Effect of age, gender, tumor load, and IPI on rituximab clearance. No correlation of rituximab clearance with age was observed when all patients were analyzed (A). However, when female and male patients were analyzed separately, clearance slightly (nonsignificantly) increased in males (B) and significantly decreased in females (C) with increasing age. As a result, differences in rituximab clearance were not found between young female and male patients but were significant between elderly female and elderly male patients, elderly and young female patients, and elderly female and young male patients (D). No significant differences in rituximab clearance were found between patients with low tumor burden (stages I/II) and high tumor burden (stages II/IIII; E), and no differences were observed between (elderly) good-prognosis and poor-prognosis patients (F); for the latter analysis, only elderly patients were evaluated because no pharmacokinetic data were available from young poor-prognosis patients.