Roche's protease inhibitor for AIDS, which does not seem to work as well as other pills in the same family, he calls "a disservice to the world".It will take time to see whether Merck has once again outsmarted its rivals.
It is a so-called "checkpoint inhibitor", which by removing a blocking mechanism allows immune-system cells called T-lymphocytes to attack cancer cells (as they are pictured doing above).
Its stable of AIDS drugs will be joined next year by two promising new compounds, a protease inhibitor called 141W94 and a reverse-transcriptase inhibitor called 1592.
It is no surprise that Vertex has been effective at cracking problems that the big pharmaceuticals have not.During the 1990s, Vertex entered the race to develop an inhibitor for inflammation.
But even a drug like Crixivan, Merck's anti-AIDS HIV-protease inhibitor, costs $5 a gram not a bad fraction of the price of gold.
To be activated they must be liberated from the chromosomal coils.A group of agents called histone deacetylase inhibitors can help here, says Sharon Lewin, director of the infectious-diseases unit at Alfred Hospital in Melbourne, who is about to start a clinical trial of a histone-deacetylase inhibitor called SAHA.
Closing hours in several EU countries also act as an inhibitor.
When patents expired on Captopril, a leading ACE inhibitor, cheap generic versions became available.
But its limited success is inspiring imitators.Aricept, made by Eisai, of Japan, is another cholinesterase inhibitor.
Takeda, another Japanese firm, also has a cholinesterase inhibitor on trial, as do Bayer, of Germany, and Forest Laboratories, an American firm.And if none of these approaches work, there is a fourth take a painkiller.
Avastin blocks angiogenesis (the formation of the new blood-vessels which feed and oxygenate a growing tumour) and Tarceva is another inhibitor of EGFR.
