How is MAAA-1162a synthesized?

MAAA-1162a (Deruxtecan, MC-GGFG-DXd) is a drug-linker complex of detrastuzumab (DS-8201a), formed by DXd (MAAA-1181a, payload) and maleimide-tetrapeptide linker (MC-GGFG) through chemical coupling. The following provides a detailed explanation from three aspects: structure, synthesis route, key steps, and purification:

Synthesis Route (divided into three main stages)

Stage 1: Payload (DXd/MAAA-1181a) synthesis (Exatecan derivation)

Starting material: 2-fluoro-1-methyl-4-nitrobenzene Bromination: NBS / Sulfuric Acid / Heptane → 2-Fluoro-4-Bromine-1-Methyl-5-Nitrobenzene Reduction + acetylation: nitro→amino→ acetanilide (three steps, total yield 37%) Heck coupling: Coupled with 3-butenoic acid under Pd(OAc)₂ catalysis to form → olefin intermediates Hydrogenation: Reduces the double bond → carboxylic acid intermediate Intramolecular cyclization: TFA/TFAA activation→ tetrahydronaphthalenone Nitrification + Reduction: Introduction of amino → bis(aminoacetic acid) intermediates Condensation + Cyclization: Condensation with aldehydes → enamines→ dehydration cyclogene→ quinoline (astereomer mixture) Salinization + Resolution: Methasulfonic acid salting, recrystallization separation of Exatecan (target) and epitropic isomers (recoverable) Derivativeization: Exatecan Hydroxyl Modification → DXd (MAAA-1181a)

Stage 2: Linker (MC-GGFG) synthesis

Skeleton construction: Solid-phase peptide synthesis (SPPS) or liquid-phase synthesis of GGFG tetrapeptides N-terminal modification: Introduction of maleimide (MC) to form MC-GGFG-COOH Activation: C-terminal carboxyl group activation (such as NHS esters, acyl chlorides), facilitating coupling with DXd

Stage 3: Drug-linker coupling (MAAA-1162a generation)

Coupling reaction: The amino/hydroxyl group of DXd reacts with activated MC-GGFG in anhydrous DMF/DMSO, forming amide/ester bonds Key Conditions: Temperature: Room temperature ~35°C Time: 12~24 h Protection: Inert gas (N₂) protected from light Product: MAAA-1162a (MC-GGFG-DXd)

3. Purification and Quality Control

Purification: Reversed-phase high-performance liquid chromatography (RP-HPLC) Crystallization / Recrystallization (non-chiral chromatography, suitable for mass production) Quality control: Purity: ≥98% (HPLC) Structural confirmation: ¹H-NMR, MS, IR Stability: Stability testing in plasma/buffer solution

4. Conjugation with Antibodies (Generating DS-8201a)

Antibody reduction: Trastuzumab uses TCEP to reduce interchain disulfide bonds, releasing 4 pairs of free mercaptol groups Coupling: The maleimide of MAAA-1162a undergoes Michael addition to the thiol group, forming a thioether bond DAR control: target DAR=8 (each antibody conjugates 8 drugs - linkers) Purification: gel filtration / ion exchange chromatography to remove unreacted drugs and aggregates

5. Summary of Core Points

MAAA-1162a=DXd+MC-GGFG linker, developed by Daiichi Sankyo. Three-step synthesis: DXd preparation→ linker synthesis→ coupling, with strict purification and quality control throughout the process. Key linker design points: plasma stability, intratumoral lysis, and uniform DAR (≈8).