Regulatory T-cell depletion in the setting of autologous stem cell transplantation for multiple myeloma: pilot study

Regulatory T-cell depletion in the setting of autologous stem cell transplantation for multiple myeloma: pilot study

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Background Progression after high-dose melphalan with autologous stem cell Furniture transplantation (ASCT) in multiple myeloma (MM) may be due in part to immune dysfunction.Regulatory T (Treg) cells reconstitute rapidly after ASCT and inhibit immune responses against myeloma cells.Methods We performed a randomized study to evaluate two methods of Treg depletion in patients with MM undergoing ASCT.No Treg depletion was performed in the control ASCT arm.

An anti-CD25 monoclonal antibody (basiliximab 20 mg IV) was administered on day +1 post-ASCT in the in vivo Treg depletion (IVTRD) arm.Tregs were depleted from autologous stem cell (ASC) grafts with anti-CD25 microbeads and the CliniMACS device in the ex vivo Treg depletion (EVTRD) arm.Results Fifteen patients were enrolled, five in each arm.The conditioning regimen was melphalan 200 mg/m2.

Primary objectives included assessments of efficiency of IVTRD/EVTRD, kinetics of Treg depletion and recovery following ASCT, and safety.EVTRD removed 90% of CD4+CD25+ cells from ASC grafts.IVTRD Hand Lotion and EVTRD led to reductions in Treg frequency between days +7 and +90 post-transplant compared with the control (p=0.007 and p<0.

001, respectively).Conclusions IVTRD and EVTRD are feasible and significantly reduce and delay Treg recovery post-ASCT for MM, and serve as a platform for using post-transplant immunotherapies to improve post-ASCT outcomes.Trial registration number NCT01526096.