Seragon Pharmaceuticals Announces Acquisition Agreement with Genentech

Acquisition Provides Opportunity to Accelerate Development of Selective Estrogen Receptor Degrader (SERD) Platform for the Treatment of Hormone Dependent Breast Cancer

July 1, 2014 San Diego, CA

Seragon Pharmaceuticals Inc., a leader in developing drugs for hormone dependent cancers, today announced a definitive agreement with Genentech, a member of the Roche Group, (SIX: RO, ROG; OTCQX: RHHBY) whereby Seragon will be acquired for $725 million in cash up front along with $1.0 billion in contingent development milestone payments that could bring the total transaction value to $1.725 billion.  The acquisition includes Seragon’s entire SERD program, including its most advanced compound, ARN-810, a next generation SERD that is currently being evaluated in a Phase I trial in patients with estrogen receptor positive (ER+) metastatic breast cancer.

Seragon, founded in August 2013, is an independent venture backed biotech company based in San Diego that was spun out of Aragon Pharmaceuticals, following its acquisition by Johnson & Johnson.  Following the spin out, Seragon retained many members of the management and R&D team, including Richard A. Heyman, Ph.D., Chief Executive Officer and co-founder of Aragon and Seragon Pharmaceuticals.  The Seragon team focused its attention to develop game changing therapies targeting ER+ breast cancer and other estrogen driven cancers including endometrial and ovarian cancers.

“This acquisition represents an ideal transition between biotech and pharma and may provide an optimal outcome for the SERD program and the breast cancer patient community.  The Seragon team has been committed to bringing new therapies to cancer patients and we are excited to have Genentech carry forward these programs.  Genentech has repeatedly demonstrated its leadership position the oncology field, and their development and commercial capabilities in the breast cancer area are unparalleled,” said Rich Heyman.

In the US alone, there are approximately 229,000 new breast cancer diagnoses and 40,000 deaths/year related to breast cancer.  The vast majority of these cancers are dependent on estrogen signaling and women with ER+ breast cancer are treated with 1st generation anti-hormonal therapies such as tamoxifen or the aromatase inhibitors. These therapies are initially effective, but many patients experience disease progression due to acquired resistance.  Seragon’s SERDs are next generation therapies that have a dual mechanism of action in that they both bind to the estrogen receptor to antagonize hormone action, and they promote receptor degradation.  These SERDs are initially being developed for the treatment of women with late-stage, progressive ER+ metastatic breast cancer, but they also have potential in treating patients with early-stage breast cancer.  Furthermore they also may offer an opportunity to be the cornerstone for future combination therapies.

“I would like to sincerely acknowledge Rich and the entire Seragon team for their commitment and dedication in advancing the ground breaking science behind both Seragon and Aragon.  In just five years since the founding of Aragon, in The Column Group’s offices, this team has advanced multiple compounds from an early idea to a clinical development program targeting hormone dependent cancers.   I would also like to thank Dr. Charles Sawyers for his foundational work helping to elucidate the molecular determinants of resistance for hormone dependent prostate cancer.  This is an ideal path, which will hopefully translate to improving the lives of patients,” said Peter Svennilson, Founder and Managing Partner of The Column Group and Chairman of both Seragon and former Chairman of Aragon.

The closing of the transaction is subject to customary closing conditions, including clearance under the Hart-Scott-Rodino Antitrust Improvements Act. The transaction is expected to close in the third quarter of 2014.

Wilson Sonsini Goodrich & Rosati served as legal advisor to Seragon Pharmaceuticals in this transaction.

About Seragon Pharmaceuticals

Seragon Pharmaceuticals is focused on the development of small-molecule drugs for the treatment of estrogen receptor dependent breast cancer. Seragon Pharmaceuticals’ orally active selective estrogen receptor degraders (SERDs) represent a potential new treatment for progressive metastatic breast cancer that may circumvent the problem of resistance to anti-hormonal therapies. The company’s lead SERD compound, ARN-810, is currently being evaluated in a Phase I clinical trial in breast cancer patients who have failed first generation anti-hormonal therapies such as tamoxifen and aromatase inhibitors.  In addition to endocrine-resistant breast cancer, SERD agents also have potential to treat other estrogen dependent cancers such as endometrial and ovarian cancers. Seragon is a privately held company founded in 2013 and headquartered in San Diego, California.  Seragon was financed by legacy Aragon investors including, The Column Group, OrbiMed Advisors, Aisling Capital, TopSpin and venBio.

For further information, please contact: Trisha Millican SVP of Finance & Chief Accounting Officer Seragon Pharmaceuticals (858) 369-7638

Source: Seragon Pharmaceuticals,

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