Patients for Part B must still meet the eligibility criteria for initial study enrollment. Patients with Grade 3 toxicity on nivolumab monotherapy, serious symptomatic disease that in the opinion of the site investigator requires immediate use of an alternative treatment approach or continued PR/CR will be excluded from enrolling in Part B. It is estimated that roughly half of the patients accrued to the first-line treatment will go on to enroll in Part B.