MADISON, Wis.—Biotechnology company Cellectar Biosciences Inc. has reported that the results of a preliminary tumor-targeting study revealed that CLR 1602, its prototype paclitaxel chemotherapeutic conjugate, may be up to 30 times more tumor-selective than free paclitaxel. The in-vivo study—which was designed to evaluate the pharmacokinetics, absorption and distribution after a single intravenous administration of CLR 1602 vs. free paclitaxel mice—showed that tumor uptake of CLR 1602’s paclitaxel payload increased by more than 30-fold over free paclitaxel. In addition, CLR 1602’s payload demonstrated an extended plasma half-life as well, with prolonged retention even at 96 hours, compared to free paclitaxel, which was cleared from plasma within 24 hours. Cellectar presented a poster on these results at the recent 35^th National Medicinal Chemistry Symposium in Chicago in late June.