A novel fusion of ALT-803 (interleukin (IL)-15 superagonist) with an antibody demonstrates antigen-specific antitumor responses

Bai Liu, Lin Kong, Kaiping Han, Hao Hong, Warren D. Marcus, Xiaoyue Chen, Emily K. Jeng, Sarah Alter, Xiaoyun Zhu, Mark P. Rubinstein, Sixiang Shi, Peter R. Rhode, Weibo Cai, Hing C. Wong

Research output: Journal article publicationJournal articleAcademic researchpeer-review

60 Citations (Scopus)


IL-15 and its receptor α (IL-15Rα) are co-expressed on antigen-presenting cells, allowing transpresentation of IL-15 to immune cells bearing IL-2RβγC and stimulation of effector immune responses. We reported previously that the high-affinity interactions between an IL-15 superagonist (IL-15N72D) and the extracellular IL-15Rα sushi domain (IL-15RαSu) could be exploited to create a functional scaffold for the design of multivalent disease-targeted complexes. The IL-15N72D·IL-15RαSuFc complex, also known as ALT-803, is a multimeric complex constructed by fusing IL-15N72D·IL-15RαSu to the Fc domain of IgG1. ALT-803 is an IL-15 superagonist complex that has been developed as a potent antitumor immunotherapeutic agent and is in clinical trials. Here we describe the creation of a novel fusion molecule, 2B8T2M, using the ALT-803 scaffold fused to four single chains of the tumor-targeting monoclonal antibody rituximab. This molecule displays trispecific binding activity through its recognition of the CD20 molecule on tumor cells, stimulation via IL-2RβγC displayed on immune effector cells, and binding to Fcγ receptors on natural killer cells and macrophages. 2B8T2M activates natural killer cells to enhance antibody-dependent cellular cytotoxicity, mediates complement-dependent cytotoxicity, and induces apoptosis of B-lymphoma cells. Compared with rituximab, 2B8T2M exhibits significantly stronger antitumor activity in a xenograft SCID mouse model and depletes B cells in cynomolgus monkeys more efficiently. Thus, ALT-803 can be modified as a functional scaffold for creating multispecific, targeted IL-15-based immunotherapeutic agents and may serve as a novel platform to improve the antitumor activity and clinical efficacy of therapeutic antibodies.

Original languageEnglish
Pages (from-to)23869-23881
Number of pages13
JournalJournal of Biological Chemistry
Issue number46
Early online date20 Sept 2016
Publication statusPublished - 11 Nov 2016
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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