Consideration of the EXiLE test for predicting anaphylaxis after diclofenac etalhyaluronate administration

Diclofenac etalhyaluronate, an active pharmaceutical ingredient in JOYCLU^® (JCL), serves as a joint function improvement agent in knee and hip osteoarthritis patients. However, frequent cases of anaphylaxis induced by JCL administration have been reported. Recent clinical research suggests the potential utility of the basophil activation test (BAT) in predicting JCL-induced anaphylaxis. Nonetheless, the BAT is deemed impractical for routine diagnostic testing due to complex procedures involving whole blood stimulation and flow cytometry-based analyses. In the study reported here, an IgE crosslinking-induced luciferase expression (EXiLE) test which uses patient sera without complicated procedures, was performed with patients who had received JCL, with or without subsequent anaphylactic symptoms. The results of this test were then compared with those of the BAT reported in a clinical research study. Of the six BAT-positive JCL-induced anaphylaxis-experienced patients, four were positive in the EXiLE test and all non-experienced patients were negative in both the BAT and EXiLE tests, thus illustrating a high concordance rate of 92.3%. Further validation of testing conditions is expected to improve these rates. Notably, complement inactivation treatment led to a positive EXiLE result in a BAT-negative patient. In conclusion, it appears that the EXiLE test exhibits promise as an alternative to BAT for predicting JCL-induced anaphylaxis, and in so doing offers a simpler diagnostic approach.