Apogee Therapeutics, Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 10-Q

(Mark One)

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended June 30,2026

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission File Number:001-41740

Apogee Therapeutics, Inc.

(Exact name of registrant as specified in its charter)

1 Letterman Drive, Building B, Suite B6-800

San Francisco, CA 94129

(650)394‑5230

(Address including zip code, and telephone number including area code, of registrant’s principal executive offices)

Former name, former address and former fiscal year, if changed since last report:

221 Crescent St., Bldg 17, Suite 102b

Waltham, Massachusetts 02453

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

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b‑2 of the Exchange Act.

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. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b‑2 of the Exchange Act). Yes☐ No☒

As of August 3, 2026, the registrant had 75,687,735 shares of common stock, $0.00001 par value per share, outstanding, comprising 62,201,093 shares of voting common stock, $0.00001 par value per share, and 13,486,642 shares of non-voting common stock, $0.00001 par value per share.