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 3, 2019

SPERO THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Delaware	001-38266	46-4590683
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)

675 Massachusetts Avenue, 14th Floor Cambridge, Massachusetts (Address of principal executive offices) 02139 (Zip Code)

Registrant’s telephone number, including area code: (857) 242-1600

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, $0.001 par value per share	SPRO	The 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 7.01 Regulation FD Disclosure.

On October 3, 2019, Spero Therapeutics, Inc. (the “Company”) issued a press release announcing that an independent review committee had evaluated interim pharmacokinetic plasma data from the Company’s ongoing ADAPT-PO pivotal Phase 3 clinical trial of SPR994, the Company’s oral carbapenem product candidate, and recommended that the Company continue the trial without modification of the protocol-defined dose. A copy of this press release is attached as Exhibit 99.1 hereto.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

Exhibit 99.1 Press Release, dated October 3, 2019

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.

	SPERO THERAPEUTICS, INC.
Date: October 3, 2019	By:	/s/ Ankit Mahadevia, M.D.
		Ankit Mahadevia, M.D. Chief Executive Officer and President