In vitro activity: PF-06273340 is a potent pan-Trk inhibitor, with an excellent LipE profile. It is profiled in a series of in vitro safety assays, showing little cytotoxicity in THLE or HepG2 cell lines (IC50> 42 μM and>300 μM, respectively). In this broad panel, all IC50/Ki values were>10 μM except for COX-1 (IC50 = 2.7 μM) and dopamine transporter assays (Ki = 5.2 μM) and PDEs 4D, 5A, 7B, 8B, and 11 (54–89% inhibition at 10 μM). PF-06273340 is screened in the Invitrogen wide kinase panel of 309 kinases, and all were inhibited by<40% when tested at 1 μM except the following: MUSK (IC50 53 nM), FLT-3 (IC50 395 nM), IRAK1 (IC50 2.5 μM), MKK (90% @ 1 μM), and DDR1 (60% @ 1 μM).

Kinase Assay: PF-06273340 is a potent, selective, and well-tolerated pan-Trk inhibitor with IC50 of 6, 4, 3 nM for TrkA, TrkB, Trk C respectively. TPX-0005 effectively overcomes this primary resistance (IC50 100 nM in cell proliferation assay) with strong inhibition of the phosphorylation of EML4-ALK (IC50 13 nM) and the SRC substrate paxillin (IC50 107 nM). PX-0005 inhibits H2228 cell migration in a wound healing assay with similar activity to saracatinib. PF-06273340 is screened in the Invitrogen wide kinase panel of 309 kinases, and all were inhibited by<40% when tested at 1 μM except the following: MUSK (IC50 53 nM), FLT-3 (IC50 395 nM), IRAK1 (IC50 2.5 μM), MKK (90% at 1 μM), and DDR1 (60% at 1 μM).

Cell Assay: PF-06273340 is profiled in a series of in vitro safety assays, showing little cytotoxicity in THLE or HepG2 cell lines with IC50> 42 μM and>300 μM, respectively. In a broad panel, all IC50/Ki values were>10 μM except for COX-1 (IC50 = 2.7 μM) and dopamine transporter assays (Ki = 5.2 μM) and PDEs 4D, 5A, 7B, 8B, and 11 (54–89% inhibition at 10 μM).