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

Executive Summary: PF-562271 HCl is a highly selective, ATP-competitive inhibitor that targets focal adhesion kinase (FAK) with an IC₅₀ of 1.5 nM and Pyk2 with an IC₅₀ of 14 nM, showing over 100-fold selectivity against most other kinases except some CDKs (product information). It reversibly suppresses FAK phosphorylation in cell and animal models, supporting dose-dependent inhibition of tumor proliferation and metastasis. The compound is widely used for mechanistic cancer studies, especially in tumor microenvironment and metastasis research (Anichini et al., 2022). Developed by APExBIO, PF-562271 HCl is optimally soluble in DMSO, with recommended storage at -20°C. Its activity profile and reproducibility make it an essential tool for advanced oncology workflows.

Biological Rationale

Focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2) are non-receptor tyrosine kinases involved in cell adhesion, migration, proliferation, and survival. Aberrant FAK/Pyk2 signaling is linked to tumor progression, metastasis, and modulation of the tumor microenvironment. Inhibiting FAK/Pyk2 can disrupt these processes, thereby serving as a strategy for cancer growth suppression and metastasis prevention (Anichini et al., 2022). Epigenetic and kinase-targeting drugs, including ATP-competitive FAK inhibitors, are increasingly explored for their role in modulating immune and tumor cell signaling. PF-562271 HCl, by selectively inhibiting FAK and Pyk2, enables precise dissection of these pathways.

Mechanism of Action of PF-562271 HCl

PF-562271 HCl is a reversible, ATP-competitive inhibitor that directly binds to the catalytic domain of FAK and Pyk2. This binding prevents phosphorylation at key tyrosine residues, including autophosphorylation at Tyr397 on FAK, which is required for downstream signaling and recruitment of Src family kinases. The compound exhibits a 10-fold lower potency for Pyk2 and over 100-fold selectivity for FAK versus most other kinases, minimizing off-target effects (product page). Its action is rapid and reversible, allowing for temporal control in cell-based and animal models. Inhibition of FAK/Pyk2 signaling leads to reduced cell motility, impaired survival signaling, and suppression of tumor cell invasion. PF-562271 HCl’s selectivity profile makes it suited for mechanistic studies and translation into preclinical cancer models (related article – this article extends the mechanistic detail presented there by including application boundaries and protocol guidance).

Evidence & Benchmarks

• PF-562271 HCl inhibits FAK with an IC₅₀ of 1.5 nM and Pyk2 with an IC₅₀ of 14 nM under in vitro kinase assay conditions at 25°C in kinase buffer (product information).
• The compound shows >100-fold selectivity against other protein kinases except some cyclin-dependent kinases, as determined by kinase profiling panels (internal article; this article clarifies selectivity benchmarks beyond those previously reported).
• In xenograft and transgenic mouse models, PF-562271 HCl dose-dependently suppresses FAK phosphorylation with an EC₅₀ of 93 ng/mL; tumor proliferation and metastasis are reduced at pharmacologically relevant doses (Anichini et al., 2022).
• The compound is soluble at ≥26.35 mg/mL in DMSO (with gentle warming) but is insoluble in water and ethanol at room temperature (product information).
• PF-562271 HCl remains stable when stored at -20°C, with minimal degradation over 12 months (internal guidance; this article updates storage and workflow recommendations for reproducibility).

Applications, Limits & Misconceptions

PF-562271 HCl is primarily used in preclinical cancer research to investigate FAK/Pyk2 signaling in tumor growth, metastasis, and microenvironment modulation. Its nanomolar potency and selectivity enable studies on cell migration, invasion, and response to chemotherapeutic agents. The compound is also used to probe the effect of FAK inhibition on immune cell infiltration and the tumor immune landscape, as seen in melanoma models treated with kinase or epigenetic inhibitors (Anichini et al., 2022). However, its activity against some CDKs and lack of water solubility require careful experimental design.

Common Pitfalls or Misconceptions

• PF-562271 HCl is not broadly selective for all tyrosine kinases; its activity is mainly restricted to FAK and Pyk2, with limited off-target inhibition except for some CDKs.
• Insolubility in water and ethanol limits its use in aqueous-only protocols; DMSO (≥26.35 mg/mL) is required for stock preparation.
• In vivo efficacy depends on achieving sufficient tissue concentrations; suboptimal dosing or formulation may yield false negatives.
• Not all tumor types are equally dependent on FAK/Pyk2 signaling; efficacy should be validated in each model.
• PF-562271 HCl is not a direct immunomodulator but can alter immune signatures indirectly via tumor signaling pathways (Anichini et al., 2022).

Workflow Integration & Parameters

For optimal use, PF-562271 HCl should be handled according to best practices for kinase inhibitor studies and solubilized using DMSO. APExBIO provides detailed product and workflow support for cancer biology applications.

Protocol Parameters

• Stock preparation: Dissolve at ≥26.35 mg/mL in DMSO with gentle warming; avoid water and ethanol to prevent precipitation (product instructions).
• Storage: Store powdered compound at -20°C in a desiccated vial; solutions are stable for several months at -20°C.
• In vitro kinase assays: Use at concentrations ranging from 1–100 nM for FAK/Pyk2 enzymatic inhibition, adjusting for cell line sensitivity.
• Cell-based studies: Treat cells with 10–500 nM, monitoring for FAK phosphorylation (Tyr397) by western blot after 1–24 h incubation.
• In vivo models: Administer via intraperitoneal or oral routes; reference published dosing regimens for xenograft efficacy (typically 10–50 mg/kg daily) (Anichini et al., 2022).

Conclusion & Outlook

PF-562271 HCl is a validated, highly selective FAK/Pyk2 inhibitor supporting mechanistic and translational cancer research. Its robust inhibition of FAK phosphorylation enables reproducible studies in tumor proliferation, invasion, and microenvironment modulation. As shown by recent work, targeting such kinases can intersect with immunomodulatory therapy strategies, underlining the compound’s value in preclinical oncology (Anichini et al., 2022). Further research may clarify optimal combinatorial use and refine model-specific protocols for greater clinical translation.

For further details on compound handling and advanced applications, see the PF-562271 HCl product page. For expanded guidance on assay design and reproducibility, consult this workflow article (this review provides compound-specific protocol parameters and troubleshooting, extending prior summaries).