Immunomedics announced that some patients who had failed prior therapy with irinotecan or camptosar, both topoisomerase-1 inhibitors, responded to IMMU-132, the company's lead antibody-drug conjugate in clinical development for the treatment of patients with solid cancers. An overall disease control rate of 82% in 22 computed tomography-assessable patients were reported. These include 15 patients with stable disease as their best response and 3 patients, one in each of triple-negative breast, colorectal and small-cell lung cancers, with a partial response. For the 18 patients who responded to IMMU-132, 8 had failed prior therapies with irinotecan or camptosar. Because irinotecan is the parent of SN-38, the Company's drug of choice in IMMU-132, we postulate that the increased amount of SN-38 delivered to the tumors by IMMU-132 overcomes the tumor's resistance to this class of drugs.