An Open-Label Phase lB/II Study of Glofitamab and Atezolizumab or Polatuzumab Vedotin in Adult Patients With Relapsed/Refractory B-Cell Non-Hodgkin's Lymphoma

Main Inclusion Criteria

1. Histologically-confirmed hematologic malignancy that is expected to express CD20 (Relapsed after or refractory to respond to at least one prior treatment regimen; no available treatment options that are expected to prolong survival or patients refusing chemotherapy or autologous stem cell transplant (SCT). Note: The expansion part is restricted to relapsed/refractory follicular lymphoma (r/r FL) and relapsed/refractory diffuse large B cell lymphoma (r/r DLBCL))
2. At least one measurable target lesion
3. Fresh pre-treatment biopsy, but if this cannot be taken, a previous archived biopsy from metastatic lesion can be taken as replacement if it is not older than 6 months and not confounded by major events (progression, treatment)
4. Eastern Cooperative Oncology Group (ECOG) performance status of 0-2
5. Adequate organ function (liver, hematological, renal)
6. Negative test results for hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV)

Inclusion Criteria Specific to Imaging Substudy

1. At least two measurable target lesions
2. Able to provide two fresh tumor biopsies (baseline and on-treatment)

Main Exclusion Criteria

1. Participants with Chronic Lymphocytic Leukemia (CLL), acute lymphoblastic leukemia (ALL), lymphoblastic lymphoma, Richter's transformation, CD20-positive ALL, Burkitt lymphoma, or lymphoplasmacytic lymphoma
2. Current > Grade 1 peripheral neuropathy (only for participants being treated in the polatuzumab vedotin arm)
3. Patients with known active infection, or reactivation of a latent infection within 4 weeks prior to Obinutuzumab (Gpt) infusion
4. Patient with history of confirmed progressive multifocal leukoencephalopathy (PML)
5. History of leptomeningeal disease
6. Current or past history of central nervous system (CNS) lymphoma
7. Current or past history of CNS disease
8. Major surgery or significant traumatic injury
9. Significant cardiovascular disease or significant pulmonary disease
10. Active or history of autoimmune disease or immune deficiency (with exceptions, e.g. hypothyroidism and Diabetes mellitus Type 1)
11. History of idiopathic pulmonary fibrosis, organizing pneumonia (e.g. bronchiolitis obliterans), drug-induced pneumonitis, or idiopathic pneumonitis, or evidence of active pneumonitis on screening chest computed tomography (CT) scan
12. Treatment with any other standard anti-cancer radiotherapy / chemotherapy including investigational therapy within 4 weeks prior to Gpt infusion
13. Prior solid organ transplantation
14. Prior allogenic stem cell transplant (SCT)
15. Autologous SCT within 100 days prior to Gpt infusion
16. Documented refractoriness to an obinutuzumab-monotherapy regimen
17. Prior treatment with anti-cancer/lymphoma therapies and systemic immunotherapeutic/immunostimulating agents within 4 weeks or 5 half-lives of the drug, whichever is shorter, prior to Gpt infusion
18. Any history of immune related >/= Grade 3 adverse events (AE) with the exception of endocrinopathy managed with replacement therapy
19. Ongoing corticosteroid use >25 milligrams/day of prednisone or equivalent within 4 weeks prior to and during study treatment
20. Treatment with systemic immunosuppressive medication
21. Administration of a live, attenuated vaccine within 4 weeks prior to Gpt infusion or anticipation that such a live attenuated vaccine will be required during the study or within 5 months after last dose of study treatment

Exclusion Criteria Specific to Imaging Substudy

1. Circulating lymphoma cells, defined by out of range (high) absolute lymphocyte count and/or the presence of abnormal/malignant cells in the peripheral blood differential signifying circulating lymphoma cell
2. Participants who have had splenectomy or functional asplenia that could compromise protocol objectives