Molecular Partners is a clinical-stage Swiss biotech focused on developing DARPin (Designed Ankyrin Repeat Protein) therapeutics for oncology. DARPins are engineered proteins significantly smaller than conventional antibodies, which Molecular Partners argues enables greater tumor penetration, higher potency at lower doses, and easier engineering into multispecific molecules. The company has no approved products and no commercial revenue; its business is entirely R&D-driven. Molecular Partners operates two core platforms: Radio-DARPin Therapeutics (RDT), which attaches radioactive isotopes to DARPins to deliver targeted radiation directly to tumors, and Immune Cell Engagers, which activate T cells against cancer cells. The lead RDT candidate, MP0712, targets DLL3 in small cell lung cancer using an alpha-emitting isotope and is in a Phase 1/2a trial. A second RDT program, MP0726, targets mesothelin in ovarian cancer. Both are co-developed 50/50 with Orano Med, with Molecular Partners retaining commercialization rights. On the immune cell engager side, MP0533 is a tetra-specific T cell engager targeting AML in Phase 1/2a. The company is also developing "Switch-DARPin" T cell engagers that only activate when two tumor antigens are simultaneously present. Molecular Partners funds operations through co-development cost-sharing with Orano Med and plans to out-license other pipeline assets. Manufacturing is fully outsourced, with DARPins benefiting from faster microbial production relative to conventional biologics.