CONTEXT

FasL (or CD95L, CD178) is a homotrimeric membrane-bound apoptosis inducer through the Fas receptor-triggered caspase-dependent apoptotic pathway. FasL also exists as a soluble form (sFasL) that is almost devoid of any apoptotic activity. We designed a polymeric form of sFasL which is highly apoptotic, and can be used to eliminate Fas-expressing cells. 

TECHNICAL DESCRIPTION

This invention describes the obtention of the polymeric sFasL molecule (called pFasL), and of chimeric form of it consisting in a fusion to a protein able to interact with a component expressed on the surface of the Fas-expressing cells to be targeted. The pFasL consists in a chimera between a self-interacting domain of the human Leukemia Inhibitory Factor receptor gp190 and sFasL, separated by a peptidic linker. As a prototype, a CD80-pFasL chimera was engineered and analysed. CD80 is a ligand of CD28. CD28 is known as a membrane costimulating receptor for T-lymphocyte antigen-dependent activation, and is also expressed on the surface of tumoral B-lymphocytes such as myeloma and plasmocytoma cells. The CD80-pFasL chimera is polymeric and is a more potent apoptosis inducer than pFasL, due to the capacity of CD80 to interact with CD28 and thereby to enhance the apoptotic activity of the pFasL moiety. No signalling effect was detected through CD28, therefore the action of CD80 occurs via an improved targeting of the pFasL towards its molecular target. 

BENEFITS

The pFasL construct can be engineered to create chimeras with other cell ligands or receptors, allowing the targeting of various kinds of cell types. The generation of pFasL-derived chimeras allows to improve the efficacy of FasL apoptosis and lowering the doses to decrease the unwanted toxicity towards Fas-sensitive cells not expressing the receptor or ligand able to interact with the targeting module.  

INDUSTRIAL APPLICATIONS

This innovation can be used for creating highly active FasL-based apoptosis inducers with the ability to interact with molecular markers expressed by unwanted cells, e.g. tumor cells, in immunotherapy protocols. 

DEVELOPMENT STAGE

The cytotoxic activity of pFasL in vitro and in vivo in a mouse model of human tumor has been demonstrated (Daburon et al, PlosOne, 2013; and Morello et al, PlosOne, 2013). The enhanced activity of CD80-pFasL when compared to pFasL has been validated using Fas-positive cell lines expressing or not CD28, from T- and B-lymphocyte lineages. Experiments are underway using primary cells from CD28 and Fas positive human myeloma and plasmocytoma cells.

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