Nektar Therapeutics has received from the US Food and Drug Administration an orphan drug designation for amphotericin B inhalation powder for prevention of pulmonary fungal infections in patients at risk for aspergillosis due to immunosuppressive therapy.

Using a small proprietary pocket size inhaler, the company has conducted two phase I trials and has long-term toxicity studies underway to support the planned pivotal trials early next year, states the company release.

Nektar developed the amphotericin B inhalation powder to target the lungs directly with this potent, broad spectrum, fungicidal 'gold-standard' antifungal drug, while potentially eliminating systemic toxicities associated with current formulations of amphotericin B which must be delivered intravenously.

Immunosuppressed patients i.e., those receiving organ or stem cell transplants, or chemotherapy or radiation therapy for haematological malignancies commonly develop fungal infections in their lungs which spread throughout the body (aspergillosis). Inhaling amphotericin B inhalation powder into the lungs prior to developing an aspergillosis infection may potentially reduce the incidence of these infections as well as the subsequent high morbidity and mortality and significant treatment costs associated with them.

"Given the high incidence of invasive aspergillosis in immunocompromised patients, and high mortality rates despite available therapies, this potential new therapy could represent a significant breakthrough in antifungal medicine," said Kieren Marr, assistant professor medicine, allergy and infectious diseases, Fred Hutchinson Cancer Research Centre, Seattle.

"In the US, more than 75,000 immunocompromised patients annually are at risk of developing often fatal and costly fungal infections in the lungs. There are no approved pharmaceutical therapies to prevent fungal infections like aspergillosis, caused when aspergillus, a widely prevalent genus of molds, infects the lungs and invades the body, causing systemic infections that are very difficult to cure and are associated with an extremely high mortality rate," said Dr. David Johnston, senior vice president, R&D, Nektar.

"Fungal spores are routinely inhaled. An immunosuppressed patient is susceptible to fungal infections, like aspergillosis, normally not seen in those with healthy immune systems. Nektar's approach delivers amphotericin B directly to the potentially vulnerable organ through inhalation in the same manner that the fungal spores are inhaled, and could represent a breakthrough in prevention of these infections with such high mortality rates," said Johnston.

Amphotericin B is a potent, broad spectrum, fungicidal drug which has been used intravenously for decades for treatment and remains the 'gold-standard' therapy for fighting fungal infections, limited only by its systemic toxicities.

Nektar Therapeutics develops and enables high-value, differentiated therapeutics with its industry-leading drug delivery technologies, expertise and manufacturing capabilities.