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

Executive Summary: PF-562271 HCl, available from APExBIO, is a potent, reversible, and ATP-competitive inhibitor of FAK and Pyk2 (Cheminformatics Tools, Moret et al. 2019). It shows an IC₅₀ of 1.5 nM for FAK and 14 nM for Pyk2, with over 100-fold selectivity relative to most other kinases. The compound is widely used to inhibit tumor growth and metastasis in preclinical models through FAK phosphorylation suppression. Its solubility profile (≥26.35 mg/mL in DMSO, insoluble in water/ethanol) and stability at -20°C make it suitable for biochemical and cellular assays. PF-562271 HCl is a validated tool for studying the tumor microenvironment and cancer cell migration, providing benchmark selectivity and potency for translational oncology research.

Biological Rationale

Focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2) are non-receptor tyrosine kinases crucial for cell adhesion, migration, proliferation, and survival. Dysregulation of FAK/Pyk2 signaling is implicated in cancer progression and metastasis (Moret et al. 2019, DOI). Inhibition of these kinases disrupts integrin-mediated signal transduction, affecting tumor cell motility and interactions with the tumor microenvironment. Because FAK and Pyk2 are frequently overexpressed in solid tumors, they are high-value targets for anti-cancer strategies. PF-562271 HCl is designed to enable precise manipulation of these pathways for mechanistic studies and therapeutic development. This approach extends analytical power beyond classical, cell-centric cancer models by incorporating microenvironmental and immune-related endpoints (see contrast: this article delineates detailed mechanistic specificity and benchmark selectivity not covered in prior reviews).

Mechanism of Action of PF-562271 HCl

PF-562271 HCl functions as a reversible, ATP-competitive inhibitor. It binds to the ATP-binding site of FAK and Pyk2, blocking their catalytic activity. The IC₅₀ for FAK inhibition is 1.5 nM, while for Pyk2 it is 14 nM, indicating roughly 10-fold selectivity for FAK over Pyk2 (Apexbt.com product data; Moret et al. 2019, DOI). PF-562271 HCl shows over 100-fold selectivity against most other kinases, except certain cyclin-dependent kinases (CDKs), where activity is reduced but not eliminated. This profile supports its application as a selective probe for FAK/Pyk2-driven processes. Upon administration to cancer cells or tumor models, PF-562271 HCl suppresses FAK phosphorylation in a dose-dependent manner, with an EC₅₀ of 93 ng/mL reported in xenograft models. This inhibition leads to decreased cell migration and proliferation, and reduced metastatic potential. The compound's high affinity and selectivity contrast with broader-spectrum kinase inhibitors, enabling clearer attribution of observed phenotypes to FAK/Pyk2 blockade (see contrast: this article details selectivity indices and ATP-competitive binding not exhaustively treated elsewhere).

Evidence & Benchmarks

• PF-562271 HCl inhibits FAK with IC₅₀ = 1.5 nM and Pyk2 with IC₅₀ = 14 nM in in vitro kinase assays (Moret et al. 2019, DOI).
• In xenograft and transgenic mouse models, PF-562271 HCl suppresses FAK phosphorylation with EC₅₀ = 93 ng/mL, resulting in significant tumor growth inhibition (Apexbt.com; Moret et al. 2019, DOI).
• Shows over 100-fold selectivity for FAK vs. most other kinases, except certain CDKs, where selectivity is reduced (Moret et al. 2019, DOI).
• Soluble at ≥26.35 mg/mL in DMSO with gentle warming; insoluble in water and ethanol (Apexbt.com product page: PF-562271 HCl).
• Stable at -20°C for long-term storage, allowing reproducible compound handling (Apexbt.com; Moret et al. 2019, DOI).

Applications, Limits & Misconceptions

PF-562271 HCl is used in cancer research to:

• Dissect focal adhesion kinase signaling in tumor biology.
• Study the role of FAK/Pyk2 in cell migration, invasion, and metastasis.
• Evaluate the contribution of the tumor microenvironment to cancer progression.
• Validate FAK/Pyk2 as therapeutic targets in preclinical models.
• Support biomarker and combination therapy discovery efforts (see contrast: this article provides quantitative benchmarks and selectivity matrices for translational researchers).

Common Pitfalls or Misconceptions

• PF-562271 HCl is not effective against all protein kinases; its selectivity is high for FAK/Pyk2, but some CDKs are partially inhibited.
• It is not recommended for use in aqueous buffers or ethanol due to poor solubility; always dissolve in DMSO with gentle warming.
• Results from tumor cell lines may not fully predict effects in complex in vivo systems or immune-competent models.
• Long-term stability is only guaranteed at -20°C; room temperature or repeated freeze-thaw cycles reduce potency.
• PF-562271 HCl does not address all mechanisms of tumor resistance; combination approaches may be necessary.

Workflow Integration & Parameters

PF-562271 HCl (A8345) is supplied as a solid with a molecular weight of 543.95 and the formula C₂₁H₂₁ClF₃N₇O₃S. For experimental use, dissolve at ≥26.35 mg/mL in DMSO with gentle warming. Avoid water or ethanol as solvents. Stock solutions should be aliquoted and stored at -20°C. Working concentrations typically range from 1 nM to 10 μM, depending on assay design and cell type. In cellular assays, PF-562271 HCl is often used at concentrations sufficient to achieve >90% FAK phosphorylation inhibition, as determined by immunoblot or ELISA. For in vivo studies, dose and schedule should be optimized for each tumor model. The compound’s selectivity and solubility support high-content screening and dose-response profiling. Always confirm kinase selectivity in the relevant biological context. For detailed product specifications and ordering, visit the official APExBIO product page.

Conclusion & Outlook

PF-562271 HCl stands as a benchmark ATP-competitive inhibitor for FAK/Pyk2, offering unmatched selectivity and potency for mechanistic cancer research. Its robust performance in xenograft and transgenic models supports both basic and translational studies. The compound's solubility and storage stability streamline laboratory integration. Ongoing research leverages PF-562271 HCl to unravel interactions between tumor cells and the microenvironment, and to develop targeted therapies and biomarker strategies (see contrast: this article foregrounds selectivity data and workflow parameters for clinical translation). Future work may include combination therapies and immune-oncology applications, building on the strong mechanistic foundation provided by PF-562271 HCl.