Molecular Targeting and Treatment of Composite EGFR and EGFRvIII- Positive Gliomas Using Boronated Monoclonal Antibodies WeilianYang, 1 Gong Wu, 1 Rolf F. Barth, 1 Michele R. Swindall, 1 Achintya K. Bandyopadhyaya, 3 WernerTjarks, 3 Kevin Tordoff, 4 MelvinMoeschberger, 4 ThomasJ.Sferra, 2,5 PeterJ.Binns, 6 KentJ. Riley, 6 MichaelJ.Ciesielski, 7 RobertA.Fenstermaker, 7 andCarolJ.Wikstrand 8 Abstract Purpose: The purpose of the present study was to evaluate the anti ^ epidermal growth factor receptor (EGFR) monoclonal antibody (mAb), cetuximab, (IMC-C225) and the anti-EGFRvIII mAb, L8A4, used in combination as delivery agents for boron neutron capture therapy (BNCT) of a rat glioma composed of a mixture of cells expressing either wild-type (F98 EGFR ) or mutant receptors(F98 npEGFRvIII ). Experimental Design: A heavily boronated polyamidoamine dendrimer (BD) was linked by heterobifunctionalreagentstoproducetheboronatedmAbs,BD-C225andBD-L8A4.For in vivo biodistribution and therapy studies, a mixture of tumor cells were implanted intracerebrally into Fischer rats. Biodistribution studies were carried out by administering 125 I-labeledbioconjugates via convection-enhanceddelivery (CED), andfor therapy studies, nonradiolabeledbioconjugates were used for BNCT.This was carried out14 days after tumor implantation and 24 h after CED at theMassachusettsInstituteofTechnologynuclearreactor. Results: Following CED of a mixture of 125 I-BD-C225 and 125 I-BD-L8A4 to rats bearing composite tumors, 61.4% of the injected dose per gram (ID/g) was localized in the tumor compared with 30.8% ID/g for 125 I-BD-L8A4 and 34.7% ID/g for 125 I-BD-C225 alone.The corresponding calculated tumor boron values were 24.4 Ag/g for rats that received both mAbs, and12.3and13.8 Ag/g, respectively, for BD-L8A4 or BD-C225 alone.The mean survival time of animals bearing composite tumors, which received both mAbs, was 55 days (P < 0.0001) compared with 36 days for BD-L8A4 and 38 days for BD-C225 alone, which were not significantly different fromirradiated controls. Conclusions: Both EGFRvIII and wild-type EGFR tumor cell populations must be targeted using a combination of BD-cetuximab and BD-L8A4. Although in vitro C225 recognized both receptors, in vivo it was incapable of delivering the requisite amount of 10 B for BNCTof EGFRvIII-expressinggliomas. After decades of intensive research, high-grade gliomas are still extremely resistant to all current forms of therapy, including surgery, chemotherapy, and radiotherapy (1). Despite aggres- sive treatment using combinations of these modalities, the 5- year survival rate of patients diagnosed with glioblastoma multiforme (GBM) in the United States is <1% (2). The single most important advance in the treatment of these tumors over the past 30 years has been the introduction of temozolomide, initiallyincombinationwithexternalbeamphotonirradiation, and then followed by repetitive cycles of temozolomide alone (3). However, this has only increased the overall median survival by 2.5 months. The failures of surgery, chemotherapy, and radiotherapy to cure patients with high-grade gliomas are due to the inability of these modalities to completely eradicate microinvasive tumor cells within the brain (4). The survival data for patients with multicentric, metastatic brain tumors is almostasdismal(5,6),andforthisreason,thedevelopmentof new therapeutic approaches to treat both primary and metastatic brain tumors is of the highest importance. The wild-type epidermal growth factor receptor (EGFR) and its mutant isoforms are now considered prime targets for the Cancer Therapy: Preclinical Authors’ Affiliations: Departments of 1 Pathology and 2 Pediatrics, 3 College of Pharmacy, and 4 Public Health,The Ohio State University, and 5 Children’s Research Institute, Columbus, Ohio; 6 NuclearReactorLaboratory,Massachusetts Instituteof Technology, Cambridge, Massachusetts; 7 Department of Neurosurgery, Roswell Park Cancer Institute, Buffalo, NewYork; and 8 Department of Microbiology, Saba UniversitySchoolofMedicine,Saba,NetherlandsAntilles Received8/9/07;revised10/16/07;accepted11/1/07. Grant support: NIH grants1R01CA098945 (R.F. Barth) and1R01NS39071 (T.J. Sferra) the Roswell Park Alliance Foundation (R.A. Fenstermaker), and the United States Department of Energy through the program of Innovations in Nuclear Infrastructure and Education, Office of Nuclear Energy, Science andTechnology (contract no. DE-FG07-02ID14420DE-FG07-02; K14420), and the Office of EnvironmentalandBiologicalResearch(contractno.DE-FG02-02ER63358). Thecostsofpublicationofthisarticleweredefrayedinpartbythepaymentofpage charges.This article must therefore be hereby marked advertisement in accordance with18U.S.C.Section1734solely toindicatethisfact. Note: Current address forT.J. Sferra: Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK; previous address for C.J. Wikstrand: Departmentof Pathology, Duke University, Durham, NC. Requests for reprints: Rolf F. Barth, Department of Pathology,The Ohio State University, 1645 Neil Avenue, 165 Hamilton Hall, Columbus, Ohio 43210. Phone: 614-292-2177; E-mail: rolf.barth@osumc.edu. F 2008AmericanAssociationforCancerResearch. doi:10.1158/1078-0432.CCR-07-1968 www.aacrjournals.org Clin Cancer Res 2008;14(3) February 1, 2008 883