Conventional and prospective molecular targets in antitumour drug design. Concepts in antitumour research.

To introduce a rationale in a drug development program the molecular base of the pathological lesion must be carefully considered both for selecting test compounds and to apply the most appropriate assay systems. From the beginning of antitumour drug research the principal aim has always been to select chemical compounds which could selectively inhibit tumour growth. This strategy was in full harmony with the concept that tumours are build up by fast proliferating cells. Research based on this concept has resulted in the development of more than 40 cytostatic agents, which are rather diverse in their chemical properties, but all act on one of the molecular mechanisms participating in cell proliferation. However the unsatisfactory therapeutic responses which could be obtained by the cytostatic agents focused the attention on those molecular events in the tumour cells which may be more closely related to the progression of the malignant disease.