Pseudo-autologous Stem Cell Transplant for the Treatment of Secondary Central Nervous System Lymphoma

In patients who have previously undergone allogeneic stem cell transplantation and later have stem cells collected for an autologous transplant, the collected cells are sometimes referred to as "pseudo-autologous" to indicate that they are donor-derived. The use of pseudo-autologous stem cell transplantation (pASCT) has rarely been reported. We describe a case of pASCT in a 66-year-old man with multiple relapses of diffuse large B-cell lymphoma (DLBCL) despite prior chimeric antigen receptor T-cell (CAR T) therapy and a subsequent matched unrelated donor transplant. His most recent relapse after allogeneic transplantation was limited to the central nervous system (CNS) and presented with multiple cranial nerve palsies. Although previously collected autologous stem cells and donor-derived allogeneic stem cells were available, pseudo-autologous stem cells were collected during recovery from a modified salvage chemotherapy regimen (methotrexate (MTX), cytarabine, thiotepa, and rituximab (MATRix)). He subsequently received high-dose therapy with busulfan and thiotepa followed by pASCT. Despite receiving only brief (<1 month) graft-versus-host disease (GVHD) prophylaxis, he did not develop GVHD and remains disease-free 23 months after transplant. We discuss the rationale for selecting pASCT despite the availability of stored autologous and allogeneic stem cells.