AstraZeneca elarekibep Phase II Clinical Trial

Patients with moderate-to-severe asthma often face issues such as persistent airway inflammation, impaired lung function, and poor symptom control. Although significant progress has been made in systemic biologics, their pulmonary bioavailability is limited, and the subcutaneous injection route may be inconvenient. Therefore, developing inhaled biologics that act directly on the lungs holds significant clinical importance, enabling targeted local delivery, increased lung tissue exposure, and reduced systemic adverse reactions.

On April 14, a communication by Tania Hugo from the $AstraZeneca(AZN.US) Cambridge R&D department published a paper titled "Elarekibep, an inhaled anti-IL-4 receptor alpha Anticalin, in moderate-to-severe asthma: a randomized, placebo-controlled phase 2a study (APATURA)" in Respiratory Research. The study enrolled 72 patients, with Part 1 being a safety and pharmacokinetic assessment in controlled moderate asthma patients, and Part 2 being an efficacy exploration in uncontrolled moderate-to-severe asthma patients.

Results showed that in Part 1, approximately 58.8% of patients receiving elarekibep experienced at least one treatment-emergent adverse event, comparable to 50.0% in the placebo group. Most adverse events were mild, primarily including dyspnea and cough, which were typically transient and self-limiting, with no serious adverse events observed. Elarekibep absorption was steady after administration via a dry powder inhaler, with a median time to peak concentration of about 3–4 hours and an elimination half-life between 7.7 and 20 hours. Systemic exposure accumulation was observed after multiple doses, with serum concentrations still detectable on day 28.

In Part 2, the elarekibep 3 mg group showed a least squares (LS) mean difference of a 196 mL increase in pre-bronchodilator FEV1 from baseline at week 4 compared to placebo (95% CI: 14.3, 378; p = 0.035). The corresponding difference for the elarekibep 1 mg group was 23.6 mL (95% CI: −193, 240; p = 0.828). Regarding ACQ-6 scores, both dose groups showed numerically greater improvement from baseline at week 4 compared to the placebo group. The proportion of ACQ-6 responders (score decrease ≥0.5) during the entire treatment period was 76.9% in the elarekibep group, higher than 33.3% in the placebo group. FeNO levels at week 4 showed the largest numerical percentage reduction from baseline in the elarekibep 1 mg group, but the difference compared to the placebo group did not reach statistical significance.

Mechanistically, elarekibep, as an Anticalin protein, inhibits IL-4Rα signaling. This receptor is highly expressed on airway epithelial and smooth muscle cells and is closely associated with IL-4/IL-13-mediated mucus hypersecretion, airway hyperresponsiveness, and inflammation amplification. The observed improvement in lung function suggests it may alleviate airway obstruction by locally blocking the T2 inflammatory pathway. However, the small sample size and early termination limited further validation. The incidence of anti-drug antibodies (ADA) was higher in elarekibep-treated patients, with 28/34 cases in Part 1 developing treatment-emergent ADA, mainly appearing after day 20. However, no significant differences in pharmacokinetic parameters were observed between ADA-positive and ADA-negative patients, and there was no clear association with adverse event occurrence.

Safety assessments indicated that elarekibep was generally well-tolerated in both parts of the study, with no short-term safety issues identified. No clinically significant changes were observed in laboratory parameters, vital signs, or electrocardiograms. Although pulmonary pathological changes, including perivascular mononuclear cell infiltration, alveolar hemorrhage, and increased alveolar macrophages with hemosiderin deposition, were observed in a 13-week inhalation toxicology study in non-human primates, leading to development termination, these findings were considered related to chronic clinical use and were similar to other inhaled proteins. No corresponding clinical manifestations were observed in this study, supporting the safety of short-term administration.

Compared to systemic IL-4Rα-targeting monoclonal antibodies, the inhalation delivery route can achieve a higher lung:plasma exposure ratio, focusing the pharmacological effect on the airways at lower doses, thus potentially reducing risks associated with systemic exposure. The observed FEV1 improvement is consistent with previous systemic biologic data, but the inhalation route may offer patients a more convenient dosing option and reduce injection-related adverse events. These results suggest that inhaled biologics have potential advantages in managing moderate-to-severe asthma, particularly for T2-high patients with poor control on standard therapy.

Overall, this study provides preliminary evidence for the clinical application of inhaled IL-4Rα inhibitors, confirming that they can improve lung function and symptom control measures in the short term while maintaining good tolerability. Although further development was terminated due to non-clinical safety findings, the data indicate that developing inhaled biologics remains promising, potentially superior to existing systemic treatment options, and provides a reference for future optimization of local targeted therapy strategies for asthma.