89Zr-DFO-REGN3767 in PET Scans in People With Diffuse Large B Cell Lymphoma (DLBCL)

89Zr-DFO-REGN3767 is comprised of the anti-LAG-3 antibody, REGN3767 labeled with the positron-emitter zirconium-89 (89Zr) through the chelator-linker DFO. REGN3767 is an investigational monoclonal antibody that target LAG-3 receptors.

"A PET/CT scan extending from top of skull to feet will be performed to determine the biodistribution.~Part A patients will be imaged at three time points post-injection to allow for selection of optimal imaging time and dosimetry determination. For these patients, top of skull to feet scans will be acquired:~* Within one to four hours following injection of tracer on Day 1~* 24-72 hours post-injection (Day 2-4)~* 20-168 hours post-injection (once during days 5-7)"