How I choose biologic in severe asthma

16 Oct 2022 09:40 10:10
Azza Omar Speaker

Severe asthma is a subset of difficult-to-treat asthma and affects up to 10% of the adult asthma population. Malaysia is not far from the global statistics on difficult to treat asthma with the need to identify and treat accordingly. In recent decades, the mainstay of treating severe asthma has been a combination of high-dose inhaled corticosteroid and long-acting beta agonist (ICS/LABA), followed by adding a LAMA.

Unfortunately there are patients who remain uncontrolled or continue to experience frequent exacerbations and patients requiring burst oral corticosteroids (OCS). A minority of patients become OCS-dependent to maintain asthma control. However, partly by definition, severe asthma patients often do not respond to regular treatment in a satisfactory manner and require additional interventions.

Currently, our country is burdened from the cost of the new biological treatments and asthma-related healthcare costs. Hence, we should address issues such as adherence, inhaler technique and treatment of comorbidities prior starting such treatment.

The rational choice of such interventions should be based if possible, the underlying endotype, which may have Type 2 (T2) or non-Type 2 (non-T2) immunity characteristics. Only recently have new therapeutic options become available, mostly in the form of monoclonal antibodies (“biologicals”) targeting relevant inflammatory pathways.

The availability of a range of new biological treatments targeting type-2 inflammation has provided new opportunities for patients with more severe asthma. Treatment has a bigger effect on exacerbations than day-to-day symptoms, and efficacy increases with increasing intensity of type-2 airway inflammation as reflected by the blood eosinophil count and fractional exhaled nitric oxide. The similarity of the clinical effects and target populations coupled with the absence of direct head-to-head comparative data makes it difficult to choose the right biologic for a given patient.

In Malaysia, there are four biologics officially approved for use in selected severe asthmatic patients. The first of these is Omalizumab, an anti-IgE monoclonal antibody acting through various mechanisms on allergic pathways. Three more biologics for asthma, belonging to a different class, have been approved first the anti interleukin-5 (IL-5) pathway mepolizumab and benralizumab. Finally, dupilumab is a monoclonal antibody against the receptor of interleukin-4 (IL-4) which blocks the signaling pathways of IL-4 and IL-13.

Both the initial choice of a biologic as well as the option of switching to another gives the clinician an interesting but also difficult decision when choosing a biologic therapy for patients with severe asthma. This decision is mainly based on the individual characteristics of the patient, especially rate of exacerbations and use of systemic corticosteroids, but is also influenced by the presence of comorbidities and lung function impairment. No safety concerns have been raised around the use of these biologics.