Item 1.01 Entry into a Material Definitive Agreement. On June 9, 2026, Tango Therapeutics, Inc. (the “ Company”) entered into an underwriting agreement (the “ Underwriting Agreement”) with J. P. Morgan Securities LLC and Leerink Partners LLC as representatives (the “ Representatives”) to the several underwriters named in the Underwriting Agreement (collectively, the “ Underwriters”), relating to an underwritten offering (the “ Offering”) of (i) 18,166,667 shares (the “ Firm Shares”) of the Company’s common stock, $0.001 par value per share (the “ Common Stock”) and(ii) pre-fundedwarrants (the“ Pre-FundedWarrants”) to purchase up to 1,833,395 shares of Common Stock (such shares issuable upon exercise of thePre-FundedWarrants, the“ Pre-FundedWarrant Shares”). Each Share was offered and sold at an offering price of $30.00 before deducting underwriting discounts and commissions and eachPre-FundedWarrant was offered and sold at an offering price of $29.999 which is equal to the offering price per Share less the $0.001 exercise price of eachPre-FundedWarrant, before deducting underwriting discounts and commissions. Pursuant to the Underwriting Agreement, the Company granted the Underwriters a30-dayoption to purchase up to an additional 3,000,009 shares of its Common Stock (the “ Optional Shares,” and together with the Firm Shares, the “ Shares”) at the public offering price per Share, less any underwriting discounts and commissions. All of the Firm Shares and the Pre-FundedWarrants in the Offering were sold by the Company.

Item 9.01 Exhibits 1.1 Underwriting Agreement, dated June 9, 2026, among Tango Therapeutics, Inc, J. P. Morgan Securities LLC and Leerink Partners LLC, as representatives of the several underwriters named in Schedule A thereto. ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 4.1 Form of Pre-Funded Warrant 5.1 Opinion of Goodwin Procter LLP. 23.1 Consent of Goodwin Procter LLP (contained in Exhibit 5.1) 104 Cover Page Interactive Data File (embedded within Inline XBRL document). 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. TANGO THERAPEUTICS, INC. Date: June 10, 2026 By: /s/ Matthew Gall Name: Matthew Gall Title: Chief Financial Officer