Gregory S. DeLassus (Greg)

Associate / St. Louis Metro Office

Greg is inspired by the creativity and hard work of today’s innovators, and passionate about helping them bring their new technologies to market. He uses the knowledge that he gained as a molecular biologist to understand inventors’ ideas and to translate them into broad, solid and enforceable intellectual property protection. His extensive knowledge of chemical and biotech patent case-law equips him to counsel clients — all the way from start-up entrepreneurs to larger and more established businesses — with practical advice about how to achieve their IP objectives in an efficient and cost-effective manner.

Greg drafts patent applications and steers them through the patent examination process to allowance. He has drafted and prosecuted patents relating to small molecule drugs, combinations of existing drugs, recombinant microbes and viruses, cancer vaccines, humanized antibodies, PCR methods and fuel compositions. He also drafts opinion letters and advises clients about patentability, patent validity and freedom to operate, as well as how to design around potentially blocking claims. In other words, Greg knows both how to build protections for his clients’ IP and how to remove IP related obstacles that stand in his clients’ way.

In the News


Greg presents at a monthly one-on-one IP counseling series for entrepreneurs and scientists. Seminar topics Greg has presented on include:

  • “Inventorship Determination”
  • “The U.S. Supreme Court’s Decision in the Myriad Case”
  • “Publication Issues and Notebook Records”
  • “ZMapp Anti-Ebola Virus Claims: PTO & Case-Law Hurdles”
  • “Patent Subject Matter Eligibility”
  • “Publication Issues and Notebook Records”



  • Morrison, L.A. & S. DeLassus, Breach of the nuclear lamina during assembly of herpes simplex viruses. Nucleus 2:271 (2011)
  • DeLassus, G.S. & al., New signaling pathways from cancer progression modulators to mRNA expression of matrix metalloproteinases in breast cancer cells. Cell. Physiol. 226:3378 (2011)
  • Kan, J., DeLassus & al., Modulators of cancer cell invasiveness. J. Cell. Biochem. 111:791 (2010)
  • Perez, A., Q.-X. Li, P. Perez-Romero, DeLassus & al., A new class of receptor for herpes simplex virus has heptad repeat motifs that are common to membrane fusion proteins. J. Virol. 79:7419 (2005)

Awards & Distinctions

  • Missouri Lawyers Weekly, “Up & Coming Lawyer,” 2016
  • St. Louis University Law Journal, 2010-2011
  • Order of the Woolsack


  • Bar Association of Metropolitan St. Louis
  • American Intellectual Property Law Association (AIPLA)
  • American Society for Microbiology
  • American Bar Association


  • French
  • Italian
  • Spanish
  • Portuguese


J.D., magna cum laude, Saint Louis University College of Law, 2012

M.S., Microbiology, University of Michigan, 2002

B.A., Biology, summa cum laude, Truman State University, 1999

Bar & Court Admissions


U.S. Patent and Trademark Office