title: CD40 expression by human melanocytic lesions and melanoma cell lines and direct CD40 targeting with the therapeutic anti-CD40 antibody CP-870,893.
abstract: Anti-CD40 antibodies are in clinical development in patients with metastatic melanoma, a cancer that has been reported earlier to express CD40. The antitumor activity of anti-CD40 antibodies may be mediated by direct cytotoxic effects on CD40-positive melanoma cells or indirectly through modulation of host cells. In these studies, biopsies of patients with primary and metastatic melanoma, short-term cultures, and established melanoma cell lines were analyzed for CD40 expression using a combination of methods including immunohistochemistry, flow cytometry, and gene expression profiling, and the cytotoxic effects of the anti-CD40 antibody CP-870,893 on melanoma cell lines were tested using cell viability assays. CD40 was expressed at a higher frequency in metastatic melanoma lesions compared with primary melanomas. There was a variable expression of CD40 in synchronous and metachronous melanoma metastases. Expression of CD40 was present in slightly over half of a large panel of short-term primary melanoma cultures, with a wide range of expression levels by flow cytometry. Similar results were obtained in established melanoma cell lines when analyzed at the mRNA level or by surface protein staining. In approximately one-third of cell lines, the expression of CD40 could be up-regulated with a histone deacetylase inhibitor. Treatment with increasing concentrations of CP-870,893 had no antitumor activity against either CD40-positive or negative melanoma cell lines. In conclusion, approximately one-third to one-half of melanomas expresses CD40 at variable levels. Direct exposure to a CD40-activating antibody does not lead to antitumor activity in melanoma cell lines, suggesting that the antitumor effects of these antibodies in the clinic may be indirectly mediated.
authors.affiliation: Department of Medicine, Division of Hematology/Oncology, University of California Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Anusha
authors.initials: A
authors.lastname: Kalbasi
authors.forename: Ester
authors.initials: E
authors.lastname: Fonsatti
authors.forename: Pier Giorgio
authors.initials: PG
authors.lastname: Natali
authors.forename: Maresa
authors.initials: M
authors.lastname: Altomonte
authors.forename: Erica
authors.initials: E
authors.lastname: Bertocci
authors.forename: Ornella
authors.initials: O
authors.lastname: Cutaia
authors.forename: Luana
authors.initials: L
authors.lastname: Calabrò
authors.forename: Michael
authors.initials: M
authors.lastname: Chiou
authors.forename: William
authors.initials: W
authors.lastname: Tap
authors.forename: Bartosz
authors.initials: B
authors.lastname: Chmielowski
authors.forename: Michele
authors.initials: M
authors.lastname: Maio
authors.forename: Antoni
authors.initials: A
authors.lastname: Ribas
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D001706:Biopsy; D019013:CD40 Antigens / Q000819:agonists* / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D045744:Cell Line, Tumor; D002469:Cell Separation; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000276:immunology; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D007167:Immunotherapy; D008544:Melanocytes / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008545:Melanoma / Q000235:genetics / Q000276:immunology* / Q000473:pathology / Q000628:therapy*; D009362:Neoplasm Metastasis
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D019013:CD40 Antigens; D056572:Histone Deacetylase Inhibitors; C518149:selicrelumab