High-dose CD20-targeted radioimmunotherapy-based autologous transplantation improves outcomes for persistent mantle cell lymphoma

Autologous stem cell transplant (ASCT) can improve outcomes for mantle cell lymphoma (MCL) patients, yet relapses are frequent. We hypothesized that high-dose anti-CD20 radioimmunotherapy (RIT)-based conditioning could improve results in this setting. We thus assessed 162 consecutive patients with MCL at our centre undergoing ASCT following high-dose RIT-based (n = 61) or standard (n = 101) conditioning. RIT patients were less likely to be in first remission (48% vs. 72%; P = 0.002), be in complete remission (CR) (26% vs. 61%; P < 0.001) and have chemosensitive disease (84% vs. 96%; P = 0.006). Rh-based conditioning was associated with a reduced risk of treatment failure [hazard ratio (HR) 0.40; P = 0.001] and mortality (HR 0.49; P = 0.01) after adjusting for these imbalances. This difference increased as disease status worsened (from CR to partial remission to stable/progressive disease), with respective HRs of 1.14, 0.53 and 0.04 for mortality, and 0.66, 0.36 and 0.14 for treatment failure. RIT-based conditioning appears to improve outcome following ASCT for MCL patients unable to achieve CR after controlling for imbalances in important risk factors. These data support the further study of PIT and radiation-based strategies in a risk-adapted approach to ASCT for persistent MCL.