PLoS ONE (Jan 2014)

The Long-HER study: clinical and molecular analysis of patients with HER2+ advanced breast cancer who become long-term survivors with trastuzumab-based therapy.

  • Angelo Gámez-Pozo,
  • Ramón M Pérez Carrión,
  • Luis Manso,
  • Carmen Crespo,
  • Cesar Mendiola,
  • Rocío López-Vacas,
  • Julia Berges-Soria,
  • Isabel Álvarez López,
  • Mireia Margeli,
  • Juan L Bayo Calero,
  • Xavier González Farre,
  • Ana Santaballa,
  • Eva M Ciruelos,
  • Ruth Afonso,
  • Juan Lao,
  • Gustavo Catalán,
  • José V Álvarez Gallego,
  • José Miramón López,
  • Francisco J Salvador Bofill,
  • Manuel Ruiz Borrego,
  • Enrique Espinosa,
  • Juan A Fresno Vara,
  • Pilar Zamora

DOI
https://doi.org/10.1371/journal.pone.0109611
Journal volume & issue
Vol. 9, no. 10
p. e109611

Abstract

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BackgroundTrastuzumab improves survival outcomes in patients with HER2+ metastatic breast cancer. The Long-Her study was designed to identify clinical and molecular markers that could differentiate long-term survivors from patients having early progression after trastuzumab treatment.MethodsData were collected from women with HER2-positive metastatic breast cancer treated with trastuzumab that experienced a response or stable disease during at least 3 years. Patients having a progression in the first year of therapy with trastuzumab were used as a control. Genes related with trastuzumab resistance were identified and investigated for network and gene functional interrelation. Models predicting poor response to trastuzumab were constructed and evaluated. Finally, a mutational status analysis of selected genes was performed in HER2 positive breast cancer samples.Results103 patients were registered in the Long-HER study, of whom 71 had obtained a durable complete response. Median age was 58 years. Metastatic disease was diagnosed after a median of 24.7 months since primary diagnosis. Metastases were present in the liver (25%), lungs (25%), bones (23%) and soft tissues (23%), with 20% of patients having multiple locations of metastases. Median duration of response was 55 months. The molecular analysis included 35 patients from the group with complete response and 18 patients in a control poor-response group. Absence of trastuzumab as part of adjuvant therapy was the only clinical factor associated with long-term survival. Gene ontology analysis demonstrated that PI3K pathway was associated with poor response to trastuzumab-based therapy: tumours in the control group usually had four or five alterations in this pathway, whereas tumours in the Long-HER group had two alterations at most.ConclusionsTrastuzumab may provide a substantial long-term survival benefit in a selected group of patients. Whole genome expression analysis comparing long-term survivors vs. a control group predicted early progression after trastuzumab-based therapy. Multiple alterations in genes related to the PI3K-mTOR pathway seem to be required to confer resistance to this therapy.