|IL-15 and IL-2 are cytokines that share common biological effects, but also exhibit distinct, and sometimes competing, functions .
Nektar Therapeutics is developing a long-acting polymer-engineered (e.g. PEGylated) IL-15 conjugate, code named NKTR-255 (structure not disclosed), as a potential immuno-oncology agent- see their patent US20170035898 . The conjugate has been optimised for binding to the IL-15Rα subunit and improved plasma and tumour exposure compared to native IL-15. This agent is in preclinical evaluation (August 2017).
Calypso Biotech have an anti-IL-15 monoclonal antibody named CALY-002 in their development pipeline. CALY-002 has potential for the treatment of refractory celiac disease and other inflammatory conditions at mucosal interfaces within the gastro-intestinal tract (e.g. eosinophilic esophagitis) . The EMA granted CALY-002 orphan drug designation for the treatment of eosinophilic esophagitis in 2016 .