TScan Therapeutics Reports Full Year 2021 Financial Results and Highlights Key 2022 Priorities Received FDA clearance of IND for TSC-100 for the treatment of hematologic malignancies Phase 1 umbrella trial for liquid tum

TScan Therapeutics Reports Full Year 2021 Financial Results and Highlights Key 2022 Priorities

Received FDA clearance of IND for TSC-100 for the treatment of hematologic malignancies

Phase 1 umbrella trial for liquid tumor program to initiate in H1 2022; preliminary data expected in H2 2022

Two INDs for TSC-200 series anticipated by year end

Strong balance sheet with cash and cash equivalents of $161.4 million as of December 31, 2021; funds Company into 2024

WALTHAM, Mass., Mar. 9, 2022 TScan Therapeutics, Inc. (Nasdaq: TCRX), a clinical-stage biopharmaceutical company focused on the development of T-cell receptor (TCR) engineered T cell therapies (TCR-T) for the treatment of patients with cancer, today reported financial results for the full year ended December 31,

2021, and outlined key 2022 priorities.

As we had guided throughout 2021, in December we filed two INDs for our liquid tumor program. We also

completed construction of our now fully functional 7,000 square-foot GMP manufacturing facility. Both of these steps are instrumental in our transformation to a clinical-stage company, said David Southwell, President and Chief Executive

Officer. We also advanced our growing pipeline of solid tumor candidates and look forward to sharing further details around these programs in the coming months.

Recent Corporate Highlights

Upcoming Expected Milestones and Key Priorities for 2022

Liquid Tumor Programs: TScan s two lead liquid tumor TCR-T therapy candidates,

TSC-100 and TSC-101, are designed to target HA-1 and HA-2, respectively, and treat

patients with hematologic malignancies who are undergoing allogeneic hematopoietic cell transplantation.

Solid Tumor Programs: TScan s TSC-200 series of

TCR-T therapy candidates include a combination of known targets, such as HPV16 for TSC-200, PRAME for TSC-203, and MAGE-A1 for TSC-204, as well as targets that are novel antigens for TCR-T therapy, such as those for

TSC-201 and TSC-202.

Infectious Disease Program

Full Year 2021 Financial Results

As of December 31, 2021, TScan Therapeutics had cash and cash equivalents of $161.4 million excluding $5.0 million of restricted cash. Based on

current operating plans, the Company believes that existing cash and cash equivalents will be sufficient to fund its operating expenses and capital expenditure requirements into 2024.

Revenue for the year ended December 31, 2021, was $10.1 million, compared to $1.1 million for the year ended December 31, 2020 (2020

Period). This increase is due to a full year of research activities related to TScan s collaboration agreement with Novartis Institutes for Biomedical Research, on which work began in September 2020.

Research and development expenses for the year ended December 31, 2021, were $45.0 million, compared to $20.6 million for the 2020 Period. The

increase of $24.4 million was primarily a result of increased personnel expenses and facility-related expenses, as well as expenses related to the progress of the Company s liquid and solid tumor programs to IND filing.

General and administrative expenses for the year ended December 31, 2021, were $13.8 million, compared to $6.7 million for the 2020 Period. The

increase of $7.1 million in general and administrative expenses was primarily a result of increased personnel expenses and other miscellaneous expenses, including expenses related to the IPO and status as a public company.

For the year ended December 31, 2021, TScan Therapeutics reported a net loss of $48.6 million, compared to a net loss of $26.1 million for the

As of December 31, 2021, the company had issued and outstanding shares of 24,024,467 and 23,907,597, respectively.

About TScan Therapeutics, Inc.

TScan is a clinical-stage

biopharmaceutical company focused on the development of T cell receptor (TCR) engineered T cell therapies (TCR-T) for the treatment of patients with cancer. The Company s lead liquid tumor TCR-T therapy candidates, TSC-100 and TSC-101, are in development for the treatment of patients with hematologic malignancies to

eliminate residual leukemia and prevent relapse after hematopoietic stem cell transplantation. The Company is also developing multiplexed TCR-T therapy candidates for the treatment of various solid tumors. The

Company has developed and continues to build its ImmunoBank, one of the most extensive collections of known and novel solid tumor targets across different HLA types in the TCR field.

Forward-Looking Statements

This release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including, but not limited to,

express or implied statements regarding possible or assumed future results of TScan s operations, expenses and financing needs, business strategies and plans, research and development plans or expectations, the structure, timing and success of

the Company s planned preclinical development and clinical trials, expected milestones, market sizing, competitive position, regulatory matters, industry environment and potential growth opportunities, among other things. TScan intends such

forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in Section 21E of the Securities Exchange Act of 1934 and the Private Securities Litigation Reform Act of 1995. In some cases, you

can identify forward-looking statements by terms such as, but not limited to, may, might, will, objective, intend, should, could, can, would,

expect, believe, anticipate, project, target, design, estimate, predict, potential, plan, on track, or similar

expressions or the negative of those terms. Such forward-looking statements are based upon current expectations that involve risks, changes in circumstances, assumptions, and uncertainties. Important factors that could cause actual results to differ

materially from those reflected in TScan s forward-looking statements include, among others, the beneficial characteristics, safety, efficacy, therapeutic effects and potential advantages of TScan s

TCR-T therapy candidates; TScan s expectations regarding its preclinical studies being predictive of clinical trial results; the timing of the initiation, progress and expected results of TScan s

preclinical studies, clinical trials and its research and development programs; TScan s plans relating to developing and commercializing its TCR-T therapy candidates, if approved, including sales

strategy; estimates of the size of the addressable market for TScan s TCR-T therapy candidates; TScan s manufacturing capabilities and the scalable nature of its manufacturing process; TScan s

estimates regarding expenses, future milestone payments and revenue, capital requirements and needs for additional financing; TScan s expectations regarding competition; TScan s anticipated growth strategies; TScan s ability to

attract or retain key personnel; TScan s ability to establish and maintain development partnerships and collaborations; TScan s expectations regarding federal, state and foreign regulatory requirements; TScan s ability to obtain and

maintain intellectual property protection for its proprietary platform technology and our product candidates; the sufficiency of TScan s existing capital resources to fund its future operating expenses and capital expenditure requirements; and

the effect of the COVID-19 pandemic, including mitigation efforts and political, economic, legal and social effects, on any of the foregoing or other aspects of TScan s business or operations; and other

factors that are described in the Risk Factors and Management s Discussion and Analysis of Financial Condition and Results of Operations sections of TScan s Annual Report on Form

10-K for the year ended December 31, 2021, expected to be filed with the SEC on or about March 9, 2022.

TScan Therapeutics, Inc.

VP, Investor Relations

LifeSci Advisors, LLC

TScan Therapeutics, Inc.

Condensed Consolidated Balance Sheet Data

(in thousands, except share amount)

TScan Therapeutics, Inc.

Condensed Consolidated Statements of Operations

(in thousands, except share and per share amounts)