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Shares of Syros Pharmaceuticals SYRS plunged 86.9% on Wednesday after a late-stage study of its only pipeline candidate, tamibarotene, for treating higher-risk myelodysplastic syndrome (HR-MDS) failed to meet the primary endpoint of complete response (CR) rate. Tamibarotene is Syros’ proprietary, oral, selective RARα agonist.
The phase III SELECT-MDS-1 study evaluated tamibarotene in combination with azacitidine, a chemotherapy, in newly diagnosed HR-MDS patients with RARα gene overexpression. Per the data readout, the CR rate in the first 190 enrolled patients in the tamibarotene/azacitidine treatment arm was 23.8%, which failed to demonstrate statistical significance over the CR rate of 18.8% observed in the placebo/azacitidine control arm.
However, Syros reported that the combo drug was well-tolerated by the total enrolled HR-MDS patient population in the SELECT-MDS-1 study. Moreover, the treatment-related adverse events were similar to those observed in earlier company-sponsored studies.
Year to date, shares of SYRS have plunged 95.4% compared with the industry’s 3.8% decline.
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Based on the disappointing outcome, Syros has decided to stop the HR-MDS study followed by a thorough review of the clinical data to evaluate the next steps. This is a huge setback for the company, leaving SYRS without a pipeline candidate. In the same press release, the company also stated that the failure of the SELECT-MDS-1 study to meet its primary endpoint constitutes an event of default under its secured loan facility with Oxford Finance.
SYRS’ Termination of Mid-Stage Leukemia Study in August
The latest stock price drop marks the second pipeline setback for Syros in around three months. In August 2024, Syros stock plummeted after it discontinued enrollment in the mid-stage acute myeloid leukemia (AML) study of tamibarotene based on poor results from a prespecified interim analysis.
The phase II SELECT-AML-1 study evaluated the triple therapy of tamibarotene in combination with AbbVie’s ABBV Venclexta (venetoclax) and azacitidine compared with the doublet regimen of Venclexta and azacitidine in newly diagnosed, unfit AML patients with RARα gene overexpression.
The study observed similar CR/CR with incomplete hematologic recovery rates of 65% and 70% between the triplet and doublet arms, respectively. Based on such findings, Syros concluded that the likelihood of the study demonstrating superiority at the final analysis in 80 patients is low, leading to the decision to halt enrollment.