Interleukin-13 Monoclonal Antibody for Eosinophilic Esophagitis & More COVID-19 Data

A recent study (ES Dellon et al. Clin Gastroenterol Hepatol 2021; 19: 473-483. Full text: Long-term Efficacy and Tolerability of RPC4046 in an Open-Label Extension Trial of Patients With Eosinophilic Esophagitis) provides 1 year data on RPC4046, an IL-13 monoclonal antibody.

This study analyzed data from 66 patients who completed the 16-week, double-blind, induction portion of a phase 2 study of RPC4046 (180 mg or 360 mg/wk) vs placebo and then completed a 52-week LTE, receiving open-label RPC4046 360 mg/wk.  20 of the 86 initial subjects (from the 16 week induction study) did not complete the full 52-week duration of the open label extension

Key findings:

  • Overall, 42 of 66 (64%) subjects had a peak eosinophil count <15 at 52 weeks
  • In the initially-treated group, 29/57 (51%) had peak eosinophil count <15 at 16 weeks
    • 20/29 maintained a eosinophil count <15 at 52 weeks; 3 had an eosinophil count of 15 or greater at 52 weeks. Thus, 20/23 (87%) with data at 52 weeks maintained response.
  • In the initially-treated group, 28/57 (49%) had a peak eosinophil count of 15 or greater at 16 weeks
    • 10/28 (36%) had a peak eosinophil count <15 at 52 weeks and 12 continued with an eosinophil count of 15 or greater at 52 weeks. Thus, 10/22 (45%) acquired a response after the induction period.
  • In the placebo induction group (n=29), none had a peak eosinophil count <15 at week 16
    • 12/29 (43%) had a peak eosinophil count <15 at 52 weeks during open-label treatment; 9 continued with an eosinophil count of 15 or greater at 52 weeks. Thus, 12/21 (57%) developed a response without an induction treatment.

In addition to the improvements in eosinophil count, the authors identified clinical, endoscopic, and histologic improvement. “RPC4046 was well tolerated with little immunogenicity elicited in the LTE period.” Overall, the majority of treatment related adverse events were mild or moderate in severity and “no significant safety concerns.”

My take: This study shows that RPC4046 may emerge as a useful treatment for EoE.

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From Washington Post. U.S. Death rate from COVID-19 continues to decline, even though the number of reported daily cases has increased in last 3 weeks. With previous surges, deaths have been a lagging indicator. With the large number of vulnerable individuals vaccinated, it is unclear if the death rate will rise again or will continue to decline.
From Washington Post

Putting in Place a Big Piece of the Eosinophilic Esophagitis Puzzle

A recent study (Nature Genetics 2014; doi:10.1038/ng.3033 -thanks to Seth Marcus for this reference) provides novel in-depth molecular and mechanistic information on eosinophilic esophagitis (EoE).  Though the publication and supplemental material span only 8 pages, it is packed with information and highly technical assays and thus takes an effort to work through.

The authors performed a genome-wide association study (GWAS) of SNPs (single nucleotide polymorphisms) from >1.5 million genetic markers.  In total, this study involved samples from 736 EoE patients and 9246 controls. Four prominent markers were identified at 2p23, 5q22, 8p23, adn 15q13; however, the marker at 2p23 was most highly associated with a risk for EoE.  And, 2p23 included the CAPN14 gene (best SNP rs77569859).

Key Results:

  • CAPN14 is “specifically expressed in esophageal epithelium and is dynamically upregulated as a function of disease activity.”  Though CAPN14 is expressed in other tissues, it is primarily in the esophagus and pharynx (Figure 2).
  • CAPN14 encodes calpain 14, a calcium-activated cysteine protease.  CAPN14 showed the greatest upregulation in comparison to all members of the CAPN family.  Calpain proteases mediate protein cleavage for structural proteins, signaling molecules, transcription factors, and inflammatory mediators.  The latter are “germane for allergic responses.”
  • CAPN14 levels are >2-fold increase in individuals with active EoE.
  • CAPN14 gene is modified by IL-13.

Take-home message: (from the authors) This study shows the “potential centrality of CAPN14 in the etiology of EoE….We propose a model that links the interplay of allergic sensitization with an EoE-specific, IL-13-inducible esophageal response involving CAPN14.”

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