After the surgical removal of colon cancer and a liver metastasis, the next steps may involve targeted therapy, given the HER2-positive status, possibly with drugs like trastuzumab. Since the BRAF V600E mutation is negative, certain chemotherapy options may be effective. Your uncle's oncologist will tailor a treatment plan based on these findings, incorporating adjuvant chemotherapy and possibly targeted therapies. Regular follow-ups and open communication with the healthcare team will be essential for ongoing care and monitoring his response to treatment.