X0306 4 2017-12-29 0 0001374690 ZAFGEN, INC. ZFGN 0001609879 Hatfield Jeffrey S. C/O ZAFGEN, INC. 175 PORTLAND STREET, 4TH FLOOR BOSTON MA 02114 1 1 0 0 Chief Executive Officer Stock Option (Right to Buy) 3.40 2017-12-29 4 A 0 1100000 0.00 A 2027-10-09 Common Stock 1100000 1100000 D This option was granted on October 9, 2017, subject to vesting based on the Issuer's stock price appreciation and certain financial performance goals. The financial performance goals were waived on December 29, 2017 and therefore the option is deemed a reportable derivative security as of such date. The option vests and becomes exercisable based on the Issuer's common stock price during the two years after the first anniversary of the date of grant as follows: 25% of shares subject to the option vest after the stock price is equal to or greater than $10.00 per share for 20 consecutive trading days; and an additional 6.25% of the shares subject to the option vest for every additional $2.50 in stock price above $10.00 per share for 20 consecutive trading days. The option has been granted pursuant to an inducement award agreement outside of the company's 2014 Stock Option and Incentive Plan as a material inducement to the reporting person's acceptance of employment with the company in accordance with NASDAQ Listing Rule 5635(c)(4). /s/ Laurie Burlingame, Attorney-in-Fact 2017-12-29