Another anti-proliferative agent, daunomycin, has been tested in preclinical and clinical studies. The drug is an anthracycline antibiotic with efficacy in an animal model. Daunomycins appear to have a somewhat lower therapeutic index than 5-FU, principally due to its greater toxicity; but it has been tolerated in animals and in humans as a continuous intravitreal infusion of 7.5 | g/ml for 10 min. In pilot studies of patients undergoing vitrectomy, dauno-mycin was felt to be effective [26,43].A variety of other agents have been employed for the treatment of experimental PVR, with no significant published data yet in human trials. These include retinoids, which play an important role in the differentiation and proliferation of various cell types, including RPE. The treatment of RPE cells with vitamin A (all-trans-retinol) significantly inhibits cellular proliferation migration in vitro as well as having effects on morphology [44]. Immunotoxins composed of a monoclonal antibody linked to a biological toxin have been employed in experimental models, including an antibody against the human transferrin receptors to the A chain of ricin [45].

Another chemotherapeutic agent useful in cancer and also in the treatment of coronary restenosis, Taxol, has been tested for efficacy in experimental models in the eye. It appears to act as a promoter rather than an inhibitor of microtubular assembly and inhibits cell-mediated contraction of a collagen gel as well as experimental retinal detachment in various animal models [46]. A related cytoskeletal agent, Colchicine, also inhibits RPE astrocyte and fibroblast proliferation in addition to migration and was shown in one animal model to have some beneficial effects on PVR, although it has not yet been proven to be beneficial in any human studies [47].

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