Antibiotic Xenleta Is Well Tolerated in CF Adults in Phase 1 Trial

Xenleta was approved in 2019 to treat pneumonia caused by MRSA, other strains

Andrea Lobo, PhD avatar

by Andrea Lobo, PhD |

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The antibiotic Xenleta (lefamulin) was well tolerated in a Phase 1 clinical trial in adults with cystic fibrosis (CF) and showed a similar pharmacological profile to healthy volunteers.

“We are excited to share positive topline results from this important study of Xenleta in patients with CF,” said Christine Guico-Pabia, MD, chief medical officer at Nabriva Therapeutics, in a press release. Nabriva markets Xenleta and is sponsoring the trial.

“The results of this study support the potential utility of Xenleta in this difficult to treat patient population,” Guico-Pabia said.

In CF, abnormally thick and sticky mucus accumulates in various organs, including the lungs, providing an ideal environment for disease-causing bacteria to grow. Lung infections are a major health concern for CF patients.

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A common cause of lung infections in CF is Staphylococcus aureus (S. aureus), which contributes to worsening disease symptoms. This infection can be treated with antibiotics, however, the persistent use of methicillin has given rise to methicillin-resistant S. aureus (MRSA) strains, complicating treatment and affecting patients’ survival.

Xenleta was approved by the U.S. Food and Drug Administration (FDA) in 2019 to treat community-acquired pneumonia caused by several microorganisms, including MRSA strains. It works by blocking bacterial protein production — required for bacteria to grow — by binding with high affinity and specificity at molecular sites different from other antibiotics.

“Xenleta has been demonstrated to be a potent anti-staphylococcal antibiotic in in vitro [in the lab] and clinical studies, including against methicillin-resistant S. aureus,” Guico-Pabia said.

A total of 13 adults with CF were enrolled in this Phase 1 study (NCT05225805) that tested Xenleta’s safety and pharmacokinetics, or how a drug moves into, through and out of the body, at the University of Utah. Participants were given either one 150 mg intravenous dose of Xenleta followed by one 600 mg oral tablet or the same treatment in reverse, the oral dose then the intravenous dose.

The pharmacokinetic and safety data of Xenleta in CF patients were similar to what was observed in previous studies with healthy volunteers. Also, the doses used were consistent with the ones approved by the FDA to treat adults with community-acquired bacterial pneumonia.

“XENLETA was well-tolerated and the adverse event profile in CF patients was consistent with that described across our clinical program,” Guico-Pabia added.

The most common side effects reported with an injection include reactions at the injection site, elevated liver enzymes, nausea, low potassium levels, insomnia, and headache. For tablets, they are diarrhea, nausea, vomiting, and elevated liver enzymes.

Guico-Pabia said complete results are expected in the first half of 2023.

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