Immunomedics Provides Update On Phase 2 Study Of Isactuzumab Govitecan In Patients With Diverse Metastatic Solid Cancers

Immunomedics, Inc., (Nasdaq: IMMU)today announced that isactuzumab govitecan (IMMU-132), the Company'sproprietary solid-tumor antibody-drug conjugate (ADC), continues to produceencouraging results in a Phase 2 clinical trial in heavily-pretreated patientswith diverse, metastatic solid cancers. The provisional results were presentedby Dr. David M. Goldenberg, Chairman, Chief Scientific Officer, and ChiefMedical Officer, at the 5th Annual World ADC Summit in San Diego, CA.In 113 patients who have received at least one dose of isactuzumab govitecan,treatments with the ADC resulted in at least 64 patients (57%) with partialresponses and disease stabilization. All lesions were measured by computedtomography (CT) based on RECIST 1.1 criteria. The major responses wereobserved among patients with 6 different advanced cancers, includingtriple-negative breast, small-cell and non-small-cell lung, colorectal,esophageal, and urinary bladder cancers.The ADC was well tolerated at the Phase 2 dose used in the trial expansion,with neutropenia being the major toxicity, and about 10% of patients havinggrade 3 and 4 other toxicities. This suggests a higher therapeutic index(ratio of therapeutic benefit to toxicity) than historical results withirinotecan, SN-38's parent compound."We are most encouraged with the results in patients with triple-negativebreast cancer, small-cell and non-small-cell lung cancers, especially in thesepatients who have late-stage diseases," remarked Cynthia L. Sullivan,President and Chief Executive Officer. "We plan to complete the Phase 2 studybefore the end of this year. Discussions with key opinion leaders, as well aspotential corporate partners, on the further development of this valuableagent are ongoing," Ms. Sullivan added.Isactuzumab govitecan is made up of SN-38, the active metabolite ofirinotecan, conjugated to the Company's humanized anti-TROP-2 antibody. TROP-2is expressed by many human tumors, such as cancers of the breast, cervix,colon and rectum, kidney, liver, lung, ovary, pancreas, and prostate, but withonly limited expression in normal human tissues. Preclinical studies haveindicated that isactuzumab govitecan delivers up to 135-times the amount ofSN-38 to a human pancreatic tumor xenograft than when irinotecan is given. Inpatients who relapsed or were refractive to prior topoisomerase I or IIinhibitors, this ADC demonstrated subsequent activity, suggesting that it canovercome resistance to such inhibitors, including irinotecan.In addition to isactuzumab govitecan (IMMU-132), the Company is alsodeveloping another SN-38 based ADC, labetuzumab govitecan (IMMU-130), for thetreatment of patients with metastatic colorectal cancer. The clinical study ofthis agent is advancing into a Phase 2 trial, with some patients under therapyfor many months and showing long-term disease control after failing prioririnotecan-containing regimens. Here again, despite the frequent dosing, theADC appears to be well tolerated by patients, with transient and reversibleneutropenia, and manageable diarrhea the major side effects, which were mildand irregular.