The epistatic relation of PARP1 and Tdp1 in the repair of topotecan/irinotecan stabilized Topo1cc’s was highlighted in Rhabdomyosarcoma cells treated with PARP1-inhibitor and Tdp1 knockdown, and DT40tdp1-/- cells treated with combinations of PARP1-inhibitor and CPT [20,85,95]. Here, TDP1 is linked to rhabdomyosarcoma.