Administrative assistant and study volunteer Judy King recently demonstrated a new drug delivery system designed to prevent asthma attacks. (photo by Anne Rayner)
Halting asthma's assault
Researchers at Vanderbilt University Medical Center are investigating a novel treatment that could give asthma sufferers the ability to inhale medication once a week to prevent asthma attacks, instead of puffing on an inhaler after an attack has already started.
Volunteers are currently being sought for the study, which is being conducted under the direction of Dr. John J. Murray, associate professor of Medicine and Pharmacology, at the Vanderbilt Asthma, Sinus and Allergy Clinic. Murray is investigating the efficacy of inhaling a soluble form of IL-4 receptor (IL-4R) in blocking the inflammation and allergic reaction in the lungs that is thought to cause the symptoms of asthma.
IL-4 is a molecule released by T-cells of the immune system. When it binds to IL-4 receptors on other immune system cells, it activates a cascade of responses that eventually ends in the release of growth factors, toxic substances, and other chemicals which damage tissue and cause the inflammation common to asthmatic and other allergic reactions.
While this cascade evolved to deal with parasites, in asthmatics and allergy-sufferers this IL-4-mediated response actually harms the body.
"IL-4's main function is to activate TH2 cells, which are the major cells that drive asthmatic inflammation," Murray said.
The new drug being studied is a soluble form of the same receptor that the human body makes for IL-4. When inhaled, it acts as a decoy receptor and binds to any IL-4 that's around, preventing it from associating with IL-4 receptors on cells. This effectively blocks it from initiating the immune cascade, stopping the chain reaction before it can start.
The new drug will be tested in a Phase II study, meaning that testing has already been performed on animals and a small number of humans, and has demonstrated no adverse side effects.
Asthmatics who are 18 years of age or older and are currently using a rescue inhaler are eligible for the 12-week study. Those selected for the study will inhale either the drug or a placebo once a week.
An investigational delivery device which dispenses the drug in a warm mist will be used to deliver the drug.
"It's a device that was being used for people receiving morphine. They would inhale it and it reacted quickly," said Brendie Keane, research clinical specialist for Allergy/Pulmonary and Critical Care Medicine. "They changed the device for this medication, so the patient only has to inhale four packets of medicine, and it covers them for a week."
Participants will be compensated for their time over the 12-week trial and will be required to keep a diary recording drug use and symptoms.
The study is of major importance in both scientific terms and in terms of potential benefits to patients.
"The great thing about it is that it's only once a week, whereas everything right now is daily, sometimes twice a day," Keane said. "This will not be a rescue medicine; it will be a preventive medicine."