MTOR and pneumocystosis: Specifically, mTOR inhibitors (e.g., everolimus, temsirolimus) are well known to reduce IL-2 production, leading to diminished T-cell and NK-cell responses, thereby increasing the risk of opportunistic infections such as Pneumocystis jirovecii pneumonia (PJP), cytomegalovirus (CMV) reactivation, and invasive fungal infections [204,205,206,207].