Phase 1 Trial of Xenleta, Antibiotic for MRSA Infections, Fully Enrolled

Study testing safety, properties of oral and IV infusion Xenleta in CF patients

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by Somi Igbene, PhD |

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The Phase 1 clinical trial into the safety and pharmacological properties of the antibiotic Xenleta (lefamulin) in adults with cystic fibrosis (CF) is fully enrolled.

“We are happy to announce enrollment has been completed in this important study to evaluate the potential of XENLETA in the management of bacterial infections in patients with cystic fibrosis,” Christine Guico-Pabia, MD,  chief medical officer at Nabriva Therapeutics, which markets Xenleta and is sponsoring the trial, said in a press release.

Top-line results from the open-label study are expected early next year.

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CF is characterized by the accumulation of abnormally sticky and thick mucus in various organs, including the lungs, where it causes damage. It is treated with medications that include antibiotics, inhaled therapies and CFTR modulators.

Staphylococcus aureus (S. aureus) infections can be frequent in patients, worsening CF symptoms. Such infections are treated with antibiotics, but the persistent use of methicillin antibiotics has led to the development of methicillin-resistant S. aureus (MRSA) strains, making management challenging. Notably, the presence of these bacteria in the respiratory tract can be serious, affecting patient survival.

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“XENLETA has the potential to provide a well-tolerated oral and intravenous anti-MRSA treatment option with a novel mechanism for this difficult to treat patient population,” Guico-Pabia said.

A relatively new antibiotic, Xenleta was approved by the U.S. Food and Drug Administration in 2019 to treat community-acquired pneumonia caused by various susceptible bacteria, including S. aureus. It works by blocking bacterial protein production and can be taken as an oral tablet or given via an intravenous infusion.

The Phase 1 study (NCT05225805) is testing Xenleta’s safety and pharmacokinetics, or how a drug moves through the body, in 12 adults with CF at a single site in Utah. Participants are given either one 150 mg dose of Xenleta intravenously followed by one 600 mg oral tablet, or the same treatment in a reverse order, meaning the oral dose followed by the intravenous dose.

Xenleta has been shown “to be highly potent against S. aureus, including MRSA and strains obtained from patients with CF,” the trial’s NCT document noted. However, little is known about how specific CF treatments, including CFTR modulators, and antibacterial agents interact.

“We expect to report topline data in the first quarter of 2023. We look forward to sharing the results of this study with the medical community,” Guico-Pabia said, thanking “the investigators and patients who participated in this important trial, as well as Cystic Fibrosis Foundation for their support.”

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