The Development of a Piperlongumine PROTAC for Targeted TRPV2 Degradation

The extent of overexpression of the calcium channel, transient receptor potential vanilloid 2 (TRPV2) has been found to positively correlate with the degree of severity of the tumour grade in glioblastoma multiforme (GBM). GBM is a very aggressive brain cancer where therapeutic options have remained intransient for more than 30 years. Previous work in the Bernardes Group has identified, through the use of machine learning and cryo-electron microscopy, that the natural product, piperlongumine (PL), is a selective allosteric antagonist of TRPV2. In an orthotopic mouse model of GBM, treatment of induced tumours with PL, formulated into a hydrogel for improved drug delivery, led to near complete tumour remission.

The project aim is to degrade, rather than inhibit, TRPV2 through the development of a PL proteolysis-targeting chimera (PROTAC). Degradation of TRPV2 with a PL PROTAC would be a valuable research tool in order to decipher the (understudied) role of TRPV2 in both physiological and pathological processes since TRPV2 remains the least characterised and understood member of the TRPV subfamily of TRP channels, despite its numerous pathophysiological roles/functions. A PL PROTAC could also provide more longer-lasting therapeutic benefits than solely a TRPV2 antagonist for an aggressive disease with great unmet need. Lastly, it could potentially be used for other diseases where aberrant TRPV2 expression is intimately implicated in the observed disease phenotype.

Analogues of PL are required to explore its structure-activity relationship (SAR) for reversible TRPV2 binding, increase its selectivity and functionalise it for PROTAC development. To this end, PL and a selection of analogues were synthesised, and synthetic approaches developed for other analogues. An intracellular calcium imaging method was tested, in collaboration with the Klenerman Lab. Lastly, the compatibility of a PL analogue with a novel hydrogel for improved drug delivery was demonstrated, in collaboration with the Scherman Group.