On a more positive note, scientists did manage to drill through 800 meters of Antarctica ice to reach another lake, lake Whillans, without contaminating it (they used only hot water to drill, not drilling fluid). And they did find "a diverse assemblage of bacteria and archaea". From Christner et al. 2014:

Our data show that SLW supports a metabolically active and phylogenetically diverse ecosystem that functions in the dark at sub-zero temperatures, confirming more than a decade of circumstantial evidence regarding the presence of life beneath Antarctica’s ice sheet [...] Given the prevalence of subglacial water in Antarctica, our data from SLW lead us to contend that aquatic microbial ecosystems are common features of the subsurface environment that exists beneath the ~10$\small\mathsf{^7}$ km$\small\mathsf{^2}$/s Antarctic ice sheet.

However, there is a major difference with lake Vostok: lake Whillans is connected to a hydrological system, while lake Vostok is "closed" and has a water residence time of over 10,000 years. So if life is trapped in there, it could have evolved differently...