Patrick O'Brien




  • JD, Boston University School of Law, 1989
  • BA, University of Illinois, 1983


  • Massachusetts, 1989
  • New York, 2012
  • Who's Who Legal: Life Sciences (2019)
  • Legal 500, Finance (2015-2018, 2020)
  • IFLR1000: The Guide to the World’s Leading Financial Law Firms, Leading Lawyer (2013-2017), Highly Regarded (2018-2020)
  • The Best Lawyers in America (Securities and Capital Markets Law) (2006-2021)
  • Chambers USA: America's Leading Lawyers for Business (2008-2020)
  • International Who’s Who of Life Sciences (2014)
  • PLC Which Lawyer (2010-2011)

Patrick O'Brien


Patrick O’Brien is co-head of the firm’s securities and public companies practice. He concentrates his practice on representing companies and underwriters in financings as well as public and private companies in M&A transactions. More recently, Patrick has been advising clients on complex considerations arising from the COVID-19 outbreak. Patrick has extensive experience representing healthcare, life sciences and technology companies and underwriters in connection with equity and debt offerings, as well as mergers and acquisitions and royalty monetizations. 


  • Representative clients include:
    • Zai Labs
    • IQVIA Holdings, Inc.
    • Alexion Pharmaceuticals, Inc.
  • Represented the following issuers in their proposed initial public offerings: Zai Labs, IMS Health Holdings, Inc., Aptalis Holdings Inc., Par Pharmaceutical Holdings, Inc., Iasis Healthcare Corporation, and Petco Holdings, Inc. 
  • Represented the lead underwriters in initial public offerings and follow on offerings of:
    • Moderna, Inc.
    • Autolus Therapeutics
    • Cushman & Wakefield
    • Elanco Animal Health
    • AVROBIO, Inc.
    • Kiniksa Pharmaceuticals
    • Quanterix Corporation 
    • Biohaven Pharmaceutical Holdings Company Ltd.
    • Clementia Pharmaceuticals Inc.
    • CRISPR Therapeutics
    • AveXis, Inc.
    • Proteostasis Therapeutics, Inc.
    • Radius Heath
    • bluebird bio, Inc.
    • Therapeutics MD
    • Dimension Therapeutics, Inc.
    • Ocular Therapeutics, Inc.
    • Sage Therapeutics, Inc.
  • Represented Par Pharmaceutical Holdings, Inc. and Immucor, Inc. in high yield bond offerings. 
  • Represented Alexion Pharmaceuticals, Inc. in its $610 million acquisition (plus milestones) of Enobia Inc.
  • Represented LA BioMED and UCLA in its sale of a portion of its royalty interest in Kybella. 
  • Represented Canadian Pension Plan Investment Board in the purchase of a $168 million royalty interest from Dana Farber Cancer Institute.
  • Represented a leading biotechnology company in the sale of its royalty interest in Benlysta to DRI Capital. 
  • Represented a publicly traded specialty pharmaceutical company in a complex acquisition and related royalty based financing.
  • Represented a university in connection with the sale of a pharmaceutical royalty stream.


  • JD, Boston University School of Law, 1989
  • BA, University of Illinois, 1983
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