development Special Project," and contezolid has also been granted QIDP designation and Fast Track status by the US FDA. Dr. Yuan stated, "We are grateful for the participation of all the patients in this study, as well as the investigators, and I look forward to presenting more data from this pivotal Phase 3 study on September 21, 2019, at the China BioMed Innovation and Investment Conference in Suzhou."
About MicuRx Pharmaceuticals, Inc.
MicuRx Pharmaceuticals (http://www.micurx.com/) is a clinical-stage biopharmaceutical company focused on the discovery, development, and commercialization of antimicrobial therapeutics for multidrug-resistant ("MDR") "superbug" infections. Since our inception in 2007, we have built a pipeline that includes contezolid (MRX-I), contezolid acefosamil (MRX-4), MRX-8 (novel polymyxin MDR Gram-negative agent), and MRX-12 (new class MDR Gram-negative agents). Our mission is to combat pathogens on the WHO list of "superbugs". Our lead compound, contezolid (MRX-I), a next-generation oxazolidinone, was structure-designed to reduce the hematologic toxicity and monoamine oxidase inhibition risk of this antibiotic class. Contezolid acefosamil (MRX-4) is a prodrug of contezolid and is planned to advance into global Phase 3 development in battling MDR Gram-positive infections with both oral and IV formulations. MicuRx has R&D centers outside of San Francisco, California, and in Shanghai, China. The company has raised a total of US$107 million through leading venture capital firms including Morningside Ventures, BVCF, GP Healthcare Capital, GP TMT Capital, 3E Bioventures Capital, and Delian Capital. Visit www.micurx.com for more information.
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