Development of a nitroreductase-dependent theranostic payload for antibody-drug conjugate

[Display omitted] •Developing a novel theranostic payload possessed dual functions of therapy and imaging is a promising research project.•The fluorescence intensity of the theranostic payload in target cells greatly increased approximately 9 times in 120 min, and the intracellular distribution of the payload could be directly monitored.•The theranostic payload showed broad-spectrum and high antitumor activity (0.09 nM to 1.2 nM), which was equivalent to the MMAE (0.06 nM to 1.1 nM).•As all we know, this is the first theranostic payload reported so far. Theranostic payload may promote the development of theranostic payloads and novel ADCs. Antibody-drug conjugates are gradually revolutionizing anticancer therapy. Payload is one of the most crucial components of ADC for high antitumor activity. However, there is no direct and real-time monitoring method for the intracellular release mechanism of the payload. Herein, we developed a theranostic payload that possessed dual functions of therapy and imaging. This payload consisted of the classic payload MMAE and the novel nitro-coumarin probe reported for the first time, which has the dual characteristics of electron transfer ability and the on–off fluorescence property. In this paper, the theranostic property of the novel payload has been preliminarily demonstrated. The fluorescence intensity of the payload in target cells greatly increased approximately 9 times in 120 min through the high content analysis, and the intracellular distribution of the payload could be directly monitored by a confocal microscope. In in vitro cytotoxicity assays, the payload showed broad-spectrum and high antitumor activity (0.09 nM to 1.2 nM), which was equivalent to the MMAE (0.06 nM to 1.1 nM). Moreover, the ADC loaded with L-233 maintained the theranositc property. In conclusion, our work developed a theranostic payload for the first time and provides a new direct and real-time monitoring method for intracellular studies of ADC payloads.