|(a)||Amount beneficially owned:|
The Reporting Persons hold 3,999,998
warrants, convertible for an aggregate of 3,999,998 shares of Common Stock (the “Warrants”). Each Warrant is convertible
into 1 share of Common Stock. The Reporting Persons have elected to implement blocker language for the Warrants that restrict exercise
of the Warrants if, after such exercise, the Reporting Persons would beneficially own, as determined in accordance with Section
13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”), more than 9.99% of the number of shares of Common
Stock then issued and outstanding (the “Beneficial Ownership Limitation”). As of the date hereof, the Warrant exercise
limitation described in the prior sentence limits the aggregate exercise of Warrants by the Reporting Persons to 1,379,838 out
of the 3,999,998 shares of Common Stock underlying the Warrants owned by the Reporting Persons in the aggregate. In providing beneficial
ownership described herein, the Reporting Persons have assumed only certain Warrants owned by BVF would be fully exercised, and
the remaining Warrants held by BVF, BVF 2, Trading Fund OS and those in the Partners Managed
Accounts would remain unexercised, thereby bringing the Reporting Persons to the aggregate 9.99% limitation.
In addition to the Warrants, the Reporting
Persons hold $10,000,000 of the Issuer’s 2.75% convertible senior notes due 2020 (the “Convertible Notes”) convertible
into approximately 122,122 shares of Common Stock based on a ratio of 12.21225 shares of Common Stock for each $1,000 principal
amount of Convertible Notes. In providing beneficial ownership described herein, the Reporting Persons have assumed that all Convertible
Notes would be converted.
The Reporting Persons may choose to
convert or exercise, as applicable, the Warrants or Convertible Notes in other amounts among the Reporting Persons, while continuing
to comply with the Beneficial Ownership Limitation.
As of the date hereof, (i) BVF beneficially
owned 1,687,702 shares of Common Stock, including 56,518 shares of Common Stock issuable upon the conversion of Convertible Notes
held by it and including 1,379,838 shares of Common Stock issuable upon the exercise of Warrants held by it; (ii) BVF2 beneficially
owned 204,343 shares of Common Stock including 36,978 shares of Common Stock issuable upon the conversion of Convertible Notes
held by it, and (iii) Trading Fund OS beneficially owned 54,099 shares of Common Stock including 11,076 shares of Common Stock
issuable upon the conversion of Convertible Notes held by it.
Partners OS, as the general partner
of Trading Fund OS, may be deemed to beneficially own the 54,099 shares of Common Stock beneficially owned by Trading Fund OS.
Partners, as the general partner of
BVF, BVF2, the investment manager of Trading Fund OS, and the sole member of Partners OS, may be deemed to beneficially own the
2,036,860 shares of Common Stock beneficially owned in the aggregate by BVF, BVF2, Trading Fund OS, and certain Partners Managed
Accounts (the “Partners Managed Accounts”), including 90,715 shares of Common Stock held in the Partners Managed Accounts
including $1,437,000 Convertible Notes held in the Partners Managed Accounts convertible into approximately 17,549 shares of Common
BVF Inc., as the general partner of
Partners, may be deemed to beneficially own the 2,036,860 shares of Common Stock beneficially owned by Partners.