KYNTRA BIO, INC.

FIBROGEN, INC. 350 BAY ST, STE 100 # 6009 SAN FRANCISCO, CA 94133 VOTE ONLINE Before The Meeting - Go towww.proxyvote.comor scan the QR Barcode above Use the Internet to transmit your voting instructions and for electronic delivery of information up until 11:59 p.m. Eastern Time on June 3, 2025. Have your proxy card available when you access the website and then follow the instructions to cast your vote. During The Meeting - Go towww.virtualshareholdermeeting.com/FGEN2025 You may attend the meeting via the Internet and vote during the meeting. Have the information that is printed in the box marked by the arrow available and follow the instructions on your proxy card. VOTE BY PHONE - 1-800-690-6903 Use any touch-tone telephone to transmit your voting instructions up until 11:59 p.m. Eastern Time on June 3, 2025. Have your proxy card available when you call and then follow the instructions to cast your vote. VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717. We must receive it by June 3, 2025 for your vote to be counted. ELECTRONIC DELIVERY OF FUTURE PROXY MATERIALS If you would like to reduce the environmental impact of and the costs incurred by our company in mailing proxy materials, you can consent to receive all future proxy statements, proxy cards, and annual reports electronically via email or access them online. To sign up for electronic delivery, please follow the instructions above to vote online and, when prompted, indicate that you agree to receive or access proxy materials electronically in future years. TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: V71727-P30542 KEEP THIS PORTION FOR YOUR RECORDS THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. DETACH AND RETURN THIS PORTION ONLY FIBROGEN, INC. The Board of Directors recommends you vote FOR 1. To elect a Class II director to hold office until the 2028 Annual Meeting of Stockholders. Nominee: 1a. Jeffrey L. Edwards For Withhold For Against Abstain 2. To approve a reverse stock split of FibroGen, Inc.'s common stock, including granting our board of directors discretion to determine the final ratio and timing. 3. To approve, on an advisory basis, the compensation of the Company’s named executive officers. 4. To ratify the selection, by the Audit Committee of the Board, of PricewaterhouseCoopers LLP as the independent registered public accounting firm of the Company for the year ending December 31, 2025. 5. To conduct any other business properly brought before the meeting. The shares represented by this proxy, when properly executed, will be voted in the manner directed herein by the undersigned stockholder(s). If no direction is made, this proxy will be voted FOR proposals 1, 2, 3, and 4. If any other matters properly come before the meeting, or if cumulative voting is required, the persons named in this proxy will vote in their discretion. Please sign your name exactly as it appears hereon. When signing as attorney, executor, administrator, trustee or guardian, please add your full title as such. When signing as joint owners, all owners must sign. If a signer is a corporation, please sign in full corporate name by a duly authorized officer. Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting: The Notice and Proxy Statement and Annual Report on Form 10-K are available atwww.proxyvote.com. ANNUAL MEETING OF STOCKHOLDERS June 4, 2025 8:00 AM Pacific Time THIS PROXY IS SOLICITED BY THE BOARD OF DIRECTORS The stockholder(s) hereby appoint(s) Thane Wettig and John Alden, or either of them, as proxies, each with the power to appoint his substitute, and hereby authorize(s) each of them to represent and to vote, as designated on the reverse side of this ballot, all of the shares of Common Stock of FibroGen, Inc. that the stockholder(s) is/are entitled to vote at the Annual Meeting of Stockholders to be held at 8:00 AM Pacific Time on June 4, 2025, atwww.virtualshareholdermeeting.com/FGEN2025, and any adjournment or postponement thereof. THIS PROXY, WHEN PROPERLY EXECUTED, WILL BE VOTED IN THE MANNER AS DIRECTED BY THE STOCKHOLDER(S). IF NO SUCH DIRECTION IS MADE, THIS PROXY WILL BE VOTED FOR THE ELECTION OF THE NOMINEE LISTED ON THE REVERSE SIDE FOR THE BOARD OF DIRECTORS IN PROPOSAL 1 AND FOR PROPOSALS 2, 3, AND 4. IN THEIR DISCRETION, THE PROXIES ARE AUTHORIZED TO VOTE UPON SUCH OTHER BUSINESS AS MAY PROPERLY COME BEFORE THE MEETING. PLEASE MARK, SIGN, DATE, AND RETURN THIS PROXY CARD PROMPTLY USING THE ENCLOSED REPLY ENVELOPE. CONTINUED AND TO BE SIGNED ON REVERSE SIDE V71728-P30542