A Phase 3 Study to Assess Efficacy and Safety of Tafasitamab Plus Lenalidomide and Rituximab Compared to Placebo Plus Lenalidomide and Rituximab in Patients With Relapsed/Refractory (R/R) Follicular Lymphoma or Marginal Zone Lymphoma.

Inclusion Criteria: * Histologically confirmed Grade 1, 2, or 3a FL or nodal MZL, splenic MZL, or extra nodal MZL * Willingness to avoid pregnancy or fathering children * In the opinion of the investigator, be able and willing to receive adequate mandatory prophylaxis and/or therapy for thromboembolic events (eg, aspirin 70-325 mg daily or low-molecular-weight heparin) * Previously treated with at least 1 prior systemic anti-CD20 immunotherapy or chemo-immunotherapy * Documented relapsed, refractory, or PD after treatment with systemic therapy * ECOG performance status of 0 to 2 Exclusion Criteria: * Women who are pregnant or breastfeeding. * Any histology other than FL and MZL or clinical evidence of transformed lymphoma * Prior non-hematologic malignancy * Congestive heart failure * HCV positivity, chronic HBV infection or history of HIV infection * Active systemic infection * CNS lymphoma involvement * Any systemic anti-lymphoma and/or investigational therapy within 28 days prior to the start of Cycle 1 * Prior use of lenalidomide in combination with rituximab