Evaluation of a Promising New Combination of Protein Kinase Inhibitors on Organotypic Cultures of Human Renal Tumors (COMBOREIN)

Given the failure of conventional therapies in kidney cancer, both chemo and radio resistant, it was necessary to seek therapeutic alternatives.

Thus, in 2005, the first targeted therapies in kidney cancer came with protein kinase inhibitors including mTOR (mammilian target of rapamycin) inhibitors (Temsirolimus and Everolimus) and VEGFR inhibitors (Sunitinib, Sorafenib, Pazopanib and Axitinib).

Nevertheless resistance to these treatments appeared with their prolonged use as monotherapy in all cases. One of the main mechanisms of this therapeutic escape is the adaptation of the tumor cell via the use of an alternative pathway of deregulation of cell signaling.

Thus emerged the idea of simultaneously treating multiple targets to prevent the tumor cell from adapting. Phase I / II therapeutic trials have already been initiated with the combination of anti-BRAF (proto-oncogene B-Raf) and anti-MEK (MAP-ERK kinase) in metastatic melanoma or with the combination of anti-EGFR (epidermal growth factor receptor) and anti-MET in lung and breast cancer. The results are very promising since we observe a synergistic effect of two targeted therapies combined.

In kidney cancer, this escape phenomenon is also observed (example of the mTORC2 (mammilian target of rapamycin complex 2) crosstalk on AKT which limits the effect of mTORC1 (mammilian target of rapamycin complex 1) inhibitors at the level of the PI3 kinase signaling pathway).

It is therefore time to check if this strategy is applicable in kidney cancer. The investigators have, through a chemo-genomic screening of a hundred molecules stored in the CEA (French Alternative Energies and Atomic Energy Commission) chemical bank, found a combination of inhibitors targeting the kinases CK2 and ATM very effective on a human cell line of renal cell carcinoma clear. This combination has been tested on conventional cultures as well as on more innovative 3D cultures, better reproducing the tumor environment. The preliminary results obtained show that the combination is clearly more efficient in a 3D model as well as on the VHL-line (von Hippel-Lindau) in hypoxic condition, which is very encouraging.

In the context of preclinical validation, it is now essential to evaluate the therapeutic potential of these molecules by comparing their efficiency with those currently selected.