X0306 4 2017-09-18 0 0001581720 Loxo Oncology, Inc. LOXO 0001640069 Burstein Jennifer C/O LOXO ONCOLOGY, INC. 281 TRESSER BOULEVARD, 9TH FLOOR STAMFORD CT 06901 0 1 0 0 Vice President of Finance Common Stock 2017-09-18 4 M 0 1700 11.35 A 1700 D Common Stock 2017-09-18 4 S 0 643 88.3494 D 1057 D Common Stock 2017-09-18 4 S 0 957 89.4985 D 100 D Common Stock 2017-09-18 4 S 0 100 90.11 D 0 D Employee Stock Option (right to buy) 11.35 2017-09-18 4 M 0 1700 0 D 2025-04-30 Common Stock 1700 46600 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 $87.93 to $88.87 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. Represents the weighted average sales price per share. The shares sold at prices ranging from $89.08 to $89.98 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. The stock option vests and becomes exercisable as to 25% of the shares subject to the option on the one-year anniversary of the Reporting Person's employment commencement date, and thereafter vests as to 1/48th of the shares in equal monthly installments. /s/ Jennifer Burstein 2017-09-20