Niclosamide-13C6 is the 13C6 labeled Niclosamide. Niclosamide (BAY2353) is an orally bioavailable chlorinated salicylanilide, with anthelmintic and potential antineoplastic activity. Niclosamide (BAY2353) inhibits STAT3 with IC50 of 0.25 µM in HeLa cells and inhibits DNA replication in a cell-free assay.