Sierra Oncology Shares Rally As Bone Marrow Cancer Candidate Hits Primary Goal

Sierra Oncology Inc SRRA unveiled topline data for momelotinib in myelofibrosis patients who are symptomatic, anemic, and previously treated with an FDA-approved JAK inhibitor.

• With the new data in hand, Sierra now plans to submit a marketing application in Q2 FY22.
• In the Phase 3 study, 195 patients were randomized to receive either momelotinib or the control drug (danazol) for 24 weeks. 
• Related: Sierra Oncology Bets $216M On AstraZeneca's BET Inhibitor For Myelofibrosis.
• Sierra observed a reduction in disease symptoms in 25% of active arm patients, compared to just 9% in the control group (p=0.0095).
• The study also met the secondary endpoints, transfusion independence rate at least 12 weeks after the treatment period, and splenic volume reduction of at least 35% at Week 24.
• Sierra said it saw 31% of patients meet the necessary independence threshold in the active arm compared to 20% in control.
• 23% of drug arm patients got to the necessary splenic reduction level against just 3% in control.
• Momelotinib appeared to cause fewer serious side effects. 
• Sierra researchers saw Grade 3 or worse events in 54% of patients taking the drug compared to 65% in the control arm. 
• Additionally, 35% of the active arm saw a serious treatment-emergent side effect, compared to 40% in control.
• "Currently, improved JAK inhibitors address symptoms and spleen but are myelosuppressive, leading to worsening anemia and thrombocytopenia over time; some patients cannot start treatment due to baseline anemia status. If momelotinib were to be approved by the FDA, physicians would have a single drug that can treat all the key manifestations of the disease without impacting platelet counts," Sierra President & CEO Stephen Dilly told Benzinga.
• "[A]dditionally, we plan to initiate our first combination study for momelotinib with SRA515, our novel BRD4 BET inhibitor, in the first half of this year. Our thinking is that momelotinib's differentiated profile with SRA515's bivalent binding mode may have the potential to prolong improvements in anemia, symptoms, and spleen with disease-modifying activities, such as a reduction in bone marrow fibrosis and clonal proliferation."
• Price Action: SRRA shares are up 44.20% at $22.37 during the premarket session on the last check Tuesday.
• Editor's Note: The post has been updated to include comments from the Company's CEO.