CStone Pharmaceuticals, a global partner of ABL Bio (298380), confirmed a 100% complete response rate in a Phase 1b trial of CS5001 (ABL202/LCB71), an antibody-drug conjugate (ADC) drug candidate.
ABL Bio said on the 28th that CStone disclosed Phase 1b data for a CS5001 combination regimen in patients with first-line diffuse large B-cell lymphoma (DLBCL) through its semiannual business report.
CS5001 was jointly developed by combining ABL Bio's ROR1 antibody with the ADC platform technology of Ligachem Biosciences (141080). It was licensed to CStone in 2020 in a deal worth about 400 billion won ($288 million).
In the trial, 31 first-line DLBCL patients received CS5001 at doses of 40 to 90 micrograms per kilogram alongside R-CHOP, the standard treatment regimen. Complete response — meaning the cancer had entirely disappeared — was confirmed across all dose groups, for a complete response rate of 100%. The objective response rate, which also counts patients whose tumors shrank beyond a certain threshold, was likewise 100%.
CStone has decided to temporarily halt the ongoing trial and review the optimal dose and dosing interval. Because complete responses were seen even at the lowest dose of 40 micrograms per kilogram, the company plans to analyze the efficacy and safety data collected so far to identify the appropriate dose and interval for patients. It will continue development once the optimal dose and schedule are set.
"CS5001 delivered encouraging data, with a 100% complete response rate and a 100% objective response rate across all dose groups from 40 to 90 micrograms per kilogram," ABL Bio CEO Lee Sang-hoon said. "We hope it will establish itself as a new treatment option that addresses the unmet medical needs of DLBCL patients."
