Antibody drugs that go after two targets have already made their mark in blood cancers, but the field is working to improve on the safety and efficacy of this approach. Merck is getting a contender from Curon Biopharmaceutical that could have applications in both oncology and immunology.
Merck is paying $700 million up front for global rights to Curon’s CN201, a bispecific antibody in early-stage clinical development, the company announced Friday. Curon could receive up to $600 million in milestone payments tied to the development and regulatory progress of the drug candidate.
The Curon antibody is designed to bind to the protein CD3 on T cells and CD19 on B cells, an immune cell that can drive certain cancers and autoimmune diseases. Binding to both targets engages T cells to deplete the disease-driving B cells. Amgen’s Blincyto was the first CD3/CD19 bispecific antibody, approved to treat certain leukemias. Recent published research indicate this drug’s approach has potential application to autoimmune disease. But the Amgen drug comes with safety risks. Curon’s drug is designed to reduce an excessive immune response called cytokine release syndrome while retaining the cytotoxicity of T cells.
The acquisition agreement comes about two months after Curon presented preliminary data for CN201 during the annual meeting of the American Society of Clinical Oncology. In the Phase 1 study enrolling 58 adult patients with relapsed or refractory B cell non-Hodgkin lymphoma cytokine release syndrome occurred in four patients, mainly after the first dose. All of those cases were classified as low-grade. No neurotoxicity was observed. The results also showed signs of anti-tumor activity. In 22 evaluable patients who received full doses of 5 mg or higher, the objective response rate was 77% and the complete remission rate was 22%. In 11 patients with indolent B cell non-Hodgkin lymphoma, the objective response rate was 91% and the complete remission rate was 45.5%.
The encouraging preliminary data were apparently persuasive for Merck. But the pharmaceutical giant’s plans for the Curon drug go beyond cancer.
“We continue to identify opportunities to expand and diversify our pipeline,” Dean Li, president of Merck Research Laboratories said in a prepared statement. “Early clinical data have provided robust evidence for the potential of CN201 to target and deplete circulating and tissue B cells with the potential to treat a range of malignant and autoimmune diseases.”
Merck is not alone in the effort to bring bispecific antibodies to autoimmune disease. Roche’s mosunetuzumab, brand name Lunsumio, won approval two years ago as a treatment for follicular lymphoma. The Swiss pharma giant is currently in early clinical testing of this bispecific antibody in systemic lupus erythematosus, the most common form of lupus. Cullinan Oncology became Cullinan Therapeutics earlier this year, a name change that reflected its expansion into autoimmune disorders. The company’s CD3/CD19-targeting bispecific antibody, named CLN-978, is in development for lupus; an investigational new drug application is expected in the current quarter.
Startup Zenas Biopharma is developing a bifunctional monoclonal antibody named obexelimab. The clinical program for this drug candidate includes a Phase 3 testing in IgG4-related disease and Phase 2 testing in lupus and multiple sclerosis. In May, Waltham, Massachusetts-based Zenas closed a $200 million Series C round to finance the clinical trials.
Merck expects the acquisition of Curon’s CN201 will close in the third quarter of this year. The deal follows the pharma giant’s acquisition of Harpoon Therapeutics in early 2024. Harpoon is developing tri-specific engagers. The third domain of the drug extends the half-life of the therapy. Harpoon’s lead program is in Phase 1/2 testing in advanced cancers that express the protein DLL3.
Photo: Christopher Occhicone/Bloomberg, via Getty Images
