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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): October 23, 2025

TANGO THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Delaware |  | 001-39485 |  | 85-1195036
(State or other jurisdiction of incorporation) |  | (Commission File Number) |  | (IRS Employer Identification No.)

201 Brookline Ave., Suite 901 Boston, MA |  | 02215
(Address of principal executive offices) |  | (Zip code)

Registrant’s telephone number, including area code: 857-320-4900

(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 |  | Trading Symbol(s) |  | Name of each exchange on which registered
Common stock, par value $0.001 per share |  | TNGX |  | The Nasdaq Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405of 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 2.02 | Results of Operations and Financial Condition.

The information set forth in Item 8.01 under the caption “Preliminary, Unaudited Financial Information” is incorporated into this Item 2.02 by reference.

Item 8.01 | Other Events.

Preliminary, Unaudited Financial Information

On October 23, 2025, the Tango Therapeutics, Inc. (the “Company” or “Tango”) disclosed that, as of September 30, 2025, the Company estimates that it had $152.8 million of cash, cash equivalents and marketable securities.

The foregoing information is based on preliminary unaudited information and management estimates as of and for the quarter ended September 30, 2025, is not a comprehensive statement of the Company’s financial results, and is subject to completion of the Company’s financial closing procedures. During the Company’s financial closing process the Company’s estimates can differ materially from the Company’s initial estimates presented herein based on the Company’s receipt of updated information. The preliminary financial data included in this Current Report on Form 8-K has been prepared by, and is the responsibility of, the Company’s management. The Company’s independent registered public accounting firm has not audited, reviewed, examined, compiled, nor applied agreed-upon procedures with respect to the preliminary financial data. Accordingly, the Company’s independent registered public accounting firm does not express an opinion or any other form of assurance with respect thereto.

Clinical Update

On October 23, 2025, the Company made available a slide presentation relating to a clinical update from the ongoing Phase 1/2 clinical trial of vopimetostat (formerly known as TNG462), a copy of which is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference. The Company undertakes no obligation to update, supplement or amend the materials attached hereto as Exhibit 99.1.

Item 9.01. | Financial Statements and Exhibits.

(d) Exhibits

Exhibit No. |  | Description
99.1 |  | Corporate presentation of Tango Therapeutics, Inc.
104 |  | Cover Page Interactive Data File (embedded within Inline XBRL document)

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.

|  |  |  | TANGO THERAPEUTICS, INC.
Dated: October 23, 2025 |  |  |  | By: |  | /s/ Daniella Beckman
|  |  |  | Name: |  | Daniella Beckman
|  |  |  | Title: |  | Chief Financial Officer