To define how pharmacological TYK2 inhibition mediates in vivo crosstalk between the immune system and the β cells, we tested the effects of two TYK2is, BMS-986165 and BMS-986202, in three in vitro human model systems and then determined the impact of BMS-986202 in two mouse models of T1D (37,38). This evidence concerns the gene TYK2 and type 1 diabetes mellitus.