X0306 4 2018-04-16 false 0001656328 Sienna Biopharmaceuticals, Inc. SNNA 0001559583 Smither John W C/O SIENNA BIOPHARMACEUTICALS, INC. 30699 RUSSELL RANCH ROAD, SUITE 140 WESTLAKE VILLAGE CA 91362 false true false false Chief Financial Officer Stock Option (Right to Buy) 19.59 2018-04-16 4 A false 170000.00 0.00 A 2028-04-16 Common Stock 170000.00 170000.00 D The underlying shares subject to the option will vest as follows: i) 20,000 shares subject to the option vest and become exercisable upon satisfaction of a performance-based milestone and ii) 150,000 shares subject to the option vest and become exercisable with respect to 25% of 150,000 shares on the first anniversary measured from April 16, 2018, and the remaining shares subject to the option vest and become exercisable in 36 successive, equal monthly installments thereafter, subject to the Reporting Person's continued employment or service relationship with the Issuer on each such vesting date. /s/ Timothy K. Andrews, attorney-in-fact for John W. Smither 2018-04-18