Caribou Biosciences Announces Closing of Upsized Initial Public Offering

Caribou Biosciences, Inc., (Nasdaq: CRBU), a leading clinical-stage CRISPR genome-editing biopharmaceutical company, announced today the closing of its previously announced initial public offering of 19,000,000 shares of common stock, at a price to the public of $16.00 per share. In addition, Caribou has granted the underwriters a 30-day option to purchase up to an additional 2,850,000 shares of common stock at the initial public offering price, less the underwriting discounts and commissions.

The aggregate gross proceeds to Caribou from the offering were approximately $304.0 million, before deducting underwriting discounts and commissions and other offering expenses payable by Caribou. The shares began trading on the Nasdaq Global Select Market on July 23, 2021, under the ticker symbol "CRBU."

BofA Securities, Citigroup, and SVB Leerink acted as joint book-running managers for this offering.

Registration statements relating to the offering were filed with the U.S. Securities and Exchange Commission (the "SEC") and became effective on July 22, 2021. Copies of the registration statements can be accessed through the SEC's website at www.sec.gov. The offering was made only by means of a prospectus forming part of the effective registration statements. Copies of the final prospectus relating to this offering may be obtained from: BofA Securities, NC1-004-03-43, 200 North College Street, 3rd Floor, Charlotte, NC 28255-0001, Attention: Prospectus Department, or by email at dg.prospectus_requests@bofa.com; Citigroup, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, by telephone at (800) 831-9146 or by email at prospectus@citi.com; or SVB Leerink LLC, Attention: Syndicate Department, 53 State Street, 40th Floor, Boston, MA 02109, or by telephone at (800) 808-7525, ext. 6105, or by email at syndicate@svbleerink.com.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any offer or sale of these securities in any state or jurisdiction in which such offer, solicitation, or sale would be unlawful prior to the registration or qualification under the securities laws of any such state or jurisdiction.

About Caribou Biosciences, Inc.

Caribou is a clinical-stage CRISPR genome-editing biopharmaceutical company dedicated to transforming the lives of patients with devastating diseases by applying the company's proprietary chRDNA technology toward the development of next-generation, genome-edited allogeneic immune cell therapies. The company is developing a pipeline of genome-edited, off-the-shelf CAR-T and CAR-NK cell therapies for the treatment of both hematologic malignancies and solid tumors. The therapies target cell surface antigens for which autologous CAR-T cell therapeutics have previously demonstrated clinical proof-of-concept as well as additional emerging targets.