GNE-2861
Inhibitor of PAK4, PAK5, PAK6
Structure
In Cells
In Model Organisms
SERP ratings and comments
SERP Ratings
SERP Comments:
Author's note: GNE-2861 is a potent and exquisitely kinase-selective Group II PAK inhibitor, and to the best of my knowledge, it is the most selective inhibitor for this target group reported in the literature. The biochemical PAK4 Ki is 3 nM, and no significant inhibition of other kinases was observed at a concentration of 100 nM in a panel of 222 kinases. A drawback is the lack of cellular target engagement data (phosphorylation of PAK4/5/6 substrates) for this probe. The high permeability as assessed in MDCK cells (MDCK Papp (A-B) = 22.2 x 10^-6 cm/s) suggests that this probe should be able to enter cells, but obviously there is no experimental proof in the context of relevant cancer cell lines. The available cell data are limited to cellular efficacy data (wound healing and proliferation), and high drug concentrations are needed to impart effects in these assays (at least 10 uM). While this raises potential concerns, it is also possible that there isn't an efficient translation from molecular target engagement to a functional response in the specific contexts investigated, and this probe might be more efficacious in other functional settings and in combination with other targeted agents. While this is surely speculative, I believe that this probe nevertheless is more useful for assessing PAK4 biology than others that are available (e.g., PF-3758309, a promiscuous kinase inhibitor with questions on its true drivers of cellular efficacy).
(last updated: 29 Jun 2017 )
SERP Ratings
SERP Comments:
This is the best available probe for group II PAKs (4,5,6). The disconnect between enzyme (PAK4 IC50 8 nM) and cellular effect (effects observed at 10 uM & 50 uM) is highlighted by the authors as surprising but no explanation is offered. There is no attempt made to confirm target engagement in the cell assay, so it is difficult to comment further. Kinase selectivity (in an Invitrogen panel tested at 0.1 uM) is impressive, although it would have been good to include NIK data since at 1 uM it showed marginal activity. Nevertheless, the compound represents the best available probe for group II PAKs.
(last updated: 4 Jul 2017 )
SERP Ratings
SERP Comments:
GNE-2861 is a PAK4/5/6 inhibitor with isoform selectivity over group I PAKs (PAK1/2/3). The binding mode of the inhibitor is well investigated and gives an explanation of the partial isoform selectivity. Kinome selectivity was determined with a medium-sized panel consisting of 222 kinases. The screened concentration of 100vnM is considerably low (PAK4 IC50=8 nM) and, therefore, the selectivity data should be handled with caution. Cellular penetration was measured, and the compound showed an effect on the cell migration of several cancer cell lines with upregulated PAK signalling. These effects were shown at relatively high concentrations of 10-50 uM and a cellular PAK inhibition is not finally proven. When cellular target engagement is shown (e.g., by means of a PAK downstream phosphorylation assay), this compound may serve as a useful tool for the investigation of group II PAK signaling in cells.
(last updated: 4 Nov 2020 )
SERP Comments:
This is a thoroughly characterized probe and the supporting information is of high quality. The disconnect between in vitro and cellular potency, while potentially explicable and consistent with PAK4 inhibition, suggests that comparison to genetic modulation of PAK4 be included in cellular experiments to support conclusions regarding mechanism of action. Recommendation of a negative control by the authors would also increase utility.
(last updated: 4 Nov 2020 )
Author's note
GNE-2861 is a potent and exquisitely kinase-selective Group II PAK inhibitor, and to the best of my knowledge, it is the most selective inhibitor for this target group reported in the literature. The biochemical PAK4 Ki is 3 nM, and no significant inhibition of other kinases was observed at a concentration of 100 nM in a panel of 222 kinases. A drawback is the lack of cellular target engagement data (phosphorylation of PAK4/5/6 substrates) for this probe. The high permeability as assessed in MDCK cells (MDCK Papp (A-B) = 22.2 x 10^-6 cm/s) suggests that this probe should be able to enter cells, but obviously there is no experimental proof in the context of relevant cancer cell lines. The available cell data are limited to cellular efficacy data (wound healing and proliferation), and high drug concentrations are needed to impart effects in these assays (at least 10 uM). While this raises potential concerns, it is also possible that there isn't an efficient translation from molecular target engagement to a functional response in the specific contexts investigated, and this probe might be more efficacious in other functional settings and in combination with other targeted agents. While this is surely speculative, I believe that this probe nevertheless is more useful for assessing PAK4 biology than others that are available (e.g.,& PF-3758309, a promiscuous kinase inhibitor with questions on its true drivers of cellular efficacy).
(last updated: 29 Jun 2017)