The global biotechnology company Seattle Genetics earlier today confirmed development and icencing agreement with Immunomedics. Under the terms of the agreement, Seattle Genetics receives exclusive worldwide rights to develop, manufacture and commercialize sacituzumab govitecan, also known as  IMMU-132.

Sacituzumab govitecan is an investiagtional  antibody-drug conjugate or ADC targeted to TROP-2, which is expressed in several solid tumors including cancers of the breast, lung and bladder. The drug is composed of an anti-TROP-2 antibody linked to SN-38, the active metabolite of irinotecan. TROP-2 is a cell-surface receptor that is expressed on several tumors, including cancers of the breast, colon, lung and bladder.

Clinical trials
The investigational drug is in a phase I/II trial for patients with triple negative breast cancer (TNBC), as well as multiple other solid tumors.

In data reported from these phase I/II trial, in 85 evaluable patients with metastatic TNBC, 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. Sacituzumab govitecan was generally well-tolerated. The most common adverse events were nausea, neutropenia, diarrhea, anemia, vomiting and fatigue.

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Breakthrough Therapy Designation
In 2016 the drug received Breakthrough Therapy Designation from the U.S. Food and Drug Administration (FDA) for the treatment of patients with TNBC who have failed prior therapies for metastatic disease. The regulatory agency has also granted the ADC Fast Track designation for patients with small-cell lung cancer (SCLC) or non-small-cell lung cancer (NSCLC).

In addition, sacituzumab govitecan has been designated an orphan drug by the FDA for the treatment of patients with SCLC or pancreatic cancer and by the European Medicines Agency (EMA) for the treatment of patients with pancreatic cancer.

Data from the phase I/II trial are intended to serve as the basis for a planned Biologics License Application (BLA) submission under the FDA’s accelerated approval regulations.

Photo 1.0: Clay Siegall, Ph.D., President and Chief Executive Office of Seattle Genetics.

Multi-product oncology company
“This agreement would add a promising late-stage ADC to our pipeline as we continue making progress towards our goal of becoming a global, multi-product oncology company. 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,” noted Clay Siegall, Ph.D., President and Chief Executive Officer of Seattle Genetics.

“In addition, we believe our expertise in ADCs, including demonstrated success in clinical development, regulatory, manufacturing and commercialization, ideally positions Seattle Genetics to advance this program globally. We look forward to working with Immunomedics to advance this program for patients in need, including those with triple negative breast cancer and other solid tumors,” Siegall added.

“After a long and robust process, we concluded that licensing our lead asset, sacituzumab govitecan, to Seattle Genetics, the leading ADC company, would give us the best opportunity to advance this product on behalf of advanced stage cancer patients,” Cynthia L. Sullivan, President and Chief Executive Officer of Immunomedics explained.

“Sacituzumab govitecan has the potential to drive significant value for patients with multiple types of cancer who are in need of new therapy options, and we look forward to continuing its development with Seattle Genetics,” she added.

Upon closing of the transactions contemplated by the development and license agreement, Immunomedics receives an upfront payment of $250 million. In addition, Seattle Genetics pays development, regulatory and sales-dependent milestone payments across multiple indications and geographic regions of up to a total maximum of approximately $1.7 billion, as well as tiered double-digit royalties.

The closing of the transactions contemplated by the development and license agreement is subject to customary conditions, including the expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended.

Potential for other partners
In addition, for a limited period of time, Immunomedics has the right to continue discussions with a small number of parties that previously expressed interest in licensing sacituzumab govitecan. If a third party provides Immunomedics with a financially superior licensing offer, Seattle Genetics has the right to match any such offer, and if it decides not to match, Immunomedics has the right to accept the superior offer and terminate the proposed development and license agreement upon payment of a termination fee to Seattle Genetics.

Financial impact
Concurrent with the transaction, Seattle Genetics is purchasing approximately $15 million of common stock, representing a 2.8% stake in Immunomedics. Seattle Genetics has also been granted the right to purchase an additional 8,655,804 shares of common stock at a price of $4.90 per share for a defined period.

The equity purchase and rights are not subject to closing of the development and license agreement.

Seattle Genetics’ 2017 financial guidance provided on and as of February 9, 2017 does not take into account the impact of the transactions contemplated by the development and license agreement or the equity investment in Immunomedics. Seattle Genetics plans to update its 2017 financial guidance after the closing of the transactions contemplated by the development and license agreement.

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