Is Rituximab Dosing Suboptimal for Older Men with DLBCL?

Michael E. Williams, MD, ScM

Among older patients with diffuse large B-cell lymphoma, men experienced faster rituximab clearance and poorer outcomes than women.

The standard rituximab dose of 375 mg/m2 has been broadly applied for treatment of patients with B-cell lymphoproliferative and autoimmune disorders, despite a lack of pharmacokinetic data regarding specific disease entities and individual patients. To address this issue, investigators analyzed the impact of gender and age (≤60 vs. >60) on outcomes in three phase III, prospective, multicenter trials of combination chemotherapy with or without rituximab for patients with newly diagnosed, diffuse large B-cell lymphoma.

In the MInT and MegaCHOEP studies (of 823 and 262 young patients, respectively), males and females benefited equally from rituximab plus chemotherapy versus chemotherapy alone. However, in the RICOVER-60 trial of 1222 older patients, although both men and women benefited from rituximab plus chemotherapy, women experienced greater benefit. The differences were not explained by the dose intensity of rituximab or chemotherapy or by variations in tumor burden. Pharmacokinetic analyses showed significantly slower rituximab clearance in older women, leading to higher and longer-sustained rituximab serum levels.

Citation(s):

Pfreundschuh M et al. Suboptimal dosing of rituximab in male and female patients with DLBCL. Blood 2014 Jan 30; 123:640.

Habermann TM.Is rituximab one for all ages and each sex? Blood 2014 Jan 30; 123:602.