topotecan sustained-release episcleral plaque

An episcleral plaque containing sustained-release (SR) topotecan, a semisynthetic derivative of camptothecin and a cytotoxic, quinoline-based alkaloid extracted from the Asian tree Camptotheca acuminate, with potential antineoplastic activity. Upon local application of the topotecan SR episcleral plaque to the eye, topotecan is released in a sustained manner and inhibits topoisomerase I activity by stabilizing the topoisomerase I-DNA covalent complexes during S phase of cell cycle, thereby inhibiting religation of topoisomerase I-mediated single-strand DNA breaks and producing potentially lethal double-strand DNA breaks when encountered by the DNA replication machinery. The episcleral plaque allows for local delivery of topotecan for the potential treatment of retinoblastoma.