Nivolumab (Anti-PD1), Tadalafil and Oral Vancomycin in People With Refractory Primary Hepatocellular Carcinoma or Liver Dominant Metastatic Cancer From Colorectal or Pancreatic Cancers

Background: A most common liver cancer in adults is hepatocellular carcinoma. Other kinds of liver cancer happen when colorectal or pancreatic cancer spreads to the liver. Researchers want to study if a combination of drugs helps people with these cancers. The drugs are nivolumab, tadalafil, and vancomycin. Objective: To investigate if nivolumab given with tadalafil and vancomycin causes liver cancer to shrink. Eligibility: Adults ages 18 years and older with hepatocellular carcinoma or metastases to the liver from colorectal or pancreatic cancer for which standard treatment has not worked Design: Participants will be screened with: Medical and cancer history Review of symptoms and ability to perform normal activities Physical exam Heart test. Some participants may meet with a cardiologist and/or have another heart test. Scan of the chest, abdomen, and pelvis Blood and urine tests Tumor sample review. This can be from a previous procedure. Participants will receive the study drugs in 4-week cycles. In each cycle participants will: Get nivolumab through a small plastic tube in the arm on Day 1. Take tadalafil by mouth 1 time every day. Take vancomycin by mouth 4 times a day. They will take it every day for weeks 1 3, then not take it for week 4. Complete a medicine diary of dates, times, missed doses and symptoms. Throughout the study, participants will repeat screening tests and will give stool samples or rectal swabs. After their last cycle, participants will have 3 follow-up visits over 3 months. Then they will be contacted every 6 months by phone or email and asked about their general well-being. ...