TYk2 Deucravacitinib23 Mar 2023 10:19
It Deucravacitinib pure Tyk2?
Clearly it is not pure TYk2 the very nature of having selectivity over Jak1 2 and 3. However
Deucravacitinib (BMS-986165) is a potent, highly selective, allosteric, small-molecule inhibitor of TYK2 that acts through a novel mode of binding to the JH2 pseudokinase domain, which locks the kinase in an inactive state.
This binding site is more diverse among Janus kinases (JAKs) compared to the ATP binding pocket of the active site where the approved JAK inhibitors (JAKi) bind, which is highly conserved.14, 15 Thus, JAKi are ATP competitive active site inhibitors with pharmacologic activities against JAK1, JAK2, and JAK3 in differing proportions depending upon the drug.16
Notably, to date, all JAKi have some activity against JAK2, which carries specific liabilities.17 Deucravacitinib has 200-fold greater selectivity for TYK2 inhibition over JAK1/JAK3 inhibition, and 3000-fold greater selectivity for TYK2 inhibition over JAK2 inhibition in cell-based assays.18, 19 A more recent analysis of the selectivity profile of deucravacitinib also demonstrated highly selective inhibition of TYK2 and not JAK 1/2/3.19 Although TYK2 is a JAK family member, TYK2 is only involved in specific immune-regulating cytokines. In patients with psoriasis treated with nonselective JAKi, typical laboratory changes are observed, including decreased hemoglobin levels, decreased lymphocyte or neutrophil counts, and increases in cholesterol levels and liver transaminases.20-22 These changes were not observed in patients with psoriasis or psoriatic arthritis treated with deucravacitinib, and demonstrate that the in vitro selectivity profile is borne out in the clinical profile.23, 24 The efficacy observed in psoriasis is evidence of effective inhibition of IL-23 and the downstream Th17 pathway.
We can conclude that Deucravacitinib contains albeit is selective over Jak 1,2 &3.
However the claim that it only acts allosterically is based upon observing no typical laboratory changes associated with non selective Jak1.
Typical therapeutic dosing for Psoriasis is 12mg body dose.
Dose range for SDC1801 is in the range of 12.5 mg to 1000mg maximum although we have established no MTD
Comparison between dosing schedule between SDC1801 and Deucravacitinib is phenomenal to say the least.
Regards