Astex Pharmaceuticals has one too...AT13387, but not as far in trials as ganetespib.
So there you have it, the remaining Hsp90 inhibitors:
Synta (GANETESPIB)
Infinity (Retaspimycin, as stated below)
Vernalis/Novartis (AUY922)
Astex (AT13387)
Debiopharm (Debio 0932)
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.