Trillium Therapeutics Inc. — Capital/Financing Update 2020

Sep 18, 2020

FORM 51-102F3 MATERIAL CHANGE REPORT

Item 1. Name and Address of Company

Trillium Therapeutics Inc. (the “ Company ” or “ Trillium ”) 2488 Dunwin Drive Mississauga, Ontario L5L 1J9

Item 2. Dates of Material Changes

September 8, 2020, September 10, 2020, September 16, 2020, and September 18, 2020

Item 3. News Releases

The news releases dated September 8, 2020, September 10, 2020, September 16, 2020, and September 18, 2020 were disseminated through the services of GlobeNewswire and were filed on the System for Electronic Document Analysis and Retrieval (“ SEDAR ”). Copies of the news releases are available under the Company’s profile on SEDAR at www.sedar.com.

Item 4. Summary of Material Changes

On September 8, 2020, Trillium announced updated data from its ongoing TTI-622 and TTI-621 dose escalation studies:

• TTI-622 (SIRP a -IgG4 Fc) completed 8 mg/kg safety assessment in the ongoing dose escalation study in relapsed/refractory lymphoma; now escalating to 12 mg/kg dose level.

• TTI-622 monotherapy shows 6/18 (33%) objective responses at 0.8 to 8 mg/kg dose levels, including 3/6 (50%) objective responses at 8 mg/kg.

• TTI-621 (SIRPa -IgG1 Fc) well tolerated at 1.4 mg/kg; continues to show monotherapy signal and dose-dependent improvement in skin disease scores in the ongoing dose escalation study in relapsed/refractory CTCL.

Trillium announced on September 8, 2020 that it had agreed to sell 2,297,794 of its common shares at a price of $10.88 per share to Pfizer Inc. (NYSE: PFE), for gross proceeds of $25.0 million (the “Transaction”). The common shares were offered and sold to Pfizer Inc. in a registered direct offering conducted without an underwriter or placement agent. The transaction closed on September 10, 2020. The common shares were offered by means of a prospectus supplement dated September 8, 2020 and accompanying prospectus dated May 4, 2020, forming a part of the Company’s effective shelf registration statement (File No. 333-237810).

On September 10, 2020, Trillium announced that it priced its previously announced underwritten public offering of 10,000,000 common shares (the “Common Shares”) of the Company (the “Offering”). The Common Shares were sold at a public offering price of US$13.00 per Common Share. In connection with the Offering, Trillium granted the underwriters a 30-day option to purchase up to an additional 1,500,000 Common Shares. The gross proceeds to the Company from the Offering were expected to be approximately $130 million, before deducting underwriting discounts and commissions and other estimated offering expenses. The Offering closed on September 16, 2020 The common shares were offered by means of a prospectus supplement dated September 10, 2020 and accompanying prospectus dated May 4, 2020, forming a part of the Company’s effective shelf registration statement (File No. 333-237810). The Company intends to use the net proceeds of the Transaction and the Offering for its ongoing and planned clinical trials for its CD47 program, including drug supply and for working capital and general corporate purposes.

On September 16, 2020, Trillium announced the closing of its previously announced underwritten public offering of common shares of the Company at a public offering price of US$13.00 per common share (the

“Offering”). 11,500,000 common shares were sold in the Offering, including the full exercise by the underwriters of their option to purchase up to an additional 1,500,000 common shares. The gross proceeds from the Offering were US$149,500,000, before deducting underwriting commissions and other offering expenses.

On September 18, 2020, Trillium announced the appointment of pharmaceutical industry leader Michael Kamarck, Ph.D., to its Board of Directors, effective immediately.

Item 5.1. Full Description of Material Change

See attached press releases as Schedule A, Schedule B, Schedule C, Schedule D, and Schedule E.

Item 5.2. Disclosure for Restructuring Transactions

Not applicable.

Item 6. Reliance on subsection 7.1(2) of National Instrument 51-102

Not applicable.

Item 7. Omitted Information

No information has been omitted from this material change report on the basis that it is confidential.

Item 8. Executive Officer

James Parsons Chief Financial Officer Tel: (416) 595-0627 x 232 Email: james@trilliumtherapeutics.com

Item. 9 Date of Report

September 18, 2020

Schedule “A”

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FOR IMMEDIATE RELEASE

NASDAQ: TRIL TSX: TRIL

TRILLIUM THERAPEUTICS ANNOUNCES UPDATED DATA FROM ITS ONGOING TTI-622 AND TTI-621 DOSE ESCALATION STUDIES

• TTI-622 (SIRPα-IgG4 Fc) completed 8 mg/kg safety assessment in the ongoing dose escalation study in relapsed/refractory lymphoma; now escalating to 12 mg/kg dose level.

• TTI-622 monotherapy shows 6/18 (33%) objective responses at 0.8 to 8 mg/kg dose levels, including 3/6 (50%) objective responses at 8 mg/kg.

• TTI-621 (SIRPα-IgG1 Fc) well tolerated at 1.4 mg/kg; continues to show monotherapy signal and dose-dependent improvement in skin disease scores in the ongoing dose escalation study in relapsed/refractory CTCL.

• Trillium to host conference call at 5:30 p.m. ET today

CAMBRIDGE, MA, September 8, 2020 – Trillium Therapeutics Inc. (“Trillium” or the “Company”) (NASDAQ/TSX: TRIL), a clinical stage immuno-oncology company developing innovative therapies for the treatment of cancer, today announced updated data from its ongoing TTI-622 and TTI-621 dose escalation studies.

“We are exceedingly encouraged by the evolving profile of TTI-622, our SIRPα-IgG4 Fc fusion protein, as demonstrated in the ongoing dose escalation study in relapsed and refractory lymphomas,” said Jan Skvarka, Trillium’s President and Chief Executive Officer. “TTI-622 is showing substantial monotherapy activity in highly pre-treated patients, with a broad therapeutic window, a rapid onset of action, and across a range of lymphoma indications. With no significant safety signals observed, we are further escalating the dose. TTI-621, our SIRPα-IgG1 Fc fusion protein, is showing a strong safety profile, and we have not observed any dose limiting thrombocytopenia for doses up to 1.4 mg/kg. We continue to see a monotherapy activity signal, and are further dose escalating to characterize clinical activity at higher doses. We expect to declare maximum tolerated doses or recommended phase 2 doses for both molecules either towards the end of this year or in the first half of 2021. Abstracts for both trials have been submitted to the American Society of Hematology annual meeting, and we look forward to presenting further details and additional data in December.”

TTI-622 Study Update:

• TTI-622 is being evaluated in a two-part, multicenter, open-label, phase 1a/1b study in patients with advanced relapsed or refractory lymphoma or multiple myeloma (NCT03530683).

• In the phase 1a portion of the study, the safety assessment of the 8 mg/kg dosing cohort has been successfully completed. One Grade 4 thrombocytopenia dose-limiting toxicity (DLT) was reported among the six evaluable patients; no additional Grade 3 or higher thrombocytopenia events have been observed.

• A total of six objective responses (33%; 1 complete response, 5 partial responses) have been observed among 18 response evaluable patients treated at dose levels of 0.8, 2.0, 4.0 and 8.0 mg/kg. Responses have occurred across all dose levels in this range, with three of six (50%) patients achieving responses in the 8.0 mg/kg cohort (response assessment for one additional patient at 8 mg/kg dose not yet available).

• Clinical responses have been observed across multiple lymphoma indications, including diffuse large B-cell lymphoma, cutaneous T-cell lymphoma with large cell transformation, peripheral T-cell lymphoma, and follicular lymphoma.

• All responses were observed at the first assessment at 8 weeks.

• The study is currently enrolling patients at the 12 mg/kg dose level.

TTI-621 Study Update:

• TTI-621 is being evaluated in a four-part, multicenter, open-label phase 1 study in patients with advanced relapsed or refractory hematologic malignancies (NCT02663518). In the ongoing Part 4, TTI-621 dosing is being escalated beyond 0.5 mg/kg in patients with cutaneous T-cell lymphoma.

• Preliminary data from Part 4 indicate the weekly infusions of TTI-621 up to 1.4 mg/kg are well tolerated without dose-limiting thrombocytopenia. Platelet decreases generally occurred on dosing days, recovered in 2-4 days, and have not worsened with increasing dose levels. Infusion-related reactions (IRRs) typically occurred during initial infusions and often resolved without recurrence. One Grade 3 IRR DLT was observed at 1.0 mg/kg.

• Antitumor activity in the 1 mg/kg cohort includes 1 partial response and 1 skin complete response (overall assessment stable disease) in 6 evaluable patients; 2 patients were bridged to allogeneic transplantation. Preliminary data suggest dose-dependent improvements in modified severity weighted assessment tool (mSWAT) scores in the 0.5 to1.0 mg/kg cohorts (1.4 mg/kg cohort data not yet available).

• The study is currently enrolling patients at the 2.0 mg/kg dose level.

Webcast Information:

Trillium will host a live conference call and webcast at 5:30 p.m. ET today to discuss this clinical data update. The conference call may be accessed by (833) 670-0758 and with conference ID 7695694. The webcast may be accessed on Trillium’s Events and Presentations page at https://ir.trilliumtherapeutics.com/events-and-presentations or at

https://event.on24.com/wcc/r/2645255/C032FE41D7E0F23D4D47E9DFA2D71982. The archived webcast will be available on Trillium’s website for 30 days following the call.

About Trillium Therapeutics

Trillium is an immuno-oncology company developing innovative therapies for the treatment of cancer. The company’s two clinical programs, TTI-621 and TTI-622, target CD47, a “don’t eat me” signal that cancer cells frequently use to evade the immune system.

For more information visit: www.trilliumtherapeutics.com

Caution Regarding Forward-Looking Information

This press release contains forward-looking statements within the meaning of applicable United States securities laws and forward-looking information within the meaning of Canadian securities laws (collectively, "forward-looking statements"). Forward-looking statements in this press release include statements about, without limitation, the expected timing of the release of further data on Trillium’s TTI-621 and TTI-622 studies, and timing of expected maximum tolerated doses or recommended phase 2 doses. With respect to the forward-looking statements contained in this press release, Trillium has made numerous assumptions regarding, among other things: the impact of the Covid-19 pandemic on its operations, the effectiveness and timeliness of preclinical and clinical trials; and the completeness, accuracy and usefulness of the data. While Trillium considers these assumptions to be reasonable, these assumptions are inherently subject to significant scientific, business, economic, competitive, market and social uncertainties and contingencies. Additionally, there are known and unknown risk factors that could cause Trillium's actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements contained in this press release. A discussion of risks and uncertainties facing Trillium appears in Trillium's Annual Information Form for the year ended December 31, 2019 filed with Canadian securities authorities and on Form 40-F with the U.S. Securities Exchange Commission, each as updated by Trillium's continuous disclosure filings, which are available at www.sedar.com and at www.sec.gov. All forward-looking statements herein are qualified in their entirety by this cautionary statement, and Trillium disclaims any obligation to revise or update any such forward-looking statements or to publicly announce the result of any revisions to any of the forward-looking statements contained herein to reflect future results, events or developments, except as required by law.

Investor Relations:

James Parsons Chief Financial Officer Trillium Therapeutics Inc. 416-595-0627 x232 james@trilliumtherapeutics.com www.trilliumtherapeutics.com

Media Relations: Mike Beyer Sam Brown Inc. 312-961-2502 mikebeyer@sambrown.com

Schedule “B”

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FOR IMMEDIATE RELEASE

NASDAQ: TRIL TSX: TRIL

TRILLIUM THERAPEUTICS ANNOUNCES $25 MILLION EQUITY INVESTMENT FROM PFIZER INC.

• Pfizer invests $25 million in Trillium common shares at $10.88 per share

• Jeff Settleman, PhD, Pfizer’s Chief Scientific Officer for Oncology Research & Development, to join Trillium Scientific Advisory Board, currently being formed

CAMBRIDGE, MA, September 8, 2020 – Trillium Therapeutics Inc. (“Trillium” or the “Company”) (NASDAQ/TSX:TRIL), a clinical stage immuno-oncology company developing innovative therapies for the treatment of cancer, today announced that it has agreed to sell 2,297,794 of its common shares at a price of $10.88 per share to Pfizer Inc. (NYSE: PFE), for gross proceeds of $25.0 million (the “ Transaction ”). The common shares were offered and sold to Pfizer Inc. in a registered direct offering conducted without an underwriter or placement agent. The offering is expected to close on or about September 10, 2020.

In addition, Dr. Jeff Settleman, Senior Vice President and Chief Scientific Officer, Oncology, Worldwide Research, Development & Medical, Pfizer, has agreed to join Trillium’s Scientific Advisory Board (SAB), once formed. It is anticipated that the SAB will be announced later this year. The SAB will work closely with Trillium’s senior management team to guide the Company’s scientific and clinical strategic priorities.

Trillium intends to use the net proceeds of the offering to help fund its ongoing and planned clinical trials for its CD47 program, and for working capital and general corporate purposes.

The closing of the Transaction will be subject to customary closing conditions, including the listing of the common shares on the Toronto Stock Exchange (“ TSX ”) and the Nasdaq Capital Market (“ Nasdaq ”) and any required approvals of each exchange. For the purposes of the TSX approval, the Company intends to rely on the exemption set forth in Section 602.1 of the TSX Company

Manual, which provides that the TSX will not apply its standards to certain transactions involving eligible interlisted issuers on a recognized exchange, such as the Nasdaq.

The common shares were offered by means of a prospectus supplement dated September 8, 2020 and accompanying prospectus dated May 4, 2020, forming a part of the Company’s effective shelf registration statement (File No. 333-237810). The prospectus supplement and accompanying prospectus relating to this offering will be filed with the U.S. Securities and Exchange Commission (the “SEC”) and will be available on the SEC’s website at www.sec.gov.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy the common shares, nor shall there be any sale of the common shares in any state or other jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such state or other jurisdiction.

About Trillium Therapeutics

Trillium is an immuno-oncology company developing innovative therapies for the treatment of cancer. The company’s two clinical programs, TTI-621 and TTI-622, target CD47, a “don’t eat me” signal that cancer cells frequently use to evade the immune system.

For more information visit: www.trilliumtherapeutics.com

Caution Regarding Forward-Looking Information

This press release contains forward-looking statements within the meaning of applicable United States securities laws and forward-looking information within the meaning of Canadian securities laws (collectively, “ forward-looking statements ”). Forward-looking statements in this press release include, without limitation, statements relating to Trillium’s plans to consummate the Transaction and the intended use of proceeds therefrom, the planned reliance on the exemption set forth in Section 602.1 of the TSX Company Manual and the formation of the SAB and the members thereto. There can be no assurances that Trillium will be able to complete the Transaction on the anticipated terms, or at all. You should not place undue reliance on these forward-looking statements. Actual results may differ materially from those projected or implied in these forwardlooking statements. Factors that may cause such a difference include, without limitation, risks and uncertainties related to the final terms of the Transaction, market and other conditions, the satisfaction of customary closing conditions related to the Transaction, the impact of general economic, industry or political conditions in the United States, Canada or elsewhere internationally, and the risks and uncertainties facing Trillium set forth in the prospectus supplement dated September 8, 2020 and Trillium’s Annual Information Form for the year ended December 31, 2019 filed with Canadian securities authorities and on Form 40-F with the U.S. Securities Exchange Commission, each as updated by Trillium’s continuous disclosure filings, which are available at www.sedar.com and at www.sec.gov. All forward-looking statements herein are qualified in their entirety by this cautionary statement, and Trillium disclaims any obligation to revise or update any such forward-looking statements or to publicly announce the result of any revisions to any of the forward-looking statements contained herein to reflect future results, events or developments, except as required by law.

Company Contact: James Parsons Chief Financial Officer Trillium Therapeutics Inc. 416-595-0627 x232 james@trilliumtherapeutics.com www.trilliumtherapeutics.com

Media Contact: Mike Beyer Sam Brown Inc. 312-961-2502 mikebeyer@sambrown.com

Schedule “C”

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FOR IMMEDIATE RELEASE NASDAQ: TRIL TSX: TRIL

TRILLIUM ANNOUNCES PRICING OF US$130 MILLION PUBLIC OFFERING OF COMMON SHARES

CAMBRIDGE, MA, September 10, 2020 - Trillium Therapeutics Inc. (“Trillium” or the “Company”) (NASDAQ/TSX: TRIL) , a clinical stage immuno-oncology company developing innovative therapies for the treatment of cancer, today announced that it has priced its previously announced underwritten public offering of 10,000,000 common shares (the “ Common Shares ”) of the Company (the “ Offering ”). The Common Shares are being sold at a public offering price of US$13.00 per Common Share.

In connection with the Offering, Trillium has granted the underwriters a 30-day option to purchase up to an additional 1,500,000 Common Shares.

The gross proceeds to the Company from the Offering are expected to be approximately US$130 million, before deducting underwriting discounts and commissions and other estimated offering expenses. The Offering is expected to close on or around September 16, 2020, subject to the satisfaction of customary closing conditions.

The Company intends to use the net proceeds of the Offering for its ongoing and planned clinical trials for its CD47 program, including drug supply and for working capital and general corporate purposes.

Cowen and Evercore ISI are acting as joint book-running managers for the Offering. JMP Securities is acting as the lead manager and Ladenburg Thalmann and JonesTrading are acting as co-managers for the Offering.

No Common Shares will be offered or sold in Canada as part of this Offering. The Offering is subject to market conditions, as well as a number of closing conditions, including Nasdaq Capital Market (“ Nasdaq ”) and Toronto Stock Exchange (“ TSX ”) approvals, and there can be no assurance as to whether or when the Offering may be completed. For the purposes of TSX approval, the Company intends to rely on the exemption set forth in Section 602.1 of the TSX Company Manual, which provides that the TSX will not apply its standards to certain transactions involving eligible inter-listed issuers on a recognized exchange, such as Nasdaq.

The Offering is being made to purchasers outside of Canada pursuant to a U.S. registration statement on Form F-3 (File No. 333-237810), declared effective by the United States Securities and Exchange Commission (the “ SEC ”) on May 4, 2020. A preliminary prospectus supplement dated September 9, 2020

has been filed with SEC relating to the Offering and a final prospectus supplement relating to the Offering will be filed with the SEC.

Before you invest, you should read the final prospectus supplement and the other documents the Company has filed for more complete information about the Company and the Offering. Copies of the final prospectus supplement will be available for free by visiting the SEC’s website at www.sec.gov or the Company’s profiles on the SEDAR website maintained by the Canadian Securities Administrators at www.sedar.com. Alternatively, copies of the final prospectus supplement will be available upon request by contacting Cowen and Company, LLC c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, Attn: Prospectus Department, by email at PostSaleManualRequests@broadridge.com or by telephone at (833) 297-2926 or by contacting Evercore Group L.L.C., Attention: Equity Capital Markets, 55 East 52nd Street, 36th Floor, New York, New York 10055, or by telephone at (888) 474-0200, or by email at ecm.prospectus@evercore.com.

This press release does not constitute an offer to sell or the solicitation of an offer to buy securities, nor will there be any sale of the securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such jurisdiction.

About Trillium Therapeutics:

Trillium is an immuno-oncology company developing innovative therapies for the treatment of cancer. The Company’s two clinical programs, TTI-621 and TTI-622, target CD47, a “don’t eat me” signal that cancer cells frequently use to evade the immune system.

For more information visit: www.trilliumtherapeutics.com.

Caution Regarding Forward-Looking Information:

This press release contains forward-looking statements within the meaning of applicable United States securities laws and forward looking information within the meaning of Canadian securities laws (collectively, “ forward-looking statements ”). Forward-looking statements in this press release include statements relating and the intended use of net proceeds from the Offering and the planned reliance on the exemption set forth in Section 602.1 of the TSX Company Manual. You should not place undue reliance on these forward-looking statements. Actual results may differ materially from those projected or implied in these forward-looking statements. Factors that may cause such a difference include, without limitation, risks and uncertainties related to the satisfaction of customary closing conditions related to the Offering, the impact of general economic, industry or political conditions in the United States, Canada or elsewhere internationally, the discretion of our management with respect to the use of the net proceeds, and the risks and uncertainties facing Trillium set forth in the prospectus supplement and Trillium’s Annual Information Form for the year ended December 31, 2019 filed with Canadian securities authorities and on Form 40-F with the SEC, each as updated by Trillium’s continuous disclosure filings, which are available at www.sedar.com and at www.sec.gov. All forward-looking statements herein are qualified in their entirety by this cautionary statement, and Trillium disclaims any obligation to revise or update any such forwardlooking statements or to publicly announce the result of any revisions to any of the forward-looking statements contained herein to reflect future results, events or developments, except as required by law.

Company Contact:

James Parsons Chief Financial Officer Trillium Therapeutics Inc. 416-595-0627 x232

james@trilliumtherapeutics.com www.trilliumtherapeutics.com

Media Contact: Mike Beyer Sam Brown Inc. 312-961-2502 mikebeyer@sambrown.com

Schedule “D”

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FOR IMMEDIATE RELEASE

NASDAQ: TRIL TSX: TRIL

Trillium Closes US$150 Million Public Offering of Common Shares

CAMBRIDGE, MA, September 16, 2020 - Trillium Therapeutics Inc. (“Trillium” or the “Company”) (NASDAQ/TSX: TRIL) , a clinical stage immuno-oncology company developing innovative therapies for the treatment of cancer, today announced the closing of its previously announced underwritten public offering of common shares of the Company at a public offering price of US$13.00 per common share (the “ Offering ”). 11,500,000 common shares were sold in the Offering, including the full exercise by the underwriters of their option to purchase up to an additional 1,500,000 common shares.

The gross proceeds from the Offering were US$149,500,000, before deducting underwriting commissions and other offering expenses. The Company intends to use the net proceeds of the Offering for its ongoing and planned clinical trials for its CD47 program, including drug supply and for working capital and general corporate purposes.

“We would like to thank all investors who placed their trust in both our unique CD47 assets as well as Trillium people. We are committed to speedily advance our investigational program into multiple Phase 2 trials, and further drive evolution of the oncology treatment paradigm toward greater adoption of novel, ground-breaking immunotherapies” said Dr. Jan Skvarka, Trillium’s President and Chief Executive Officer.

Cowen and Evercore ISI acted as joint book-running managers for the Offering. JMP Securities acted as the lead manager and Ladenburg Thalmann and JonesTrading acted as co-managers for the Offering.

About Trillium Therapeutics:

Trillium is an immuno-oncology company developing innovative therapies for the treatment of cancer. The Company’s two clinical programs, TTI-621 and TTI-622, target CD47, a “don’t eat me” signal that cancer cells frequently use to evade the immune system.

For more information visit: www.trilliumtherapeutics.com.

Caution Regarding Forward-Looking Information:

This press release contains forward-looking statements within the meaning of applicable United States securities laws and forward looking information within the meaning of Canadian securities laws (collectively, “ forward-looking statements ”). Forward-looking statements in this press release include

statements relating to Trillium’s intended use of net proceeds from the Offering and the expected development of Trillium’s CD47 assets. You should not place undue reliance on these forward-looking statements. Actual results may differ materially from those projected or implied in these forward-looking statements. Factors that may cause such a difference include, without limitation, risks and uncertainties related to whether or not the Company will be able to raise capital through the sale of shares, positive results from preclinical and early clinical research are not necessarily predictive of results of later-stage clinical trials, market and other conditions, the impact of general economic, industry or political conditions in the United States, Canada or elsewhere internationally, the discretion of our management with respect to the use of the net proceeds, and the risks and uncertainties facing Trillium set forth in the prospectus supplement and Trillium’s Annual Information Form for the year ended December 31, 2019 filed with Canadian securities authorities and on Form 40-F with the SEC, each as updated by Trillium’s continuous disclosure filings, which are available at www.sedar.com and at www.sec.gov. All forward-looking statements herein are qualified in their entirety by this cautionary statement, and Trillium disclaims any obligation to revise or update any such forward-looking statements or to publicly announce the result of any revisions to any of the forward-looking statements contained herein to reflect future results, events or developments, except as required by law.

Contact:

James Parsons Chief Financial Officer Trillium Therapeutics Inc. 416-595-0627 x232 james@trilliumtherapeutics.com http://www.trilliumtherapeutics.com/

Media Contact:

Mike Beyer Sam Brown Inc. 312-961-2502 mikebeyer@sambrown.com

Schedule “E”

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FOR IMMEDIATE RELEASE

NASDAQ: TRIL TSX: TRIL

TRILLIUM THERAPEUTICS APPOINTS MICHAEL KAMARCK, PH.D., TO ITS BOARD OF DIRECTORS

Industry Veteran Brings Deep Biologics Manufacturing Experience to Trillium Board

CAMBRIDGE, MA, September 18, 2020 – Trillium Therapeutics Inc. (“Trillium” or the “Company”) (NASDAQ/TSX: TRIL), a clinical stage immuno-oncology company developing innovative therapies for the treatment of cancer, today announced the appointment of pharmaceutical industry leader Michael Kamarck, Ph.D., to its Board of Directors, effective immediately.

“We are excited to welcome Dr. Kamarck to the board of directors” said Robert L. Kirkman, M.D., Chair of Trillium Therapeutics. “His long experience and expertise with the development and manufacturing of biologic products will be of particular value as Trillium is preparing to scale up its clinical development activities, with multiple phase 2 programs expected to start next year.”

Dr. Kamarck has significant expertise in biologics manufacturing and a breadth of management and technical experience, having served in senior leadership positions at a number of leading pharmaceutical companies during a career that spans over 25 years. He currently serves as Chief Technology Officer for Vir Biotechnology, Inc., where he manages a multi-modality technical approach to the development of treatments for serious infectious diseases such as COVID-19, influenza and hepatitis B.

“I am honored to join Trillium’s Board and look forward to contributing my knowledge in pharmaceutical research, technical operations and biologics manufacturing as the company advances towards clinical and commercial success,” said Dr. Kamarck. “This is truly an exciting time for Trillium, which is well positioned to become a leading player in the CD47 field, with a unique pipeline of two differentiated agents that are showing best-in-class potential.”

Before joining Vir, Dr. Kamarck was Senior Vice President of Global Vaccines and Biologics Manufacturing and President of Merck BioVentures where he was instrumental in establishing

Merck’s global biosimilars business. Prior to Merck, Dr. Kamarck held various senior executive positions at Wyeth Pharmaceuticals, including President, Technical Operations and Product Supply, and was responsible for establishing a global biotechnology network with $3.5 billion of capital investment to manufacture several blockbuster products, including Enbrel (etanercept). He began his pharmaceutical career at Bayer serving in numerous roles in research and technical operations, including Senior Vice President of Operations for Bayer Biologicals.

Dr. Kamarck received his B.A. from Oberlin College, his Ph.D. in biochemistry from Massachusetts Institute of Technology and was a Leukemia Society Fellow at Yale University. He has authored more than 50 peer-reviewed publications and has 20 issued patents.

About Trillium Therapeutics

Trillium is an immuno-oncology company developing innovative therapies for the treatment of cancer. The company’s two clinical programs, TTI-621 and TTI-622, target CD47, a “don’t eat me” signal that cancer cells frequently use to evade the immune system.

For more information visit: www.trilliumtherapeutics.com

Caution Regarding Forward-Looking Information

This press release contains forward-looking statements within the meaning of applicable United States securities laws and forward-looking information within the meaning of Canadian securities laws (collectively, "forward-looking statements"). Forward-looking statements in this press release include statements about, without limitation, the expected timing of the release of further data on Trillium’s TTI-621 and TTI-622 studies and the belief that Trillium’s programs could achieve best-in class status. With respect to the forward-looking statements contained in this press release, Trillium has made numerous assumptions regarding, among other things: the impact of the Covid19 pandemic on its operations, the effectiveness and timeliness of preclinical and clinical trials; and the completeness, accuracy and usefulness of the data. While Trillium considers these assumptions to be reasonable, these assumptions are inherently subject to significant scientific, business, economic, competitive, market and social uncertainties and contingencies. Additionally, there are known and unknown risk factors that could cause Trillium's actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements contained in this press release. A discussion of risks and uncertainties facing Trillium appears in Trillium's Annual Information Form for the year ended December 31, 2019 filed with Canadian securities authorities and on Form 40-F with the U.S. Securities Exchange Commission, each as updated by Trillium's continuous disclosure filings, which are available at www.sedar.com and at www.sec.gov. All forwardlooking statements herein are qualified in their entirety by this cautionary statement, and Trillium disclaims any obligation to revise or update any such forward-looking statements or to publicly announce the result of any revisions to any of the forward-looking statements contained herein to reflect future results, events or developments, except as required by law.

Investor Relations:

James Parsons Chief Financial Officer Trillium Therapeutics Inc. 416-595-0627 x232 james@trilliumtherapeutics.com www.trilliumtherapeutics.com

Media Relations: Mike Beyer Sam Brown Inc. 312-961-2502 mikebeyer@sambrown.com