Pirtobrutinib (LOXO-305)

Pirtobrutinib (LOXO-305, LY 3527727, RXC-005) is a highly selective, non-covalent, next generation BTK inhibitor with an IC50 of 5.69 nM in WT BTK HEK cells. Pirtobrutinib shows more than 300-fold selective for BTK over 98% of 370 other kinases.

Pirtobrutinib (LOXO-305) is a highly selective, non-covalent, next-generation Bruton's tyrosine kinase (BTK) inhibitor, which potently inhibits the cellular activity of BTK C481S, T and R mutations and displays strong equilibrium binding to WT BTK and several BTK C481 substitution mutations.^{<a class="sref" href="#s_ref">[2]</a>}

• Cell lines

  WT BTK HEK293T cells

• Concentrations

  --

• Incubation Time

  2 h

• Method

  HEK293T cell lines transiently expressing WT BTK and BTK C481 substitution mutations were incubated with LOXO-305, ibrutinib or acalabrutinib for 30 min followed by the addition of orthovanadate. After 2 h, cells were lysed, and phosphorylated Y223 BTK and total BTK levels were detected by immunoblot (BTK WT, C481S, and C481T) or MesoScale (C481R). Bands and MSD signals were quantified, and the IC50 values calculated with GraphPad Prism.