FLT PET assesses Non-Hodgkin's Lymphoma treatment

PET along with the radiolabeled thymidine analog [18F]Fluorothymidine (FLT) is “a promising, sensitive tool” for assessing drug effects on tumor growth in patients with diffuse large B-cell lymphoma, according to a study released at SNM’s 53rd Annual Meeting this week in San Diego.

“Conventional imaging modalities—such as computed tomography, ultrasound and magnetic resonance tomography—determine response to therapy by changes in tumor size,” said Ken Herrmann, resident with the nuclear medicine clinic at the Technical University in Munich, Germany. “However, changes in tumor proliferation may represent a more sensitive tool in differentiating non-responding tumors,” added the co-author of “Change of Tumor Cell Proliferation During R-CHOP Chemotherapy of Diffuse Large B-Cell Lymphoma (DLBCL) Measured by 18FLT PET.” He indicated, “Our results need to be confirmed by future studies comprising a larger patient population and a variety of different therapy approaches.”

In their study, researchers evaluated FLT PET to see if it “allows monitoring early response to therapy in patients with DLBCL lymphoma,” said Herrmann. They monitored 17 patients who were treated with Rituximab immunotherapy combined with CHOP chemotherapy (R-CHOP), one of the most common chemotherapy regimens for treating NHL. Treatment with the antibody Rituximab led to a temporary increase of FLT uptake in several patients, perhaps reflecting an upregulation (an increase in the number of receptors on the surface of target cells) of DNA synthesis within the lymphoma cell compartment or a recruitment and proliferation of tumor-invading lymphocytes, noted Herrmann. “In contrast, CHOP led to a rapid decrease of FLT uptake early after application—presumably due to a reduction of tumor cell proliferation,” he said.

Abstract: K. Herrmann, B. Krause, H. Wester, H. Wieder and M. Schwaiger, Nuclear Medicine, Technical University, Munich, Germany; T. Dechow, M. Schoeffel, C. v. Schilling and C. Peschel, Medizinische Klinik, Rechts der Isar, Technical University, Munich, Germany; and W. Weber, Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, Calif., “Change of Tumor Cell Proliferation During R-CHOP Chemotherapy of Diffuse Large B-Cell Lymphoma (DLBCL) Measured by 18FLT-PET,” SNM’s 53rd Annual Meeting, June 3–7, 2006, Scientific Paper 486.