Clinical response and corresponding blood transcriptome pathways before and after treatment of hereditary angioedema prodromes compared to active swelling attacks.

Background: Approximately 85% of hereditary angioedema (HAE) attacks are associated with prodromal symptoms.

Objective: We investigated the clinical effect of treating HAE C1-esterase inhibitor (HAE-C1-INH) type 1 patients with recombinant human C1-INH (rhC1-INH) during their prodrome versus an active swelling episode and associated changes in blood transcriptomic genes and pathways before and after treatment.

Methods: A 2-center, unblinded, case-crossover study randomly assigned 5 HAE-C1-INH type 1 patients to prodrome or attack treatment groups; after a patient was treated for either 2 prodromes or 2 HAE attacks, they were crossed over to be treated for 2 HAE attacks or 2 prodromes. All patients were treated during the prodrome or acute attack with rhC1-INH; (conestat alfa, 50 IU/kg body weight, maximum 4200 IU for body weight ≥85 kg). Blood samples for analysis by RNA sequencing were obtained (1) at baseline, (2) during the prodrome before and after treatment, and (3) during an attack before and after treatment. Differentially expressed genes and pathways were elucidated by Ingenuity Pathway Analysis (IPA; Qiagen).

Results: Treatment during the HAE prodrome with rhC1-INH was as effective at preventing progression to a swelling episode as treatment of an acute attack. HAE prodromes were associated with upregulation of multiple inflammatory extracellular matrix genes, neuropeptide, and inflammasome member genes (eg, SPARCL1, AGRP, NLRP9; log₂ fold change = 4.1, 3.9, and 3.0, respectively). TNF-α and IL-10 were 2 major hub genes in prodrome-associated enriched gene networks. rhC1-INH treatment resulted in reversal of the disease signature in HAE-associated dysregulated pathways. Approximately 42% of prodrome-associated differentially expressed genes were also associated with HAE attacks. The enriched gene networks with hub genes for prodrome (ERK and VEGF) and for acute attack (insulin and SERPINA1) stages of HAE were identified. The major enriched pathways shared between HAE prodrome and attack were associated with neutrophil function and prostaglandin metabolism.

Conclusion: Treatment of HAE-C1-INH type 1 patients who have a well-defined prodrome that historically results in an acute attack may be justified clinically and mechanistically. This approach would represent a paradigm shift for management of HAE on-demand treatment.