Trillium Therapeutics Inc. — Proxy Solicitation & Information Statement 2021

Sep 27, 2021

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Trillium Therapeutics, Inc. • SVC_XPP_Composer • 09/24/21 @ 17:15 p.m. (es#:120)

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100 CambridgePark Drive, Suite 510 Cambridge, MA 02140

NOTICE OF SPECIAL MEETING OF SHAREHOLDERS AND WARRANT HOLDERS

To Be Held on Tuesday, October 26, 2021

NOTICE IS HEREBY GIVEN, in accordance with an interim order (the “Interim Order”) of the Supreme Court of British Columbia (the “Court”) dated September 20, 2021, that a special meeting (the “Meeting”) of the holders of common shares (the “Common Shareholders”), the holders of Series II NonVoting Convertible First Preferred Shares (the “First Preferred Holders” and together with the Common Shareholders, the “Shareholders”), and the holders of common share purchase warrants and Series II NonVoting Convertible First Preferred Share purchase warrants (the “Warrant Holders” and together with the Shareholders, the “Securityholders”) of Trillium Therapeutics Inc. (“Trillium”) will be held on Tuesday, October 26, 2021, at 1:00 p.m. (Toronto time). The Meeting will be conducted as a virtual-only meeting. Shareholders and Warrant Holders as of the Record Date (as defined below) and duly appointed proxyholders may attend the virtual Meeting at https://meetnow.global/MRQH66P. The Meeting will be held for the following purposes:

1. to consider, pursuant to the Interim Order, and, if deemed advisable, to pass, with or without variation, a special resolution (the “Arrangement Resolution”), the full text of which is set forth in Appendix B to the accompanying Management Information Circular and Proxy Statement of Trillium (the “Information Circular”), approving a statutory arrangement (the “Arrangement”) under Division 5 of Part 9 of the Business Corporations Act (British Columbia) (the “BCBCA”), all as more particularly described in the Information Circular;

2. to consider and, if deemed advisable, pass an advisory (non-binding) resolution on specified compensation that may become payable to the named executive officers of Trillium in connection with the Arrangement, all as more particularly described in the Information Circular; and

3. to transact such other business, including amendments to the foregoing, as may properly be brought before the Meeting or any adjournment or postponement thereof.

Shareholders and Warrant Holders at the close of business of September 24, 2021 (the “Record Date”) will be entitled to vote at the Meeting. Only Registered Securityholders (as defined in the Information Circular) as at the close of business on the Record Date or their duly appointed proxyholders are entitled to receive notice of, attend and vote at the Meeting, and any adjournment or postponement of the Meeting. If a Beneficial Securityholder (as defined in the Information Circular) wishes to attend and vote at the Meeting in person (or have another attend and vote on the Beneficial Securityholder’s behalf), such Beneficial Securityholder must complete, sign and return a voting instruction form in accordance with the directions provided.

Due to ongoing concerns related to the spread of COVID-19 and in order to protect the health and safety of Trillium’s shareholders, employees, other stakeholders and the community in general, the Meeting will be held virtually. Shareholders and Warrant Holders can participate online using their smartphone, tablet or computer. Shareholders and Warrant Holders will need the latest version of Chrome, Safari, Edge or Firefox. By participating online, Shareholders and Warrant Holders will be able to listen to a live webcast of the Meeting and Registered Securityholders can ask questions online and submit votes in real time.

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Pursuant to the BCBCA and the Interim Order, in order for the Arrangement Resolution to become effective, the Arrangement Resolution must be passed by: (i) an affirmative vote of at least two-thirds (66[2] ∕3%) of the votes cast by Shareholders, voting as a single class, present in person or represented by proxy at the Meeting and entitled to vote thereat, each being entitled to one vote per share; and (ii) an affirmative vote of at least two-thirds (66[2] ∕3%) of the votes cast by Shareholders and Warrant Holders, voting as a single class, present in person or represented by proxy at the Meeting and entitled to vote thereat, each being entitled to one vote per share and one vote per share underlying each warrant, respectively.

This Notice of Special Meeting to Shareholders and Warrant Holders is accompanied by the Information Circular, a form of proxy or voting instruction form, as applicable and a form of letter of transmittal (a “Letter of Transmittal”).

A summary of the arrangement agreement dated August 20, 2021 entered into among Trillium, PF Argentum Acquisition ULC and Pfizer Inc. (the “Arrangement Agreement”) and the plan of arrangement (the “Plan of Arrangement”) is included in the Information Circular, and the full text thereof is attached as Appendix A and Appendix C, respectively, to the Information Circular and is also available under Trillium’s profile on the System for Electronic Document Analysis and Retrieval (“SEDAR”) at www.sedar.com and on the Electronic Data Gathering, Analysis, and Retrieval system (“EDGAR”) at www.sec.gov/edgar. The full text of the Interim Order is attached as Appendix D to the Information Circular. Securityholders should carefully review and consider all of the information in the Information Circular.

Pursuant to and in accordance with the Interim Order and the provisions of Sections 237 to 247 of the BCBCA (as modified or supplemented by the Interim Order, the Plan of Arrangement and any other order of the Court), Registered Securityholders have a right to dissent with respect to the Arrangement Resolution and, if the Arrangement becomes effective, to be paid the fair value of their Shares and/or Warrants (as such terms are defined in the Information Circular), less any applicable tax withholdings (the “Dissent Rights”). Dissent Rights are more particularly described in the Information Circular. The dissent procedures require that a Registered Securityholder who wishes to exercise Dissent Rights send Trillium a written notice to inform Trillium of his, her or its intention to exercise Dissent Rights (the “Dissent Notice”), which notice must be received by Trillium at its office located at 100 CambridgePark Drive, Suite 510, Cambridge, Massachusetts 02140, United States, Attention: Benjamin Looker, General Counsel and Secretary, with a copy to Trillium’s legal counsel, Baker & McKenzie LLP, 181 Bay Street, Suite 2100, Toronto, Ontario M5J 2T3, Canada, Attention: David Palumbo, not later than 5:00 p.m. (Vancouver time) on the day that is two business days immediately preceding the date of the Meeting (as it may be adjourned or postponed from time to time). Persons who are Beneficial Securityholders who wish to exercise Dissent Rights should be aware that only Registered Securityholders are entitled to exercise Dissent Rights. Accordingly, a Beneficial Securityholder who desires to exercise Dissent Rights must make arrangements for the Shares and/or Warrants beneficially owned by such holder to be registered in the holder’s name prior to the time the Dissent Notice is required to be received by Trillium or, alternatively, make arrangements for the registered holder of such Shares and/or Warrants to exercise Dissent Rights on the holder’s behalf. It is strongly suggested that any Securityholder wishing to dissent seek independent legal advice, as the failure to comply strictly with the provisions of Sections 237 to 247 of the BCBCA (as modified by the Interim Order, the Plan of Arrangement and any other order of the Court) may result in the loss of all rights thereunder.

If you are a Registered Securityholder and are unable to attend the Meeting, please complete, date, sign and return the enclosed form of proxy. Instructions on how to complete and return your proxy are included in the form of proxy and in the Information Circular. To be effective, the proxy form must be deposited with Trillium’s transfer agent, Computershare Investor Services Inc.: (i) by mail or courier, using the enclosed return envelope or one addressed to Computershare Investor Services Inc., Proxy Department, 8th Floor, 100 University Avenue, Toronto, Ontario M5J 2Y1; (ii) by delivery to Computershare Investor Services Inc., 8th Floor, 100 University Avenue, Toronto, Ontario M5J 2Y1; (iii) by telephone to 1-866-732-VOTE (8683) (toll free within North America) or to 1-312-588-4290 (outside North America); or (iv) through the internet by using the control number located at the bottom of your proxy form at www.investorvote.com, on or before 1:00 p.m. (Toronto time) on October 22, 2021 or, if the Meeting is adjourned or postponed, at least 48 hours (excluding Saturdays, Sundays and holidays) before the time that the Meeting is reconvened.

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If you are a Registered Securityholder, please also complete the accompanying Letter of Transmittal in accordance with the instructions included therein, date, sign and return it to the Depositary, Computershare Investor Services Inc., in the postage-prepaid envelope provided, together with the certificate(s) representing such Registered Securityholder’s Shares and/or Warrants and any other required documents. The Letter of Transmittal contains complete instructions on how to exchange the certificate(s) representing a Registered Securityholder’s Shares and/or Warrants for the Consideration (as defined in the Information Circular) payable for such Registered Securityholder’s Shares and/or Warrants pursuant to the Plan of Arrangement. Registered Securityholders will not receive their Consideration under the Arrangement until after the Arrangement is completed and until such Registered Securityholder has returned their properly completed documents, including the Letter of Transmittal, and the certificate(s) representing such Registered Securityholder’s Shares and/or Warrants to the Depositary. Please do NOT enclose or return your certificate(s) with your form of proxy.

Beneficial Securityholders that receive the Meeting materials through their broker or through another intermediary must complete and return the enclosed voting instruction form in accordance with the instructions provided to such Beneficial Securityholder by their intermediary to ensure that their Shares and/or Warrants are voted at the Meeting in accordance with their instructions. In addition, Beneficial Securityholders should contact their intermediary to arrange for such intermediary to complete the necessary transmittal documents (including the Letter of Transmittal) and to ensure that they receive the Consideration for their Shares and/or Warrants through such intermediary if the Arrangement is completed.

Further voting information can be found in the Information Circular.

A Shareholder or Warrant Holder that has questions or requires more information with regard to the voting of their Shares and/or Warrants should contact Trillium’s proxy solicitation agent, MacKenzie Partners, Inc. by calling toll-free at 800-322-2885 or collect at 212-929-5500.

DATED as of the 27[th] day of September, 2021

BY ORDER OF THE BOARD OF DIRECTORS

/s/ Dr. Jan Skvarka

Dr. Jan Skvarka

Director, President and Chief Executive Officer