Efficacy and Safety of Spleen Aminopeptide Oral Lyophilized Powder in Patients with Frequent Acute Exacerbations of Bronchiectasis: A Randomized, Double-blind, Placebo-controlled, Single-center Clinical Trial

Background: Bronchiectasis is a common chronic inflammatory and infectious disease of the airway, which has a high prevalence and frequent acute exacerbations. The treatment approaches for bronchiectasis include mucolytic agents and an immune enhancement strategy, but the latter lacks evidence from randomized controlled trials (RCTs) supporting their efficacy. Spleen Aminopeptide Oral Lyophilized Powder (SAOLP) is a bidirectional immune modulator, mainly composed of a complex of peptides and nucleotides, with an average molecular weight of around 3500. It contains various amino acids and immune regulatory factors, which can trigger and enhance cellular immune function, and promote the immune balance of the body. Methods: A randomized, double-blind, placebo-controlled, single-center clinical trial of SAOLP was conducted in patients with non-cystic fibrosis bronchiectasis. The participants received placebo or SAOLP 4mg/d for 3 months and were followed up for 6 months. The primary outcome was a number of acute exacerbations in 6 months. The secondary outcome was the presence of respiratory symptoms at 6 months. Adverse effects were also recorded and analyzed. Results: SAOLP decreased the number of acute exacerbations (corrected χ2 test, p = 0.038) and alleviated respiratory symptoms (p = 0.0141) in non-cystic fibrosis bronchiectasis compared with placebo. There was no significant increase in adverse events in the SAOLP group (p > 0.9999) compared with the placebo group. Conclusion: Usage of SAOLP for 3 months may have potential benefits for non-cystic fibrosis bronchiectasis in reducing acute exacerbations and improve respiratory symptoms. More large and multi-center studies are needed to provide more evidence for its clinical use and determine the duration of treatment.