ATM inhibition potentiates the anticancer activity of pyrazolo[4,3-e]tetrazolo[1,5-b][1,2,4]triazine sulfonamides in colorectal cancer cells in vitro

Abstract Colorectal cancer (CRC) remains a leading cause of cancer-related mortality, with chemoresistance posing major treatment challenges. Here, we investigated the anticancer potential of pyrazolo[4,3- e ]tetrazolo[1,5- b ][1,2,4]triazine sulfonamides (MM129 and MM137) in combination with the ATM inhibitor KU-60,019 in HCT-116 and HT-29 CRC models. Combinatorial treatment significantly decreased cell viability, suppressed proliferation (BrdU and Ki-67), and increased neutral comet and γH2AX-associated DNA damage parameters compared to single-agent treatments. Cell death analyses showed mainly apoptosis-associated changes, while partial protection by NEC-1 suggests that additional non-apoptotic mechanisms may contribute under selected conditions. Our results indicate that MM compounds exhibit measurable anticancer activity in 3D spheroid models and that their combination with ATM inhibition modulates both viability and spheroid morphology, as reflected by changes in ATP levels, core size, and diffusion parameters. Further optimization and mechanistic studies are required to determine the extent and basis of any combinatorial benefit in this context.