A Study Evaluating the Safety and Efficacy of Atezolizumab in Combination With Obinutuzumab Plus Lenalidomide in Patients With Relapsed or Refractory Follicular Lymphoma

Inclusion Criteria:

* Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1, or 2
* Relapsed or refractory FL after treatment with at least one prior chemoimmunotherapy regimen that included an anti-CD20 monoclonal antibody and for which no other more appropriate treatment option exists as determined by the investigator
* Histologically documented CD20-positive lymphoma as determined by the local laboratory
* Fluorodeoxyglucose-avid lymphoma (i.e., PET-positive lymphoma)
* At least one bi-dimensionally measurable lesion (\>1.5 cm in its largest dimension by CT scan or magnetic resonance imaging \[MRI\])
* Availability of a representative tumor specimen and the corresponding pathology report for retrospective central confirmation of the diagnosis of FL
* Agreement to comply with all local requirements of the lenalidomide risk minimization plan
* For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use two adequate methods of contraception, including at least one method with a failure rate of \<1% per year, for at least 28 days prior to Day 1 of Cycle 1, during the treatment period (including periods of treatment interruption), and for at least 18 months after the last dose of study treatment
* For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures and agreement to refrain from donating sperm for at least 3 months after the last dose of study treatment

Exclusion Criteria:

* Grade 3b follicular lymphoma
* History of transformation of indolent disease to diffuse large B-cell lymphoma (DLBCL)
* Known CD20-negative status at relapse or progression
* Central nervous system lymphoma or leptomeningeal infiltration
* Prior allogeneic stem-cell transplantation (SCT)
* Completion of autologous SCT within 100 days prior to Day (D) 1 of Cycle (C) 1
* Prior standard or investigational anti-cancer therapy as specified in protocol
* History of resistance to lenalidomide or response duration of \<1 year
* Treatment with systemic immunosuppressive medications
* History of solid organ transplantation
* Clinically significant toxicity from prior therapy that has not resolved to Grade \<=2 (according to the National Cancer Institute Common Terminology Criteria for Adverse Events \[NCI CTCAE\], v4.0) prior to Day 1 of Cycle 1
* History of erythema multiforme, Grade \>= 3 rash, or blistering following prior treatment with immunomodulatory derivatives such as thalidomide and lenalidomide
* Active bacterial, viral, fungal, or other infection
* Positive for hepatitis B surface antigen (HBsAg), total hepatitis B core antibody (HBcAb), or hepatitis C virus (HCV) antibody at screening
* Known history of HIV positive status
* History of progressive multifocal leukoencephalopathy
* History of autoimmune disease
* Contraindication to treatment for TE prophylaxis
* Grade \<= 2 neuropathy
* History of other malignancy that could affect compliance with the protocol or interpretation of results
* Evidence of any significant, uncontrolled concomitant disease
* Inadequate hematologic function (unless due to underlying lymphoma)
* Abnormal laboratory values (unless due to underlying lymphoma)
* Pregnant or lactating or intending to become pregnant during the study