The work focused on optimizing a previously identified pyrazole-pyrimidinone derivative capable of significantly improving the function of different class III CFTR mutations. This project aims to optimize the pharmacodynamic profile of our hit compound, with the aim of identifying novel modulators that, alone or in combination, can efficiently rescue variants of gating-deficient and therapy-resistant CFTRs.

A second generation of pyrazole-pyrimidinone derivatives was designed by computational-aided methodologies. The preliminary screening identified six compounds capable of outperforming the Kaftrio combination on G551D- and N1303K-CFTR when administered with VX-770 or VX445. The additive activity was observed in both the N1303K-16HBE cell model and in differentiated primary human nasal epithelia of one patient homozygous for N1303K: some analogs exhibited nanomolar potency for N1303K-CFTR gating potentiation. The strong synergistic effect on the CFTR function enhancement exerted by our compounds in association with all other potentiators tested suggests the involvement of a novel and independent mechanism of action. The pharmacokinetic profile of the most active compounds were investigated with promising results for further development.

Thus, we demonstrate that the triple potentiation efficacy leads to the substantially augmented function of the N1303K-CFTR channel that would likely translate to significant clinical benefit in a subset of people with cystic fibrosis.