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British Journal of Cancer (2001) 85, 1787–1793. doi:10.1054/bjoc.2001.2170
Published online 27 November 2001

Internalisation enhances photo-induced cytotoxicity of monoclonal antibody-phthalocyanine conjugates

M Carcenac1, M Dorvillius1, V Garambois1, F Glaussel1, Ch Larroque2, R Langlois3, N E Hynes4, J E van Lier3 and A Pèlegrin1

  1. 1EA2989 Centre de Recherche en Cancérologie, CRLC Val d'Aurelle-Paul Lamarque, Montpellier, F-34298 cedex 5, France
  2. 2INSERM U128, BP5051, Montpellier, F-34033, France
  3. 3University of Sherbrooke, Québec, J1H 5N4, Canada
  4. 4Friedrich Miescher Institute, PO Box 2543, Basel, CH-4002, Switzerland

Received 21 March 2001; Revised 2 October 2001; Accepted 4 October 2001; Corrected online 16 November 2011



Immunophototherapy of cancer combines the specificity of a monoclonal antibody (MAb) to an overexpressed tumor marker with the phototoxic properties of the conjugated dye. To analyze the potential role of internalisation of the dye on photo-induced cytotoxicity, we compared two target antigens, carcinoembryonic antigen (CEA) that does not internalise and ErbB2 that does. Human ovarian carcinoma SKOv3 cells that express a high level of ErbB2 were transfected with the CEA cDNA. Using FACS analysis, the resulting cell line, SKOv3-CEA-1B9, demonstrated comparable levels of expression of the two target antigens. Aluminium tetrasulfophthalocyanine (AlPcS4) was covalently coupled to anti-CEA MAb 35A7, anti-ErbB2 MAb FSP77 and a non-specific MAb PX, via a five-carbon sulfonamide spacer chain (A1) at molar ratios ranging from 6 to 9 moles of AlPcS4 per mole of MAb. The 35A7-(AlPcS4A1)8 conjugate induced 68% growth inhibition of the SKOv3-CEA-1B9 cell line after a 20h incubation at 2.50μg/ml (based on AlPcS4A1 content) following light exposure. However, the FSP77-(AlPcS4A1)6 conjugate gave a 51% growth inhibition for an AlPcS4A1 concentration as low as 0.04μg/ml after the same incubation time and exposure to the same light dose. At a 1.25μg/ml AlPcS4A1 concentration, the FSP77-(AlPcS4A1)6 conjugate gave a 67% growth inhibition after an incubation time as short as 1h, reaching a 96% inhibition after an 8h incubation time. Using an unique cell line that expresses two different target antigens, we demonstrated a clear advantage of an internalising over a non-internalising MAb-dye conjugate in terms of phototoxic efficacy. in vivo evaluation of the photodynamic properties of the conjugates is in progress. © 2001 Cancer Research Campaign


immunophototherapy; phthalocyanine; monoclonal antibody; CEA; ErbB2


MAb, monoclonal antibody; PBS, phosphate-buffered saline; EDC, 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride; sulfo-NHS, N-hydroxysulfosuccinimide; AlPcS4, aluminium tetrasulfophthalocyanine; CEA, carcinoembryonic antigen; Al, five carbon spacer chain; Px, IgG1 purified from mouse myeloma P3-X63; %ID/g, percentage of injected dose per gram; PS, photosensitizer; IPT, immunophototherapy; mTHPC, metatetrahydroxyphenylchlorin



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