Bicycle Therapeutics

Bicycle Therapeutics, based in Cambridge in the United Kingdom and listed as BCYC, is the inventor of bicyclic peptide drug conjugates, a class of small, synthetic alternatives to antibody-drug conjugates. Its lead Nectin-4 conjugate, zelenectide pevedotin, or BT8009, was deprioritised in 2026 after regulatory feedback, BT5528 targets EphA2, and its Bicycle radio-conjugates are partnered with Bayer and Novartis in radiopharmaceuticals. OnCo links it to bladder and urothelial cancer, to the zelenectide pevedotin drug record, and to the peptide-drug and small-molecule-drug conjugate technology. Whether bicyclic peptides find their place as radiopharmaceutical carriers rather than as cytotoxic conjugates is the question the 2026 decision poses. Zelenectide pevedotin has its own page.