KaloBios Pharmaceuticals has published phase I study results for KB001, a first-generation, anti-Pseudomonas aeruginosa (Pa) type III secretion system (TTSS) antibody for use in patients with cystic fibrosis (CF). Data from this initial single-dose clinical study support the continuation of KaloBios' ongoing phase II study of KB001-A, a second-generation, anti-TTSS antibody in CF patients with chronic Pa infections.

The phase I study results appear online in the journal Pediatric Pulmonology, authored by Carlos Milla, M.D., of the Center for Excellence in Pulmonary Biology, Stanford University, and other members of the KB001 study group.

"Many patients with CF are chronically infected with Pa which contributes to disease progression by causing a strong inflammatory response that destroys lung tissue," said Nestor A. Molfino, M.D., M.Sc, KaloBios chief medical officer. "Treating Pa infection with antibiotics has long been shown to benefit CF patients; however, Pa is not eradicated by such treatments and antibiotic-resistant strains soon emerge. KB001-A is a novel, non-antibiotic agent against Pa that targets and inhibits the bacterium's TTSS that is responsible for Pa's virulence and pro-inflammatory effects.

"The safety, pharmacokinetic and pharmacodynamic results obtained for KB001 in this initial single-dose phase I clinical study supports the continuation of the phase II study currently underway of KB001-A as a potential non-antibiotic treatment to reduce airway inflammation and tissue damage in CF patients with chronic Pa infection," Molfino concluded.

The published study results showed a single intravenous dose of KB001 to have an acceptable safety profile and a trend toward a short-term reduction in markers of inflammation, particularly neutrophil elastase which has long been recognized as the main enzyme responsible for lung damage in CF patients. The investigators concluded that repeat-dosing studies are required to evaluate the durability of the anti-inflammatory effects and how treatment with KB001 might translate into clinical benefit.

KaloBios currently is enrolling patients in a phase II multi-dose, randomized, double-blind, placebo-controlled clinical trial with KB001-A in CF patients chronically infected with Pa. This 180-patient study is intended to evaluate the efficacy and safety of repeat doses of KB001-A. The primary endpoint is time-to-need for antibiotics.