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

Conditionally Active Antibodies for

Immuno-oncology Corporate Deck | January 2024 Exhibit 99.1

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 circumstances create an implication that the

information contained herein is correct as of any time after such date or that information will 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, pharmacokinetic and efficacy profile of our product candidates, including SNS-101; the expected timing of clinical data from our Phase 1/2 clinical trial

of SNS-101; the expansion of the Phase 1 clinical trial to include additional patients with specific tumor types; and our belief that our existing cash and cash equivalents will be sufficient to fund our operations at least into the fourth quarter

of 2025 and reach midway into Phase 2 clinical studies of SNS-101. 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 similar 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, including the risk of delay or

cessation of any clinical trials of Sensei's product candidates; the risk that prior results, such as signals of safety, activity or durability of effect, observed from preclinical trials and early results from the clinical trial of SNS-101,

will not be replicated or will not continue in ongoing or future studies or clinical trials involving Sensei's product candidates, including SNS-101; our reliance on third parties over which we may not always have full control; risks regarding

the accuracy of our estimates of expenses, capital requirements and needs for additional financing; and other risk and uncertainties that are described in our Quarterly Report on Form 10-Q filed with the SEC on or about November 7, 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.

Company Highlights Sensei Bio's

proprietary platform is designed to harness the unique acidic tumor microenvironment to widen the therapeutic window and enable druggability of promising oncology targets SNS-101, the company's lead asset, targets VISTA, a critical negative

regulator of T-cell function and promising immune checkpoint target SNS-101 is currently in Phase 1 clinical testing with data to date displaying an attractive safety profile and potentially best-in-class pharmacokinetics Three additional

early-stage drug candidates Cash runway into the fourth quarter of 2025, which is expected to fund operations midway into Phase 2 studies of SNS-101 Anticipated near-term milestones include topline Phase 1 monotherapy data in Q2 2024

Leadership Team with History of

Antibody Oncology Success Erin Colgan Chief Financial Officer John Celebi, MBA President and CEO Christopher Gerry, J.D. VP, General Counsel Edward van der Horst, Ph.D. Chief Scientific Officer Stephanie Krebs, M.S., MBA Chief Business Officer Ron

Weitzman, M.D. Chief Medical Officer (part-time)

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

growing fast1 PD-1/PD-L1 monotherapy does not benefit 70% of patients2 2020 2026 Survival Benefit 20-30% No Survival Benefit 70% The Modern-Day Challenge in Immuno-Oncology (IO) 1. Gerber et al., Biochemical Pharmacology 2016 2. Market estimates

from PD-1 and PDL-1 Inhibitors Market Size in 2021 - MarketWatch, 360 Research

Industry Problem Sensei's

Solution Conventional antibodies target immune checkpoints that are highly expressed in normal tissues, resulting in: Dose-limiting toxicities due to on-target/off-tumor action Pharmacological sink effect requires higher & more frequent dosing

Suboptimal activity due to poor PK & dose-limiting toxicities Conditionally active antibodies are selectively targeted to the tumor microenvironment, potentially providing: Little or no toxicity due to selective on-target/on-tumor action Lower

& less frequent doses with tumor-specific binding Powerful activity selectively focused on the tumor microenvironment One new IO checkpoint inhibitor approved after the CTLA-4 and PD-1/PD-L1 group 2011 2014 2022 Lack of Tumor Targeting is a

Major Obstacle in IO Innovation Ipilimumab (anti-CTLA-4) Pembrolizumab (anti-PD-1) Relatlimab (anti-LAG-3)

The TMAb Platform: pH-sensitive

Antibodies Selectively Bind to Targets in the Low-pH Tumor Microenvironment Exploits the tumor microenvironment using pH-selective properties Intended to alleviate undesirable PK/PD properties: Dose-limiting toxicities due to

on-target/off-tumor binding Higher and more frequent dosing due to poor pharmacokinetics Bolsters specific activities Unlocks previously undruggable immune targets Sensei's technology identifies pH-sensitive antibodies designed to bind only at

the tumor The tumor microenvironment of pH ~6 is lower than physiological pH of 7.4

Innovative Pipeline of IO Drugs with

Broad Commercial Potential *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. *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.

VISTA is a Potent T cell Checkpoint

Extensively Expressed on Myeloid Cells VISTA is a B7 family member that inhibits T cell activation1 Immunosuppressive function believed to be mediated by PSGL-1 receptor Upregulated on immune suppressive myeloid-derived suppressor cells (MDSCs)

via hypoxia2 Increased expression on tissue infiltrating immune cells upon checkpoint therapy failure3 IS ACTIVATED IN A pH SENSITIVE MANNER T-cell proliferation & activation Extensive VISTA expression on off-tumor myeloid-lineage cells demands

a conditionally active antibody approach VISTA has inherent pH sensitivity: its extracellular domain is uniquely rich in histidines4 Myeloid lineage cell or tumor cell (less common) 1 Wang et al, JEM, 2011 2 Deng et al, Cancer Immunonol Res

2019 3 Gao et al., Nat Med. 2017 4 Johnston et al., Nature 2019

SNS-101: Selectively Targets VISTA

via a pH-sensitive Antibody pH 6.0 pH 7.4 0.218 nM 132 nM (~No binding) Additional SNS-101 features IgG1 format Active Fc Monovalent Affinity (KD) SNS-101 strongly inhibits the VISTA:PSGL-1 interaction and all other potential

binding partners at pH 6.0 in vitro IC50 = 7nm 2.59 Resolution SNS-101 heavy chain SNS-101 light chain Human VISTA (shown in green and red) Human VISTA epitope for SNS-101 Selectivity for active VISTApH6 over VISTApH7.4 VISTA:SNS-101

co-crystal structure demonstrates epitope of SNS-101 encompasses VISTA's PSGL-1 epitope SNS-101 is a differentiated, pH-sensitive antibody SNS-101 blocks the key receptor regulating VISTA's immunosuppressive activity

Competitors Halted Development of

VISTA Antibodies as a Result of Severe Toxicities From Non-Tumor Activity & Poor PK Dose-limiting toxicity Grade 3 CRS-associated encephalopathy JNJ-61610588 Human Plasma Concentration JNJ-61610588 (CI-8993) was the first anti-VISTA antibody to

be studied in clinical trials in 2016 (NCT02671955) 1 Transient Cytokine Release Syndrome (CRS) observed in several patients at 0.15 mg/kg Transient Grade 3 CRS-associated encephalopathy observed at 0.3 mg/kg, after which Janssen halted the study

Challenging PK profile Non-linear PK, short t1/2 1 Curis, Inc., Corporate Presentation, Feb 2022

SNS-101 is Designed to Overcome

VISTA's Unique Challenges Potential Best-in-Class Safety and PK Profile Supported by Initial Clinical Data No observed CRS or dose-limiting toxicity and no evidence of target-mediated drug disposition through 3 mg/kg monotherapy*

Enrolling Phase 1/2 Clinical Trial Multi-center U.S. study as single agent and in combination with PD-1 inhibitor Libtayo First VISTA-blocking antibody administered at a dose anticipated to be therapeutically relevant without

eliciting dose-limiting toxicity** Achieving "Firsts" for the VISTA Field Differentiated Design and Mechanism IgG1, Fc-active antibody designed to selectively block VISTA in the acidic tumor microenvironment Anticipated Near-Term Clinical

Milestones Initial combination PK/safety data in Q1 2024 Topline monotherapy dose escalation data in Q2 2024 Topline combination dose escalation data in Q3 2024 Initial dose expansion data by end of 2024 *As of data cut-off of October 3, 2023

**Anticipate therapeutically relevant clinical doses at approximately 3mg/kg or higher based on preclinical studies

SNS-101 is Unique and

Differentiated From Its Peers Johnston et al., Nature 2019; Kineta website; Snyder et al, AACR Annual Meeting 2016; Pierre Fabre website; Hummingbird website; Thakkar et al, J of Immunother Cancer, 2022; PharmAbcine website KVA12123 (Kineta) Phase 1

Phase 1 Phase 1 Phase 1 Phase 1 Preclinical Phase 1 (IgG1) (IgG1) (IgG1) (IgG4) (IgG1)

SNS-101 Phase 1/2 Study * Libtayo

350 mg + As of January 2, 2024, cleared Cohort A5 (15.0 mg/kg) ^ As of January 2, 2024, Cohort B2 (10.0 mg/kg of SNS-101 + Libtayo) enrolled, pending DLT assessment period RP2D = Recommended Phase 2 Dose MTD = Maximum Tolerated Dose Cohort A1 0.3

mg/kg N=1 Cohort B1 3.0 mg/kg + Libtayo* N=6 Cohort A2 1.0 mg/kg N=3 Cohort A3 3.0 mg/kg N=3 Cohort A4 10.0 mg/kg N=3 Cohort A5+ 15.0 mg/kg N=6 Cohort B2^ 10.0 mg/kg + Libtayo* N=3 Cohort B3 TBD + Libtayo* N=TBD Monotherapy 15 mg/kg N=up to 10

Combination Dose TBD N=up to 30 CRC Basket (CRC, NSCLC, H&N, Melanoma) Monotherapy Dose Escalation SNS-101 (Q3W) Combination Dose Escalation SNS-101 + Libtayo* (Q3W) Phase 1 Dose Expansion Phase 1 Dose Escalation BOIN design in patients with

advanced solid tumors Phase 1 Study Objectives Primary Safety, tolerability, MTD/RP2D Secondary PK, immunogenicity & anti-tumor activity Phase 2 Single-arm, Simon two-stage minimax design SNS-101 (RP2D) +/-

Libtayo (Q3W) Indications TBD Phase 2 Study Objectives Primary Anti-tumor activity Secondary Safety, tolerability, PK & immunogenicity CRC = colorectal cancer NSCLC = non small cell lung cancer H&N = head and neck cancer

= cleared DLT assessment period Additional tumor types and doses may be considered for both the monotherapy & combination dose expansion

SNS-101 Displayed Favorable Safety

& Tolerability Profile Through 3 mg/kg Monotherapy DLT = Dose-limiting toxicity CRS = Cytokine release syndrome TEAE = Treatment emergent adverse event SAE = Serious adverse event 0.3 mg/kg N=1 n (%) 1.0 mg/kg N=3 n (%) 3.0 mg/kg N=3 n (%) Total

N=7 n (%) At least 1 TEAE 1 3 1 5 (71.4) At least 1 SAE 0 0 1* 1* (14.3) At least 1 TEAE leading to discontinuation 0 0 1* 1* (14.3) DLTs 0 0 0 0 CRS events 0 0 0 0 Grade 3 TEAE 0 0 1* 1* (14.3) Related TEAE 0 1# 0 1# (14.3) *One patient

experienced an SAE, Grade 5 bronchial obstruction, that resulted in death; Event was considered related to disease progression, not SNS-101. # One patient experienced a Grade 2 dermatitis acneiform considered to be related to SNS-101. The event

resolved following phototherapy treatment. Well Tolerated with No Evidence of Cytokine Release Syndrome and No Dose-Limiting Toxicities Observed Data from monotherapy dose escalation arm as of cut-off date of October 3, 2023

Monotherapy Data Consistent with

Lack of Observed Cytokine Release Syndrome Through 3.0 mg/kg Cytokine analysis: Blood samples were taken pre-dose, 3 hours post-infusion and 6 hours post infusion at C1D1, and pre- and 3hr-post thereafter. Serum was assayed for indicated cytokines

using a platform (MSD) that has been validated for clinical sample analysis. Data from monotherapy dose escalation arm as of cut-off date of October 3, 2023 No Significant Changes in Key Inflammatory Cytokines

SNS-101 Monotherapy Data Show

Linear Pharmacokinetics and Long Half-Life in Stark Contrast to Prior Anti-VISTA mAbs Supports Every 3 Week Dosing Data from monotherapy dose escalation arm as of cut-off date of October 3, 2023

Key SNS-101 Differentiators:

Potential Best-in-Class Therapeutic 0.1 Dose (mg/kg) 0.3 3 10 1 JNJ-61610588 P1 DLT (CRS) SNS-101 current dose level+ ~50X 15 Dosing every 3 weeks vs. every 1 or 2 weeks for competitors Linear elimination kinetics vs. non-linear for competitors

Safety Parameters On Track Highest dose to date for any anti-VISTA antibody SNS-101 at a dose ~50x higher than the JNJ dose (0.3mg/kg) that caused DLT and termination of trial No observed DLTs or CRS through 3.0mg/kg monotherapy* No routine

prophylaxis per protocol Potential Best-In-Class PK Profile +Represents highest dose level in monotherapy arm as of January 2, 2024 *As of cut-off date of October 3, 2023 Anti-Tumor Activity Preclinical data demonstrate monotherapy activity in PD-1

resistant tumor model and deepened anti-tumor responses to PD-1 combo Topline monotherapy data expected in Q2 2024 with topline combination data to follow in Q3 2024

Completed and Anticipated SNS-101

Clinical Milestones First patient dosed with SNS-101 First patient dosed in combination with Libtayo Initial monotherapy dose escalation PK & safety data Initial combination dose escalation PK & safety data

Topline Phase 1 monotherapy dose escalation data Topline Phase 1 combination dose escalation data Initial Phase 1 dose expansion data - End of Phase 1 FDA meeting May 2023 September 2023 November 2023 Q2 2024 Q3 2024 Q4 2024 Q1 2024

A B Tissue macrophages (Kupffer

cells) in the liver Tumor-associated macrophages in tumors & stroma (inset) In the liver, VSIG-4 Is expressed on Kupffer cells1-2 Appears to drive significant target-mediated drug disposition (TMDD) and clearance In the tumor

microenvironment, VSIG-4 Correlates with immunosuppressive "M2" macrophage infiltration3 Inhibits T cell activation4 Promotes tumor growth based on data from a syngeneic Lewis lung carcinoma model in knockout mice5 VSIG4 is an

Immunosuppressive Receptor with On-Target, Off-Tumor Challenges doi: 10.1016/j.cell.2005.12.039. doi: 10.4049/jimmunol.2101109. doi: 10.4414/smw.2016.14301. doi: 10.1172/JCI25673. doi: 10.1038/labinvest.2014.73.

SNS-102 is a pH-sensitive Antibody

Designed With the Goal of Reversing T-cell Suppression within the Tumor Microenvironment SNS-102 blocks the interaction of VSIG4 with its novel counter-receptor, which has been provisionally identified SNS-102 is 585-fold more selective for VSIG4 at

low pH conditions pH 6.0 pH 7.4 0.7nm 410 nm (~No binding) Monovalent Affinity (KD) Ratio = 585