This is a single-center, single-arm pilot trial designed to evaluate the expression of PD-L1 in patients with Large B-cell lymphoma (LBCL) and its role in non-responsiveness to chimeric antigen receptor (CAR) T-cell therapy in a non-invasive manner. Moreover, within this trial 89Zr-atezolizumab PET/CT imaging as a tool to distinguish lymphoma activity from a treatment-related inflammatory signal (histiocytic/sarcoid-like reaction) in patients with an end-of-treatment positive FDG PET/CT signal will be evaluated.

Inclusion Criteria:

• Histologically confirmed LBCL and associated subtypes, defined by WHO 2016 classification
• Tumor lesion(s) of which a histological biopsy can safely be obtained according to Standard clinical care procedures.
• Measurable disease, as defined by Lugano criteria.
• If has history of central nervous system (CNS) disease, then must have no signs or symptoms of CNS disease, no active disease on magnetic resonance imaging (MRI) and absence of large cell lymphoma in cerebral spinal fluid (CSF) on cytospin preparation and flow cytometry, regardless of the number of white blood cells.
• If has history of cerebral vascular accident (CVA), the CVA event must be 12 months prior to apheresis and any neurological deficits must be stable.
• Signed informed consent.
• Age >18 at the time of signing informed consent.
• Life expectancy >12 weeks.
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1
• Ability to comply with the protocol.

Exclusion Criteria:

• Signs or symptoms of active infection within 2 weeks prior to 89Zr-atezolizumab injection, unless treated to resolution.
• Prior CD19-directed CAR T-cell therapy or other bi-specific antibodies targeting CD19 receptor (e.g.blinatumomab).
• History of severe allergy, anaphylactic, or other hypersensitivity reactions to chimeric or humanized antibodies or fusion proteins.
• Any other diseases, metabolic dysfunction, physical examination finding, or clinical laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of 89Zr-atezolizumab, or that may affect the interpretation of the results or render the patient at high risk for complications.