The pharmacokinetics of ¹³¹I-rituximab in a patient with CD20 positive Non-Hodgkin Lymphoma: Evaluation of the effect of radioiodination on the biological properties of rituximab

Article type: Research Article

Authors: Tran, L.^{a; *} | Baars, J.W.^b | de Boer, J.P.^b | Hoefnagel, C.A.^c | Beijnen, J.H.^{a; d} | Huitema, A.D.R.^a

Affiliations: [a] Department of Pharmacy and Pharmacology, The Netherlands Cancer Institute/Slotervaart Hospital, Amsterdam, The Netherlands | [b] Department of Medical Oncology, The Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands | [c] Department of Nuclear Medicine, The Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands | [d] Faculty of Pharmaceutical Sciences, Department of Biomedical Analysis, Section of Drug Toxicology, Utrecht University, Utrecht, The Netherlands

Correspondence: [*] Corresponding author: Ly Tran, PhD, Slotervaart Hospital, Department of Pharmacy and Pharmacology, P.O. Box 90440, 1006 BK, Amsterdam, The Netherlands. Tel.: +31 20 512 4665; Fax: +31 20 512 4753; E-mail: Ly.Tran@slz.nl.

Abstract: Purpose:To report the pharmacokinetics of 131I-rituximab a patient with a CD20 positive non-Hodgkin Lymphoma who has received 131I-rituximab as consolidation treatment after remission induction and to evaluate the effect of radioiodination on the biological properties of rituximab. Results:The patient was a 65-year-old male with a relapsed CD20 positive follicular non-Hodgkin Lymphoma. After induction therapy the patient was in partial remission. Following administration of a diagnostic dose of 185 MBq 131I-rituximab, remaining lesions were identified on the wholebody scans. The patient then received a therapeutic dose of 1000 MBq 131I-rituximab. The uptake by the tumor in the right axilla was 0.17–0.21% of the injected dose. The calculated biological half-life of 131I-rituximab was 684 hrs. This biological half-life corresponded well with the half-life of unlabeled rituximab which was approximately 720 hrs. Discussion and conclusion:Even though radioiodination of rituximab results in a reduced binding capacity, whole body scans demonstrated localization of 131I-rituximab in the tumor area. This observation supports the specific targeting of 131I-rituximab. The half-life of 131I-rituximab corresponded to the half-life of unlabeled rituximab. Hence, the pharmacokinetics of 131I-rituximab was not relevantly affected by the radioiodination process.

DOI: 10.3233/HAB-2011-0240

Journal: Human Antibodies, vol. 20, no. 1-2, pp. 37-40, 2011