Src inhibitors in early breast cancer: a methodology, feasibility and variability study

Jones, Rob; Young, Oliver; Renshaw, Lorna; Jacobs, Vivien N.; Fennell, Michael; Marshall, Anna; Green, T. P.; Elvin, Paul; Womack, Christopher J.; Clack, Glen; Dixon, JM

doi:10.1007/s10549-008-9997-1

Cited by 17 publications

(19 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There was a substantial difference in the ability of AZD0530 to inhibit Src that was constitutively activated in a cellular context (IC 50 ϭ 2.12 M) compared with the isolated enzyme (IC 50 ϭ 0.14 M). This suggests that higher concentrations of Src inhibitors such as AZD0530 might be required for in vivo efficacy than has been considered previously (Jones et al, 2008). Results from the present study can be considered as the proof-of-concept for using FAK phosphorylation as a biomarker to determine the efficacy of Src inhibition in vivo.…”

Section: Analysis Of a Biomarker Of Src Activity 663mentioning

confidence: 64%

“…The recommended concentration of AZD0530 for inhibition of Src kinases in cell culture is 1 M. At this concentration, AZD0530 has been shown by Western blot to reduce the phosphorylation of Src substrates such paxillin (Hennequin et al, 2006;Jones et al, 2008). AZD0530 is a potent inhibitor of FAK phosphorylation in vitro.…”

Section: Analysis Of a Biomarker Of Src Activity 663mentioning

confidence: 99%

See 1 more Smart Citation

Quantification of Focal Adhesion Kinase Activation Loop Phosphorylation as a Biomarker of Src Activity

Ciccimaro

Hanks²,

Blair

2009

Molecular Pharmacology

View full text Add to dashboard Cite

A recently developed stable isotope dilution liquid chromatography-multiple reaction/mass spectrometry method to quantify focal adhesion kinase (FAK) -benzodioxol-4-yl)-7-[2-(4-methylpiperazin-1-yl)ethoxy]-5-(tetrahydro-2H-pyran-4-yloxy)quinazolin-4-amine (AZD0530). Phosphorylation of FAK at Tyr 576 /Tyr 577 was inhibited by AZD0530 in a dose-dependent manner both in cell culture and in vitro. However, there was a substantial difference in the ability of AZD0530 to inhibit Src that was constitutively activated in a cellular context (IC 50 ϭ 2.12 M) compared with the isolated enzyme (IC 50 ϭ 0.14 M). When normal MEFs and Y529 FSrc-expressing MEFs were treated with pervanadate (a global phosphatase inhibitor), pTyr 576 /pTyr 577 -FAK accounted for almost 60% of the total FAK present in the cells. This suggests that activation loop phosphorylation is regulated by tyrosine phosphatases. These results confirm that FAK phosphorylation is a useful biomarker of Src inhibition in vivo. The accuracy and specificity of stable isotope dilution liquid chromatography-mass spectrometry methodology offers significant advantages over current immunochemical approaches for monitoring Src activity.

show abstract

Section: Analysis Of a Biomarker Of Src Activity 663mentioning

confidence: 64%

Section: Analysis Of a Biomarker Of Src Activity 663mentioning

confidence: 99%

Quantification of Focal Adhesion Kinase Activation Loop Phosphorylation as a Biomarker of Src Activity

Ciccimaro

Hanks²,

Blair

2009

Molecular Pharmacology

View full text Add to dashboard Cite

show abstract

“…For Luminex assessment, the p-PAX/total PAX ratio was predefined as the primary measure of Src activity based on a pilot study (8). Immunohistochemical samples were assessed using H-score based on intensity and location of staining by review of samples by a blinded pathology panel comprising three pathologists.…”

Section: Assessment Of Src Activity In Tumor Biopsiesmentioning

confidence: 99%

“…These proteins mediate Src control of adhesion and migration and are central to the biology of Src in cancer (5). Preclinical studies have shown that phosphorylated forms of FAK (p-FAK) and PAX (p-PAX) are relevant and direct biomarkers of Src activity in tumor cells (5)(6)(7), and a study in patients with breast cancer confirmed the validity and reproducibility of p-FAK and p-PAX assessment as biomarkers in the clinical trial setting (8).…”

mentioning

confidence: 93%

Phase I Safety, Pharmacokinetics, and Inhibition of Src Activity Study of Saracatinib in Patients with Solid Tumors

Baselga

Cervantes

Martinelli

et al. 2010

Clinical Cancer Research

102

View full text Add to dashboard Cite

Purpose: This dose-escalation study evaluated the safety, tolerability, and pharmacokinetics (PK) of the oral Src inhibitor saracatinib (AZD0530) in patients with advanced solid malignancies. Tumor biopsy samples were taken to investigate the effect of saracatinib on Src activity in tumors.Experimental Design: Part A of the study followed a multiple-ascending dose design to establish the maximum tolerated dose (MTD) of saracatinib. Part B was a randomized, parallel-group, cohort-expansion phase to further assess tolerated doses. Safety, tolerability, and Src activity (immunohistochemistry and lysate-based methodologies) were assessed after 21 days of once-daily oral dosing. PK was assessed after single and multiple dosing.Results: In part A, 30 patients received once-daily saracatinib at doses of 60 to 250 mg; the MTD was established as 175 mg. In part B, 51 patients were randomized to receive 50 mg (n = 16), 125 mg (n = 16), or 175 mg (n = 19) of saracatinib. The most common grade ≥3 events considered to be treatment related were anemia, diarrhea, and asthenia. Tumor Src activity was reduced following saracatinib treatment. The area under the concentration-time curve and C max of saracatinib increased with increasing dose. Saracatinib accumulated 4-to 5-fold on once-daily dosing to reach steady-state exposure after 10 to 17 days of dosing. The half-life was ∼40 hours.Conclusions: Saracatinib was well tolerated in patients with advanced solid malignancies. A reduction in tumor Src activity was observed. PK data show that saracatinib is suitable for once-daily oral dosing. Based on this study, the recommended dose for the phase II studies was chosen to be 175 mg/d.

show abstract

“…In a preclinical model using mouse xenografts and the Src inhibitor saracatinib (AZD0530), Src activity was measured by phosphorylation levels of the target proteins FAK (p-FAK) and pax (p-pax); and, as a corollary, Src inhibition induced by saracatinib was measured by decreased phosphorylation of these proteins (7). A recent phase I trial of saracatinib utilized this biomarker platform in 81 patients with advanced solid tumors, including 13 with metastatic breast cancer (MBC), and showed a reduction in tumor Src activity (8).…”

Section: Introductionmentioning

confidence: 99%

Phase II Trial of Dasatinib in Patients with Metastatic Breast Cancer Using Real-Time Pharmacodynamic Tissue Biomarkers of Src Inhibition to Escalate Dosing

Herold

Chadaram

Peterson

et al. 2011

Clinical Cancer Research

View full text Add to dashboard Cite

Purpose: A phase II study of dasatinib, an inhibitor of multiple oncogenic tyrosine kinases including Src, was conducted to evaluate 16-week progression-free rate and tolerability in patients with previously treated metastatic breast cancer (MBC). Real-time assessment of potential tissue biomarkers of Src inhibition was used to optimize dosing.Experimental Design: Eligibility criteria required that patients have measurable MBC, biopsiable tumor, and unlimited prior therapies. For the analysis of change in protein biomarkers of Src inhibition, focal adhesion kinase, paxillin, and p-Src, patients underwent metastatic biopsies at baseline and 4 weeks. Patients who tolerated the starting dose of dasatinib (50 or 70 mg orally twice daily) for the first 28-day cycle, and displayed suboptimal Src inhibition, were escalated to a higher dose (70 or 100 mg).Results: The trial was closed early with 31 patients because of a statistical boundary that required at least 4 (13%) patients without disease progression to continue accrual. These 31 patients had a median of 2 prior lines of chemotherapy for MBC. The most notable toxicity was pleural effusions in 16 patients (52%). Twenty patients had evaluable metastatic biopsies. None of the tumors showed the predefined optimal level of Src inhibition at week 4.Conclusions: Single-agent dasatinib did not exhibit significant antitumor activity in patients with heavily pretreated MBC. There were no clinically meaningful decreases before and after dasatinib exposure between exploratory tissue biomarkers of Src inhibition which may be attributable to challenges in defining biomarker endpoints for multitargeted tyrosine kinase inhibitors.

show abstract

Src inhibitors in early breast cancer: a methodology, feasibility and variability study

Cited by 17 publications

References 17 publications

Quantification of Focal Adhesion Kinase Activation Loop Phosphorylation as a Biomarker of Src Activity

Quantification of Focal Adhesion Kinase Activation Loop Phosphorylation as a Biomarker of Src Activity

Phase I Safety, Pharmacokinetics, and Inhibition of Src Activity Study of Saracatinib in Patients with Solid Tumors

Phase II Trial of Dasatinib in Patients with Metastatic Breast Cancer Using Real-Time Pharmacodynamic Tissue Biomarkers of Src Inhibition to Escalate Dosing

Contact Info

Product

Resources

About