title: CD200 expression on tumor cells suppresses antitumor immunity: new approaches to cancer immunotherapy.
abstract: Although the immune system is capable of mounting a response against many cancers, that response is insufficient for tumor eradication in most patients due to factors in the tumor microenvironment that defeat tumor immunity. We previously identified the immune-suppressive molecule CD200 as up-regulated on primary B cell chronic lymphocytic leukemia (B-CLL) cells and demonstrated negative immune regulation by B-CLL and other tumor cells overexpressing CD200 in vitro. In this study we developed a novel animal model that incorporates human immune cells and human tumor cells to address the effects of CD200 overexpression on tumor cells in vivo and to assess the effect of targeting Abs in the presence of human immune cells. Although human mononuclear cells prevented tumor growth when tumor cells did not express CD200, tumor-expressed CD200 inhibited the ability of lymphocytes to eradicate tumor cells. Anti-CD200 Ab administration to mice bearing CD200-expressing tumors resulted in nearly complete tumor growth inhibition even in the context of established receptor-ligand interactions. Evaluation of an anti-CD200 Ab with abrogated effector function provided evidence that blocking of the receptor-ligand interaction was sufficient for control of CD200-mediated immune modulation and tumor growth inhibition in this model. Our data indicate that CD200 expression by tumor cells suppresses antitumor responses and suggest that anti-CD200 treatment might be therapeutically beneficial for treating CD200-expressing cancers.
authors: Alexion Antibody Technologies, San Diego, CA 92121, USA.
authors: Anke
authors: A
authors: Kretz-Rommel
authors: Fenghua
authors: F
authors: Qin
authors: Naveen
authors: N
authors: Dakappagari
authors: E Prenn
authors: EP
authors: Ravey
authors: John
authors: J
authors: McWhirter
authors: Daniela
authors: D
authors: Oltean
authors: Shana
authors: S
authors: Frederickson
authors: Toshiaki
authors: T
authors: Maruyama
authors: Martha A
authors: MA
authors: Wild
authors: Mary-Jean
authors: MJ
authors: Nolan
authors: Dayang
authors: D
authors: Wu
authors: Jeremy
authors: J
authors: Springhorn
authors: Katherine S
authors: KS
authors: Bowdish
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use*; D015703:Antigens, CD / Q000032:analysis / Q000187:drug effects* / Q000276:immunology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry; D006801:Humans; D007167:Immunotherapy / Q000379:methods*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains; D009369:Neoplasms / Q000188:drug therapy / Q000628:therapy*; D019151:Peptide Library; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use*; D023041:Xenograft Model Antitumor Assays
chemical_list: D019138:Antibodies, Blocking; D015703:Antigens, CD; D019151:Peptide Library; D011994:Recombinant Proteins; C042739:antigens, CD200