Opna Bio Releases Interim Data from Phase 1 Study of OPN-2853 and Ruxolitinib in Advanced Myelofibrosis

SAN DIEGO—Opna Bio, a biopharmaceutical company dedicated to oncology, shared interim results from its primary clinical program, OPN-2853, targeting advanced myelofibrosis. The findings, presented at the American Society of Hematology (ASH) annual meeting, highlighted notable spleen reduction among participants, with minimal toxicity and adverse effects. Additionally, preclinical studies for OPN-6602 demonstrated significant tumor regression in multiple myeloma models.

OPN-2853 is currently evaluated in a Phase 1 study for patients with advanced myelofibrosis who have not responded adequately to ruxolitinib alone. Myelofibrosis, a blood cancer, leads to bone marrow fibrosis, anemia, and spleen enlargement. The study involves three dose levels of OPN-2853 (20 mg, 40 mg, and 80 mg), administered orally once daily with ruxolitinib. As of February 2024, 16 patients from various UK locations had been enrolled, coordinated by the Cancer Research UK's Clinical Trials Unit at the University of Birmingham.

Among 12 patients whose data were assessable, median spleen size decreased significantly, with half of the patients experiencing non-palpable spleens. The combination treatment was generally well-tolerated, with most patients completing eight treatment cycles.

Principal investigator Adam Mead, PhD, MRCP, FRCP, from the University of Oxford, expressed optimism about these initial findings. He noted that combining OPN-2853 with ruxolitinib was well-tolerated and effective in spleen size reduction for myelofibrosis patients with limited treatment options. The team anticipates determining a recommended Phase 2 dose by early 2025, with further clinical development planned for OPN-2853.

In preclinical studies, OPN-6602, an oral inhibitor of EP300 and CBP, is undergoing a Phase 1 trial for multiple myeloma (MM), a cancer originating from malignant plasma cells in bone marrow. In MM mouse models, OPN-6602 achieved 71% tumor suppression alone and complete tumor regression when combined with dexamethasone, pomalidomide, or mezigdomide, with a sustained response. RNA sequencing revealed that OPN-6602 downregulated critical MM driver and signature genes, showcasing its potential to overcome resistance to standard treatments.

Gideon Bollag, PhD, co-founder and chief scientific officer of Opna Bio, highlighted the promising clinical and preclinical data for OPN-2853 and OPN-6602. He emphasized the unique pharmacokinetic profiles of these drug candidates, which feature a high Cmax and short half-life, enabling continuous daily dosing, effective target engagement, and rapid clearance to minimize toxicities. This gives them an advantage both as single agents and in combination therapies.

Opna Bio specializes in developing novel oncology therapeutics, focusing on various cancer drivers. The company's portfolio includes a unique discovery program targeting the fragile-X multifunctional RNA-binding protein (FMRP) and other promising oncology assets. The Opna team has a strong track record of advancing multiple FDA-approved drugs to market, demonstrating significant scientific expertise and commercial success. Their leading clinical compounds are OPN-2853, a BET bromodomain inhibitor studied in myelofibrosis patients, and OPN-6602, a dual EP300/CBP inhibitor currently in a Phase 1 trial for multiple myeloma.