Immunogenicity and therapeutic response
The data in the literature are very mixed. A meta-analysis with systematic review of the literature by Garcês et al., which included 865 patients with RA, SpA, psoriasis or IBD, showed that the presence of ADAbs reduced the therapeutic response by 68%, but with significant heterogeneity between studies (p=0.037) that did not allow a definite link between immunogenicity and clinical response to be established [5].
Indeed, there are studies which, in agreement with our results, found no link between immunogenicity and therapeutic response at the time of sampling [34-36]. Actually, in our study no association was found between the presence of anti IFX or anti ADA and therapeutic response at the time of sampling for RA, SpA or CD. In the study of Cludts et al. including patients with RA (n=18), psoriatic arthritis (n=9), SpA (n=12) treated with ADA, no significant differences in DAS28 or BASDAI scores were found between ADAbs+ and ADAbs- patients [35]. The lack of correlation between immunogenicity and therapeutic response could be explained by the fact that, as mentioned above, the ELISA technique only allows the determination of free ADAbs. However, complexed ADAbs are those that would have a real therapeutic impact [36]. Another theory was proposed, that there are transient ADA with no real clinical impact, while the persistent ADA are responsible for treatment failure [37]. The fact that the assay was performed only once did not allow us to differentiate whether the ADAbs detected in our study were persistent or not.