I absolutely agree that any drug is many years away, unless someone is extremely lucky and the pre-clinical and clinical trials go unbelievably well, which almost certaintly won't occur with an anti-cancer drug.
The first question, what type of molecule to use, is a tough call. A priori, one might go after nucleoside analogs since telomerase is a DNA polymerase. If one does this, however, side effects are an extremely severe possibility due to interactions with other DNA replication enzymes (In fact, because of the potential for side effects, my understanding is that Merck studiously avoids nucleoside analogs as potential drugs. I disagree with this philosophy, however, since you will miss drugs such as acyclovir.). Alternatively, you might try and find an unusual structure that would tightly bind the active site since this would likely avoid many of the side effects. However, this requires a lot of luck.
There has been some discussion about using rational drug design ideas for telomerase inhibitors. With the present knowledge of telomerase, this approach will almost certainly not be used. First, there is no X-ray structure, and even if there was, it may or may not be immediately obvious where the active site is located. Second, even with a good X-ray structure and knowledge of the active site, there is no evidence that rational drug design ideas (molecular mechanics simulations to pick out compounds that will likely bind) are better, or even as good as, the classical brute-force screening studies.
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