Azide-Propionyl-Val-Ala-PAB(m-PEG8)-Exatecan piperidine 68 SMILES CC1=C(SC=N1)C1=CC=C(CNC(=O)[C@@H]2C[C@@H](O)CN2C(=O)[C@@H](NC(=O)CCOCCO)C(C)(C)C)C=C1 Purity (HPLC)

68 SMILES CC1=C(SC=N1)C1=CC=C(CNC(=O)[C@@H]2C[C@@H](O)CN2C(=O)[C@@H](NC(=O)CCOCCO)C(C)(C)C)C=C1 Purity (HPLC) >= 95% Shipping Conditions Room temperature Storage Conditions Refrigerated Shelf Life 12 months after the date of delivery Regulatory Statement For Research Use Only

405 SMILES NCCNC(=O)C1=CC=C2C(=C1)C(=O)OC21C2=CC=C(O)C=C2OC2=C1C=CC(O)=C2 Purity (HPLC) 98% Shipping Conditions Room Temperature Storage Conditions Refrigerated Regulatory Statemen: For Research Use Only

89 SMILES ClCCOCCOCCOCCOC1=C2C(=O)N(C3CCC(=O)NC3=O)C(=O)C2=CC=C1 Purity (HPLC) >= 95% Shipping Conditions Room temperature Storage Conditions Refrigerated Shelf Life 12 months after the date of delivery Regulatory Statement For Research Use Only

the enzyme first removes the succinyl group

421 Purity (HPLC) >= 95% Solubility DMSO

Azide-Propionyl-Val-Ala-PAB(m-PEG8)-Exatecan piperidine 68 SMILES CC1=C(SC=N1)C1=CC=C(CNC(=O)[C@@H]2C[C@@H](O)CN2C(=O)[C@@H](NC(=O)CCOCCO)C(C)(C)C)C=C1 Purity (HPLC)SOLU KNEX cleavable linker features a Val Ala dipeptide. m PEG8 is attached to the commonly used self immolative para aminobenzyl (PAB) moiety to increase aqueous solubility. The payload is Exatecan, a highly potent topoisomerase I inhibitor derived from camptothecin, which induces DNA damage by stabilizing the topoisomerase IDNA complex, resulting in cell cycle arrest and apoptosis. Derived from established ADC linker architectures, SOLU KNEX ADC