We report on the plasma drug exposure-response relationships of the oral p38 alpha kinase inhibitor neflamapimod across all clinical trials, with a focus on the Rewind-LB Trial In patients with dementia With Lewy bodies (DLB). We found a consistent pharmacokinetic-pharmacodynamic relationship was observed across studies, with a trough plasma drug concentration threshold (~4 ng/mL) associated with biomarker and clinical effects in early AD and DLB. The findings support the mechanism of action, strengthen RewinD-LB efficacy results in DLB, and support the choice of 50mg TID as the optimal dose and regimen for future clinical trials.