LAUSR

Dear Editor, We have read with great interest the report by Wang et al. [1] regarding autologous hematopoietic stem cell transplantation (ASCT) following polatuzumab vedotin combined with rituximab-bendamustine (Pola-BR) for relapsed diffuse large B-cell lymphoma (rDLBCL) to improve its prognosis. Pola-BR was demonstrated to be more effective than conventional salvage therapies for rDLBCL [2, 3], but no reports have adequately described the administration of Pola-BR prior to autograft. We herein report a case of ASCT performed following Pola-BR therapy for rDLBCL. A 32-year-old previously healthy man presented to our hospital complaining of gradually worsening back pain that had first developed 3 months earlier. His Eastern Cooperative Oncology Group performance status was 1 and lactate dehydrogenase was 848 U/L (> 3 times higher than the upper limit of the normal range). Computed tomography revealed multiple masses in the left liver lobe, pancreatic body, and both kidneys, as well as multiple enlarged lymph nodes. A liver biopsy revealed diffuse proliferation of large cells that were CD20( +), CD79a( +), CD10 ( −), bcl-2( +), bcl-6( +), c-myc(-), MUM1( +), and Ki-67 strongly positive, with few normal liver cells. Based on the above findings, DLBCL stage IV was diagnosed. After six courses of R-CHOP, complete response (CR) was achieved, but back pain reoccurred 1 month following treatment conclusion. Magnetic resonance imaging revealed no mass in the left liver lobe or pancreas body, but showed multiple masses in both the kidneys and multiple enlarged lymph nodes in the abdominal cavity. Recurrence was diagnosed in the patient and R-ESHAP was performed, but tumor shrinkage could not be achieved. Since a partial response was achieved after the first course of Pola-BR treatment, stem cell collection (SCC) at the conclusion of the second course was planned. G-CSF 10 μg/kg was administered for 5 days starting on day 22, plerixafor 0.24 mg/kg was administered on day 25, and stem cells were collected on day 26. The total number of nucleated and CD34( +) cells was 13.1 × 108/kg and 12.5 × 106/kg, respectively, in 1 day (Fig. 1). MEAM (ranimustine, etoposide, cytarabine, and melphalan) with ASCT was subsequently performed and CR was achieved. Bendamustine is considered an alkylating agent and is known to negatively affect mobilization of peripheral blood stem cells [4, 5]. SCC after BR is challenging; the failure rate of SCC in 1 day has been reported to be eight times higher than in other treatments [6, 7]. However, the total dose of bendamustine and the period from administration to collection reportedly did not significantly influence SCC [8]. In recent reports, Pola-BR was used as a bridging treatment to chimeric antigen receptor T-cell (CAR-T) therapy [9]. In cases of rDLBCL in which ASCT is not possible, a 6-month survival is difficult to achieve [10], and Pola-BR can be used for these patients as a bridging treatment. The present case highlights the potential utility of Pola-BR as a salvage therapy for rDLBCL cases scheduled for ASCT. Pola-BR may be used increasingly frequently in the future as a preceding therapy for patients scheduled to undergo CAR-T therapy or allogeneic transplantation.