Study Investigating the Safety and Efficacy of Blinatumomab in Combination With Pembrolizumab in Adults With Relapsed or Refractory Diffuse Large B Cell Lymphoma (DLBCL)

The primary objective of the study is to determine the maximum tolerated dose (MTD) of blinatumomab in combination with pembrolizumab in adults with relapsed or refractory (r/r) DLBCL.

The study was planned as 2 parts: * Part 1 will test the safety of up to 3 different blinatumomab target dose levels in combination with pembrolizumab in a rolling 6 design. A Dose Level Review Team (DLRT) will review the safety data to evaluate possible drug effects and dose-limiting toxicities (DLTs). * Part 2 will consist of an expansion cohort to assess pharmacokinetics (PK), safety, and preliminary efficacy data at the chosen target dose. The part 2 dose will be determined by the totality of the clinical data from part 1 as determined by the DLRT. Based on the results from Part 1, a decision was made not to proceed with Part 2 of this study. Secondary objectives of the study are to evaluate the safety, efficacy, and pharmacokinetics (PK) of blinatumomab in combination with pembrolizumab. Tumor response will be evaluated according to the Revised Response Criteria for Malignant Lymphoma (Cheson et al, 2007). With implementation of Protocol Amendment 5, response will also be assessed according to the Lugano Classification (Cheson et al, 2014). Only participants enrolled after implementation of Protocol Amendment 5 (03 December 2019) will have tumor assessments using the Lugano criteria.