Cancer Therapy: Clinical An Imaging-Based Rapid Evaluation Method for Complement- Dependent Cytotoxicity Discriminated Clinical Response to Rituximab-Containing Chemotherapy Yuji Mishima, 1,2 Natsuhiko Sugimura, 1,5 Yuko Matsumoto-Mishima, 2,3 Yasuhito Terui, 1,2,3 Kengo Takeuchi, 4 Suzuka Asai, 2 Daisuke Ennishi, 3 Hiroaki Asai, 3 Masahiro Yokoyama, 3 Kiyotsugu Kojima, 5 and Kiyohiko Hatake 1,3 Abstract Purpose: Rituximab has greatly improved the efficacy of chemotherapy regimens for CD20-positive non-Hodgkin's lymphoma. However, although several mechanisms of action of rituximab have been identified, the exact therapeutic functions of these me- chanisms remains to be clarified. In addition, there is no established prognostic marker to predict an individual response. This study verified the validity of ex vivo comple- ment-dependent cytotoxicity (CDC) susceptibility as a predictor of pathologic tumor regression in patients undergoing rituximab-containing chemotherapy and examined whether CDC contributes to the mechanism of action of rituximab. Experimental Design: A rapid assay system was established to evaluate the tumoricidal activity of rituximab using a living cell–imaging technique. We analyzed lymph node biopsies obtained from 234 patients with suspected lymphomas and estimated the association between CDC susceptibility and the response to rituximab-containing che- motherapy in diffuse large B-cell lymphoma and follicular lymphoma. Results: This study revealed that CDC susceptibility of lymphoma cells freshly obtained from patients was strongly associated with response to rituximab-containing chemo- therapy in both diffuse large B-cell lymphoma and follicular lymphoma. This correla- tion was not apparent in cases that received chemotherapy without rituximab. Conclusions: The system that we have established allows a successful assessment of rituximab-induced CDC and can distinguish cases refractory to rituximab-containing chemotherapy. The association between CDC susceptibility and therapy response sug- gests that CDC is pivotal in the ability of chemotherapy including rituximab to induce remission. Although rituximab can be combined with chemotherapies used in the treatment of non-Hodgkin's lymphoma, efficacy varies from patient to patient. In addition, no prognostic mark- er to predict individual response has been established to date. Several mechanisms of action have been proposed and tested in vitro, mainly in tumor cell lines (1–3). Through its human IgG 1 Fc domain, rituximab can activate cellular effectors for an- tibody-dependent cellular cytotoxicity (ADCC) or phagocytosis and can recruit serum proteins for complement-dependent cytotoxicity (CDC; ref. 4). Moreover, cross-linking of CD20 mo- lecules on tumor cell lines has been reported to trigger apopto- sis, as well as having an antiproliferative effect on some, but not all, cell lines (5, 6). Despite these insights, the mechanisms me- diating tumor cell eradication in vivo are not well understood. Recently, analyses of FcγRIIIa polymorphisms have clearly shown that ADCC is one of the critical effector functions responsible for the clinical efficacy of therapeutic antibodies (7–9). The FcγRIIIa gene (FCGR3A) displays an allelic polymor- phism that generates molecules containing either a phenylala- nine (F) or a valine (V) at amino acid position 158, which is critical in mediating ADCC. A greater clinical response in pa- tients with the FcγRIIIa allotype (FcgRIIIa-158V), which has a high affinity for human IgG 1 , has been observed compared with results obtained from patients with the low-affinity allo- type (FcγRIIIa-158F; ref. 10). These reports show the impor- tance of ADCC in clinical outcomes. On the other hand, there are few reports that indicate a contribution to clinical effect in Authors' Affiliations: 1 Olympus Bio-Imaging Laboratory, 2 Clinical Chemotherapy, Cancer Chemotherapy Center, 3 Department of Clinical Oncology and Hematology, Cancer Institute Hospital, 4 Department of Pathology, Cancer Institute of the Japanese Foundation for Cancer Research, Tokyo, Japan, and 5 Olympus Corporation, Ltd., Tokyo, Japan Received 7/8/08; revised 1/27/09; accepted 2/9/09; published OnlineFirst 5/5/09. Grant support: Scientific Research no. 19590170 from the Ministry of Edu- cation of Japan (Y. Mishima), Grant-in-aid for scientific research on priority area ‘cancer’ no. 12218226 from the Ministry of Education, Culture, Sports, Science and Technology of Japan (K. Hatake). Thecostsofpublicationofthisarticleweredefrayedinpartbythepaymentof page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/). Requests for reprints: Kiyohiko Hatake, Japanese Foundation for Cancer Research, 3-10-6, Ariake, Koto-ku, Tokyo, Japan. Phone: 81-3-3520-0111; Fax: 011-81-81-3-3570-0465; E-mail: khatake@jfcr.or.jp. F 2009 American Association for Cancer Research. doi:10.1158/1078-0432.CCR-08-1536 3624 Clin Cancer Res 2009;15(10) May 15, 2009 www.aacrjournals.org Research. on April 13, 2016. © 2009 American Association for Cancer clincancerres.aacrjournals.org Downloaded from