Hematopoietic stem cell transplantation for diffuse large B-cell lymphoma having 8q24/MYC rearrangement in Japan

The prognosis of diffuse large B-cell lymphoma (DLBCL) having MYC rearrangement (MYC-R), including double hit lymphoma (DHL), is poor by standard immunochemotherapy. To evaluate the significance of hematopoietic stem cell transplantation (SCT) for DLBCL with MYC-R, we retrospectively analyzed Japanese SCT registry data. In total, 54 patients with DLBCL with MYC-R were identified from 4336 registered adult DLBCL patients. Detailed clinical and cytogenetic information was obtained for 48 patients. The median age at diagnosis of the 48 patients was 54.5 (range 21-67) years. Twenty-six (54%) patients had MYC-R only (single hit), and 22 (46%) had MYC-R and BCL2, and/or BCL6 rearrangement (double/triple hit). In 12 patients who received auto-SCT during the first complete response (CR), both the 2-year overall survival (OS) and progression-free survival (PFS) rates were 75.0% (95% confidence interval [CI], 40.8%-91.2%). In 20 patients who received auto-SCT after relapsed or refractory state, the 2-year OS and PFS rates were 68.2% (95% CI, 41.9%-84.5%) and 59.6% (95% CI, 35.1%-77.4%), respectively. In 17 patients who received allo-SCT, only 4 patients underwent SCT in CR. The 2-year OS and PFS rates were 29.4% (95% CI, 10.7%-51.1%) and 17.6% (95% CI, 4.3%-38.3%), respectively. The rate of non-relapse mortality at 1 year was 41.2% (95% CI, 17.1%-64.0%) in this group. The outcomes of single hit and double or triple hit were not different. These findings suggest that auto-SCT may be effective for MYC-R DLBCL, including DHL patients of chemosensitive relapsed or refractory state. Since most patients received allo-SCT not in CR, the outcome of allo-SCT was unsatisfactory due to high non-relapse mortality and early relapse. To clarify the role of allo-SCT for MYC-R DLBCL, further accumulation of patients is necessary.