Xixi Sun

Xixi Sun is an associate in Goodwin’s Business Law department, where he advises life sciences clients on a broad range of intellectual property matters. He works closely with clients to identify and secure high-value patent opportunities and to navigate the risks and complexities of the existing patent landscape.

Xixi specializes in strategic patent counseling and global patent prosecution, with a particular emphasis on biotechnology and pharmaceutical innovations. He regularly guides clients through the full patent lifecycle, from early-stage portfolio development to later-stage optimization, aligning intellectual property strategy with clients’ business objectives.

Xixi advises companies, investors, and underwriters on intellectual property due diligence in connection with licensing transactions, strategic partnerships, and private and public financings. He also has extensive experience advising venture capital firms and companies on IP strategy for cross-border transactions.  

In addition, Xixi advises companies approaching or at commercialization on intellectual property matters, including patent portfolio management in connection with key regulatory milestones (such as Orange Book listings and patent term extensions), as well as freedom-to-operate analyses.

Prior to entering the patent field, Xixi conducted research in the laboratory of Nobel laureate Omar M. Yaghi at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory. He received his PhD in Organic Chemistry from Boston College. Xixi’s technical background allowed him to advise clients on a diverse range of technologies, ranging from small molecules to large molecules (such as antibody-drug conjugates (ADCs), targeted protein degraders, peptides, and oligonucleotides), and to gene and cell therapies.

• Advising Marshall Wace on co-leading Achieve Life Sciences’ $354 million private placement
• Advising CrossBridge Bio, a pre-IND biotech company developing next-generation dual-payload antibody-drug conjugates (ADCs), on its acquisition by Eli Lilly for up to $300 million
• Advising Jiangsu Hengrui Pharmaceuticals on its license agreement with Braveheart Bio for a cardiac myosin inhibitor ($65 million upfront, and up to $1+ billion total payments)
• Advising Jiangsu Hengrui Pharmaceuticals on its global license agreement with Merck (MSD) for a Lp(a) inhibitor ($200 million upfront, and up to $1.7+ billion total payments)
• Advising Jiangsu Hengrui Pharmaceuticals on its global license and collaboration agreement for three innovative GLP-1 drugs to Kailera Therapeutics established and funded by a $400 million investment from Bain Capital, Atlas Venture, RTW Capital, and Lyra Capital
• Advising Jiangsu Hengrui Pharmaceuticals on its global license agreement with Merck KGaA for a PARP1 inhibitor and an Claudin 18.2 antibody-drug conjugate ($160+ million upfront, and up to $1.4+ billion total payments)
• Advising CinCor Pharma on its acquisition by AstraZeneca (up to $1.8 billion value)
• Advising various public companies, including Moderna, Black Diamond Therapeutics, and Ascentage Pharma, on their US IPOs, ATMs, and Follow-On Offerings
• Advising the underwriters of the IPOs, ATMs, and Follow-On Offerings of various public companies, including Altimmune, Akuous, GH Research Schrodinger, Xilio Therapeutics, and Zentalis Pharmaceuticals

Publications:

• Co-author, “Weaving of Organic Threads into a Crystalline Covalent Organic Framework,” Science, January 2016 
• Co-author, “Catalyst Recognition of cis-1,2-Diols Enables Site-Selective Functionalization of Complex Molecules,” Nature Chemistry, August 2013