Adicet Reports Fourth Quarter and Full Year 2020 Financial Results and Provides Business Update Received IND clearance and initiated first-in-human Phase 1 clinical trial for lead asset, ADI-001, an anti-CD20 allogeneic

Adicet Reports Fourth Quarter and Full Year 2020 Financial Results and Provides Business Update

Menlo Park, CA and Boston, MA March 11, 2021

Adicet Bio, Inc. (Nasdaq: ACET), a biotechnology company discovering and developing allogeneic gamma delta T cell therapies for cancer and other diseases, today reported financial results and provided a business update for the fourth quarter and

full year ended December 31, 2020.

Over the past year, Adicet achieved several development and operational milestones including the initiation

of our first-in-human Phase 1 for ADI-001 for the treatment of B cell non-Hodgkin s lymphoma, the completion of our merger with resTORbio, and the expansion of our leadership team with the appointments of Nick Harvey as Chief Financial Officer,

Dr. Don Healey as Chief Technology Officer and Dr. Bastiano Sanna and Dr. Andrew Sinclair to our Board of Directors, said Chen Schor, President and Chief Executive Officer of Adicet. Recently, we successfully raised

significant capital to support further development of our robust pipeline comprising of gamma delta T cell therapies. These accomplishments have put us in a strong position to execute on our Phase 1 study of ADI-001, with interim clinical data

expected in 2021, and expand our pipeline of off-the-shelf gamma delta T cell therapies that will potentially provide for a targeted, durable, and on demand treatment option for solid and hematologic tumors.

Full Year 2020 & Recent Business Updates:

In October 2020, Adicet

announced the appointment of Don Healey, Ph.D., as Chief Technology Officer. Dr. Healey leads the development of Adicet s genetically-modified T cell therapies for clinical development and commercialization, including manufacturing, viral

vector operations and analytics. Dr. Healey brings nearly two decades of experience in cell therapy development and manufacturing to the Adicet team.

Financial Results for Fourth Quarter and Full Year 2020:

Three months Ended December 31, 2020

Twelve Months Ended December 31, 2020

About Adicet Bio, Inc.

Adicet Bio, Inc. is a

biotechnology company discovering and developing allogeneic gamma delta T cell therapies for cancer and other diseases. Adicet is advancing a pipeline of

off-the-shelf gamma delta T cells, engineered with chimeric antigen receptors and T cell receptor-like antibodies to enhance selective tumor targeting,

facilitate innate and adaptive anti-tumor immune response, and improve persistence for durable activity in patients. For more information, please visit our website at http://www.adicetbio.com.

Forward-Looking Statements

This press release contains

forward-looking statements of Adicet within the meaning of the Private Securities Litigation Reform Act of 1995 relating to business and operations of Adicet including, but not limited to, express or implied statements regarding

preclinical and clinical development of Adicet s product candidates, including future plans or expectations for ADI-001 and ADI-002 and potential therapeutic

effects of ADI-001 and ADI-002, the timing and outcome of discussions

with FDA and other regulatory agencies, expectations regarding the design, implementation, timing, and success of its current and future clinical studies of

ADI-001, including whether they are pivotal or would support registration, expectations regarding its other CAR T cell therapy development activities, Adicet s growth as a company and the anticipated

contribution of the members of its board of directors to its operations and progress, and its expectations regarding its uses of capital, expenses, future accumulated deficit and other fourth quarter and year end 2020 financial results. Any

forward-looking statements in this press release are based on management s current expectations and beliefs of future events, and are subject to a number of risks and uncertainties that could cause actual results to differ materially and

adversely from those set forth in or implied by such forward-looking statements, including without limitation, the effect of COVID-19 on Adicet s business and financial results, including with respect to

disruptions to its clinical trials, business operations, and ability to raise additional capital; Adicet s ability to execute on its strategy; that positive results from a clinical study may not necessarily be predictive of the results of

future or ongoing clinical studies; future clinical studies may fail to demonstrate adequate safety and efficacy of our product candidates, which would prevent, delay, or limit the scope of regulatory approval and commercialization; regulatory

approval processes of the FDA and comparable foreign regulatory authorities are lengthy, time-consuming, and inherently unpredictable; regulatory developments in the United States and foreign

countries; Adicet s estimates regarding expenses, future revenue, and capital requirements; as well as those risks and uncertainties set forth in Adicet s most recent annual report on Form 10-K and

subsequent filings with the Securities and Exchange Commission. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause Adicet s actual results to differ from those contained

in the forward-looking statements, see the section entitled Risk Factors in Adicet s most recent annual report on Form 10-K and our periodic reports on Form

10-Q and Form 8-K filed with the SEC, as well as discussions of potential risks, uncertainties, and other important factors in Adicet s other filings with the

SEC. All information in this press release is as of the date of the release, and Adicet undertakes no duty to update this information unless required by law.

Investor and Media Contacts

Stern Investor Relations, Inc.

Consolidated Statements of Operations and Comprehensive Loss

thousands, except share and per share amounts)