STIM1 and ORAI1 mutations leading to tubular aggregate myopathies are sensitive to the Store-operated Ca2+-entry modulators CIC-37 and CIC-39.

Gain-of-function mutations on STIM1 and ORAI1 genes are responsible for an increased store-operated calcium entry, and underlie the characteristic symptoms of three overlapping ultra-rare genetic disorders (i.e tubular aggregate myopathy, Stormorken syndrome, York platelet syndrome) that can be grouped as tubular aggregate myopathies. These mutations lead to a wide spectrum of defects, which usually include muscle weakness and cramps. Negative modulators of store-operated Ca2+-entry targeting wild-type STIM1 and ORAI1 have entered clinical trials for a different array of disorders, including pancreatitis, COVID-19, cancer, and autoimmune disorders and, while efficacy data is awaited, safety data indicates tolerability of this STIM1/ORAI1 mutations are amenable to pharmacological intervention. If this were so, given that there are no approved treatments or clinical trials ongoing for these rare disorders, it could be envisaged that these agents could also rehabilitate tubular aggregate myopathy patients. In the present contribution we characterized the Ca2+-entry patterns induced by eleven STIM1 and three ORAI1 mutations in heterologous systems or in patient-derived cells, i.e. fibroblasts and myotubes, and evaluated the effect of CIC-37 and CIC-39, two novel store-operated calcium entry modulators. Our data show that all STIM1 and ORAI1 gain-of-function mutations tested, with the possible exception of the R304Q STIM1 mutation, are amenable to inhibition, albeit with slightly different sensitivities, paving the way to the development of SOCE modulators in tubular aggregate myopathies.

CIC-39Na reverses the thrombocytopenia that characterizes tubular aggregate myopathy.

Store-operated Ca2+-entry is a cellular mechanism that governs the replenishment of intracellular stores of Ca2+ upon depletion caused by the opening of intracellular Ca2+-channels. Gain-of-function mutations of the 2 key proteins of store-operated Ca2+-entry, STIM1 and ORAI1, are associated with several ultra-rare diseases clustered as tubular aggregate myopathies. Our group has previously demonstrated that a mouse model bearing the STIM1 p.I115F mutation recapitulates the main features of the STIM1 gain-of-function disorders: muscle weakness and thrombocytopenia. Similar findings have been found in other mice bearing different mutations on STIM1. At present, no valid treatment is available for these patients. In the present contribution, we report that CIC-39Na, a store-operated Ca2+-entry inhibitor, restores platelet number and counteracts the abnormal bleeding that characterizes these mice. Subtle differences in thrombopoiesis were observed in STIM1 p.I115F mice, but the main difference between wild-type and STIM1 p.I115F mice was in platelet clearance and in the levels of platelet cytosolic basal Ca2+. Both were restored on treatment of animals with CIC-39Na. This finding paves the way to a pharmacological treatment strategy for thrombocytopenia in tubular aggregate myopathy patients.

The [1,2,4]Triazolo[4,3-a]pyridine as a New Player in the Field of IDO1 Catalytic Holo-Inhibitors.

Inhibitors of indoleamine 2,3-dioxygenase 1 (IDO1) are considered a promising strategy in cancer immunotherapy as they are able to boost the immune response and to work in synergy with other immunotherapeutic agents. Despite the fact that no IDO1 inhibitor has been approved so far, recent studies have shed light on the additional roles that IDO1 mediates beyond its catalytic activity, conferring new life to the field. Here we present a novel class of compounds originated from a structure-based virtual screening made on IDO1 active site. The starting hit compound is a novel chemotype based on a [1,2,4]triazolo[4,3-a]pyridine scaffold, so far underexploited among the heme binding moieties. Thanks to the rational and in silico-guided design of analogues, an improvement of the potency to sub-micromolar levels has been achieved, with excellent in vitro metabolic stability and exquisite selectivity with respect to other heme-containing enzymes.

Store-Operated Calcium Entry as a Therapeutic Target in Acute Pancreatitis: Discovery and Development of Drug-Like SOCE Inhibitors.

Store-operated calcium entry (SOCE) is important in the maintenance of calcium homeostasis and alterations in this mechanism are responsible for several pathological conditions, including acute pancreatitis. Since the discovery of SOCE, many inhibitors have been identified and extensively used as chemical probes to better elucidate the role played by this cellular mechanism. Nevertheless, only a few have demonstrated drug-like properties so far. Here, we report a class of biphenyl triazoles among which stands out a lead compound, 34, that is endowed with an inhibitory activity at nanomolar concentrations, suitable pharmacokinetic properties, and in vivo efficacy in a mouse model of acute pancreatitis.