Plasma Thymidine Kinase Activity as a Biomarker in Patients with Luminal Metastatic Breast Cancer Treated with Palbociclib within the TREnd Trial

Amelia McCartney, Martina Bonechi, Francesca De Luca, Chiara Biagioni, Giuseppe Curigliano, Erica Moretti, Alessandro Marco Minisini, Mattias Bergqvist, Matteo Benelli, Ilenia Migliaccio, Francesca Galardi, Emanuela Risi, Irene De Santo, Irene De Santo, Dario Romagnoli, Laura Biganzoli, Angelo Di Leo, Luca Malorni, Luca Malorni, Luca Malorni

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: Thymidine kinase 1 (TK1) is downstream to the CDK4/ 6 pathway, and TK activity (TKa) measured in blood is a dynamic marker of outcome in patients with advanced breast cancer (ABC). This study explores TK1 as a biomarker of palbociclib response, both in vitro and in patients with ABC. Experimental Design: Modulation of TK1 levels and activity by palbociclib were studied in seven estrogen receptor-positive breast cancer cell lines: sensitive (PDS) and with palbociclib acquired resistance (PDR). TKa was assayed in plasma obtained at baseline (T0), after one cycle (T1), and at disease progression on palbociclib (T2) in patients enrolled in the To Reverse ENDocrine Resistance (TREnd) trial (n = 46). Results: Among E2F-dependent genes, TK1 was significantly downregulated after short-term palbociclib. Early TKa reduction by palbociclib occurred in PDS but not in PDR cells. In patients, median TKa (mTKa) at T0 was 75 DiviTum units per liter (Du/L), with baseline TKa not proving prognostic. At T1, mTKa decreased to 35 Du/L, with a minority of patients (n = 8) showing an increase correlating with a worse outcome than those with decreased/stable TKa (n = 33; mPFS 3.0 vs 9.0 months; P = 0.002). At T2, mTKa was 251 Du/L; patients with TKa above the median had worse outcomes on post-study treatment compared with those with lower TKa (2.9 vs 8.7 months; P = 0.05). Conclusions: TK is a dynamic marker of resistance to palbociclib which may lead to early identification of patients in whom treatment escalation may be feasible. In addition, TKa may stratify prognosis in patients with acquired resistance to palbociclib. 2020 American Association for Cancer Research.

Original languageEnglish
Pages (from-to)2131-2139
Number of pages9
JournalClinical Cancer Research
Volume26
Issue number9
DOIs
Publication statusPublished - May 1 2020

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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