Briggs Morrison’s little biotech Syndax concedes 2 key trial setbacks for its lead drug, as shares shrivel some more
It takes a little patience, but if you bore through some comments about how enthusiastic Syndax $SNDX CEO Briggs Morrison is about their ongoing pivotal trial in breast cancer with their lead drug, you’ll find that the therapy just failed a couple of key combination studies with two approved PD-L1s.

Morrison — who had a senior R&D post at AstraZeneca before making the leap to biotech — notes that the 2 Phase Ib/II studies combined entinostat with Roche’s Tecentriq and Pfizer/Merck KGaA’s Bavencio for triple negative breast cancer and ovarian cancer. But it failed to extend progression-free survival significantly.
As a result, the Waltham, MA-based biotech is deferring the PD-1 program for entinostat, which includes a study in non-small cell lung cancer. Instead, the biotech is circling the wagons around entinostat “in HR+ breast cancer and SNDX-5613, a Menin inhibitor being developed for genetically-defined population(s) of acute leukemias.”
Morrison, who’s kept a low profile since leaving AstraZeneca, prefers to focus on the positive. In a prepared statement, he noted:
We remain highly encouraged by the potential for a positive overall survival readout in E2112, our Phase III registration trial of entinostat plus exemestane in HR+, HER2- breast cancer, and expect the next interim analysis in the second quarter. As a reminder, any positive overall survival result would allow us to file for full regulatory approval in an indication for which existing therapies have failed to show a survival benefit. In addition, we continue to expect to file an IND in the second quarter for our targeted therapy, SNDX-5613, an inhibitor of the Menin-MLL interaction.
A failure would probably capsize the company at this point.
The small-cap biotech has a little more than $80 million in reserves, which accounts for close to half of its market cap of $155 million. Its stock is trading at less than half of where it peaked in the spring of 2018, and slid 12% in after-market trading.