New Oral Drug Trial Targets Devastating, Drug-Resistant Lung Infection

MENLO PARK, CA – March 31, 2026 – In a significant development for patients battling a notoriously difficult-to-treat pulmonary disease, AN2 Therapeutics has initiated a Phase 2 clinical trial for epetraborole, a novel, orally administered drug candidate. The trial aims to combat lung infections caused by Mycobacterium abscessus (M. abscessus), a rapidly growing, multidrug-resistant pathogen that leaves patients with few, often grueling, treatment options.

The investigator-initiated study represents a critical step forward in addressing a major unmet medical need, as there are currently no therapies specifically approved by the U.S. Food and Drug Administration (FDA) for this debilitating condition.

A Desperate Need for New Weapons

Mycobacterium abscessus is considered one of the most antibiotic-resistant mycobacteria, causing chronic and progressive lung disease, particularly in individuals with underlying conditions like cystic fibrosis, bronchiectasis, or COPD. The infection can lead to severe respiratory decline, significant morbidity, and, in some cases, mortality.

For those diagnosed, the treatment journey is arduous and often heartbreaking. Current medical practice relies on prolonged, complex regimens combining multiple antibiotics, many of which must be administered intravenously for months or even years. These cocktails are not only burdensome, requiring long-term central line access, but are also poorly tolerated and fraught with severe side effects.

Drugs like amikacin, a cornerstone of many regimens, carry risks of permanent hearing loss and kidney damage. Other agents can cause severe gastrointestinal distress, bone marrow suppression, or nerve damage. Despite this aggressive approach, treatment success is highly variable, with some studies showing sputum culture conversion rates—a key measure of success—as low as 25%. The pathogen's intrinsic ability to form protective biofilms and its genetic resistance to many classes of antibiotics make it a formidable foe for clinicians.

This grim reality has left patients and doctors in desperate need of safer, more effective, and less burdensome alternatives. An oral therapy that could replace or supplement the toxic IV regimens would represent a paradigm shift in managing the disease and dramatically improve patient quality of life.

A Novel Approach in a Pill

Epetraborole, developed from AN2 Therapeutics' proprietary boron chemistry platform, offers a new strategy in this fight. It is a first-in-class, once-daily oral tablet that works by inhibiting leucyl-tRNA synthetase (LeuRS), a critical enzyme necessary for bacteria to synthesize proteins. By disrupting this fundamental process, the drug is designed to halt bacterial growth.

This novel mechanism of action is distinct from most existing antibiotics, offering a potential way to circumvent the resistance pathways that M. abscessus has developed. The promise of an effective oral agent is profound. It could potentially reduce or eliminate the need for long-term IV access, freeing patients from the constant risk of line infections and the logistical nightmare of daily infusions.

“Individuals living with M. abscessus lung disease face an incredibly difficult treatment journey, and today’s milestone reflects our commitment to changing that trajectory,” said Eric Easom, Co-founder, Chairman, President, and CEO of AN2 Therapeutics. “We believe epetraborole’s oral dosing and targeted novel mechanism provide a strong foundation as we work to deliver better, more accessible treatment solutions for patients who urgently need them.”

The Path Forward: A Crucial Clinical Trial

The newly initiated Phase 2 trial is a multicenter, randomized, double-blind study designed to rigorously evaluate the safety, efficacy, and pharmacokinetics of epetraborole. The trial, which has already begun screening patients, will enroll 84 individuals across an estimated 10 to 15 clinical sites in the United States. Topline data from the study is anticipated in late 2027.

The study is being led by Dr. Kevin L. Winthrop, a renowned infectious disease expert and Professor at Oregon Health & Science University (OHSU). The investigator-initiated nature of the trial, driven by a leading academic researcher, adds a layer of independent scientific validation to the drug's development program.

“Mycobacterium abscessus remains one of the most challenging pulmonary pathogens, with limited treatment options consisting of prolonged, poorly tolerated, complex, multidrug daily IV regimens,” said Dr. Winthrop, the study's principal investigator. “An orally administered, novel investigative agent such as epetraborole, if shown to be safe and effective in humans, has the potential to become a backbone agent in multidrug regimens for the treatment of M. abscessus lung disease. A new therapeutic that could reduce the burden imposed by current treatment options and improves outcomes for patients with this difficult-to-treat infection would be welcomed by patients and care providers alike.”

Broader Implications for Patients and Biotech

For AN2 Therapeutics, a clinical-stage biopharmaceutical company, the advancement of epetraborole into Phase 2 for M. abscessus marks a pivotal moment for its infectious disease pipeline. A successful outcome could position the company as a leader in a niche but critical market with a high unmet need, validating its boron chemistry platform and potentially paving the way for a first-in-class therapy.

Beyond the corporate implications, the trial provides a tangible glimmer of hope for a patient community that has long felt overlooked. Advocacy groups and patients have consistently highlighted the devastating impact of the disease and the urgent need for innovation. The possibility of a future where treatment is managed with a daily pill rather than a constant tether to an IV pole could fundamentally transform the experience of living with M. abscessus lung disease.

While the path through clinical trials is long and success is never guaranteed, the initiation of this study is a crucial and promising development in the global fight against antimicrobial resistance. For the thousands of patients battling this relentless pathogen, that glimmer of hope is a significant step forward.