Chen Bihua bought BLSM

Footnotes

The shares purchased are beneficially owned by Master Fund.; Represents an aggregate of (i) 959,090 shares beneficially owned by Master Fund, (ii) 1,228,315 shares beneficially owned by Fund III, (iii) 1,052,460 shares beneficially owned by Fund V, and (vi) 374,169 beneficially owned by Fund VI.; Cormorant Asset Management, LP ("Cormorant") serves as the investment manager of Cormorant Global Healthcare Master Fund, LP (the "Master Fund"), Cormorant Private Healthcare Fund III, LP ("Fund III"), Cormorant Private Healthcare Fund V, LP ("Fund V") and Cormorant Private Healthcare Fund VI, LP ("Fund VI"). Cormorant Global Healthcare GP, LLC ("GP LLC"), Cormorant Private Healthcare GP III, LLC ("GP III"), Cormorant Private Healthcare GP V, LLC ("GP V") and Cormorant Private Healthcare GP VI, LLC ("GP VI") serve as General Partner of the Master Fund, Fund III, Fund V and Fund VI, respectively.; Bihua Chen serves as manager of Cormorant, GP LLC, GP III, GP V and GP VI. Each of the Reporting Persons disclaims beneficial ownership of the shares reported herein except to the extent of its or her pecuniary interest therein, and the filing of this Form 4 shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any such shares for purposes of Section 16(a) of the Securities Exchange Act of 1934 or for any other purpose.