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Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

3440 - Prospective biomarker study in advanced RAS wild-type colorectal cancer. POSIBA trial.

Date

21 Oct 2018

Session

Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

Presenters

Xabier García Albéniz

Citation

Annals of Oncology (2018) 29 (suppl_8): viii150-viii204. 10.1093/annonc/mdy281

Authors

X. García Albéniz1, V. Alonso2, P. Escudero3, M. Méndez4, J. Gallego Plazas5, J.R. Rodriguez6, A. Salud Salvia7, J. Fernández-Plana8, H. Manzano Alemany9, M. Zanui10, E. Falcó11, J. Feliu Batlle12, M. Gil-Raga13, C. Fernández-Martos14, U. Bohn Sarmiento15, M.C. Alonso López16, V. Calderero Aragón17, F. Rojo18, M. Cuatrecasas19, J. Maurel20

Author affiliations

  • 1 Epidemiology, Harvard T.H. Chan School of Public Health, MA 02115 - Boston/US
  • 2 Medical Oncology Service, Hospital Miguel Servet, 50009 - Zaragoza/ES
  • 3 Medical Oncology, Hospital Clinico Universitario Lozano Blesa, 50009 - Zaragoza/ES
  • 4 Medical Oncology Service, Hospital de Móstoles, 28935 - Móstoles/ES
  • 5 Medical Oncology, Hospital General Universitario de Elche, 3203 - Elche/ES
  • 6 M, Hospital Infanta Cristina, Madrid/ES
  • 7 Medical Oncology, Hospital Arnau de Vilanova, 25198 - Lleida/ES
  • 8 Medical Oncology Service, Hospital Mútua de Terrasa, 08221 - Terrassa, Barcelona/ES
  • 9 Medical Oncology Service, Hospital Universitario Son Espases, 7010 - Palma de Mallorca/ES
  • 10 Medical Oncology Service, Hospital de Mataró, 08304 - Mataró/ES
  • 11 Medical Oncology Service, Hospital Son Llàtzer, 07198 - Palma/ES
  • 12 Medical Oncology Service, Hospital Universitario La Paz, 28046 - Madrid/ES
  • 13 Medical Oncology Service, Hospital de Sagunto, 46500 - Sagunto/ES
  • 14 Medical Oncology Service, Fundación Instituto Valenciano de Oncología, 46009 - Valencia/ES
  • 15 Medical Oncology Service, Hospital de Gran Canaria Dr. Negrin, 35020 - Las Palmas/ES
  • 16 Medical Oncology Service, Complejo Hospitalario Universitario de Albacete, 2006 - Albacete/ES
  • 17 Medical Oncology Service, Hospital de Barbastro, 22300 - Barbastro/ES
  • 18 Pathology, University Hospital "Fundacion Jimenez Diaz", 28040 - Madrid/ES
  • 19 Department Of Pathology, Hospital Clínic de Barcelona, 08036 - Barcelona/ES
  • 20 Medical Oncology, Hospital Clínic of Barcelona, 08036 - Barcelona/ES
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Resources

Abstract 3440

Background

RAS testing is used to select patients sensitive to anti-EGFR therapies in metastatic colorectal cancer (mCRC) but other biomarkers such as BRAF, PIK3CA/PTEN and p-IGF-1R+/MMP7 + (DP phenotype) have not prospectively assessed to predict anti-EGFR resistance.

Methods

We designed a multicenter prospective trial (NCT01276379) to evaluate if the following biomarkers BRAF mutation, PIK3CA mutation/PTEN loss and DP phenotype can improve the prediction of 12-months progression-free survival (PFS) over the use of only clinical variables in patients with RAS WT mCRC treated with standard chemotherapy plus biweekly Cetuximab as first-line therapy. The planned sample size was 170 RAS WT patients to detect a 20% difference in 12-month PFR based on analysis of clinical and selected biomarkers (alpha=.05, beta=.2). The discriminatory capacity of the biomarkers was evaluated using ROC curves.

Results

We included 181 RAS WT patients. The biomarker distribution was: BRAF mutant 20 patients (11%), PIK3CA mutated/PTEN loss 98 patients (58%) and DP 23 patients (12.7%). Median PFS: BRAF WT 11.4 vs BRAF mutant 5.9 months (p = 0.004). PIK3CA/PTEN pathway and DP phenotype did not discriminate PFR (p=NS). Baseline clinical variables with good prognosis in a multivariable model were PS = 0, left sided tumor and resectable liver metastases (i.e. liver only metastases (<3 nodules and <5cm)).

Conclusions

A clinical score discriminates between two groups of patients who benefitted differently from chemotherapy plus cetuximab. The addition of BRAF, PIK3CA/PTEN and DP to the clinical score does not improve the prediction of 12m PFS.

Clinical trial identification

EudraCT: 2010-019236-12.

Legal entity responsible for the study

Grupo Español Multidisciplinar de Cáncer Digestivo.

Funding

Merck.

Editorial Acknowledgement

Disclosure

All authors have declared no conflicts of interest.

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