Actually, not true.
Infinity Pharmaceuticals (INFI) has an Hsp90 inhibitor-- Retaspimycin HCL. Theirs targets similar cancer patient populations as Synta's. But their market cap is double that of Synta's!!! (in part, they do have a second very promising drug, IPI-145). Synta is still quite UNDER-valued, and has a lot of room to run. Look at Infinity's yearly chart. I predict that will be our chart as well in 2013....
Vernalis (partnered with Novartis) also has hsp90 inhibitor, AUY922, in phase 2 trials. Trials are still continuing, despite ocular toxicity.... I think it's treading on thin ice.
We have a GOLD mine here in ganetespib.
The others have fallen by the wayside. Vernalis' will crumble due to ocular toxicity. Astex's has shown to be less effective than ganetespib. That leaves Infinity's, Synta's, and maybe Debiopharm's in the game, and we are much farther ahead than theirs. Do your own research. Hsp90 inhibition is the real deal, and we likely have the MOST potent drug with the LEAST side effects.