Syndax Pharmaceuticals Reports Fourth Quarter 2017 Financial Results and Provides Clinical and Business Update - Phase 2 ENCORE 601 PD-(L)1 refractory melanoma cohort data and melanoma registration strategy disclosure fo

Syndax Pharmaceuticals Reports Fourth Quarter 2017 Financial Results and

Provides Clinical and Business Update

- Phase 2 ENCORE 601 PD-(L)1 refractory melanoma cohort data and melanoma registration strategy disclosure forthcoming in 2Q18 -

- ENCORE 601 PD-(L)1 refractory NSCLC cohort data expected 2Q18 -

- Initial data on MSS-CRC cohort of ENCORE 601 to drive decision on advancement into second stage expected in 2Q18 -

- Company to host conference call today at 4:30 p.m. ET -

WALTHAM, Mass., March 5, 2018 (PRNEWSWIRE) -- Syndax Pharmaceuticals, Inc. ("Syndax," the "Company" or "we") (Nasdaq: SNDX), a clinical stage biopharmaceutical company developing an innovative pipeline of cancer therapies, today reported its financial results for the fourth quarter ended December 31, 2017. In addition, the Company provided a clinical and business update. As of December 31, 2017, Syndax had $133.2 million in cash, cash equivalents and short-term investments.

"In 2017, we continued to advance our pipeline of potentially transformative best-in-class candidates for the treatment of various cancers. We made significant progress on the clinical development of both our lead product candidate, entinostat, and SNDX-6352, our monoclonal antibody that blocks the colony stimulating factor 1 receptor. We also expanded our pipeline with the addition of a portfolio of preclinical, orally-available small molecule Menin-MLL inhibitors," said Briggs W. Morrison, M.D., Chief Executive Officer of Syndax. "We look forward to several key data readouts in the next six months, including progression free survival data from the Phase 3 E2112 trial of entinostat in combination with exemestane for advanced HR+, HER2- breast cancer. We also anticipate results next quarter from the PD-(L)1 refractory melanoma and NSCLC cohorts of ENCORE 601, as well as initial data and a decision on whether to advance to the second stage of the ENCORE 601 cohort of patients with microsatellite stable colorectal cancer."

Fourth Quarter 2017 Financial Results

As of December 31, 2017, Syndax had cash, cash equivalents and short-term and long-term investments of $133.2 million and 24,390,033 shares issued and outstanding.

License fee revenue increased to $1.2 million in the fourth quarter 2017 from $0.3 million for the comparable period in the prior year. License fee revenue for the year ended December 31, 2017 increased to $2.1 million compared to $1.2 million for the prior year. The increases are due to the ratable recognition of a $5.0 million milestone payment from KHK for the achievement of a development milestone.

Fourth quarter 2017 research and development expenses increased to $16.6 million from $8.5 million for the comparable period in the prior year. Research and development expenses for the year ended December 31, 2017 increased to $48.2 million compared to $31.7 million for the prior year. The increases were primarily due to increased clinical trial activities related to our Phase 1 clinical pharmacology trials, increased enrollment in ENCORE 601, costs related to SNDX-6352 trials, increased activities in ENCORE 602 and ENCORE 603, and CMC activities, increased headcount, legal and consultant expenses, facility costs and travel costs. In 2017 Syndax expensed a nonrefundable upfront payment of $5.0 million to Allergan for the Menin Assets and in 2016 Syndax expensed a nonrefundable upfront payment of $5.0 million related to the UCB license agreement.

General and administrative expenses totaled $4.1 million during the fourth quarter of 2017 and $15.9 million for the year, similar to the $3.0 million and $13.3 million expense level for the respective prior year periods. The increase in general and administrative expenses was primarily due to increases in headcount, increases in pre-commercialization work, professional fees and other costs related to being a public company. These increases were partially offset by decreases in legal expenses.

For the three months ended December 31, 2017, Syndax reported a net loss attributable to common stockholders of $19.1 million or $0.80 per share compared to $10.8 million or $0.59 per share for the comparable prior year period. For the year ended December 31, 2017, Syndax reported a net loss attributable to common stockholders of $60.1 million or $2.90 per share, compared to $47.1 million or $3.22 per share for the prior year period.

Today the Company provided operating expense guidance for the first quarter and full year 2018. For the first quarter and full year 2018, research and development expenses are expected to be $18 to $22 million and $67 to $76 million, respectively, and total operating expenses are expected to be $22 to $26 million and $86 to $96 million, respectively.

Conference Call and Webcast

In connection with the earnings release, Syndax's management team will host a conference call and live audio webcast at 4:30 p.m. ET today, Monday, March 5, 2018.

The live audio webcast and accompanying slides may be accessed through the Events & Presentations page in the Investors section of the Company's website at www.syndax.com. Alternatively, the conference call may be accessed through the following:

Conference ID: 5589398

Domestic Dial-in Number: 1-855-251-6663

International Dial-in Number: 281-542-4259

Live webcast: https://edge.media-server.com/m6/p/tbzo2gon

For those unable to participate in the conference call or webcast, a replay will be available for 30 days on the Investors section of the Company's website, www.syndax.com.

About Syndax Pharmaceuticals, Inc.

Syndax Pharmaceuticals is a clinical stage biopharmaceutical company developing an innovative pipeline of cancer therapies. The Company is developing its lead product candidate, entinostat, a once-weekly, oral, small molecule, class I HDAC inhibitor, in combination with exemestane and several approved PD-1/PD-L1 antagonists. The Company's pipeline also includes SNDX-6352, a monoclonal antibody that blocks the colony stimulating factor 1 (CSF-1) receptor, as well as a portfolio of potent and selective inhibitors targeting the binding interaction of Menin with MLLr. For more information, please visit www.syndax.com or follow the Company on Twitter and LinkedIn.

Syndax's 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. Forward-looking statements contained in this press release include, but are not limited to, statements about the progress, timing, clinical development and scope of clinical trials and the reporting of clinical data for Syndax's product candidates, the potential use of our product candidates to treat various cancer indications, and Syndax's first quarter and full-year 2018 net cash used in research and development and total operating activities. Many factors may cause differences between current expectations and actual results including unexpected safety or efficacy data observed during preclinical or clinical studies, clinical trial site activation or enrollment rates that are lower than expected, changes in expected or existing competition, changes in the regulatory environment, failure of Syndax's collaborators to support or advance collaborations or product candidates and unexpected litigation or other disputes. Other 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 U.S. Securities and Exchange Commission, including the "Risk Factors" sections contained therein. 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.