BVF PARTNERS L P/IL bought IMUX

Footnotes

This Form 4 is filed jointly by Biotechnology Value Fund, L.P. ("BVF"), Biotechnology Value Fund II, L.P. ("BVF2"), Biotechnology Value Trading Fund OS LP ("Trading Fund OS"), BVF Partners OS Ltd. ("Partners OS"), BVF I GP LLC ("BVF GP"), BVF II GP LLC ("BVF2 GP"), BVF GP Holdings LLC ("BVF GPH"), BVF Partners L.P. ("Partners"), BVF Inc. and Mark N. Lampert (collectively, the "Reporting Persons"). Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein except to the extent of his or its pecuniary interest therein.; The option vests in monthly increments over a period of one year from the grant date.; Partners, BVF Inc. and Mr. Lampert may be deemed to have a pecuniary interest in the securities reported owned herein due to a certain agreement between Partners and R. Thorvald Nagel, who serves on the Issuer's board of directors and as a Principal of Partners, pursuant to which Mr. Nagel is obligated to transfer the economic benefit, if any, received upon the sale of the shares issuable upon exercise of the securities reported owned herein to Partners. As such, Mr. Nagel disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein.