16 July 2018

What the new class of asthma drugs offers

Clinical Respiratory

Patients with severe asthma may benefit from shaking up their treatment plan, as more biologicals come onto the market, experts say.

Many patients with severe asthma struggle with disease control and frequently use oral steroids, despite being treated with high dose inhaled corticosteroids and long-acting beta2-agonists.

“We know the more courses of steroids that you have over time, it does bad things to your bones, you can get cataracts, put on weight and have mental health issues,” Professor John Upham, a respiratory medicine specialist at Princess Alexandra Hospital in Brisbane, said. 

“So we are starting to think about ways of minimising the amount of steroids that people are getting exposed to.”

There are now two monoclonal antibodies listed on the PBS for severe asthma that may help patients dial down their steroid dosage. These drugs halt certain biological pathways associated with specific subgroups of severe asthma; omalizumab targets IgE, while mepolizumab reduces eosinophil numbers.

“For some of the patients it really transforms their life,” Professor Upham said. “They get off steroid tablets, they stop having asthma attacks and it makes an enormous difference.”

In an MJA article, which was published as part of a supplement on severe asthma this month, Professor Upham, and his colleague Dr Li Ping Chung, a respiratory physician from Fiona Stanley Hospital in Perth, provided more detail on this new class of drugs.

Omalizumab cuts asthma exacerbation rates by about 45% and hospitalisations by more than 80%. It may allow patients to reduce their inhaled corticosteroid use or stop using them entirely. Mepolizumab reduces asthma exacerbations and symptoms, and also has an oral steroid-sparing role. 

The drugs are expensive, however, so the government has restricted access to patients that have been treated by a specialist for a six to 12-month period. 

After six months of biologic injections, specialists have to provide documentation to demonstrate that the patient is actually improving. 

“If they are not improving after six months, there is no point in continuing,” Professor Upham said.

GPs are the conduit through which patients with severe asthma can access these new treatments. 

A lot of patients with severe asthma will already be receiving specialist care. “But there are probably a group of people that are out there in GP land who have never seen a specialist that probably should,” Professor Upham said. 

“Not everybody will necessarily go onto the biologics but … there’s a group of people that are going to do very well on them.”

People hospitalised for asthma or people taking two or more courses of steroid tablets a year would probably benefit from referral to a specialist to assess their eligibility for biologics, he said. 

GPs had been managing injections of biologic therapies for patients with rheumatoid arthritis for about a decade, so they were well-placed to administer omalizumab or mepolizumab injections,  Professor Upham said.

“Once we get approval from PBS then we might give the first few injections in the hospital or the specialist rooms but then, after that, they normally go back to their GP for their injections,” he said. 

“Most GPs are probably going to end up with a couple of people in their practice who will be coming along every month or so for an injection.”

Biologic injections can cause allergic reactions and anaphylaxis in a small number of people, so GPs generally ask patients to wait for half an hour after each injection. If allergic reactions occur, it is usually during the first few injections, but not always. 

“Sometimes it can happen when people have been on it for six months or 12 months,” Professor Upham said.