Seattle Genetics said today it has acquired exclusive global rights to the Immunomedics cancer antibody–drug conjugate (ADC) sacituzumab govitecan in a deal that could generate up to about $2 billion-plus for Immunomedics.
Sacituzumab govitecan (IMMU-132) is an ADC that links an anti-trophoblast cell-surface antigen 2 (TROP-2) antibody to SN-38, the active metabolite of irinotecan. TROP-2 is a cell-surface receptor expressed on tumors that include cancers of the breast, colon, lung, and bladder.
Sacituzumab govitecan is now under study in a Phase I/II trial for patients with triple-negative breast cancer, as well as multiple other solid tumors. Data from the trial will support a planned Biologics License Application (BLA) submission under the FDA’s accelerated approval regulations.
Last month, Immunomedics disclosed positive data about the ADC from the Phase I/II trial, saying that in 85 evaluable patients with metastatic triple-negative breast cancer, sacituzumab govitecan showed an objective response rate of 29% and a median duration of response of 10.8 months. For all 89 patients in the intent-to-treat population, the estimated median overall survival was 18.8 months. The ADC was generally well tolerated, Immunomedics added, with the most common adverse events being nausea, neutropenia, diarrhea, anemia, vomiting, and fatigue.
“This agreement would add a promising late-stage ADC to our pipeline as we continue making progress toward our goal of becoming a global, multiproduct oncology company,” Seattle Genetics president and CEO Clay Siegall, Ph.D., said in a statement. “Sacituzumab govitecan would complement our existing pipeline by providing a potential near-term opportunity to commercialize a second drug in the United States, expand our international capabilities in Europe and elsewhere, and extend our efforts in solid tumors.”
Seattle Genetics agreed to pay Immunomedics $250 million upfront, up to approximately $1.7 billion in payments tied to achieving development, regulatory, and sales-dependent milestones, plus tiered double-digit royalties.
Concurrent with the licensing agreement, Seattle Genetics will take a 2.8% stake in Immunomedics by purchasing approximately $15 million of common stock. Seattle Genetics also has rights to buy an additional 8,655,804 shares of common stock at $4.90 per share for a defined period.
The stock transactions and rights are not subject to closing of the development and license agreement, Seattle Genetics said.
The licensing deal is subject to customary conditions that include expiration or termination of the waiting period under the Hart–Scott–Rodino Antitrust Improvements Act of 1976, as amended.
Upon closing of the deal, Seattle Genetics said, it will revise its 2017 financial guidance to investors, disclosed just yesterday. Under that guidance, the company said it expected to generate 2017 total revenues ranging from $405 million to $445 million.
Last year, the FDA gave its Breakthrough Therapy Designation to sacituzumab govitecan for treatment of patients with triple-negative breast cancer who have failed prior therapies for metastatic disease. The agency has also granted the ADC Fast Track designation for patients with small-cell lung cancer (SCLC) or non-small-cell lung cancer (NSCLC).
Sacituzumab govitecan has also received orphan drug designations—by the FDA for the treatment of patients with SCLC or pancreatic cancer and by the European Medicines Agency for the treatment of patients with pancreatic cancer.