Patent Evaluation: Use of the camptothecin derivative topotecan for the treatment of colorectal cancer

Abstract

Novelty: A process for treating colorectal cancer in humans, by administering a water-soluble camptothecin derivative such as topotecan, is disclosed. It is claimed that, relative to camptothecin, topotecan has greater clinical efficacy, more acceptable dose-limiting toxicity, more predicatable toxicity, greater solubility in aqueous solvents and a longer shelf-life.

Biology: Regimes for both parenteral and oral administration of topotecan, to both non-treated and heavily pretreated patients, are given. Anecdotal evidence describes a patient with colorectal cancer who was treated iu with topotecan (1.5 mg/m² of body surface area) over a twenty-four hour period, repeated weekly at least four times. A 50% regression in tumour size was observed. This patient was refractory to previous standard therapy for adenocarcinoma of the colon.

Chemistry: Data pertaining to the stability of a topotecan are presented. Topotecan diluted in saline (10 μg/ml or 500 μg/ml) or dextrose (6.7 μg/ml or 330 μg/ml) is stable in a hang-bag for twenty-four hours, with at least 95% recovery.