enGene (NASDAQ: ENGN) stock suffered an 83% plunge this past week that reflects just how competitive the field is among drug candidates for nonmuscle invasive bladder cancer (NMIBC)—and how questions over clinical data are enough to send investors scurrying to sell their shares. enGene shares cratered 81% Thursday from $8.85 to $1.72, then fell another 13% Friday, reaching a 52-week low as it finished the week at $1.50. The sharp falloff followe…