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