• Age between 18 and 60 years (upper age limit applies to phase I)
• Histologically confirmed classical Hodgkin's lymphoma at first relapse or refractory to first-line treatment
• Only one prior systemic therapy for Hodgkin's lymphoma
• Eligible for autologous stem-cell transplantation
• Performance status 0 to 2 on the ECOG scale
• Adequate blood counts: neutrophils 5 1,500/mmc, platelets 5 75,000/mmc, hemoglobin 5 8.0 g/dL without transfusions
• Willing and able to follow study visit schedule and procedures
• Use effective contraception from 28 days before treatment until at least 6 months after treatment ends, and agree not to donate semen or eggs during this time

• More than one prior systemic therapy for Hodgkin's lymphoma
• Presence of autoimmune diseases such as lupus, autoimmune thyroid disease, Sj�f6gren's syndrome, multiple sclerosis, rheumatoid arthritis, vasculitis, idiopathic pulmonary fibrosis, or inflammatory bowel disease
• Previous severe skin toxicity like Stevens-Johnson syndrome
• Prior allogeneic stem-cell or solid organ transplantation
• History of active tuberculosis or leptomeningeal disease
• Treatment with oral or IV antibiotics within 2 weeks before study treatment
• Central nervous system involvement by lymphoma
• Major surgery (except lymph node biopsy) within 28 days before consent
• Positive hepatitis B or C infection without appropriate antiviral treatment
• Positive HIV infection
• Active infections requiring IV antibiotics or hospitalization within 2 weeks before treatment
• Life expectancy under 6 months
• Prior cancers other than Hodgkin's lymphoma unless disease-free for 5 years (except certain skin or cervical cancers)
• Significant liver or kidney function abnormalities
• Significant heart disease within 3 months before treatment
• History of severe allergic reactions to antibodies or fusion proteins
• Hypersensitivity to components of atezolizumab
• Pregnancy or breastfeeding or unwillingness to use contraception
• Any serious medical or psychiatric condition preventing consent or increasing risk

Exceptions include controlled autoimmune hypothyroidism, controlled type 1 diabetes on insulin, and certain well-controlled skin conditions with limited area and mild treatment requirements.