Spero Therapeutics, Inc.

675 Massachusetts Avenue, 14th Floor

Cambridge, Massachusetts 02139

March 24, 2021


United States Securities and Exchange Commission

Division of Corporation Finance

100 F Street, N.E.

Washington, D.C. 20549

Attention: Alan Campbell



    Spero Therapeutics, Inc.


    Registration Statement on Form S-3 File No. 333-254170


    Request for Acceleration of Effectiveness

Ladies and Gentlemen:

In accordance with Rule 461 promulgated under the Securities Act of 1933, as amended, Spero Therapeutics, Inc. (the “Company”) hereby requests acceleration of the effective date of the Registration Statement on Form S-3 (File No. 333-254170) (the “Registration Statement”), so that it may become effective at 4:00 p.m., Washington, D.C. time on March 29, 2021 or as soon as possible thereafter.

The Company hereby authorizes Matthew J. Gardella, Esq. of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. to orally modify or withdraw this request for acceleration.

The Company respectfully requests that it be notified of such effectiveness by a telephone call to Mr. Gardella at (617) 348-1735 and that such effectiveness also be confirmed in writing. Any questions regarding this request may be addressed to Mr. Gardella.


Very truly yours,




/s/ Satyavrat Shukla

Satyavrat Shukla

Chief Financial Officer




Spero Therapeutics, Inc.



Ankit Mahadevia, M.D., President and Chief Executive Officer


Tamara Joseph, Esq., Chief Legal Officer



Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.



Matthew J. Gardella, Esq.


Matthew W. Tikonoff, Esq.


Lewis J. Geffen, Esq.