Amendment No. 2 to the Exclusive License Agreement, dated April 17, 2013, by and among the Registrant, The Regents of the University of California, and the University of Vienna

Certain identified information has been excluded from this exhibit because it is both not material and is the type that the registrant treats as private or confidential. Information that was omitted has been noted in this document with a placeholder identified by the mark “[***]”.

Exhibit 10.23

Confidential

Amendment No. 2 to Exclusive License Agreement for Methods and Compositions for RNA-Directed Target DNA Modification and for RNA-Directed Modulation of Transcription

This Amendment No. 2 is made to the Exclusive License Agreement for Methods and Compositions for RNA-Directed Target DNA Modification and for RNA-Directed Modulation of Transcription, dated April 16, 2013, as amended by an Amendment Agreement, dated April 17, 2013 (collectively, the “License Agreement”), by and among The Regents of the University of California, the University of Vienna, and Caribou Biosciences, Inc., and is effective March 14, 2019 (the ‘‘Amendment Effective Date”). Caribou Biosciences, Inc. is referred to as “LICENSEE” and The Regents of the University of California (“REGENTS”) and the University of Vienna are collectively referred to as “LICENSORS.” Capitalized terms not defined herein shall have the meaning set forth in the License Agreement.

WHEREAS, LICENSEE and LICENSORS wish to amend the License Agreement, as set forth herein.

NOW, THEREFORE, in consideration of the mutual covenants contained herein, and for other good and valid consideration, the amount and sufficiency of which are hereby acknowledged, LICENSEE and LICENSORS agree as follows:

[***]

IN WITNESS WHEREOF, the parties hereto have executed this Amendment No. 2 as of the Amendment Effective Date by their duly authorized officers or representatives.