Unum Therapeutics Reports First Quarter 2019 Financial Results and Provides Business Update - Advancing ACTR Clinical Programs in Non-Hodgkin Lymphoma, Multiple Myeloma, and HER2+ Advanced Cancers Through Dose Escalation

Unum Therapeutics Reports First Quarter 2019 Financial Results and Provides Business Update

- Advancing ACTR Clinical Programs in Non-Hodgkin Lymphoma, Multiple Myeloma,

and HER2+ Advanced Cancers Through Dose Escalation Studies with Data Expected

from All Four Ongoing Trials in Second Half of 2019 -

- Advancing and Expanding BOXR Pipeline Focused on Solid Tumor Cancers

Through Preclinical Discovery and Development -

CAMBRIDGE, MA, May 13, 2019 Unum Therapeutics Inc. (NASDAQ: UMRX), a clinical-stage biopharmaceutical company focused on the development of

cellular immunotherapies to treat cancer based on its novel T cell technology platforms, today reported financial results and provided a corporate update for the first quarter ended March 31, 2019, and recent activities.

We remain on track to deliver on key milestones across our pipeline of hematologic and solid tumor cancer programs, said Chuck Wilson, President

and CEO of Unum. The dose escalation phases of our non-Hodgkin lymphoma, multiple myeloma, and HER2+ advanced cancer trials based on our Antibody-Coupled T cell Receptor (ACTR) platform are proceeding as

planned, positioning us to report data and drive decisions on next steps. Simultaneously, we continue to advance and expand our preclinical pipeline of Bolt-On Chimeric Receptor (BOXR) programs, aiming to

address the unmet need in solid tumor cancers by engineering improved T cell functionality.

First Quarter 2019 Financial Results

Investor Call and Webcast Information

Unum will host a live conference call and webcast today, May 13, 2019, at 8:00 a.m. ET, to discuss these financial results and company updates. To access

the call, please dial 866-300-3411 (domestic) or 636-812-6658 (international) and refer

to conference ID number 1443149. A webcast will be available at https://investors.unumrx.com/ at least 10 minutes before the event begins. The archived webcast will be available at the same location approximately two hours after the event and will

be archived for 90 days.

About Unum Therapeutics

Unum Therapeutics is a clinical-stage biopharmaceutical company providing potentially curative T cell therapies to treat a broad range of cancer patients.

Unum s novel proprietary technologies include Antibody-Coupled T cell Receptor (ACTR), a universal, engineered cell therapy intended to be used in combination with a wide range of tumor-specific antibodies to target different tumor types, and Bolt-On Chimeric Receptor (BOXR), an approach for improving T cell functionality in solid tumor cancer applications. Unum has four programs currently in Phase I clinical testing, including ACTR707 used in

combination with rituximab in adult patients with r/r NHL; ACTR087 used in combination with the novel antibody SEA-BCMA in r/r multiple myeloma; and ACTR707 used in combination with trastuzumab in adult

patients with HER2+ advanced cancer. The Company is headquartered in Cambridge, MA.

Forward looking Statements

This press release contains forward-looking statements including, without limitation, statements regarding our future expectations, plans and prospects,

including projections regarding future revenues and financial performance, our long-term growth, enrollment and results for our preclinical and clinical activities, the development of our product candidates, including the lead ACTR product

candidates and the BOXR platform and product candidates, and the anticipated timing of any of our clinical trials and regulatory filings, as well as other statements containing the words anticipate, believe,

continue, could, estimate, expect, intend, may, might, plan, potential, predict, project, should,

target, will, or would and similar expressions, constitute forward-looking statements within the meaning of the safe harbor provisions of The Private Securities Litigation Reform Act of 1995, as amended. We may

not actually achieve the forecasts disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results could differ materially from the projections disclosed in the forward-looking

statements we make as a result of a variety of risks and uncertainties, including risks related to the accuracy of our estimates regarding expenses, future revenues, capital requirements, and the need for additional financing, the success, cost and

timing of our product development activities and clinical trials, our ability to obtain and maintain regulatory approval for our product candidates, and the other risks and uncertainties described in the Risk Factors sections of our

public filings with the Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent our views as of the date hereof. We anticipate that subsequent events and developments may cause our

views to change. However, while we may elect to update these forward-looking statements at some point in the future, we specifically disclaim any obligation to do so. These forward-looking statements should not be relied upon as representing our

views as of any date subsequent to the date hereof.

Stern Investor Relations, Inc.

Stephanie Ascher, 212-362-1200

Arleen Goldenberg, 202-930-4762

UNUM THERAPEUTICS INC.

CONSOLIDATED STATEMENTS OF OPERATIONS

(unaudited, in thousands, except share and per share amounts)

UNUM THERAPEUTICS INC.

CONSOLIDATED SELECTED BALANCE SHEET DATA

(unaudited, in thousands)