Immunomedics Reports Interim Phase 2 Results With Sacituzumab Govitecan in Lung Cancers

Immunomedics, Inc., IMMU today announced that sacituzumab govitecan, the Company's lead investigational antibody-drug conjugate (ADC), continues to produce durable responses in patients with metastatic lung cancer who had relapsed or were refractory to their last cancer therapy. At the time of this analysis, a total of 57 patients with metastatic lung cancer (28 non-small-cell lung cancer (NSCLC) and 29 small-cell lung cancer (SCLC)) had been enrolled into this multicenter study at doses ranging from 8-18 mg/kg given on days 1 and 8 every 21 days. The median number of prior lines of therapy in the NSCLC and SCLC patients was 3 and 2.5, respectively. Across all tumor types, 12 mg/kg was declared the maximal tolerated dose and 10 mg/kg declared the recommended Phase 2 dose. Accrual at 10 mg/kg continues. Treatment response in lung cancer patients administered doses of ≤12 mg/kg was assessed by computed tomography using the rules set by the Response Evaluation Criteria In Solid Tumors (RECIST 1.1). In NSCLC, the most common type of lung cancer, 6 of 19 patients achieved an objective response (objective response rate = 32%). In SCLC, 6 of 20 patients achieved an objective response (objective response rate = 30%). In the 10 mg/kg cohorts, the objective response (partial response) rates in NSCLC and SCLC were 3/10 (30%) and 3/5 (60%), respectively. In NSCLC, the interim median progression-free survival (PFS), which is the length of time patients are living without their cancer progressing, was 5.4 months for those patients receiving sacituzumab govitecan at the dose level of 10 mg/kg. At the time of analysis, fifty-six percent of NSCLC patients in this dose group had experienced a PFS event. For patients with SCLC, interim median PFS was 4.6 months at the 10 mg/kg dose level. At the time of analysis, eighty-three percent of SCLC patients in this dose group had experienced a PFS event. Overall survival (OS) data were too early to report. "These results, while still early, seem to show noticeable activity of this drug in a heavily pretreated lung cancer population," commented Dr. D. Ross Camidge, Joyce Zeff Chair in Lung Cancer Research at the University of Colorado Cancer Center, who presented these data in an Oral Session at the 16th World Conference on Lung Cancer. "Based on these compelling results, we consider both NSCLC and SCLC to be of primary interest, along with triple-negative breast, esophageal, urothelial, and colorectal cancers, for further study with sacituzumab govitecan," remarked Cynthia L. Sullivan, President and Chief Executive Officer of Immunomedics. "Updated results in these other solid cancers are expected at future national and international cancer conferences," Ms. Sullivan added. According to the American Cancer Society, lung cancer accounts for more deaths than any other cancer in both men and women. An estimated 158,040 deaths are expected to occur in 2015, accounting for about 27% of all cancer deaths. Sacituzumab govitecan is a first-in-class antibody-drug conjugate (ADC) developed by the Company by conjugating the moderately-toxic drug, SN-38, site-specifically and at a high ratio of drug to antibody, to a humanized antibody that targets the TROP-2 receptor expressed by many solid cancers. SN-38 is the active metabolite of irinotecan (Camptosar), which is used to treat certain solid cancers, particularly metastatic colorectal cancers, as a part of combination therapies, so its pharmacology and properties are well-known. In addition, the ADC also continues to demonstrate a highly tolerable and easily managed toxicity profile, despite repeated dosing. In the 31 lung cancer patients receiving sacituzumab govitecan at the dose of 10 mg/kg, the major toxicity reported was 10% Grades 3 and 4 neutropenia. Remarkably, there was no reported incidence of Grade 3 or 4 diarrhea, which is a major side effect with irinotecan. At 10 mg/kg 13% of lung cancer patients required a dose reduction in sacituzumab govitecan. Dr. Wells A. Messersmith, a colleague of Dr. Camidge at the University of Colorado Cancer Center, also participated in this multicenter study. Other Principal Investigators include Dr. Alexander N. Starodub, Indiana University Health Center for Cancer Care, Goshen, IN; Dr. Allyson J. Ocean, Weill Cornell Medical College, New York, NY; Drs. Aditya Bardia and Rebecca Heist, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA; Dr. Sajeve S. Thomas, UF Health Cancer Center, Orlando, FL; and Drs. Gregory A. Masters and Michael J. Guarino, Helen F. Graham Cancer Center & Research Institute, Newark, DE.