Synthetic Analogues of the Actinomycin, Quinamycin and Nogalamycin Groups of Antitumour Antibiotics

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The principal difficulty in the treatment of the common solid tumours that cause the majority of cancer deaths is the problem of drug resistance. For example, many patients with cancer of the lung, breast or colon respond well to drug treatment with their tumours initially regressing, only to return later in an aggressive drug-resistant form. In this event, the inevitable outcome is that the tumour grows through drug treatment and the patient eventually succumbs and dies. This is also a familiar scenario in the treatment of adults with leakaemias and non-Hodgkins lymphomas. The underlying cause of drug resistance is the genetic instability of cancer cells which results in tumours that are heterogeneous, making it almost inevitable that a cancer cell will arise that is resistant to treatment. There are many mechanisms of resistance, some of which are peculiar to particular drug types, some are permeability barriers and some involve genetic deregulation of the biochemistry of cell death. One way of subverting resistance is by the use of drugs whose mechanism of action is novel so that the tumour is challenged to devise a new defense. Here, we are attempting to develop synthetic analogues of a class of naturally- occurring antitumour antibiotic whose mechanism of action is unusual but which has not been exploited by medicinal chemists because of the difficulty of the chemistry involved. These antibiotics work by binding to DNA and inhibiting the first step in the process whereby genes are turned into proteins. We have designed compounds that are chemically accessible that our preliminary work suggests mimic the DNA-binding and biological properties of the natural antibiotics. The proposed work will enable us to evaluate whether this new class of agent has experimental antitumour activity, particularly amongst drug-resistant tumours.