** Cancer therapy developer Kronos Bio's shares rise 4% to 90 cents premarket

** KRON to lay off about 83% of its employees by year-end

** CEO Norbert Bischofberger has stepped down after nearly six years in the role - KRON

** KRON appoints chief financial officer Deborah Knobelman as interim CEO

** As of March 11, KRON had 62 full-time employees and one part-time employee - SEC filing

** KRON had announced ~21% reduction in its workforce earlier this year

** As of last close, stock has fallen ~31% YTD

(Reporting by Kamal Choudhury in Bengaluru)

((Kamal.Choudhury@thomsonreuters.com;))