Syndax Pharmaceuticals, Inc. (NASDAQ:SNDX) Q4 2019 Earnings Conference Call - Final Transcript

Mar 03, 2020 • 04:30 pm ET

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Syndax Pharmaceuticals, Inc. (NASDAQ:SNDX) Q4 2019 Earnings Conference Call - Final Transcript

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Presentation
Executive
Briggs W. Morrison

that program this year. And finally, we will continue to collect data that will further clarify the potential of our anti-CSF-1R antibody, axatilamab, to treat chronic graft versus host disease.

So let's review each of these opportunities in greater detail. Slide 4 summarizes the design of the Phase III trial of entinostat in hormone receptor positive, HER2-negative breast cancer. Trial randomized 608 patients to exemestane plus placebo versus exemestane plus entinostat, and the focus of this trial is now on the final overall survival analysis. Final analysis will be conducted once there are 410 events, which based on our modeling and recent discussions with ECOG, we believe will occur in the second quarter of this year. A positive outcome would allow us to file for regulatory approval in the United States based upon the terms of our breakthrough therapy designation in hormone receptor positive metastatic breast cancer and the special protocol assessment process with FDA.

Our team is prepared to submit a regulatory filing should the trial be positive within about 6 months of receiving the data from ECOG, which would set us up to launch entinostat in 2021. Trial has 80% power to detect a hazard ratio of 0.75, the maximum hazard ratio that would yield a statistically significant positive trial is 0.82. Based upon the design assumptions, if E2112 achieved a hazard ratio of 0.82, that would indicate that patients receiving the combination had about a 5-month improvement in median overall survival or about 22 months in the control group to 27 months in the entinostat arm.

Slide 5 emphasizes the potential for the entinostat-exemestane regimen to be the preferred agent after a first-line aromatase inhibitor, which is typically given either as a single agent or in combination with the CDK4/6 inhibitor. Our current estimate is that between 30% and 50% of the patients in E2112 will have received a CDK4/6 inhibitor prior to entering the trial. Thus, we should have a highly relevant data set in the post-CDK4/6 patient population.

In our opinion, the rapid adoption of CDK4/6 inhibitors, such as Ibrance, in the first-line setting underscores the desire of physicians and patients to improve the outcomes associated with anti-estrogen therapy. In the setting of a positive E2112 result, we would expect entinostat to achieve similar widespread use. This population of patients is substantial with an estimated 34,000 patients in the U.S. each year who go on to receive hormone therapy after failing first-line therapy and who could, therefore, be eligible to receive the entinostat regimen.

Importantly, we will be prepared to launch entinostat in the U.S. on our own. We are actively building out our internal commercial team to ensure we are well positioned for the potential launch of entinostat in 2021 while concurrently entering into discussions with potential rest-of-world commercial partners.

Slide 6 emphasizes the clinical potential of entinostat in hormone receptor positive breast cancer. In preparation for launching entinostat, we have conducted qualitative market research with community physicians and breast cancer experts. We tested