Molecular Partners’ Radio-DARPins Show Comparable 177Lu and 203Pb Profiles, Securing Eckert & Ziegler Pact
Two Radio-DARPin candidates targeting distinct tumor antigens demonstrated highly comparable biodistribution profiles when labeled with Lutetium-177 or Lead-203, showing similar uptake and washout rates in tumor-bearing mice. Molecular Partners also entered an agreement with Eckert & Ziegler to develop and manufacture Radio-DARPin therapeutics using Actinium-225 and Lutetium-177.
1. Preclinical Data on 177Lu and 203Pb Show Isotopic Flexibility
Molecular Partners presented data on two Radio-DARPin candidates, each specific for a different tumor target, demonstrating that labeling with Lutetium-177 or Lead-203 yields highly comparable biodistribution profiles in mouse models. Both candidates exhibited similar tumor uptake and washout rates, confirming the vector design’s amenability to multiple imaging isotopes.
2. Isotope-Agnostic Platform Enables Late-Stage Alpha Emitter Selection
The interchangeable imaging behavior with 177Lu and 203Pb enables predictive insights for therapeutic isotopes Actinium-225 and Lead-212, allowing the company to choose the optimal alpha emitter based on initial clinical data without restarting discovery or development processes.
3. MP0712 Imaging Validates Clinical Development of 212Pb Candidate
MP0712, a DLL3-targeted Radio-DARPin co-developed with Orano Med and currently in a Phase 1/2a trial, has shown supportive imaging results under compassionate use with 203Pb. These data underpin the advancement of MP0712 carrying 212Pb for patients with small cell lung cancer and other DLL3-expressing neuroendocrine tumors.
4. Eckert & Ziegler Alliance Secures Manufacturing of Radio-DARPins
In February 2026, Molecular Partners signed a strategic agreement with Eckert & Ziegler to support development and manufacturing of Radio-DARPin therapeutics using 225Ac as the therapeutic payload and 177Lu as the imaging payload. This partnership provides access to isotope-related components and comprehensive services for clinical supply and scale-up.