Atiratecan (TP300) is a prodrug of camptothecin analog CH0793076. Atiratecan shows antitumor activity against both breast cancer resistance protein (BCRP)-positive and -negative xenografts in mouse xenograft models[1]. Atiratecan does not inhibit acetylcholinesterase (AChE) activities.

Atiratecan (TP300) is stable in acidic solution but rapidly converts to CH0793076 under physiological pH conditions, such as in sera[1]. It exhibits antiproliferative activity against camptothecin-resistant cell lines, with IC50s of 9.4 nM for A2780 cells and 1.1 nM for A2780/SN75 cells[1].

The eVective dose range of Atiratecan is between 0.30 and 47 mg/kg (MTD/ED50=157). The toxic dose is 63 mg/kg for Atiratecan[1]. Atiratecan (24 mg/kg; IV; once per week for 6 weeks) in combination with capecitabine results in synergistic eVects in the HCT116 human colon cancer and NCI-N87 human gastric cancer xenograft models and an additive eVect in the WiDr human colon cancer xenograft model which is BCRP-positive and CPT-11-insensitive[1]. Atiratecan (TP300; 47 mg/kg; IV; once per week for 3 weeks) shows more than 50% of tumor growth inhibition in all nine models, regardless of the expression of BCRP[1].