COHORT II: Patients receive guadecitabine subcutaneously (SC) on days 1-5. Treatment repeats every 28 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. Patients also receive atezolizumab IV over 30-60 minutes on days 8 and 22. Treatment repeats every 28 days for up to 24 courses in the absence of disease progression or unacceptable toxicity.