World GI 2017: Best Abstracts Session on Colorectal Cancer

Speaker: Filippo Pietrantonio

Filippo Pietrantonio explains that RET fusions are rare in colorectal cancer (CRC) with incidence below 2.5%, but are associated with poor prognosis. These alterations may represent therapeutic target for which we need better efforts in future in term of identification. 

Recent results showed that RET fusion positive metastatic CRC is associated with a certain clinical (older age and right side tumour location) and molecular profile of patients (100% RAS and BRAF wild-type, 43% MSI high). Presence of RET fusion may represent new treatment targets for intervention with novel agents.
Liquid biopsy is emerging as an extremely helpful clinical decision tool. 
In the first presentation minor allele frequency assessment was used as prognotic indication in RAS mutated metastatic CRC patients.
The second presentation was showing data on techniques to detect acquired resistence to targeted treatments. The research shows that mecanisms are multiple and overlapping which confirms the need for more data to achieve methods applicable to clinical practice.


  • O-011: RET rearrangements define a new and rare molecular subtype of metastatic colorectal cancer (mCRC)
  • O-010: Impact in prognosis of circulating tumor DNA mutant allele fraction (MAF) in RAS mutant metastatic colorectal cancer (mCRC)
  • O-001: Systematic liquid biopsy identifies novel and heterogeneous mechanisms of acquired resistance in gastrointestinal (GI) cancer patients

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