Proteosome inhibitor - bortezomib - a multiple myeloma drug

http://www.nature.com/nature/journal/v480/n7377_supp/full/480S40a.html

But two classes of drug that became available in the past decade — proteasome inhibitors and immunomodulators — have been far more effective than any previous drugs against this form of cancer. Just three of these new drugs have so far been licensed — a proteasome inhibitor called bortezomib and two immunomodulatory drugs, thalidomide and its cousin lenalidomide — with additional drugs currently in clinical trials.

In multiple myeloma, plasma cells reproduce furiously, creating piles of damaged proteins that must be cleared from the cell. Protein complexes called proteasomes normally remove them, aided by enzymes that slice up the amino-acid chains. But in myeloma cells, this proteasome, known as 26S, can barely keep up with demand, suggesting a weakness that could be exploited. In 1993, Alfred Goldberg, a cell biologist at Harvard Medical School in Boston, Massachusetts, created the first proteasome inhibitor, MG132. It worked by interfering with protein clearing. Myeloma cells, which are already awash with damaged proteins, proved particularly vulnerable to MG132 and would suffocate in their own waste protein.