Plasma thymidine kinase-1 activity predicts outcome in patients with hormone receptor positive and HER2 negative metastatic breast cancer treated with endocrine therapy
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Martina Bonechi1,*, Francesca Galardi1,*, Chiara Biagioni2, Francesca De Luca1, Mattias Bergqvist3, Magnus Neumüller3, Cristina Guarducci1, Giulia Boccalini1, Stefano Gabellini1, Ilenia Migliaccio1, Angelo Di Leo1,4, Marta Pestrin1,4,** and Luca Malorni1,4,**
1“Sandro Pitigliani” Translational Research Unit, Hospital of Prato, Prato, Italy
2Bioinformatics Unit, Hospital of Prato, Prato, Italy
3Biovica International, Uppsala Science Park, Uppsala, Sweden
4“Sandro Pitigliani” Medical Oncology Department, Hospital of Prato, Prato, Italy
Luca Malorni, email: [email protected]
Keywords: metastatic breast cancer; endocrine therapy; thymidine kinase-1; liquid biopsy; circulating biomarkers
Received: October 15, 2017 Accepted: February 28, 2018 Published: March 27, 2018
The aim of this study was to investigate if thymidine kinase-1 (TK1), a well-known proliferation marker, could represent a valid circulating biomarker to identify hormone receptor positive (HR+)/HER2 negative (HER2neg) metastatic breast cancer (MBC) patients most likely to benefit from endocrine therapy (ET). We used the DiviTumTM assay to analyze TK1 activity in cell lysates of three HR+/HER2neg BC cell lines and in plasma of 31 HR+/HER2neg MBC patients receiving ET. Blood samples were collected at treatment initiation, after one month and at disease progression. CTCs count and ESR1/PIK3CA mutations in circulating tumor DNA were performed and correlated with TK1 activity. TK1 activity was reduced in the two endocrine-sensitive cell lines after 2 days of treatment. In patients, high baseline TK1 activity correlated with CTCs positivity (p-value=0.014). Patients with low baseline levels of TK1 activity had a significantly better PFS compared to those with high baseline TK1 activity (p-value=0.012). Patients with an early drop of TK1 activity after one month of treatment had a significantly better PFS compared to those who experienced an increase (p-value=0.0026). Our study suggests that TK1 could be a potential prognostic, predictive and monitoring marker of early ET response in HR+/HER2neg MBC patients.
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