EGFR and Pleural effusion: As for other EGFR-TKIs, Masago et al. investigated the pharmacokinetics of erlotinib in NSCLC with malignant pleural effusion, and found repeated erlotinib dosing led to significant accumulating drug concentrations in malignant effusions, with the mean percentage of erlotinib penetration from plasma to pleural effusion to be 18% on Day 1 and 112% on Day 8 [15].