IL17A and Alzheimer disease: However, there are still challenges in the field of immunotherapy where efficacy has not met expectations, for example, a phase II study showed that for the treatment of AD, strategies targeting IL-17A in isolation had limited efficacy even in the hyper-activated state of Th17 (135), and that there was no significant difference in the treatment of AD for the anti-IL-22 monoclonal antibody compared to placebo (136).