Scientists have used a single injection in lab mice to repress asthma symptoms for at least a year, holding out the promise of a therapy for long-lasting relief from the world’s most prevalent respiratory disorder.

The experimental therapy based on chimeric antigen receptor-T (CAR-T) cells blocked the functions of proteins involved in asthma’s disease mechanisms, repressed lung inflammation and alleviated symptoms in mice, Chinese researchers announced on Monday.

“Our study presents proof of concept… for achieving long-term remission of a common chronic disease, asthma, through engineered long-lived multifunctional T cells,” said Men Ping, a medical immunologist at Tsinghua University, Beijing, and his colleagues, describing their work in the journal Nature Immunology.

Public health experts estimate that asthma affects nearly 300 million people worldwide and causes over 250,000 deaths annually. The disease is marked by symptoms of breathlessness, cough and chest tightness and is severe in
3-5 per cent of patients who sometimes require hospital care.

Most patients with moderate or severe asthma need to take some combination of oral or inhaled medications in repeated cycles to curb the risk of exacerbated symptoms. Asthma is considered a chronic respiratory disorder that currently lacks any treatment that can provide long-term relief with a single administration.

Men Ping and his colleagues decided to explore whether it would be possible to deploy CAR-T cells — a therapy approved since 2017 for the treatment of certain blood cancers, including some forms of leukaemia — against asthma.

CAR-T cells are tailored for each individual patient. They are created by collecting immune system cells called T cells from a patient and “engineering” them in the lab to produce certain proteins on their surface called chimeric antigen receptors (CARs). These CARs recognise and bind to specific proteins on the surfaces of cancer cells, killing them.

The Chinese researchers designed a CAR-T cell therapy focused on an inflammatory substance called interleukin-5 (IL-5), known for playing a key role in the disease mechanisms that drive severe asthma.

They assessed the efficacy of their CAR-T cell therapy in mice with chronic asthma induced by either a protein called ovalbumin or by house dust mites which, the researchers said, are clinically relevant as they are among triggers for asthma exacerbations in humans.

In their study, a single infusion of the CAR-T cells provided long-term protection against asthma recurrence and exacerbation that lasted months to a year. The researchers have described the long-term efficacy after a single infusion as “an unparalleled advantage” over other current therapies.

“Despite currently available therapies, asthma sometimes continues to cause loss of school or work days and impairs the quality of life,” said Rajesh Chawla, a consultant pulmonologist and critical-care specialist at the Apollo Hospital, New Delhi. “Long-term relief from a single injection could be a game changer.”