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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

3887 - First-line treatment outcomes according to cfDNA analysis of RAS mutation status in metastatic colorectal cancer (mCRC) patients (pts). PERSEIDA study

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

Topics

Targeted Therapy

Tumour Site

Colon and Rectal Cancer

Presenters

Pilar García Alfonso

Citation

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

Authors

P. García Alfonso1, M. Valladares-Ayerbes2, J. Muñoz Luengo3, P. Pimentel4, J.M. Viéitez5, J.J. Cruz Hernandez6, M. Llanos7, C. Garcia Girón8, A. Salud Salvia9, A. Lloansí Vila10

Author affiliations

  • 1 Medical Oncology Department, Hospital General Universitario Gregorio Marañon, 28007 - Madrid/ES
  • 2 Medical Oncology Department, University Hospital Reina Sofia. CIBERONC Instituto de Salud Carlos III, 14004 - Córdoba/ES
  • 3 Medical Oncology Department, Hospital San Pedro de Alcántara, 10003 - Cáceres/ES
  • 4 Medical Oncology Department, Hospital General Universitario Santa Lucia, 30202 - Cartagena/ES
  • 5 Medical Oncology Department, Hospital Central de Asturias, 33011 - Oviedo/ES
  • 6 Medical Oncology Department, Hospital Universitario de Salamanca, 37007 - Salamanca/ES
  • 7 Medical Oncology, Hospital Universitario de Canarias, Santa Cruz de Tenerife/ES
  • 8 Medical Oncology Department, Hospital Universitario de Burgos, Burgos/ES
  • 9 Medical Oncology Department, Hospital Arnau de Vilanova, 25198 - Lleida/ES
  • 10 Medical Oncology Department, Amgen S.A., Barcelona/ES
More

Resources

Abstract 3887

Background

Tumour-tissue biopsy testing is the standard of care (SOC) to assess RAS mutation in mCRC pts. However, the analysis of circulating cell-free DNA (cfDNA) has the added advantage of being able to evidence genetic tumour heterogeneity. We explored the correlation of the RAS mutational status assessed in plasma samples with first-line (1L) treatment outcomes in SOC RAS wild type (wt) mCRC pts.

Methods

Prospective, observational, multi-centre study in mCRC pts with RASwt according to tumour-tissue biopsy and treated following standard clinical practice. Plasma samples were collected before starting 1L treatment and sent to Sysmex Inostics GmbH for BEAMing analysis. The lower threshold limit was a mutant allele fraction (MAF) ≥ 0.02%. Tumour response (TR) was evaluated approximately every 3 months based on RECIST criteria.

Results

119 pts were included (61% male; median age: 65 y). 113 received chemotherapy (CT) + anti-EGFR, 4 CT + anti-VEGF and 2 CT alone. Overall response rate (ORR) was 68.1% (95%CI: 58.9-76.3) for all pts and 75% (95%CI: 65.8-82.8) in the108 pts with TR data. In pts treated with panitumumab (n = 92), the most homogeneous group, 76.1% (n = 70) presented left-sided tumours and 19.6% (n = 18) right-sided; overall ORR was 78.3% (95%CI: 68.4-86.2); 81.4% (95%CI: 70.3-89.7) for left and 72.2% (95%CI: 46.5-90.3) for right-sided pts. ORR in the panitumumab subgroup according to RAS mutational status analysed in cfDNA for the three MAF (cut-offs) considered is presented in the table.Table: 546P

ORR (not confirmed) % (95% CI)ORR (not confirmed) % (95% CI)Odds Ratio (95% CI); P-value*
Mutant allele fraction, cut-off (n)RASwtRASmt
≥1% (90 wt/2 mt)78.9 (69.0 – 86.8)50.0 (1.3 - 98.7)3.7 (0.2 – 62.6) 0.389
≥0.1% (87 wt/5 mt)79.3 (69.3 – 87.3)60.0 (14.7 - 94.7)2.6 (0.4 – 16.5) 0.297
≥0.02% (80 wt/12 mt)80.0 (69.6- 88.1)66.7 (34.9-90.1)2.0 (0.5 – 7.5) 0.285
*

Fisher Test; CI=confidence interval; ORR: Overall Response Rate.

Conclusions

A high ORR was observed in pts treated with panitumumab independently of the localization. ORR in panitumumab treated patients tends to be higher in plasma RASwt. ORR in pts with plasma RASmt increases when a lower MAF cut-off is used. Further investigation is needed to find the optimal clinical cut-off. Study supported by Amgen.

Clinical trial identification

Legal entity responsible for the study

Amgen.

Funding

Amgen.

Editorial Acknowledgement

Disclosure

P. García Alfonso: Consulting fees: Amgen, Bristol, Merck, Sanofi, Roche, Bayer, Servier. M. Valladares-Ayerbes: Research grants: Roche; Consulting fees: Amgen, Roche, Merck, Sanofi, Servier. J.M. Viéitez: Research grants: Amgen, Roche; Consulting fees: Amgen, Roche, Servier, Shire, Bayer. J.J. Cruz Hernandez: Consulting fees: Amgen, Merck, Roche, BMS. A. Lloansí Vila: Full time employee, stocks: Amgen. All other authors have declared no conflicts of interest.

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