TML-2Cl is a dichlorinated trimethyl-lock adapter used in antibody-drug conjugates and payload releasers. It undergoes a 1,6-elimination reaction followed by rapid self-cyclization to facilitate the release of the payload Exatecan after cleavage by cathepsin B-related linkers. TML-2Cl exhibits high stability and inherent hydrophobicity when conjugated to drugs. It is also applicable in gastric cancer research.