Syndax Announces Closing of Public Offering of Common Stock and Exercise in Full of the Underwriters' Option to Purchase Additional Shares

Syndax Announces Closing of Public Offering of Common Stock and Exercise in Full of the Underwriters' Option to Purchase Additional Shares

WALTHAM, Mass., December 19, 2023 /PRNewswire/ -- Syndax Pharmaceuticals, Inc. ( Syndax, the Company or we ) (Nasdaq: SNDX), a clinical-stage biopharmaceutical company developing an innovative pipeline of cancer therapies, today announced the closing of its previously announced underwritten public offering of 12,432,431 shares of its common stock, which includes the exercise in full of the underwriters' option to purchase 1,621,621 additional shares. The public offering price of each share of common stock was $18.50. The aggregate gross proceeds to Syndax from this offering, before deducting underwriting discounts and commissions and estimated offering expenses, were approximately $230.0 million. Following the closing of the Offering, Syndax has 84,809,736 shares issued and outstanding as of December 19, 2023.

Goldman Sachs & Co. LLC, J.P. Morgan, TD Cowen and Stifel acted as joint book-running managers for the offering. B. Riley Securities acted as manager for the offering.

The shares were offered pursuant to a shelf registration statement previously filed and declared effective by the Securities and Exchange Commission (SEC). A final prospectus supplement and accompanying prospectus relating to the offering were filed with the SEC and are available on the website of the SEC at www.sec.gov. Copies of the final prospectus supplement and accompanying prospectus relating to the offering may be obtained from: Goldman Sachs and Co. LLC, Attention: Prospectus Department, 200 West Street, New York, NY 10282, telephone: 866-471-2526, facsimile: 212-902-9316 or by emailing Prospectus-ny@ny.email.gs.com; J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, telephone: (866) 803-9204, or by emailing prospectuseq_fi@jpmchase.com; Cowen and Company, LLC, 599 Lexington Avenue, New York, NY 10022, by emailing Prospectus_ECM@cowen.com or by telephone at (833) 297-2926; or Stifel, Nicolaus & Company, Incorporated, Attention: Prospectus Department, One Montgomery Street, Suite 3700, San Francisco, California 94104, by telephone at (415) 364-2720 or by emailing syndprospectus@stifel.com.

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

Syndax Pharmaceuticals is a clinical stage biopharmaceutical company developing an innovative pipeline of cancer therapies. Highlights of the Company's pipeline include revumenib, a highly selective inhibitor of the menin KMT2A binding interaction, and axatilimab, a monoclonal antibody that blocks the colony stimulating factor 1 (CSF-1) receptor. For more information, please visit www.syndax.com or follow the Company on Twitter and LinkedIn.

Cautionary Note on Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as may, will, expect, plan, anticipate, estimate, intend, believe and similar

expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. These forward-looking statements are based on Syndax's expectations and assumptions as of the date of this press release. Each of these forward-looking statements involves risks and uncertainties. Actual results may differ materially from these forward-looking statements. Factors that may cause Syndax's actual results to differ from those expressed or implied in the forward-looking statements in this press release are discussed in Syndax's filings with the SEC, including the Risk Factors sections contained therein, as well as the risks identified in the registration statement and the final prospectus supplement relating to the offering. These forward-looking statements are based on Syndax's expectations and assumptions as of the date of this press release. Except as required by law, Syndax assumes no obligation to update any forward-looking statements contained herein to reflect any change in expectations, even as new information becomes available.

Syndax Pharmaceuticals, Inc.