PF-562271 HCl: Selective FAK/Pyk2 Inhibitor for Cancer Research

Executive Summary: PF-562271 HCl is a highly selective, ATP-competitive, and reversible inhibitor of focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2), with IC₅₀ values of 1.5 nM and 14 nM, respectively. The compound demonstrates over 100-fold selectivity against most other kinases, except for some cyclin-dependent kinases (CDKs) (APExBIO product information). In preclinical mouse models, PF-562271 HCl effectively suppresses tumor proliferation and metastasis by dose-dependently inhibiting FAK phosphorylation, achieving an EC₅₀ of 93 ng/mL. Its physicochemical properties and stability profile support reliable performance in experimental workflows. The compound’s precision targeting of FAK/Pyk2 pathways enables advanced investigation of tumor progression and microenvironment modulation.

Biological Rationale

Focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2) are non-receptor tyrosine kinases involved in cell adhesion, migration, survival, and proliferation. Aberrant activation of FAK/Pyk2 is implicated in the progression and metastasis of multiple solid tumors. Pharmacological inhibition of these kinases disrupts oncogenic signaling and alters tumor-stroma interactions, making FAK/Pyk2 inhibitors such as PF-562271 HCl crucial for cancer research and drug development (Anichini et al., 2022). The specificity and reversibility of PF-562271 HCl enable precise dissection of focal adhesion kinase signaling pathways in both in vitro and in vivo settings.

Mechanism of Action of PF-562271 HCl

PF-562271 HCl is a reversible, ATP-competitive inhibitor that binds to the kinase domains of FAK and Pyk2, preventing autophosphorylation and downstream signaling. With an IC₅₀ of 1.5 nM for FAK and 14 nM for Pyk2, it demonstrates marked selectivity, exhibiting roughly 10-fold lower potency for Pyk2 and over 100-fold selectivity against most other protein kinases (with the exception of some CDKs) (APExBIO product page). Inhibition of FAK/Pyk2 activity leads to reduced phosphorylation of key substrates, disruption of cell adhesion structures, and attenuation of migratory and invasive tumor cell phenotypes. The compound’s action is reversible, allowing fine temporal control in experimental designs.

Evidence & Benchmarks

• PF-562271 HCl inhibits FAK autophosphorylation with an IC₅₀ of 1.5 nM and Pyk2 with 14 nM, demonstrating high selectivity relative to other kinases (APExBIO).
• In xenograft and transgenic mouse models, PF-562271 HCl dose-dependently suppresses FAK phosphorylation (EC₅₀ = 93 ng/mL), resulting in significant tumor proliferation and metastasis inhibition (APExBIO).
• PF-562271 HCl exhibits >100-fold selectivity against non-FAK/Pyk2 kinases, with limited off-target action except for several cyclin-dependent kinases (APExBIO).
• Epigenetic and kinase pathway modulation, as described for similar agents, can alter tumor immune signatures and may provide synergistic effects with immunotherapies (Anichini et al., 2022, see Figures 2–4).
• PF-562271 HCl is soluble at ≥26.35 mg/mL in DMSO with warming, but insoluble in water and ethanol, facilitating reliable preparation for cell-based and animal assays (APExBIO).

This article extends the workflow-focused discussion in 'PF-562271 HCl (SKU A8345): Reliable FAK/Pyk2 Inhibition...' by providing deeper mechanistic and benchmark evidence, and clarifies selectivity boundaries highlighted in 'PF-562271 HCl: Reliable FAK/Pyk2 Inhibition for Cancer Research'.

Applications, Limits & Misconceptions

PF-562271 HCl is widely used to investigate the roles of FAK/Pyk2 in tumor biology, including studies on cell migration, invasion, proliferation, and survival. Its robust inhibition of FAK/Pyk2 signaling pathways enables researchers to model tumor growth, metastasis, and the modulation of the tumor microenvironment. The compound is also employed in combination studies with immunomodulatory and epigenetic agents, given the emerging evidence for synergistic effects on immune-related gene expression and tumor immunogenicity (Anichini et al., 2022). However, its off-target activity against some CDKs should be considered when interpreting data involving cell cycle regulation.

Common Pitfalls or Misconceptions

• Not a pan-kinase inhibitor: PF-562271 HCl is highly selective for FAK/Pyk2 and does not inhibit most kinases at relevant concentrations.
• Limited water solubility: The compound is insoluble in water and ethanol, requiring DMSO for stock solution preparation; improper solvent can compromise efficacy (APExBIO).
• Reversible inhibition: Its effects are reversible, so sustained pathway suppression depends on continuous presence in cell culture or animal models.
• Cross-reactivity with CDKs: Some off-target inhibition of cyclin-dependent kinases can confound cell cycle data.
• Not validated for all tumor types: Efficacy and selectivity should be verified in new cellular contexts before broad generalization.

Workflow Integration & Parameters

PF-562271 HCl (APExBIO, SKU A8345) is supplied as a solid compound with a molecular weight of 543.95 and formula C₂₁H₂₁ClF₃N₇O₃S. It should be stored at -20°C for optimal stability. Stock solutions are typically prepared at ≥26.35 mg/mL in DMSO with gentle warming. For in vitro experiments, serial dilutions are recommended to achieve final concentrations in the nanomolar to low micromolar range, depending on assay sensitivity and cell line characteristics (APExBIO product information).

Protocol Parameters

• Stock solution preparation: Dissolve PF-562271 HCl in DMSO at concentrations ≥26.35 mg/mL with gentle warming; avoid water or ethanol.
• Storage: Store powder and stock solutions at -20°C; minimize freeze-thaw cycles to preserve activity.
• Working concentration: For cell culture assays, use 1–1000 nM, adjusting based on IC₅₀ data for the specific cell type.
• Animal studies: Dose according to published xenograft protocols, monitoring for dose-dependent FAK phosphorylation inhibition (EC₅₀ = 93 ng/mL).
• Assay compatibility: Confirm DMSO-tolerance of cell lines or animal models; use vehicle controls in all experiments.

For practical integration tips and troubleshooting, see also 'PF-562271 HCl: Advanced FAK/Pyk2 Inhibitor for Tumor Rese...', which complements this article by focusing on workflow acceleration and combinatorial therapy design.

Conclusion & Outlook

PF-562271 HCl, provided by APExBIO, is a validated, selective FAK/Pyk2 inhibitor that addresses key mechanistic questions in oncology. Its nanomolar potency, robust selectivity, and standardized solubility make it a reliable reagent for both in vitro and in vivo studies. Emerging evidence supports its role not only in direct tumor growth inhibition but also in enabling combinatorial strategies with immunomodulatory and epigenetic agents, as seen with analogous drug-induced immune signatures (Anichini et al., 2022). Future research will clarify optimal integration points for PF-562271 HCl within evolving cancer therapy paradigms.