KRAS and 2 rare PI3KCA mutations coexisting in a metastatic colorectal cancer patient with aggressive and resistant disease

We describe a metastatic colorectal cancer patient, treated with first-line 5-fluorouracil, irinotecan, bevacizumab, and oxaliplatin (FIr-BFOx) therapy, with aggressive and resistant disease. KRAS, NRAS, BRAF, and PI3KCA were analyzed in primary tumor and liver metastasis. KRAS c.34G>A mutation was detected in primary tumor and liver metastasis, which additionally revealed 2 rare PI3KCA mutations (c.1633G>C and c.1645G>C). The c.1645G>C was never reported in colorectal cancer. Akt/p-AktSer473, phosphatase and tensin homolog, mismatch repair, and epidermal growth factor receptor expression was evaluated. Normal mismatch repair and epidermal growth factor receptor expression was detected. Akt was shown by primary tumor and liver metastasis, whereas p-AktSer473 was identified only in the latter, despite positive phosphatase and tensin homolog expression. Patient showed 7 months of progression-free survival and 15 months of overall survival, lower than median values reported in KRAS exon 2-mutant patients treated with the same therapy. Results lead to the hypothesis of a putative role of these mutations in worsening of the disease and are open to further confirmatory studies.