The aim of this work was to search for selective NKCC1 inhibitors devoid of undesired diuretic effects as a sustainable therapeutic solution for brain disorders characterized by defective NKCC1/KCC2 expression-ratio.

Proper intracellular chloride concentration is fundamental for physiological brain development and function. Accordingly, the aberrant expression-ratio of chloride-importer NKCC1 and -exporter KCC2 is implicated in several brain conditions, including drug-resistant epilepsy (e.g. temporal lobe epilepsy (TLE) and Dravet syndrome (DrS)), autism spectrum disorders (ASD) and Down syndrome (DoS). Interestingly, NKCC1 inhibition rescues core symptoms of these disorders in rodent models and/or clinical trials. However, current NKCC1 inhibitors have diuretic effects inhibiting the kidney chloride-transporter NKCC2. This creates critical issues with health concerns, strongly jeopardizing them from becoming a viable therapy for chronic treatment.

We performed rational drug design supported by computational methods to develop selective NKCC1 inhibitors, which we tested in several cell-based assays in vitro and in mouse models of neurodevelopmental/neurological disorders.  

Here, we present the discovery of a new class of selective NKCC1 inhibitors. The lead compound IAMA-6, currently in advanced preclinical studies, which rescues social/repetitive behaviours in ASD mice and cognitive deficits in DoS mice, without showing any diuretic or toxic effect. The ongoing investigation of IAMA-6 in two rodent models of drug-resistant epilepsy (TLE and DrS) will provide solid data on the efficacy of our new class of NKCC1 inhibitors in ameliorating core symptoms of neurological conditions representing a highly unmet medical need.

IAMA-6 represents an effective and solid lead compound to be developed into a clinical candidate. IAMA-6 efficacy in refractory epilepsy will expand our pipeline of therapeutic indications. Finally, the discovery of new classes of selective NKCC1 inhibitors with different properties will further increase the number of candidates to be tested in additional and diverse conditions characterized by NKCC1/KCC2 imbalance.