Effective Treatment with PD-1 Antibody, Chidamide, Etoposide, and Thalidomide (PCET) for Relapsed/Refractory Natural Killer/T-Cell Lymphoma: A Report of Three Cases

Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTL) is a specific subtype of peripheral T cell lymphoma (PTCL) with a poor prognosis. To date, there exist no standard therapeutic regimens for relapsed/refractory (R/R) ENKTL. More potent treatment strategies are urgently needed to improve the survival of these patients with R/R ENKTL. Herein, we present three R/R ENKTL patients who failed prior therapies (L-asparaginase containing chemotherapy, radiotherapy or biological-cell therapy, etc.) benefited from the combination regimen comprised of anti-programmed-death-1 (PD-1) antibody toripalimab, chidamide, etoposide, and thalidomide. They received the treatment regimen continuously until the disease progression occurs. As of data collec-tion, two patients achieved complete remission (CR) after 4, 6 cycles of treatment, respectively, and another patient was evaluated as partial remission (PR) after 2 cycles. Treatment-related adverse events (AEs) mainly presented grade 2 similar to 3 leukocytopenia and anemia, which were controllable. It follows that PD-1 antibody, chidamide, etoposide, and thalidomide (PCET) regimen may be a promising choice for patients with R/R ENKTL and warrants further investigation.