Sensei Biotherapeutics (SNSE) revises 2026 board reconstitution timeline

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Filing Exhibits & Attachments

8-K Event Classification

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Key Terms

What board changes did Sensei Biotherapeutics (SNSE) announce for 2026?

Why is Karen Vousden’s appointment to the Sensei Biotherapeutics (SNSE) board delayed?

When will Sensei Biotherapeutics (SNSE) vote on the Required Company Stockholder Matters?

What is the planned size of the Sensei Biotherapeutics (SNSE) board?

What role will Bob Holmen have at Sensei Biotherapeutics (SNSE) if stockholders approve the proposals?

Filing Impact

(Moderate)

Filing Sentiment

(Neutral)

Form Type

8-K

Sensei Biotherapeutics updated its plans for reconstituting its board of directors around the 2026 Annual Meeting of Stockholders scheduled for June 10, 2026. Due to personal reasons, the planned appointment of Karen Vousden, Ph.D. to the board will be delayed, with the board intending to consider her appointment in the third or fourth quarter of 2026.

If the Required Company Stockholder Matters are approved at the Annual Meeting, the board plans to appoint Bob Holmen as chair of the Nominating and Corporate Governance Committee effective June 12, 2026, when other described appointments would take effect. The board has also approved a board size of five directors as of that date.

Item 8.01 — Other Events

1 item

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

Annual Meeting date: June 10, 2026 Effective date for board changes: June 12, 2026 Board size: Five directors +1 more

4 metrics

Annual Meeting date June 10, 2026 Date of 2026 Annual Meeting of Stockholders

Effective date for board changes June 12, 2026 Planned effective date for certain board appointments

Board size Five directors Approved board size as of June 12, 2026

Appointment timing window Q3–Q4 2026 Intended period to consider appointing Karen Vousden, Ph.D.

Required Company Stockholder Matters, Nominating and Corporate Governance Committee, Definitive Proxy Statement, forward-looking statements

4 terms

Required Company Stockholder Matters financial

"If the Required Company Stockholder Matters (as defined in the Definitive Proxy Statement) are approved at the Annual Meeting"

Nominating and Corporate Governance Committee financial

"the Board intends to appoint Bob Holmen as chair of the Nominating and Corporate Governance Committee"

A nominating and corporate governance committee is a group within a company's board of directors responsible for selecting and recommending individuals to serve as company leaders, such as directors or executives. They also develop and oversee policies to ensure the company is run fairly, ethically, and transparently. This committee matters to investors because it helps ensure the company is well-managed and guided by qualified, responsible leadership.

Definitive Proxy Statement regulatory

"as described in the Company’s definitive proxy statement filed with the Securities and Exchange Commission on April 27, 2026 (the “Definitive Proxy Statement”)"

A Definitive Proxy Statement is a detailed document that a company sends to its shareholders before a big meeting, like voting on important decisions. It explains what's being voted on and gives important information so shareholders can make informed choices. It matters because it helps shareholders understand and participate in key company decisions.

forward-looking statements regulatory

"This on contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933"

Forward-looking statements are predictions or plans that companies share about what they expect to happen in the future, like estimating sales or profits. They matter because they help investors understand a company's outlook, but since they are based on guesses and assumptions, they can sometimes be wrong.

Understanding 8-K Material Events →

05/22/2026 - 04:01 PM

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): May 22, 2026

Sensei Biotherapeutics, Inc.

(Exact Name of Registrant as Specified in its Charter)

Delaware

001-39980

83-1863385

(State or Other Jurisdiction

of Incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)


1405 Research Blvd, Suite 125
Rockville, MD		20850
(Address of Principal Executive Offices)		(Zip Code)

Registrant’s telephone number, including area code: (240) 243-8000

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 Securities Exchange Act of 1934:

Title of each class

Trading

symbol

Name of each exchange

on which registered

Common Stock

SNSE

The Nasdaq Stock 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 8.01. Other Events.

On May 22, 2026, Sensei Biotherapeutics, Inc. (the “Company”) announced an update regarding the expected reconstitution of the board of directors of the Company (the “Board”) in connection with the Company’s 2026 Annual Meeting of Stockholders to be held on June 10, 2026 (the “Annual Meeting”), as described in the Company’s definitive proxy statement filed with the Securities and Exchange Commission (the “SEC”) on April 27, 2026 (the “Definitive Proxy Statement”).

Due to personal reasons, Karen Vousden, Ph.D. has requested that her appointment to the Board be delayed until later in 2026. The Board intends to consider appointing Dr. Vousden in the third or fourth quarter of 2026. If the Required Company Stockholder Matters (as defined in the Definitive Proxy Statement) are approved at the Annual Meeting, the Board intends to appoint Bob Holmen as chair of the Nominating and Corporate Governance Committee, effective June 12, 2026, when the other board appointments described in the Definitive Proxy Statement would become effective. The Board has also approved a Board size of five directors as of that date.

Forward-Looking Statements

This Current Report on Form 8-K contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements include, but are not limited to, statements regarding: (i) the expected reconstitution of the Board if the Required Company Stockholder Matters are approved; (ii) the anticipated timing and effectiveness of Board appointments, including the appointment of Bob Holmen as chair of the Nominating and Corporate Governance Committee; (iii) the Board’s intention to consider the appointment of Karen Vousden, Ph.D. in the third or fourth quarter of 2026; and (iv) the anticipated size of the Board. These forward-looking statements are based on the Company’s current expectations and assumptions and are subject to risks and uncertainties that could cause actual results to differ materially from those anticipated. Factors that could cause or contribute to such differences include, but are not limited to: (i) the receipt of stockholder approval of the Required Company Stockholder Matters; (ii) changes in the expected timing or composition of the reconstituted Board; and (iii) other risks and uncertainties described in the Company’s filings with the SEC, including the Definitive Proxy Statement. The Company undertakes no obligation to update or revise any forward-looking statements, whether as a result of new information, future events, or otherwise, except as required by applicable law.

SIGNATURES

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.

Source: View Original Filing on SEC EDGAR

Sensei Biotherapeutics outlined changes to its board tied to the 2026 Annual Meeting. Plans include appointing Bob Holmen as chair of the Nominating and Corporate Governance Committee and setting the board size at five directors, subject to certain stockholder approvals.

Karen Vousden, Ph.D. requested that her appointment to Sensei Biotherapeutics’ board be delayed for personal reasons. The board intends to consider appointing her later in 2026, specifically in the third or fourth quarter, instead of around the June 2026 Annual Meeting.

The Required Company Stockholder Matters are scheduled for a vote at Sensei Biotherapeutics’ 2026 Annual Meeting of Stockholders on June 10, 2026. Approval of these matters is a condition for certain planned board appointments and committee leadership changes to take effect.

Sensei Biotherapeutics’ board has approved a future board size of five directors as of June 12, 2026. This sizing is linked to the broader board reconstitution expected to follow the 2026 Annual Meeting and related stockholder approvals.

If the Required Company Stockholder Matters are approved at the 2026 Annual Meeting, the board intends to appoint Bob Holmen as chair of the Nominating and Corporate Governance Committee. His appointment as chair would become effective on June 12, 2026.

Sensei Biotherapeutics, Inc.

Date: May 22, 2026

/s/ Christopher W. Gerry

Christopher W. Gerry

President and General Counsel

3 documents