Phase II study of nivolumab and relatlimab in advanced mismatch repair deficient (dMMR) cancers resistant to prior PD-(L)1 inhibition.

TPS839 Background: Cancers deficient in DNA mismatch repair (dMMR) are highly immunogenic tumors exhibiting high rates of response to immune checkpoint inhibitors targeting the programmed cell death-1 (PD-1)/PD-1 ligand (PD-L1) interaction. These tumors are characterized by high levels of microsatellite instability (MSI-H) and an exceptionally high tumor mutation burden, thought to underlie responsiveness to immunotherapy, with higher predicted...