Pyrazoloacridine is a pyrazolo[3,4,5-kl]acridine derivative patented by Warner-Lambert Co. as an anticancer agent. Pyrazoloacridine acts as topoisomerase I and II inhibitor that decrease the formation of topoisomerase-DNA adducts. In vitro experiments, Pyrazoloacridine shows efficacy against multidrug-resistant neuroblastoma doxorubicin-resistant human colon carcinoma and breast cancer cell lines. In clinical trials, Pyrazoloacridine demonstrates moderate efficacy in metastatic breast cancer and a high level of adverse events. The dose-limiting toxicity was grade 4 neutropenia. Other grade 3 and 4 toxicities include vomiting, nausea, neurotoxicity, fatigue, and anemia.