IL-7 was originally discovered by Immunex Corporation (now part of Amgen) and through a process of intellectual property acquisition resulting from several mergers, the compound eventually ended up at what is today Sanofi-Aventis, from whom Cytheris holds the exclusive worldwide license.  Cytheris also holds the rights to an additional IL-7 patent family acquired under an exclusive worldwide license from the Washington Research Foundation of the University of Washington, Seattle.

As the exclusive licensee, Cytheris holds all original patents protecting IL-7 and various uses including the use for T cell expansion and for enhancing humoral immunity.

Cytheris has filed two patent applications protecting the purified protein as a drug substance for therapeutic use with the correct disulfide bridging, the appropriate glycosylation profile and polypeptidic purity. In 2009 and 2010 Cytheris received Issue Notifications from the USPTO for both of these patents, These new patents protect IL-7 and close analogs until 2023 and 2026.