American Association for Cancer Research
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Supplementary Table 1 from Plasma Thymidine Kinase Activity as a Biomarker in Patients with Luminal Metastatic Breast Cancer Treated with Palbociclib within the TREnd Trial

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posted on 2023-03-31, 22:25 authored by 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, Dario Romagnoli, Laura Biganzoli, Angelo Di Leo, Luca Malorni

Baseline characteristics of studied c-TREnd biomarker population - including all patients with at least one sample available for analysis at any timepoint(s), compared to the overall original TREnd cohort. Fisher exact test was used to calculate p-values. *Denotes patients included in intention-to-treat population of TREnd, despite breach of eligibility criteria (discovered post-enrolment).

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Associazione Italiana per la Ricerca sul Cancro

Breast Cancer Research Foundation

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ARTICLE ABSTRACT

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. 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). 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). 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.

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