ITGB3 and major depressive disorder: The lower ITGB3 expression level observed in the PBMCs obtained from the MDD patients is noteworthy, and suggests that increased ITGB3 expression on chronic SSRI treatment plays a role in the therapeutic action of these drugs in MDD.17 Further studies with larger patient cohorts are required to clarify the potential role of reduced PMBC SSRI sensitivity as an informative biomarker for TR MDD.