Patients with a difficult-to-treat form of asthma should be getting routine access to GlaxoSmithKline's novel asthma biologic Nucala on the NHS after final guidance backing its use was issued by cost regulators.

The National Institute for Health and Care Excellence has endorsed the drug's use in adults with severe refractory eosinophilic asthma, but stipulations include a blood eosinophil count of 300 cells/microlitre or more in the previous 12 months, and that the person has had four or more attacks in the previous 12 months.

Nucala (mepolizumab) is the first biologic therapy that targets interleukin-5 (IL-5) - the main promotor of eosinophil growth, activation and survival - in severe asthma and stops it from binding to its receptor, thereby interrupting the inflammation pathway.

In one study underpinning the drug's regulatory submissions (MEA115588), Nucala cut the frequency of clinically significant exacerbations of asthma by 47 percent versus placebo, while the 100mg dose cut the amount by 53 percent.

This first in class biological medicine targeting this specific type of severe asthma - which affects around 100,000 people in the UK - is now also the first to be granted national access by NICE. It will be made available to patients in specialist centres providing severe asthma services.

Nucala is given by injection every four weeks. Its list price is £840 per dose but the what the NHS will actually pay remains confidential.