X0306 4 2018-04-16 false 0001560241 G1 Therapeutics, Inc. GTHX 0001706847 Velleca Mark A. C/O G1 THERAPEUTICS, 79 TW ALEXANDER DR. 4501 RESEARCH COMMONS, SUITE 100 RESEARCH TRIANGLE PARK NC 27709 true true false false President and CEO Common Stock 2018-04-16 4 M false 7500.00 3.72 A 7500.00 D Common Stock 2018-04-16 4 S false 7000.00 35.9452 D 500.00 D Common Stock 2018-04-16 4 S false 500.00 36.71 D 0.00 D Stock Options (Right to Buy) 3.72 2018-04-16 4 M false 7500.00 0.00 D 2025-12-21 Common Stock 7500.00 151933.00 D The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan. The price represents the weighted average price with a low of $35.62 and a high of $36.45. The shares underlying this option vested as to 25% of the shares on December 21, 2016, with the remainder vesting in 36 equal monthly installments thereafter, subject to the Reporting Person's continued service through each applicable vesting date. /s/ Peter N. Cunningham, attorney-in-fact 2018-04-17