Karyopharm Therapeutics 延长债务契约暂缓执行期至 11 月 1 日

KARYOPHARM THERAPEUTICS INC.

Date: October 22, 2026

/s/ Michael Mano

Michael Mano

Executive Vice President, Chief Legal Officer and Secretary

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 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 22, 2026

Karyopharm Therapeutics Inc.

(Exact Name of Registrant as Specified in Charter)

Delaware

001-36167

26-3931704

(State or Other Jurisdiction

of Incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)

85 Wells Avenue, 2nd Floor

Newton, Massachusetts

02459

(Address of Principal Executive Offices)

(Zip Code)

Registrant’s telephone number, including area code: (617) 658-0600

(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 (see General Instruction A.2. below):

☐	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, $0.0001 par value

KPTI

Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 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.

As previously disclosed in the Current Reports on Form 8-K filed by Karyopharm Therapeutics Inc. (the “Company”) on September 11, 2026 and October 14, 2026, the Company entered into a Forbearance Agreement and Limited Waiver to Indentures, dated September 10, 2026 (the “Forbearance Agreement”), and the applicable parties subsequently extended the Forbearance Period (as defined in the Forbearance Agreement) to October 22, 2026.

On October 22, 2026, in accordance with Section 19 of the Forbearance Agreement, the applicable parties further extended the date on which the Forbearance Period will end, absent earlier termination, from 11:59 p.m., Eastern time, on October 22, 2026 to 11:59 p.m., Eastern time, on November 1, 2026.

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.