ORBIMED ADVISORS LLC bought QTTB

Footnotes

These shares of the Issuer's common stock were purchased from the Issuer in a private placement.; These securities are held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis"). OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis and OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by Genesis and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by Genesis.; This report on Form 4 is jointly filed by OrbiMed Advisors, OrbiMed GP, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. The Reporting Persons have designated a representative, Diyong Xu, an employee of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any such person or entity, including the Reporting Persons, is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.