Hexadecylphosphocholine may produce reversible functional defects of the retinal pigment epithelium

Hexadecylphosphocholine is a synthetic phospholipid derivative that has antitumor activity due to its interference with membrane functions. Animal experiments have shown photoreceptor and retinal pigment epithelium (RPE) degeneration after its systemic application. In a phase II trial of hexadecylphosphocholine therapy in 23 patients with advanced metastatic colorectal or lung cancer, visual acuity and color vision testing, slit-lamp examination, tonometry, fundoscopy (including photodocumentation), visual field testing, electrooculography (EOG), and electroretinography (ERG) were performed. A baseline examination was carried out prior to therapy. Patients were reexamined after 2 months and after 5 months. In all, 71% of the patients had a reduced light peak in the EOG during therapy. After the end of therapy the light peak improved again and became normal in most patients. The statistical analysis showed that the light-peak values during therapy were significantly lower than the baseline and posttreatment values. This indicates that hexadecylphosphocholine might be capable of producing a partly reversible functional defect of the RPE. Apart from this finding, no other functional or morphological ocular side effect was detected. The functional changes observed in our patients as well as the morphological changes found in animal experiments are similar to those reported for known diseases of the RPE-photoreceptor complex. Therefore, hexadecylphosphocholine-induced retinopathy might become useful as an animal model for such diseases.