Background: The response of colorectal tumours to chemotherapy is highly variable. Preclinical work has shown that the Kirsten ras (KRAS) oncogene sensitizes colorectal tumour cells to oxaliplatin and capecitabine in a wild-type tumour suppressor p53 (TP53)-dependent manner. Therefore, whether or not the combined mutation status of KRAS and TP53 could predict response to chemotherapy in metastatic colorectal cancer was tested.
Patients and methods: A subgroup of patients from the CAIRO2 study (randomized phase III study on capecitabine, oxaliplatin, bevacizumab with or without cetuximab in first-line advanced colorectal cancer) that received capecitabine plus oxaliplatin (CAPOX) treatment in combination with bevacizumab was selected. The tumours were analyzed for KRAS and TP53 mutations by PCR/sequencing. The relationship between tumour response and genotype was analyzed.
Results: The following KRAS/TP53 genotypes were identified: KRASmut/TP53mut n=21, KRASmut/TP53wt n=20, KRASwt/TP53mut n=25, KRASwt/TP53wt n=15. No genotype was associated with a significantly better or worse progression-free or overall survival.
Conclusion: The combined mutation status of KRAS and TP53 does not predict response to CAPOX in patients with metastasized colorectal cancer.