Syndax Pharmaceuticals Inc (SNDX) SEC Filing 10-Q Quarterly report for the period ending Sunday, September 30, 2018

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At the International Association for the Study of Lung Cancer (IASLC) 19th World Conference on Lung Cancer (WCLC) in September, the Company presented data from the full cohort of PD-(L)1 refractory non-small cell lung cancer (NSCLC) patients enrolled in the ENCORE 601 trial of entinostat in combination with KEYTRUDA® (pembrolizumab). The data continued to support the prior observation of enhanced clinical benefit in a subpopulation of patients with elevated baseline levels of peripheral classical blood monocytes. In October, the Company announced plans to commence a focused, biomarker-driven, randomized registration trial comparing the entinostat-pembrolizumab combination to standard of care chemotherapy in patients whose disease has progressed after both platinum-based chemotherapy and PD-1 antagonist therapy. The trial will seek to validate peripheral classical monocytes as a marker of response to the combination and to determine whether the combination can improve progression free survival (PFS) over standard of care chemotherapy in the high monocyte population. The Company anticipates beginning the trial in the first half of 2019.

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In October, Syndax announced that enrollment has concluded in E2112, the Phase 3 registration trial of entinostat plus exemestane in advanced hormone receptor positive, human epidermal growth factor receptor 2 negative (HR+, HER2-) breast cancer, with a total of 608 patients enrolled. ECOG-ACRIN Cancer Research Group and the National Cancer Institute informed the Company that the trial did not meet the statistical hurdle for the first primary endpoint of improving PFS, which would have provided the earliest regulatory filing opportunity. Following the most recent interim overall survival (OS) analysis conducted by the trial’s Data Safety Monitoring Committee, ECOG-ACRIN also informed Syndax that the trial is continuing as planned, with the next interim analysis for the OS primary endpoint scheduled for the second quarter of 2019. Additional interim analyses will be conducted every six months until either an OS benefit is observed, or the final target number of events occur. E2112 was designed, and obtained Breakthrough Therapy Designation for this indication, based on positive Phase 2b OS results. Any positive OS assessment would enable the Company to file for full regulatory approval.