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21/06/2021 - Press release

PEGASUS study launched to optimise post-surgical treatment of colon cancer using liquid biopsy

By analysing tumoral DNA circulating in the blood, it is hoped that it will be possible to detect the presence of micrometastases, responsible for post-operative relapse, and which are currently impossible to locate in radiological examinations

As a result of the collaboration between research centres in Italy and Spain, the PEGASUS study has been launched with the aim of demonstrating that, thanks to the liquid biopsy guidance tool, it is possible to increase the precision of post-surgical treatment for colon cancer patients. The Vall d'Hebron Institute of Oncology (VHIO), part of the Vall d'Hebron Campus, and the Hospital del Mar Medical Research Institute (IMIM), both in Barcelona; and the INCLIVA Health Research Institute at Hospital Clínico in Valencia, are the three Spanish centres taking part in this project. The study was instigated by Dr. Silvia Marsoni, from the FIRC Institute of Molecular Oncology (IFOM) in Milan, and is supported by the AIRC Foundation within the 5x1000 programme, which is coordinated by Prof. Alberto Bardelli of the University of Turin and the Institute of Candiolo FPO-IRCCS.

Surgery is the first course of treatment for eight out of ten colon cancer patients. However, for some it is not enough, as micrometastases may be present, which cannot be detected in the radiological examinations performed both before and after surgery. These micrometastases could grow and cause a recurrence of the tumour in two to three years. Because of this, most patients are treated with adjuvant chemotherapy as a precaution. "More than half of these patients do not actually need it, so there is a clear demand for a diagnostic test that helps us to determine whether these micrometastases are present. This would confine the use of adjuvant therapy to only those patients who really do need it. PEGASUS is an excellent example of how research can lead to the best treatment for each patient", explains Dr. Josep Tabernero, Director of the VHIO and Head of the Medical Oncology Department at Vall d'Hebron University Hospital, who is the principal investigator of the clinical part of the PEGASUS study in Spain.

To meet the challenge of detecting micrometastases after surgery for colon cancer, liquid biopsy has been proposed. Through a simple blood sample from patients, this tool makes it possible to analyse the tumoral DNA circulating in the blood, identify the presence of these micrometastases, and define the most appropriate subsequent therapy in each case. "At present, we are unable to identify precisely which patients need chemotherapy as their tumour is likely to recur, and which do not because their tumour has already been completely eradicated thanks to the operation. The search for tumoral DNA in the patient's own blood will show us whether that patient has a higher risk of relapse and therefore needs more intensive treatment compared to another who does not present this DNA", explains Dr. Clara Montagut, head of the Gastrointestinal Cancer Unit at the Medical Oncology Service of Hospital del Mar. Dr. Montagut runs the laboratory of the Clinical and Translational Research Group on New Therapies and Biomarkers in Colorectal Cancer at the IMIM and will be the principal investigator of the translational part of the Alfa-Omega project related to the PEGASUS study.

Drs Josep Tabernero, Clara Montagut i Andrés Cervantes

Dr. Andrés Cervantes, chief physician for the PEGASUS study at INCLIVA, who will be the principal investigator of another related project, TUMICC, stresses the importance of this personalisation in adjuvant therapies for patients with colon cancer. "This is a very interesting study in terms of reducing unnecessary treatments to lower the risk of recurrence in this disease. In addition, the patients who will participate in PEGASUS will be monitored for the presence of tumoral DNA in their blood throughout the clinical-therapeutic phase, allowing personalised therapeutic choices to be made as part of the treatment strategy." It should not be forgotten that each year more than one million new colon cancers are diagnosed worldwide, of which almost 325,000 are in Europe and more than 30,000 in Spain. Colon cancer is the second most common malignant tumour in women and the third most common in men.

A total of 140 patients will take part in the PEGASUS study. They will all be colon cancer patients who have undergone surgery. "Through this study, we want to provide important information that will help to further advance precision medicine. We hope to be able to help identify which patients need to be treated, and always do that in the most appropriate way. This will help to improve the quality of life of patients who will not be unnecessarily exposed to the effects of adjuvant chemotherapy", explains Dr. Elena Élez, head of the PEGASUS study at the VHIO.

The PEGASUS trial is possible thanks to the collaboration with Guardant Health Inc, VHIO, and the GISCAD foundation. The project involves a network of clinical centres of excellence in Italy and Spain, supported by the 5X1000 AIRC and coordinated by Prof. Salvatore Siena, director of the Department of Haematology and Oncology at Niguarda Hospital in Milan.

Two translational subprojects to further complement it

In addition, there are two translational subprojects associated with this study: the Alfa-Omega project, whose principal investigator is Dr. Clara Montagut from the IMIM; and the TUMICC project, which is also funded by a grant from the Spanish Association Against Cancer, and whose principal investigators will be Dr. Andrés Cervantes, Dr. Héctor G. Palmer and Dr. Clara Montagut.

Alfa-Omega is a translational project for obtaining biological samples before and during cancer treatment as part of the clinical trial. It also includes a retrospective cohort from the same project, which will be used to collect phenotypic information and tumour samples for biomarker validation and correlative studies.

The TUMICC project is designed to identify the mechanisms tumour cells use to develop therapy resistance and identify the patient's primary resistance prior to initiating treatment. To do this, tumour samples will be collected from patients during their surgery for PDX and organoid generation. It will also involve a retrospective cohort for the molecular characterisation of the tumour.

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