Prediction of Chemotherapy Benefit by EndoPredict in Patients with Breast Cancer who received Adjuvant Endocrine Therapy Plus Chemotherapy or Endocrine Therapy Alone1

Ivana Sestak1, Miguel Martin2, Peter Dubsky3, Federico Rojo4, Jack Cuzick1, Martin Filipits5, Amparo Ruiz6, William Gradishar7, Hatem Soliman8, Lee Schwartzberg9, Richard Buus10, Dominik Hlauschek11, Alvaro Rodriguez-Lescure12, Michael Gnant13

1 Centre for Cancer Prevention, QMUL, London, UK; 2 Hospital General Universitario Gregorio Maranon/GEICAM, Madrid, Spain; 3 Klink St. Anna/ABCSG, Lucerne, Switzerland; 4 CIBERONC-ISCII Fundacion Jimenez Diaz/GEICAM, Madrid, Spain; 5
Medical University Vienna/ABCSG, Vienna, Austria; 6 Instituto Valenciano de Oncologia/GEICAM, Madrid, Spain; 7 Robert H. Lurie Comprehensive Cancer Centre of NWU, Chicago, US; 8 H. Lee Moffitt Cancer Center, Tampa, US; 9 West Cancer
Center, Germantown, US; 10 The Breast Cancer Now Toby Robins Research Centre/ICR, London, UK; 8 Austrian Breast and Colorectal Group (ABCSG), Vienna, Austria; 9 Hospital Universitario de Elche/GEICAM, Valencia, Spain

Summary

  • Chemobenefit validated:
    • In over 3,700 patients with ER+, HER2- breast cancer.
    • With modern (taxane-containing) treatment regimens.
  • Patients with a low-risk EndoPredict result did not benefit from the addition of chemotherapy.
  • Patients with a higher EndoPredict score had a greater benefit from chemotherapy.

Background

EndoPredict (EPclin) is a prognostic test validated for early breast cancer patients with estrogen (ER) receptor positive, HER2-negative disease to help make decisions between 5 years of endocrine therapy alone or with chemotherapy.2,3,4

Objective

To investigate in a non-randomized setting whether EPclin can predict chemotherapy benefit in pre- and post-menopausal women with ER-positive, HER2-disease who have received five years of endocrine therapy alone (ET) or in combination with chemotherapy (ET+C).

Methods

  • A total of 3,746 women with ER-positive, HER2-negative disease were included in this analysis.
  • The primary objective was to evaluate the 10-year distant recurrence-free interval (DRFI) rates as a continuous function of EPclin separately for patients in ET+C and ET.

Results

  • Patients with a low-risk EndoPredict result did not benefit from the addition of chemotherapy.
  • Patients with higher EndoPredict scores had a greater benefit from chemotherapy.
  • Baseline demographics for the two cohorts are shown in Table 1.
  • Median follow-up for those on ET alone was 9.6 years (IQR 6.0-10.0) vs. 9.2 years (7.5-10.0) for ET+C.
  • Clear distinction in 10-year risk between ET alone vs ET+C as the EndoPredict score increases (Figure 2).
  • Interaction between EPclin and treatment was significant (P=0.02).

Conclusions

  • Patients with a high EPclin score on ET+C had a significantly lower 10-year distant recurrence (DR) risk than those on ET alone.
  • No differences in 10-year DR risks were observed between ET alone and ET+C for low EPclin scores (<3.3 low risk cut-off).
  • Interaction between EPclin and treatment was significant (P=0.02).
  • Potential benefit of adding chemotherapy to those with high EPclin scores.
  • Patients with higher EPclin scores have a disproportionate benefit from chemotherapy.
  • Results give insight into the predictive value of EPclin for women with ER-positive, HER2-negative breast cancer.

References

1. Sestak I. et al.: Breast Cancer Res Treat. 2019; 176:377-386; 2. Dubsky et al., 2012; 3. Buus et al., 2017; 4. Martin et al., 2014

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