6. Be willing and medically fit to undergo a fresh (newly obtained) diagnostic biopsy of a metastatic lesion or primary site of disease before receiving nivolumab, pembrolizumab or atezolizumab. "Fresh (newly-obtained)" is defined as a specimen obtained up to 6 weeks prior to initiation of treatment with nivolumab, pembrolizumab or atezolizumab on Day 1.