This is a single institution phase I/II study using an ADAM17 inhibitor (INCB7839) with rituximab as consolidation therapy after an autologous hematopoietic cell transplant (HCT) for patients with diffuse large B cell lymphoma (DLBCL). The study consists of two phases. The dose finding phase is a modified version of a phase I trial and the extended phase is a modified version of a phase II trial.