Synthesis and evaluation of KX-01 analogs with an exploration of linker attachment points for antibody-drug conjugates.

KX-01 (tirbanibulin, Klisyri®) is a recently FDA-approved drug for treating actinic keratosis, with a distinct dual mechanism of action combining microtubule disruption and non-ATP-competitive Src inhibition. This unique mechanism and novel chemotype highlight KX-01's potential as a payload for antibody-drug conjugates. In this study, we synthesized and evaluated KX-01 derivatives to enhance anticancer potency and explore functional groups suitable for antibody conjugation. Notably, replacing the morpholine group with an N-benzoylpiperazine scaffold resulted in an analog with significantly improved in vitro antiproliferative activity, attributed to enhanced microtubule disruption and Src inhibition. Furthermore, introducing a phenol or aniline functionality as a common linker attachment point preserved substantial cytotoxicity. These results suggest the potential of KX-01 derivatives for future use as ADC payloads.