X0306 4 2017-12-20 0 0001581720 Loxo Oncology, Inc. LOXO 0001242613 MAYLEBEN TIMOTHY M C/O LOXO ONCOLOGY, INC. 281 TRESSER BLVD, 9TH FLOOR STAMFORD CT 06901 1 0 0 0 Common Stock 2017-12-20 4 S 0 10000 80.4948 D 0 D The transactions reported on this Form 4 were effected pursuant to a 10b5-1 trading plan adopted by the reporting person. Represents the aggregate of sales effected on the same day at different prices. Represents the weighted average sales price per share. The shares sold at prices ranging from $80 to $80.89 per share. Full information regarding the number of shares sold at each price shall be provided upon request to the staff of the U.S. Securities and Exchange Commission, the Issuer, or a security holder of the Issuer. /s/ Jennifer Burstein, by power of attorney 2017-12-22