CFF Awards $2.4M to Advance CB-280 in Preventing Lung Infections

The Cystic Fibrosis Foundation (CFF) has awarded up to $2.4 million to Calithera Biosciences to advance in testing CB-280, its investigative oral therapy that aiming to lower the risk of lung infections in people with cystic fibrosis (CF).

An enrolling clinical trial is underway in the U.S. testing CB-280 in adult patients with chronic lung infections due to Pseudomonas aeruginosa, a common and hard-to-treat bacteria in CF lungs.

“We are grateful to the Cystic Fibrosis Foundation for their support to accelerate the clinical development of CB-280 as a potentially first-in-class new treatment for this often devastating disease,” Susan Molineaux, PhD, president and CEO of Calithera, said in a press release.

CB-280 is a potent inhibitor of the enzyme arginase, which normally converts arginine — one of the 23 amino acids (protein building blocks) found in the body — into urea and ornithine.

Because this enzyme is usually overly active in people with CF, arginine levels in their lungs tend be lower than normal. The resulting shortage can increase patients’ risk of developing lung infections, because arginine is required for the production of nitric oxide (NO), a naturally occurring gas known to help the lungs fight disease-causing microbes (pathogens).

By blocking arginase and raising arginine levels in the lungs, CB-280 is expected to increase NO production to improve lung function and resistance to pathogens, including the bacteria P. aeruginosa.

Inhibiting arginase was seen in preclinical studies in CF mouse models to lower the bacteria load in the animals’ airways, and benefit their overall lung health.

“Based on preclinical data and the unique pathology [disease mechanisms] of cystic fibrosis, we believe that arginase inhibition represents a novel, promising opportunity to improve the standard-of-care for CF patients,” Molineaux said.

Calithera finished a Phase 1 trial that evaluated the safety, tolerability, and pharmacological properties of CB-280 in healthy volunteers.

It then opened a Phase 1b trial (NCT04279769) assessing the therapy’s safety and tolerability at escalating doses in up to 32 adults with CF and chronic lung infections caused by P. aeruginosa. This trial is currently enrolling eligible patients at 11 clinical sites across the U.S. More information can be found here.

Trial participants will be randomly assigned to one of four doses of CB-280 (50, 100, 200, or 400 mg), or a matched placebo, both taken as oral capsules twice daily for 14 days. Patient dosing began in July, and Calithera expects to announce interim trial findings in 2021.

“New approaches are needed to address the difficult-to-treat infections that remain a hallmark of cystic fibrosis,” J.P. Clancy, MD, the CFF’s vice president of clinical research, said in a foundation press release. “Identifying and progressing novel ways to fight infections remains a top priority for the CF Foundation, and we look forward to learning more about this potential new treatment and its ability to prevent bacteria from taking hold in the lungs.”

This award is part of the CFF’s Infection Research Initiative, which set aside $100 million through 2023 to support work into better ways of  diagnosing and treating CF-related infections.