On February 17, 2017 Immunomedics, Inc., (NASDAQ: IMMU) ("Immunomedics" or "the Company") reported that sacituzumab govitecan (IMMU-132) is active in patients with metastatic urothelial cancer (UC) and has the potential to become a second line or later treatment to platinum-based or immuno-oncology therapy for these patients (Filing, 8-K, Immunomedics, FEB 17, 2017, View Source [SID1234517768]).
"With larger numbers than the initial report, I remain impressed with the safety and efficacy results produced by sacituzumab govitecan in a difficult-to-treat patient population that had a median of two prior therapies and had extensive metastatic disease," commented Dr. Scott T. Tagawa, the Richard A. Stratton Associate Professor in Hematology and Oncology, and an Associate Professor of Clinical Medicine and of Clinical Urology at Weill Cornell Medicine and an oncologist at NewYork-Presbyterian, who presented the results at the GU conference.
"While patients with metastatic UC usually respond well to initial therapy with a platinum-containing regimen, few options are available after they become refractive. Second-line immune checkpoint-inhibitor (IO) therapy was recently approved by the FDA, such as atezolizumab and nivolumab, with expected approval of pembrolizumab as well. Although responders to the new IO therapy may do well for a prolonged period of time, about three-fourths do not respond and overall median PFS is less than 2.5 months and median OS less than 13 months have been reported," added Dr. Tagawa, who has served as a consultant to Immunomedics.
In the ongoing Phase 2 study with sacituzumab govitecan in metastatic UC, the ORR among 36 assessable patients was 31% (11/36), including one confirmed CR and ten confirmed PRs. The median duration of response for these ten patients was 7.5 months (95% confidence interval [CI], 4.4 to 12.9 months), with one patient having a PR for more than 18 months and continuing therapy. Overall, 69% of patients showed tumor shrinkage from baseline with sacituzumab govitecan therapy, and 14 patients are still under therapy.
For the 41 intention-to-treat patients, median PFS was 7.2 months (95% CI, 6.7 to 11.7 months) and median OS was 15.5 months (95% CI, 8.9 to 17.2 months). Of the twelve patients with progression after prior IO therapy and chemotherapy, there were one unconfirmed PR and six patients with stable disease following sacituzumab govitecan treatment.
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The Company announced on February 10, 2017 that an exclusive global licensing agreement was entered into with Seattle Genetics (NASDAQ: SGEN), providing Seattle Genetics worldwide rights to develop, manufacture and commercialize sacituzumab govitecan in multiple indications, including UC.
"We are pleased with these promising results, especially the long-term control of advanced disease in patients who failed multiple prior therapies, and look forward to working closely with Seattle Genetics to bring this important investigational product to cancer patients expeditiously," stated Cynthia L. Sullivan, President and Chief Executive Officer of Immunomedics. Ms. Sullivan added, "We remain on target to commence our Phase 3 randomized trial in patients with advanced triple-negative breast cancer in March, and are working diligently to complete the submission of our Biologics License Application to FDA for Accelerated Approval of this indication."
In addition to Dr. Tagawa, other clinical investigators participating in this study include Drs. Allyson J. Ocean, Bishoy Faltas, and Ana Molina, his colleagues at NewYork-Presbyterian and Weill Cornell Medicine, New York, NY; Dr. Elaine Lam, University of Colorado Cancer Center, Aurora, CO; Drs. Philip Saylor and Aditya Bardia, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA; Dr. Julio J. Hajdenberg, UF Health Cancer Center-Orlando Health, Orlando, FL; Dr. Alicia K. Morgans, Vanderbilt-Ingram Cancer Center, Nashville, TN; Drs. Kevin Kalinsky and Emerson Lim, NewYork-Presbyterian/Columbia University Medical Center-Herbert Irving Comprehensive Cancer Center, New York, NY; and Dr. Matthew D. Galsky, Icahn School of Medicine Mount Sinai, Tisch Cancer Institute, New York, NY.
A total of 44 patients with metastatic UC had been enrolled into this open-label multicenter study. Sites of metastases included liver (N=9; 25%), lymph nodes (N=14; 39%), lungs (N=14; 39%, pelvis (N=9, 25%), and bone (N=4; 11%). Patients received a median of six doses (range, 1-50) of sacituzumab govitecan, which was administered at 8 or 10 mg/kg on days 1 and 8 of 3-week cycles. Despite repeated dosing, grade 3 or higher adverse events were limited to neutropenia (30%), febrile neutropenia (11%), fatigue (11%), and diarrhea (3%).
Treatment response was assessed by computed tomography (CT) every 8 weeks. Patients with more than 30% tumor shrinkage required confirmation within 4 to 6 weeks after the initial response in accordance with by RECIST 1.1 for single-arm studies.