Shanghai-based MicuRx Pharmaceutical (SSE: 688373) announced plans to grant Switzerland's ClearideBio Therapeutics AG exclusive worldwide rights to MRX-23, a preclinical antibody-drug conjugate (ADC), under an agreement providing USD 1 million upfront and up to USD 223 million in development, regulatory, and sales milestones. A separate agreement gives ClearideBio options to license up to six additional projects using MicuRx's STOPIN ADC platform, with potential milestones of up to USD 750 million if all options are exercised and all milestones achieved.
The two agreements carry a combined maximum of USD 974 million in disclosed upfront and milestone payments, excluding additional option-exercise fees, sublicensing revenue shares, and potential sales royalties. MicuRx stressed that the milestone figures represent contingent theoretical ceilings rather than guaranteed payments or expected revenue.
MRX-23 is a preclinical bispecific ADC developed using MicuRx's proprietary STOPIN platform, which incorporates a novel camptothecin-based cytotoxic payload designed to improve antitumor activity while reducing toxicity. The company's 2025 annual report describes MRX-23 as targeting two tumor-associated antigens, although the specific target combination was not identified. Neither MRX-23 nor the STOPIN platform has completed human clinical validation.
Under the MRX-23 agreement, ClearideBio would assume responsibility for subsequent worldwide development and commercialization across all indications. A near-term USD 3.5 million development milestone, included within the USD 223 million ceiling, would be triggered by the first clinical trial application approval for a licensed product. MicuRx would also be eligible for sublicensing revenue shares or sales royalties, depending on ClearideBio's commercialization strategy.