CHICAGO, June 2, 2014 (GLOBE NEWSWIRE) -- Immunomedics, Inc., (Nasdaq:IMMU) today reported 10 of 14 patients (71%) with metastatic colorectal cancer (mCRC) responded to IMMU-130, the Company's novel investigational antibody-drug conjugate (ADC) that comprises an anti-CEACAM5 antibody and SN-38, the active metabolite of irinotecan. Commenting on this finding, Cynthia L. Sullivan, President and Chief Executive Officer said, "We believe the high response rate from these heavily pretreated patients who had failed prior irinotecan treatment suggests that IMMU-130 was able to deliver SN-38 to the tumor at an amount high enough to overcome the tumor's resistance to this class of drugs." A total of 21 patients with mCRC have been enrolled into the multicenter Phase I trial to receive IMMU-130 either once or twice weekly for 2 weeks in 3-week cycles. Treatment responses from 14 patients with at least one computed tomography (CT) assessment were presented at the 2014 Annual Meeting of the American Society of Clinical Oncology in Chicago, IL. The 14 CT-assessable patients had a median of 4.5 prior therapies (range 1 - 11), one of which must have been an irinotecan-containing regimen. Median time to progression for all 14 patients was at least 15.0 weeks (range 5.9 - >41.1 weeks), with 1 patient showing an 84% tumor shrinkage and an ongoing duration of partial response of more than 7 months. This patient continues to receive treatment and has received a total of 42 doses of the ADC thus far. However, to date, retreated patients have not shown an immune response to the ADC. The frequent dosing of IMMU-130 appears to be well tolerated by patients, with transient and reversible neutropenia, and manageable diarrhea the major side effects, which were mild and irregular. "In addition to CRC, CEACAM5 expression is also elevated in breast and lung cancers, as well as other tumors, making them potential targets for IMMU-130, which has shown in this trial to have a high therapeutic index," Ms. Sullivan remarked.