Sensei Biotherapeutics : Company Presentation May 2023

Conditionally Active Antibodies for Immuno-oncology

MAY 2023 | Nasdaq: SNSE

Disclaimer

This presentation has been prepared by Sensei Biotherapeutics, Inc. (the "Company," "we," "us") and is made for informational purposes only. The information set forth herein does not purport to be complete or to contain all of the information you may desire. Statements contained herein are made as of the date of this presentation unless stated otherwise, and neither the delivery of this presentation at any time, nor any sale of securities, shall under any circumstanc es create an implication that the information contained herein is correct as of any time after such date or that information wil l be updated or revised to reflect information that subsequently becomes available or changes occurring after the date hereof.

This presentation contains estimates and other statistical data made by independent parties and by us relating to market shares and other data about our industry. This presentation also contains "forward-looking" statements as that term is defined in the Private Securities Litigation Reform Act of 1995 that are based on our management's beliefs and assumptions and on information currently available to management. These forward-looking statements include, without limitation, expectations regarding the development and potential therapeutic benefits of our product candidates; the expected safety profile of our product candidates; the expected timing and design of our Phase 1/2 clinical trial of SNS -101; the availability of data from our preclinical studies; the timing of selection of product candidates; and our belief that our existing cash and c ash equivalents will be sufficient to fund our operations at least into the second half of 2025.

When used in this presentation, the words and phrases "designed to," "may," "believes," "intends," "seeks," "anticipates," "plans," "estimates," "expects," "should," "assumes," "continues," "could," "will," "future" and the negative of these or sim ilar terms and phrases are intended to identify forward-looking statements. Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Risks and uncertainties that may cause actual results to differ materially include uncertainties inherent in the development of therapeutic product candidates, such as preclinical discovery and development, conduct of clinical trials and related regulatory requirements, our reliance on third parties over which we may not always have full control, and other risk and uncertainties that are described in our Annual Report on Form 10-K filed with the SEC on March 29, 2023 and our other Periodic Reports filed with the SEC. Forward-looking statements represent our management's beliefs and assumptions only as of the date of this presentation and include all matters that are not historical facts. Our actual future results may be materially different from what we expect. Except as required by law, we assume no obligation to update these forward- looking statements publicly, or to update the reasons actual results could differ materially from those anticipated in the forward-looking statements, even if new information becomes available in the future.

Certain information contained in this presentation relates to, or is based on, studies, publications, surveys and other data obtained from third-party sources and the Company's own internal estimates and research. While the Company believes these third-party sources to be reliable as of the date of this presentation, it has not independently verified, and makes no representation as to the adequacy, fairness, accuracy or completeness of, any information obtained from third-party sources. In addition, all of the market data included in this presentation involves a number of assumptions and limitations,

and there can be no guarantee as to the accuracy or reliability of such assumptions. Finally, while we believe our own internal research is reliable, such research has not been verified by any independent source.

Engineered Selectivity to Extend the Clinical Reach of Immuno-oncology Agents

THE CHALLENGE

Systemically delivered I/O drugs often fail in the clinic due to on-target/off-tumor effects (TMDD, CRS)

OUR LEAD PROGRAM

SNS-101 is a clinical stage pH-sensitive antibody targeting the VISTA receptor with first patient first dose expected in mid-2023

OUR STRATEGY

Conditionally active antibodies engineered to enable druggability of promising oncology targets

OUR FINANCIAL POSITION

Ended Q1 2023: $95.5M* Cash runway into 2H 2025

*Consists of cash, cash equivalents and marketable securities

3

Innovative Pipeline of IO Drugs with Broad Commercial Potential

*Sensei has entered into a Cooperative Research and Development Agreement (CRADA) with the National Cancer Institute. The goal of this collaborative effort is to further elucidate the role of VISTA in immune checkpoint resistance and expand the potential of SNS-101 as a combination therapy beyond anti-PD-1.

*Sensei has entered into a clinical supply agreement with Regeneron supporting

the planned evaluation of SNS-101 in combination with Regeneron's anti-PD-1

therapy Libtayo® (cemiplimab) in a Phase 1/2 clinical trial in solid tumors.

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The Modern-Day Challenge in Immuno-Oncology

The PD-1/PD-L1 market is big and growing fast1

2020

2026

PD-1/PD-L1 monotherapy does not benefit 70% of patients2

Survival

Benefit

20-30%

No Survival Benefit 70%

1. Gerber et al., Biochemical Pharmacology2016	5
2. Market estimates from PD-1 and PDL-1 Inhibitors Market Size in 2021 - MarketWatch, 360 Research