8-K
false 0001783328 0001783328 2024-04-16 2024-04-16

 

 

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

 

 

FORM 8-K

 

 

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported) April 16, 2024

 

 

TSCAN THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

 

 

 

Delaware   001-40603   82-5282075

(State or other jurisdiction

of incorporation)

 

(Commission

File Number)

 

(I.R.S. Employer

Identification No.)

 

830 Winter Street,

Waltham, Massachusetts

  02451
(Address of principal executive offices)   (Zip Code)

Registrant’s telephone number, including area code (857) 399-9500

Not Applicable

(Former name or former address, if changed since last report)

 

 

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

 

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

 

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

 

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

 

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

 

Title of each class

 

Trade

Symbol(s)

 

Name of each exchange

on which registered

Voting Common Stock, $0.0001 par value per share   TCRX   The Nasdaq Global Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

 

 

 


Item 7.01

Regulation FD Disclosure.

On April 16, 2024, TScan Therapeutics, Inc. (the “Company”) issued a press release to provide an update on its solid tumor and heme malignancies clinical programs. The Company also released an updated company presentation, which includes, among others, additional details of its solid tumor and heme malignancies clinical programs. Copies of the press release and the updated company presentation are attached as Exhibits 99.1 and 99.2 to this Current Report on Form 8-K. The updated company presentation will also be available in the investor relations section of the Company’s website at https://ir.tscan.com. Information contained on the Company’s website is not incorporated by reference into this Current Report on Form 8-K, and you should not consider any information on, or that can be accessed from, the Company’s website as part of this Current Report on Form 8-K.

The information under this Item 7.01, including Exhibits 99.1 and 99.2 hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. The Company undertakes no obligation to update, supplement or amend the material attached hereto as Exhibits 99.1 and 99.2.

 

Item 8.01

Other Events.

On April 16, 2024, the Company provided an update on its solid tumor and heme malignancies clinical programs.

Solid Tumor Program: TScan continues to expand the ImmunoBank, a collection of therapeutic TCR-Ts that target different cancer-associated antigens presented on diverse HLA types. TScan’s strategy is to treat patients with multiple TCR-Ts to overcome tumor heterogeneity and prevent resistance that may arise from either target or HLA loss (screening protocol: NCT05812027; treatment protocol: NCT05973487).

 

   

Phase 1 solid tumor clinical study has been initiated; first three patients expected to be dosed in early May 2024.

 

   

More than 40 patients have completed all biomarker testing in the screening protocol across a broad array of tumor types. 60% of patients qualify for at least one TCR-T in the ImmunoBank and approximately 30% are eligible for multiplex therapy (T-Plex), potentially enabling rapid enrollment into the treatment protocol upon disease progression.

 

   

Patients have been identified across all six TCR-T cohorts with dosing expected to commence early May.

 

   

Initial data on patients from both singleplex and multiplex cohorts expected in the second half of 2024.

 

   

Additional IND filings planned to continue to expand the ImmunoBank.

 

   

Long-term duration of response data for multiplex therapy anticipated in 2025.

Heme Malignancies Program: TScan’s two lead TCR-T cell therapy candidates, TSC-100 and TSC-101, are designed to treat residual disease and prevent relapse in patients with acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), or myelodysplastic syndromes (MDS) undergoing allogeneic hematopoietic cell transplantation (HCT) (NCT05473910).

 

   

All eight patients treated with TSC-100 or TSC-101 remain MRD negative, relapse-free with no detectable cancer to date in either bone marrow biopsies or peripheral blood (median follow-up of >10 months) and no dose limiting toxicities observed to date.

 

   

To date, all but one patient has exhibited complete donor chimerism in all subsets of blood cells at all time-points, indicating that only donor-derived cells are present in these patients following treatment with either TSC-100 or TSC-101. One patient with T-ALL who was treated with TSC-100 at the lowest dose level exhibited minimally detectable (<0.3%) mixed donor chimerism at 10.5 months and 12 months post-transplant.

 

   

No detectable mixed chimerism was observed in the malignant cell lineage (CD3+ T-cells) for this patient; mixed chimerism was only observed in healthy nonmalignant blood cells (CD33+ myeloid cells)


   

In contrast, for the control arm (transplant alone), eight patients have now been enrolled and only one has achieved and maintained complete donor chimerism to date. Two patients relapsed approximate six months post-transplant and one of these patients died approximately three months later. A third patient required clinical intervention on day 133 because of concerns of impending relapse, and a fourth died 21 days post-transplant.

 

   

Opening of expansion cohorts at the recommended Phase 2 dose level to further characterize safety and evaluate translational and efficacy endpoints is planned for the third quarter of 2024.

 

   

Completion of Phase 1 enrollment and reporting of one-year clinical and translational data on initial patients is anticipated in the second half of 2024.

 

   

Expects to initiate registration trial pending feedback from regulatory authorities and report two-year relapse data in 2025.

 

Item 9.01

Financial Statements and Exhibits.

(d) Exhibits:

 

Exhibit
No.
  

Description

99.1    Press release, dated April 16, 2024
99.2    Company Presentation
104    Cover Page Interactive Data File (embedded within the Inline XBRL document)

Forward-Looking Statements

This Current Report on Form 8-K contains forward-looking statements that are based on the Company’s beliefs and assumptions and on information currently available to the Company on the date of this Current Report. These forward-looking statements involve substantial risks and uncertainties. Any statements in this Current Report on Form 8-K other than statements of historical fact, including statements about the Company’s future expectations, plans and prospects, constitute forward-looking statements for purposes of the safe harbor provisions under the Private Securities Litigation Reform Act of 1995. Forward-looking statements include any statements about the Company’s strategy, operations and future expectations and plans and prospects for the Company, and any other statements containing the words “anticipate,” “believe,” “estimate,” “expect,” “intend”, “goal,” “may”, “might,” “plan,” “predict,” “project,” “seek,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue,” and similar expressions. Such forward-looking statements involve substantial risks and uncertainties that could cause the Company’s financial and operating results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements, including the factors discussed in the “Risk Factors” section contained in the quarterly and annual reports that the Company files with the Securities and Exchange Commission. Any forward-looking statements represent the Company’s views only as of the date of this Current Report on Form 8-K. The Company anticipates that subsequent events and developments may cause its views to change. While the Company may elect to update these forward-looking statements at some point in the future, the Company specifically disclaims any obligation to do so except as required by law even if new information becomes available in the future.


SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

 

    TScan Therapeutics, Inc.
Date: April 16, 2024     By:  

/s/ Gavin MacBeath

      Gavin MacBeath
      Chief Executive Officer
EX-99.1

Exhibit 99.1

 

LOGO

TScan Therapeutics Provides Clinical Pipeline Update and Highlights Near-Term Priorities

Over 40 solid tumor patients have completed all biomarker testing in the screening protocol; ~60% of these patients qualify for at least one TCR-T in the ImmunoBank and ~30% are eligible for multiplex therapy

Patients identified across all six TCR-T cohorts in solid tumor program with dosing of first three expected in early May

All eight patients in the heme program treated with TSC-100 or TSC-101 remain relapse-free with no detectable cancer to date; median follow-up of >10 months

WALTHAM, Mass., April 16, 2024 — 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 provided an update on its solid tumor and heme malignancies clinical programs.

“We continue to make meaningful progress across both our solid tumor and heme malignancies Phase 1 clinical programs. As we rapidly approach dosing the first patients in the solid tumor program, I am pleased to share that over 40 patients have completed all biomarker testing in the screening protocol, with the majority qualifying for at least one TCR-T in our ImmunoBank and many qualifying for multiplex therapy. This should allow for rapid enrollment into the treatment protocol over the course of the year,” said Gavin MacBeath, Ph.D., Chief Executive Officer. “With respect to the heme program, we are encouraged to see continued positive data with all treatment-arm patients remaining relapse-free with no detectable cancer to date, now with a median follow-up of over 10 months.”

Solid Tumor Program: TScan continues to expand the ImmunoBank, a collection of therapeutic TCR-Ts that target different cancer-associated antigens presented on diverse HLA types. TScan’s strategy is to treat patients with multiple TCR-Ts to overcome tumor heterogeneity and prevent resistance that may arise from either target or HLA loss (screening protocol: NCT05812027; treatment protocol: NCT05973487).

 

   

Phase 1 solid tumor clinical study has been initiated; first three patients expected to be dosed in early May 2024.

 

   

More than 40 patients have completed all biomarker testing in the screening protocol across a broad array of tumor types. 60% of patients qualify for at least one TCR-T in the ImmunoBank and approximately 30% are eligible for multiplex therapy (T-Plex), potentially enabling rapid enrollment into the treatment protocol upon disease progression.


   

Patients have been identified across all six TCR-T cohorts with dosing expected to commence early May.

 

   

Initial data on patients from both singleplex and multiplex cohorts expected in the second half of 2024.

 

   

Additional IND filings planned to continue to expand the ImmunoBank.

 

   

Long-term duration of response data for multiplex therapy anticipated in 2025.

Heme Malignancies Program: TScan’s two lead TCR-T cell therapy candidates, TSC-100 and TSC-101, are designed to treat residual disease and prevent relapse in patients with acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), or myelodysplastic syndromes (MDS) undergoing allogeneic hematopoietic cell transplantation (HCT) (NCT05473910).

 

   

All eight patients treated with TSC-100 or TSC-101 remain MRD negative, relapse-free with no detectable cancer to date in either bone marrow biopsies or peripheral blood (median follow-up of >10 months) and no dose limiting toxicities observed to date.

 

   

To date, all but one patient has exhibited complete donor chimerism in all subsets of blood cells at all time-points, indicating that only donor-derived cells are present in these patients following treatment with either TSC-100 or TSC-101. One patient with T-ALL who was treated with TSC-100 at the lowest dose level exhibited minimally detectable (<0.3%) mixed donor chimerism at 10.5 months and 12 months post-transplant.

 

   

No detectable mixed chimerism was observed in the malignant cell lineage (CD3+ T-cells) for this patient; mixed chimerism was only observed in healthy nonmalignant blood cells (CD33+ myeloid cells)

 

   

In contrast, for the control arm (transplant alone), eight patients have now been enrolled and only one has achieved and maintained complete donor chimerism to date. Two patients relapsed approximate six months post-transplant and one of these patients died approximately three months later. A third patient required clinical intervention on day 133 because of concerns of impending relapse, and a fourth died 21 days post-transplant.

 

   

Opening of expansion cohorts at the recommended Phase 2 dose level to further characterize safety and evaluate translational and efficacy endpoints is planned for the third quarter of 2024.

 

   

Completion of Phase 1 enrollment and reporting of one-year clinical and translational data on initial patients is anticipated in the second half of 2024.

 

   

Expects to initiate registration trial pending feedback from regulatory authorities and report two-year relapse data in 2025.


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 TCR-T candidates, TSC-100 and TSC-101, are in development for the treatment of patients with hematologic malignancies to prevent relapse following allogeneic hematopoietic cell transplantation. The Company is also developing multiplex TCR-T candidates for the treatment of various solid tumors. The Company has developed and continues to expand its ImmunoBank, the Company’s repository of therapeutic TCRs that recognize diverse targets and are associated with multiple HLA types, to provide customized multiplex TCR-T candidates for patients with a variety of cancers.

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 the Company’s plans, progress, and timing relating to the Company’s hematologic malignancies and solid tumor programs; the potential benefits of any of the Company’s proprietary platforms, multiplexing, or current or future product candidates in treating patients; and the Company’s goals, strategy, and focus. 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. The express or implied forward-looking statements included in this release are only predictions and are subject to a number of risks, uncertainties and assumptions, including, without limitation: the beneficial characteristics, safety, efficacy, therapeutic effects and potential advantages of TScan’s TCR-T therapy candidates; the progress of the solid tumor and heme malignancies Phase 1 clinical programs being indicative or predictive of the success of each program; TScan’s expectations regarding its preclinical studies being predictive of clinical trial results; the completion of biomarker testing of over 40 patients being indicative or predictive of enrollment of the patients over the course of the year; TScan’s recently approved INDs being indicative or predictive of bringing TScan closer to its goal of providing customized TCR-T therapies to treat patients with cancer; the timing of the launch, initiation, progress, expected results and announcements of TScan’s preclinical studies, clinical trials and its research and development programs; TScan’s timeline regarding its filing of INDs for its TCRs throughout the year; TScan’s timeline of the solid tumor program and the heme malignancies program; TScan’s ability to enroll patients for its clinical trials within its expected timeline; 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 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 most recent Annual Report on Form 10-K and any other filings that TScan has made or may make with the SEC in the future. Any forward-looking statements contained in this release represent TScan’s views only as of the date hereof and should not be relied upon as representing its views as of any subsequent date. Except as required by law, TScan explicitly disclaims any obligation to update any forward-looking statements.

Contacts

Heather Savelle

TScan Therapeutics, Inc.

VP, Investor Relations

857-399-9840

hsavelle@tscan.com

Melissa Forst

Argot Partners

212-600-1902

TScan@argotpartners.com

EX-99.2

Exhibit 99.2 TScan Therapeutics April 2024


Disclaimers and forward-looking statements This presentation and the accompanying discussion contain forward-looking TScan’s plans relating to developing and commercializing its TCR-T therapy statements within the meaning of the Private Securities Litigation Reform Act of candidates, if approved, including sales strategy; estimates of the size of the 1995, including, but not limited to, express or implied statements regarding the addressable market for TScan’s TCR-T therapy candidates; TScan’s manufacturing Company’s plans, progress, and timing relating to the Company’s solid tumor capabilities and the scalable nature of its manufacturing process; TScan’s programs and the presentation of data, the Company’s current and future research estimates regarding expenses, future milestone payments and revenue, capital and development plans or expectations, the structure, timing and success of the requirements and needs for additional financing; TScan’s expectations regarding Company’s planned preclinical development, submission of INDs, and clinical trials, competition; TScan’s anticipated growth strategies; TScan’s ability to attract or the potential benefits of any of the Company’s proprietary platforms, multiplexing, retain key personnel; TScan’s ability to establish and maintain development or current or future product candidates in treating patients, the Company's ability to partnerships and collaborations; TScan’s expectations regarding federal, state and fund its operating expenses and capital expenditure requirements with its existing foreign regulatory requirements; TScan’s ability to obtain and maintain cash and cash equivalents, and the Company’s goals and strategy. TScan intends intellectual property protection for its proprietary platform technology and our such forward-looking statements to be covered by the safe harbor provisions for product candidates; the sufficiency of TScan’s existing capital resources to fund forward-looking statements contained in Section 21E of the Securities Exchange Act its future operating expenses and capital expenditure requirements; and other of 1934 and the Private Securities Litigation Reform Act of 1995. In some cases, you factors that are described in the “Risk Factors” and “Management’s Discussion can identify forward-looking statements by terms such as, but not limited to, “may,” and Analysis of Financial Condition and Results of Operations” sections of TScan’s “might,” “will,” “objective,” “intend,” “should,” “could,” “can,” “would,” “expect,” most recent Annual Report on Form 10-K and any other filings that TScan has “believe,” “anticipate,” “project,” “target,” “design,” “estimate,” “predict,” made or may make with the SEC in the future. “potential,” “plan,” “on track,” or similar expressions or the negative of those terms. Such forward-looking statements are based upon current expectations that involve Any forward-looking statements contained in this presentation represent TScan’s risks, changes in circumstances, assumptions, and uncertainties. The express or views only as of the date hereof and should not be relied upon as representing its implied forward-looking statements included in this presentation are only views as of any subsequent date. Except as required by law, TScan explicitly predictions and are subject to a number of risks, uncertainties and assumptions, disclaims any obligation to update any forward-looking statements. including, without limitation: 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; 2 CONFIDENTIAL


How do we aim to cure cancer? PROBLEM PROVEN SOLUTIONS • Cancer is heterogeneous Treat cancer when it is 1 • Cancer is rapidly evolving at its lowest HEME PROGRAM Tumor Treat with multiple 2 agents simultaneously SOLID TUMOR PROGRAM Blood vessel 3 CONFIDENTIAL


TScan is building on the remarkable success of immunotherapy What we have learned from immuno-oncology Our proposed solution is TCR-T cell therapy Genetically reprogramming T cells with Checkpoint therapy (Keytruda®, Yervoy®, Opdivo®) T-cell receptors leverages the body’s natural mechanism for fighting cancer Unleashing a patient’s T cells can lead to long-term remissions and even cures Most patients lack anti-cancer T cells and do not respond Tumor cell CAR-T therapy (Kymriah®, Yescarta®, Breyanzi®) Genetically reprogramming T cells cures patients T-cell receptor with certain heme malignancies Broader applications of CAR-T, particularly in solid tumors, remains challenging T cell 4 CONFIDENTIAL


T-cells search for and kill abnormal cells Normal cell Cancer cell T-cell T-cell TCR Tumor-specific antigen Self antigen HLA HLA Healthy cell Cancer cell Healthy cells display normal self-antigens that do Tumor-specific antigens activate circulating T-cells not activate circulating T-cells to kill cancer cells 5 CONFIDENTIAL


TScan is targeting the most frequent HLAs to address a broad patient population Everyone has six ~90% of people in the U.S. are class I HLAs positive for at least one of the top six HLA types Chromosome 6 Tumor cell Mother Father % people positive A A for each HLA type C C B B United HLA type Europe Asia States HLA class I (e.g., A*02:01) A*02:01 42 47 19 CD8α/β A*01:01 24 26 14 A*03:01 22 25 7.0 Target antigen B*07:02 20 21 8.1 (e.g., PRAME) C*07:02 24 23 24 TCR There are 100s of A*24:02 17 19 37 different HLA types Most TCR-T companies only target one HLA (A*02:01) TScan is developing a broad pipeline targeting the top six HLAs T cell 6 CONFIDENTIAL


TScan is a fully integrated, next-generation TCR-T cell therapy company Proprietary discovery platform Rapidly-growing oncology pipeline T-cell receptor (TCR) Clinical-phase programs in heme Rapid discovery of targets and TCRs and solid tumor malignancies In-house GMP manufacturing Broad therapeutic potential Oncology Infectious Autoimmune Transposon-based T cell engineering disease disease 7 CONFIDENTIAL


Platform delivers broad proprietary pipeline HLA type Indications Programs (target) Discovery Lead optimization IND-enabling Phase 1 Phase 2/3 TSC-100 AML, HLA-A*02:01 (HA-1) HEMATOLOGIC MDS, MALIGNANCIES TSC-101 ALL HLA-A*02:01 (HA-2) Head & Neck, HPV+ TSC-200 HLA-A*02:01 Cervical, SOLID TUMORS (HPV16) HLA-C*07:02 Anogenital HLA-B*07:02 TSC-201 HLA-A*02:01 (MAGE-C2) HLA-A*24:02 TSC-202 NSCLC, HLA-A*02:01 (MAGE-A4) Melanoma, SOLID TUMORS (T-PLEX) HLA-A*02:01 Head & Neck, TSC-203 HLA-B*07:02 Ovarian (PRAME) HLA-A*24:02 HLA-A*02:01 HLA-C*07:02 TSC-204 HLA-A*01:01 (MAGE-A1) HLA-A*03:01 HLA-B*07:02 AUTOIMMUNITY Crohn's 8 CONFIDENTIAL


TScan programs are designed to sequentially build value • Melanoma • NSCLC >100k • Head & Neck • Ovarian ~15k + HPV solid tumors U.S. market size ~7k Heme malignancy program Time to market 9 CONFIDENTIAL Target heterogeneity


Steady value-generating data flow planned across clinical programs Heme Program Fully enroll clinical study Launch pivotal study Report updated data Open expansion cohorts at at TANDEM RP2D One-year data on initial Two-year relapse data patients H1 2024 H2 2024 YE 2024 2025 Initiate multiplexed dosing Additional IND filings Dose first patient in clinical Duration of response data study for multiplexed therapy Initial data for singleplex Initial data for multiplexed therapy therapy Solid Tumor Program 10 CONFIDENTIAL


Heme malignancies: targeting residual disease to prevent relapse in patients undergoing allogeneic HCT


Relapse after hematopoietic cell transplant remains an unmet need AML, MDS, some ALL not ~35,000 addressed by CAR-T due cases/year US to shared antigens with normal blood cells Targeting antigens 1 mismatched between ~7,350 Allogeneic hematopoietic undergo transplant patients and donors can cell transplant (HCT) potentially prevent expected to remain >33% relapse relapse after allo-HCT standard of care 2 within 2 years RIC range 38-44% MAC range 26-30% Allo-HCT creates a unique opportunity to safely target residual cancer cells >90% while sparing normal mortality blood cells 2 within 1 year 1. CIBMTR summary statistics 2022, allogeneic transplants for malignant diseases in 2019 before the COVID-19 pandemic 2. CIBMTR analysis of AML, ALL, MDS allogeneic transplants with myeloablative (MAC) or reduced intensity conditioning (RIC) between 2017-2019 with 2-year follow-up; MAC relapse range 26-30%, RIC relapse range 38-44% 12 CONFIDENTIAL


TSC-100 and TSC-101 are engineered TCR-T cells designed to eliminate residual recipient cells and prevent relapse following HCT POST-TRANSPLANT PATIENT PATIENT HA-1 or HA-2 positive Cancer Residual HA-1 or HA-2 cell cancer Residual negative Conditioning cancer therapy HA-1 or HA-2 positive CURE Residual Normal Residual patient blood cell patient blood cell Normal blood cell blood cell DONOR HA-1 or HA-2 TCR Stem cells Hematopoietic cell Stem T-cell cell transplant HA-1 or HA-2 negative T cell TCR T-cell therapy 13 CONFIDENTIAL


Multi-arm Phase 1 trial for TSC-100 & TSC-101 has reached highest dose level AML, MDS, ALL undergoing haploidentical transplant with reduced intensity conditioning Control Arm Treatment Arms Dose Day Level (HLA-A*02:01 negative) (HLA-A*02:01 positive: 42%) 21 61 6 5×10 /kg 1 Transplant Transplant Transplant Alone + TSC-100 + TSC-101 ‡ ‡ 6 6 (HA-1 positive ) (HA-2 positive ) 5×10 /kg 5×10 /kg 2 Key endpoints 6 7 5×10 /kg 2×10 /kg 3 • Safety: adverse event profiles, GvHD rates/ grades • Relapse rates: 6m, 1y, 2y • Exploratory endpoints: donor chimerism, MRD Expected relapse rates for HCT alone 6 months 22% 1 year 33% 2 years 42% CIBMTR analysis of RIC-haplo transplants from 2017-2019 14 ‡ >99% patients are either HA-1 or HA-2 positive CONFIDENTIAL


Risk factors well-balanced between control-arm and treatment-arm patients Control Arm TSC-100 TSC-101 TSC-101 TSC-101 Control Control Control Control Control Control Control Control TSC-100 TSC-100 TSC-100 TSC-100 TSC-101 TSC-101 Patient ID DL2- DL3- 1 2 3 4 5 6 7 8 DL1 DL2 DL3 DL3 DL1 DL2 supp supp Diagnosis MDS MDS MDS AML AML AML AML AML T-ALL AML AML MDS MDS AML B-ALL B-ALL Trisomy Trisomy IDH2, Del5q Mono 7, SETB1, FLT3-ITD mTP53 8 SRSF2 Molecular 8, ATM FLT3- Del5q, SRSF2, None Mono 7 RUNX1, WT1, NPM1 Pending KRAS IDH2, ASXL1 n/a n/a Markers SRSF2 <2% ITD mTP53 ASXL1 NRAS, STAG2 mTP53 EZH2 DNMT3A WT1 ALK ASXL1 CUX1 ASXL1 Pre-HCT Positive Negative Positive Negative Positive Negative Negative Positive Positive Negative Positive Positive Positive Positive Negative Negative MRD RIC Flu/ Cy/ Flu/ Cy/ Flu/Mel/ Flu/ Cy/ Flu/Mel/T Flu/Mel/ Flu/Mel/ Flu/Cy/ Flu/ Cy/ Thio/ Flu/Mel Flu/Cy/ Flu/ Flu/Mel Flu/Mel Flu/Mel regimen TBI TBI Thio TBI BI TBI TBI TBI TBI Bu/ Flu / TBI TBI Mel/ TBI / TBI / TBI / TBI Dose ‡ ‡ N/A DL1 DL2 DL3 DL3 DL1 sDL2 DL2 sDL3 Level TCR-T Day 27 Day 21 Day 27 Day 25 Day 34 Day 27 dosing N/A Day 29 Day 21 Day 76 Day 75 Day 69 Day 82 Day 62 Day 70 Day Last Post- Day 528 Day 161* Day 180* Day 227 Day 148 Day 133 Day 21* Day 63 Day 388 Day 351 Day 217 Day 164 Day 421 Day 358 Day 295 Day 190 HCT Day ‡ Dose did not meet target dose criteria; *Patient came off study due to relapse or death 15 Data cutoff April 12, 2024 CONFIDENTIAL


Donor chimerism serves as an early surrogate of efficacy Post-transplant Patient Complete donor chimerism Mixed donor chimerism 1,2 1,2 (low risk of relapse ) (high risk of relapse ) Malignant, patient-derived blood cell Nonmalignant, patient-derived blood cell Normal, donor- Normal, donor- derived blood cell derived blood cell 1. Lindhal, Bone Marrow Transpl, 2022 16 2. Ciurea, Al Malki, Blood Rev, 2023 CONFIDENTIAL


All 8 patients on the treatment arm remain relapse-free with no detectable cancer Treatment-arm patients Control-arm patients Day TSC-100 TSC-100 TSC-100 TSC-100 TSC-101 TSC-101 TSC-101 TSC-101 Control Control Control Control Control Control Control Control post 1 2 3 4 5 6 7 8 DL 1 DL 2 DL 3 DL 3 DL 1 DL 2-supp DL 2 DL 3-supp ‡ HCT Day Deceased 21/28 Day 21 Day 42 TSC-100/101 dosing Mixed donor Day 56 chimerism Complete donor Day 77 chimerism * Clinical intervention for Day 105 increasing mixed chimerism Day 133 Relapse Day 161 * Not detected in Day 161 cancer cell lineage * Relapse in most recent Day 228 Day 180 measurement Deceased Day 318 Day 265 1 year Accompanied by increase Day 388 in TCR-T cell activation * 17 Donor chimerism detected by high-sensitivity next-generation sequencing (NGS) assay (AlloHeme) with limit of detection 0.13% ‡ Data cutoff April 12, 2024 Measurements taken at indicated day post HCT ± 3 days CONFIDENTIAL


No relapses and complete chimerism in cancer lineage in treatment arms Two relapses, two deaths and mixed chimerism in cancer lineage in control arm Control arm Treatment arms Donor chimerism in control arm: C R D3+ ecipi an en d t CD3 chime 3+r su ism bsets Donor chimerism in treatment arms: Recipient chimerism CD3+ and CD33+ subsets CD33 CD33 100 died 100 CD3 CD3 withdrawal of immunosuppression 10 relapsed, 10 died relapsed 1 1 Healthy normal cells 0.13 Below detection limit 0.13 Below detection limit Days post transplant Days post transplant 1st dose TSC-100/TSC-101 All relapses occurred in patients with mixed chimerism in cancer lineage Median post-transplant follow-up in treatment arms: 10.7 months (range 5.5-14 months); Median follow-up in control arm: 5.2 months (range 0.7-18 months) 18 Data cutoff April 12, 2024 CONFIDENTIAL Baseline D7 D14 D21 D28 D42 D56 D70 D77 D84 D98 D105 D133 D161 D180 D228 D318 D388 Baseline D7 D14 D21 D28 D42 D56 D70 D77 D84 D98 D105 D133 D161 D180 D228 D318 D388 % Recipient chimerism % Recipient chimerism


Early data from ACROBAT trial* show low risk of relapse in patients not showing increasing mixed chimerism 1 Chimerism by ultra-sensitive NGS assay • Early data from the ACROBAT trial suggest a 1 relapse out of favorable prognosis for patients that rapidly 50 patients achieve and maintain complete chimerism • None of the patients treated with TSC-100/TSC-101 show increasing mixed chimerism, suggesting a very low risk of relapse 1 Limit of detection ~0.13% recipient chimerism + + iMC: ≥0.2% increasing mixed chimerism in CD3 , CD33 , or whole blood 139 patients with complete NGS and STR chimerism testing, median F/U [Q1,Q3] = 365 [270,484] days • NCT04635384, Kothari, TCT 2024 abstract # 555; CareDx sponsored clinical study 19 CONFIDENTIAL


Minimal residual disease serves as a supportive surrogate of efficacy Post-transplant patient Minimal Residual Disease (MRD) Nonmalignant, patient-derived Next-generation sequencing blood cell • Deep sequencing of leukemia- associated genes (centrally) • Sensitivity 0.05-0.1% Malignant, MRD+ patients post-transplant have patient-derived 1,2 ~90% chance of relapse blood cell 1. Craddock, J Clin Oncol, 2021 2. Loke, ASH, 2021 Normal, donor- derived blood cell 20 CONFIDENTIAL


* All treated patients to date achieved MRD negativity Dose Pre-HCT 6 months 12 months level MRD Rx Disease TSC-100/TSC-101 dose Control-1 MDS # MRD-positive MDS Control-2 RELAPSE MRD-negative MDS Control-3 RELAPSE X AML Control-4 Clinical intervention # AML Control-5 Death X AML Control-6 Ongoing follow-up Control-7 AML X Control-8 AML TSC-101 1 MDS TSC-100 1 T-ALL ‡ TSC-101 2s AML TSC-100 2 AML TSC-101 2 B-ALL TSC-100 3 AML ‡ TSC-101 3s B-ALL TSC-100 3 MDS 0 150 300 450 600 Time (days post-transplant) Data cutoff April 12, 2024 21 *MRD determined by NGS (lower limit of detection 0.05-0.1%) ‡Dose did not meet target dose criteria in supplemental cohorts CONFIDENTIAL


Very different outcomes observed for two patients with TP53-mutated MDS Pre-HCT MRD 6 months 12 months Disease RELAPSE Death X Control-3 Del5q, Mono7, mTP53 MDS FPI (TSC-101) Del5q, mTP53 MDS HCT Feb 16, 2023 0 100 200 300 400 Time (days post-transplant) TSC-101 dose MRD-positive Complete chimerism MRD-negative Mixed chimerism MRD and chimerism determined by NGS (lower limits of detection 0.1% and 0.13%, respectively) 22 Data cutoff April 12, 2024 CONFIDENTIAL


TSC-100 & TSC-101 persisted in peripheral circulation for over 12 months • TSC-100 and TSC-101 TCR-T cells detected in all patients at all time points to date • Repeat dosing resulted in increased levels of circulating TCR-T cells Single dose cohorts Repeat dose cohorts Persistence of engineered T cells- Dose Levels 2,3 Persistence of engineered T cells- Dose Level 1 4 7.5 TSC-101-DL2-supp TSC-101-DL1 6.0 TSC-101-DL2 3 TSC-100-DL1 Average TCR-T Average TCR-T TSC-101-DL3-supp 4.5 2 Day 100-204 Day 100-204 TSC-100-DL2 3.0 0.052% 0.614%* TSC-100-DL3 1 1.5 TSC-100-DL3 0.2 0.2 0.1 0.1 0.0 0.0 0 50 100 150 200 250 300 350 400 0 50 100 150 200 250 300 Days post infusion Days post infusion Dose 1 Dose 2 Dose 1 *Average TCR-T Day 100-204 DL3: 1.73%; DL2 and DL-supp: 0.22% 23 Data cutoff April 12, 2024 CONFIDENTIAL TSC-100/TSC-101 - % of peripheral T cells TSC-100/TSC-101 - % of peripheral T cells


Serious adverse events were similar between treatment and control arms Control-arm Highest Serious Adverse Event Post-transplant Day TSC Relatedness Patient Grade* Control 3 Cytokine release syndrome 2 +2 Not Applicable Control 4 Neck pain 3 +53 Not Applicable Control 2 Acute graft versus host disease in skin 3 +49 Not Applicable Same Acute graft versus host disease in gastrointestinal Control 2 3 +53 Not Applicable patient tract Control 2 Pneumonia 3 +56 Not Applicable Control 5 RSV Pneumonia 3 +28 Not Applicable Control 7 Acute kidney injury, septic shock 5 +7 Not Applicable *Grading by CTCAE v5.0 or MAGIC consortium grading for GvHD See next slide for treatment-arm patients 24 Data cutoff April 12, 2024 CONFIDENTIAL


Serious adverse events were similar between treatment and control arms Treatment-arm Highest Serious Adverse Event Post-transplant Day TSC Relatedness Patient Grade* TSC-100-DL3 Sepsis, respiratory failure 4 +9 Not applicable (pre-TSC) TSC-100-DL2 Pyrexia 1 +136 Not related # TSC-100-DL3 Pericardial effusion 4 +77 Not related Acute graft versus host disease in gastrointestinal TSC-101-DL1 3 +49 Possibly related # tract , acute kidney injury Adenovirus viremia, Pneumonia, Clostridium difficile TSC-101-DL1 2 +71 Not Related infection Same TSC-101-DL1 Pyrexia 1 +148 Not Related patient TSC-101-DL1 Interstitial pneumonitis 2 +182 Not Related TSC-101-DL1 Pneumonia 3 +368 Not Related TSC-101-DL1 Pneumonia, pleural effusion 3 +400 Not Related TSC-101-sDL2 HHV-6 reactivation 1 +21 Not applicable (pre-TSC) Same TSC-101-sDL2 Influenza viremia, pneumonia, pleural effusion 3 +252 Not Related patient TSC-101-sDL2 Urinary tract infection 2 +295 Not Related TSC-101-sDL3 COVID-19, catheter infection 3 +95 Not Related Donor Acute pulmonary embolism 3 N/A Not applicable *Grading by CTCAE v5.0 or MAGIC consortium grading for GvHD # Research testing by flow cytometry or immunohistochemistry for TSC-100/101 markers did not find evidence of involvement See previous slide for control-arm patients 25 Data cutoff April 12, 2024 CONFIDENTIAL


Adverse events of special interest similar between treatment and control arms All cytokine release syndrome (CRS) events occurred before TSC-100/ TSC-101 treatment Arm-Dose Level Grade* Adverse Event HCT Day of Onset Duration TSC relatedness TSC-100-DL2 Grade 1 CRS +3 2 days Not applicable (pre-TSC) TSC-100-DL3 Grade 1 CRS +3 3 days Not applicable (pre-TSC) TSC-101- DL2supp Grade 2 CRS +1 3 days Not applicable (pre-TSC) +1 TSC-101-DL2 Grade 1 CRS 5 days Not applicable (pre-TSC) TSC-101-sDL3 Grade 1 CRS +1 3 days Not applicable (pre-TSC) Control 1 Grade 1 CRS +2 3 days Not applicable Control 2 Grade 1 CRS +3 2 days Not applicable Control 3 Grade 2 CRS +2 2 days Not applicable +1 Control 6 Grade 1 CRS 3 days Not applicable TSC-100-DL1 Grade 1 Skin GvHD +48 8 days Possibly related TSC-101-DL1 Grade 3 GI GvHD +49 8 days Possibly related TSC-101-DL2supp Grade 1 Skin GvHD +43 3 days Possibly related +127 TSC-101-DL2 Grade 1 Skin GvHD 7 days Possibly related Control 2 Grade 3 GI GvHD +53 18 days Not applicable Control 2 Grade 3 Skin GvHD +49 12 days Not applicable Control 1 Grade 1 Skin GvHD +180 Pending Not applicable Control 3 Grade 1 Skin GvHD +131 >50 days (off study) Not applicable 26 *MAGIC consortium grading for graft-versus host disease (GvHD); ASTCT grading for cytokine release syndrome (CRS) Data cutoff April 12, 2024 CONFIDENTIAL


Significant increase in enrollment of heme trial post-TANDEM SUN MON TUE WED THU FRI SAT 25 26 27 28 29 1 2 3 4 5 6 7 8 9 Feb/Mar 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 SUN MON TUE WED THU FRI SAT 1 2 3 4 5 6 7 8 9 10 11 12 13 April/May 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10 11 Manufacturing initiated Heme 27 CONFIDENTIAL


Current program addresses sizable patient population, with several global and lifecycle management opportunities 20,000 Expansion opportunities in oncology and other 15,000 malignancies Current clinical program 10,000 New TCRs/HLAs Expansion to 5,000 Europe Change in practice 0 - Increased adoption of haploidentical donors - Increased eligibility of - Enable transplant for relapsed, AML, MDS, ALL patients refractory heme malignancies - Increased use of more tolerable conditioning - Use as a conditioning regimen pre-transplant Source: SEER, CIBMTR, ClearView analysis 28 CONFIDENTIAL Addressable patients


Solid Tumors: Developing multiplex TCR-T to overcome tumor heterogeneity


TScan is learning from nature to understand, exploit, and enhance how T cells recognize and fight cancer The challenge: Nature’s solution: Cancer cells T cells CD8+ CD4+ Heterogeneous target Diverse repertoire expression of CD4+ and CD8+ T cells HLA loss What do T cells Hostile TME (e.g., TGFβ) naturally recognize and how can we use that Blood vessel information to design better therapeutics? 30 CONFIDENTIAL


TScan is building an ImmunoBank of TCRs to enable enhanced, multiplex TCR-T cell therapy Cancer patient ImmunoBank of therapeutic TCRs Customized TCR-T therapy HLAs T cells HLA Type Profile tumor Cancer cells with different HLA types and targets • Determine target and HLA expression in patient tumor • Manufacture and administer customized, multiplex TCR-T therapy 31 CONFIDENTIAL Targets


Target heterogeneity in solid tumors limits the efficacy of singleplex therapies Melanoma Melanoma MAGE-C2 MAGE-A4 MAGE-C2 PRAME • Treatment with a TCR-T against one target does not address the full tumor • TCR-T therapy against multiple targets may be required improve efficacy and durability 32 CONFIDENTIAL


Multiplex TCR-T may address the problem of heterogeneity in solid tumors Multiplex TCR-T is designed to overcome Non-engineered T-cells TSC-203-A0201 (PRAME) target heterogeneity and HLA loss Target 1 Target 2 HLA 1 HLA 2 Singleplex Multiplex TCR-T TCR-T for Target 1 for Target 1 + Target 2 TSC-204-A0101 (MAGE-A1) T-Plex Targeting long-term Relapse remission or cure • Treat patients with multiple TCR-Ts Green cells: SKMEL5 (PRAME-positive) Red cells: A101D (MAGE-A1-positive) • Prospectively select patients for target and HLA expression 33 CONFIDENTIAL


TScan’s enhancements address the hostile tumor microenvironment Enhanced TCR-T to combat the hostile tumor CD8α/β enhances cytokine production in vitro microenvironment 5000 4000 Tumor cell With CD8α/β 3000 2000 Cytotoxicity Cytotoxicity Without CD8 1000 0 Target peptide TCR CD8α/β CD8α/β TCR CD4 DN-TGFβRII improves responses in mouse models Cytotoxic DN-TGFβRII Helper T cell T cell 800 Vehicle TGFβ 600 IL-2 Untransfected T cells 400 TSC-204-A0201 Cytokine support (no DN-TGFβRII) 200 TSC-204-A0201 • Co-deliver CD8α/β to engage helper T-cells 0 (+ DN-TGFβRII) 0 10 20 30 40 50 • Co-deliver DN-TGFβRII to enhance T-cell expansion/persistence Days post implant 34 CONFIDENTIAL 3 Tumor volume (mm ) IL-2 (pg/mL)


Programs address targets frequently co-expressed in prevalent solid tumors Head & Neck Melanoma 66 K Incident Patients in U.S. 100 K Incident Patients in U.S. 100 90 100 90 80 80 50 50 50 60 60 45 40 40 40 25 25 20 20 0 0 0 HPV16 MAGE-C2 MAGE-A4 PRAME MAGE-A1 HPV16 MAGE-C2 MAGE-A4 PRAME MAGE-A1 Cervical (Uterine cervix) NSCLC 15 K Incident Patients in U.S. 230 K Incident Patients in U.S. 100 90 100 80 80 50 60 50 50 50 60 40 40 25 25 10 20 20 ? 0 0 0 HPV16 MAGE-C2 MAGE-A4 PRAME MAGE-A1 HPV16 MAGE-C2 MAGE-A4 PRAME MAGE-A1 Source: American Cancer Society 35 CONFIDENTIAL Patients % Patients % Patients % Patients %


TScan is rapidly filling the ImmunoBank to enable multiplexed TCR-T therapy in solid tumors TCRs covering multiple antigen HLAs and HLA alleles may enable 50-75% of patients to receive multiplex therapy INDs HPV16 TSC-200 Cleared MAGE-C2 TSC-201 Planned 2024 INDs MAGE-A4 TSC-202 Discovery Currently INDs for 6 TCRs PRAME TSC-203 INDs planned for this year MAGE-A1 TSC-204 Expand the ImmunoBank through ongoing discovery ImmunoBank 36 CONFIDENTIAL Targets A*02:01 A*01:01 A*03:01 B*07:02 C*07:02 A*24:02


Dose escalation scheme provides a rapid path to multiplex TCR-T in Phase 1 TSC-204-A0201 TSC-204-C0702 TSC-200-A0201 TSC-203-A0201 TSC-201-B0702 TSC-204-A0101 (MAGE-A1) (HPV16) (PRAME) (MAGE-C2) (MAGE-A1) (MAGE-A1) 0.5B 0.5B 0.5B 0.5B 0.5B 0.5B DL1 2B 2B 2B 2B 2B 2B DL2 Option for singleplex (HPV16) T-Plex 2B 2B 2B 2B 4B 4B Any two TCR-Ts that 28 days 28 days + + DL3 have cleared DL2 First dose Second dose First dose Second dose 5B 5B 5B 5B 10B 10B Any two TCR-Ts that 28 days 28 days DL4 + + have cleared DL3 First dose Second dose First dose Second dose 37 CONFIDENTIAL


Prospectively selecting for target and HLA expression maximizes chance of success Tumor TCR-T selection Germline Target testing HLA LOH HLA loss detected HLA testing Target HLAs on HLA loss intact haplotype IHC / ISH HLA in ImmunoBank No HLA loss Neogenomics Target HLAs on opposite haplotypes Tempus Archival sample <6mo OR fresh biopsy 38 CONFIDENTIAL


Screening protocol pre-identifies patients for treatment Patient journey Leukapheresis T-Plex D2 T-Plex D1 Current Lympho- Progression 28 days Follow-up therapy depletion Screening protocol: Treatment protocol: • Pre-screens patients for trial eligibility • Rapid enrollment during standard-of-care therapy/before • Vein-to-vein time 25 days progression • No IL-2 given • Germline HLA testing • Endpoints: • Archival tumor sample: - Primary: Safety - Tumor IHC - Secondary: ORR, DOR - HLA LOH testing - Exploratory: T-cell persistence 39 CONFIDENTIAL


Investigators are highly motivated and have screened over 250 patients to date Enrollment status 1000 251 222 165 127 97 100 71 Targeting 43 20 sites 28 20 20 16 15 15 14 14 14 13 12 11 10 10 9 9 8 10 4 3 2 2 1 1 1 1 Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr Q2 2023 2024 # of sites open in screening study # of sites open in treatment study # of patients enrolled in screening study 40 CONFIDENTIAL


Broad array of tumor types with ~70% matching to an HLA in the ImmunoBank ~70% of patients have at least one HLA TUMOR TYPES match to the ImmunoBank Cutaneous melanoma 68, 31% 88, 43% NSCLC 36, 17% HNSCC 151, 69% 28, 14% Ovarian Other 15, 7% 18, 9% Cervical 5 Acral 2 Endometrial 2 Uveal melanoma Anal 7, 3% Adenocarcinoma 2 13, 6% Fallopian Tube 1 HLA positive HLA negative Osteosarcoma 1 Peritoneal 1 Meningioma 1 Unknown 1 41 CONFIDENTIAL


High percentage of patients have a TCR match for singleplex therapy and many would be eligible for T-Plex ~60% of patients with all testing completed ~30% of patients with TCR-T have at least one TCR in ImmunoBank would qualify for T-Plex 50 44 3, 11% 40 5, 19% 27 30 20 19, 70% 10 0 All testing complete Any TCR-T match Singleplex 2-T-Plex Combo 3-T-Plex Combo 42 CONFIDENTIAL # of patients


Patients identified across all cohorts and into DL2 and DL3 in some cohorts Dose Level MAGE-A1 A*02:01 MAGE-A1 C*07:02 HPV-16 A*02:01 PRAME A*02:01 MAGE-A1 A*0101 MAGE-C2 B*0702 DL1 • Melanoma (Yale) • Melanoma • Head & Neck • Melanoma (Orlando) • Head & Neck • Melanoma • Apheresis 4/30 (Alleghany) (HonorHealth) • Manufacturing (Alleghany) (HonorHealth) • First dose early • Currently in • Currently in complete • Apheresis 5/7 • Pending clinical status June manufacturing manufacturing • First dose early May • First dose mid June • Targeting apheresis in • Also PRAME • First dose early May • First dose early May May positive DL2 • Head & Neck • Melanoma (Yale) (Norton) • Apheresis 4/23 • Targeting apheresis in May DL3 • Anal (Columbia) • NSCLC (Alleghany) • Pending clinical • Apheresis 5/1 status • Also PRAME and MAGE-A1 positive 43 CONFIDENTIAL


Enrollment proceeding rapidly across heme and solid tumor programs SUN MON TUE WED THU FRI SAT 25 26 27 28 29 1 2 3 4 5 6 7 8 9 Feb/Mar 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 SUN MON TUE WED THU FRI SAT 1 2 3 4 5 6 7 8 9 10 11 12 13 April/May 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10 11 Manufacturing initiated Heme ST 44 CONFIDENTIAL


Patient eligibility expected to increase rapidly as ImmunoBank grows HPV16+ cancers Other solid tumors 100 100 Head & Neck-single 80 80 Melanoma -single NSCLC-single 60 60 Head & Neck-multi 40 40 Melanoma-multi NSCLC-multi HPV+ tumors 20 20 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 Number of TCRs Number of TCRs in ImmunoBank Eligible patients include patients who do not require Eligible patients include patients who are multiplexing (homozygous or hemizygous for targeted positive for at least 2 TCR-Ts in the ImmunoBank. HLA type) or are eligible for at least 2 HPV16 TCRs. 45 CONFIDENTIAL Eligible patients (%) Eligible patients (%)


TScan highlights Q4 2023: Transformative platform Hematologic malignancies Solid tumor program to $192.0 M enables rapid discovery program to prevent deliver enhanced of TCRs and targets for relapse with HCT multiplex TCR-T Net cash, cash engineered T cell therapy Eight patients treated to INDs cleared for six TCR-Ts equivalents, and date are relapse-free with with regulatory path to Recent collaboration marketable securities highlights applicability no detectable cancer multiplexing funds Company into outside oncology No DLTs observed to date Patients identified and 2026 In-house GMP scheduled for all six TCR-Ts TSC-100 and TSC-101 manufacturing progressed to third and final First three patients to be using non-viral vectors dose level dosed in early May 2024 46 CONFIDENTIAL


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