Bortezomib and High-Dose Melphalan as a Novel Conditioning Regimen for Patients with POEMS Syndrome Undergoing Autologous Peripheral Blood Stem Cell Transplantation.

POEMS syndrome is a multisystem disorder associated with plasma cell dyscrasias which characterized by polyneuropathy (P), organomegaly (O), endocrinopathy (E), serum M-protein (M), and skin changes (S). Recently, we successfully treated two POEMS syndrome patients by using bortezomib-based regimen(VDD) and followed by autologous peripheral blood stem cell transplantation (APBSCT) with bortezomib combined with high-dose melphalan(Mel) conditioning regimen.

According to the latest Mayo Clinic criteria, two patients’ diagnosis of POEMS syndrome could be comfirmed. Both of them had no response to the classical treatments, but achieved near complete remission(CR) after 4 cycles and 1 cycle of VDD respectively(Bortezomib 1.3–1.6 mg/m²/w×4 weeks; 40 mg of Liposomal doxorubicin on the fourth day of the first week; and 10 mg of dexamethasone during the initial 4 days of first cycle. Each course was at 21 days interval). Then, autologous peripheral blood stem cell collection was performed sucessfully (2.16×10⁶/kg and 3×10⁶/kg respectively) after mobilization by cyclophosphamide (3g/m²/d for 1 day) with subcutaneous G-CSF. APBSCT were performed approximately 1 month after stem cell collection. Two patients were conditioned with Bortezomib 1.6mg/m²(d-13,d-6,d+1,d+7)+Mel 200mg/m²(d-3)and Bortezomib 1.3 mg/m²(d-8,d-1,d+6,d+13)+ Mel 200mg/m²(d-2) respectively.

No toxic death or serious adverse effects occurred during APBSCT. Neutrophil and platelet recoveried at +10d, +27d and +7d, +20d respectively. Only case 1 patient developed mild hypoxemia during neutrophil engraftment period, but was successfully treated with corticosteroid and antibiotic therapy. The case 2 presented mucositis, diarrhea and nausea during neutropenic peroid. A follow-up period were 12 and 6 months respectively. Both of them achieved continuous CR. There was a dramatic improvement in clinical symptoms and serum VEGF levels in all two patients post VDD treatment including organomegaly (splenomegaly), M-protein, pericardiac/pleural effusion,ascites and polyneuropathy.

This is the first report of POEMS patients treated by APBSCT with bortezomib and high dose Melphalan conditioning regimen. Our results suggest that Bortezomib is a new effective and relative safe therapeutic option for POEMS syndrome not only in the conventional treatment but also in APBSCT procedure.

No relevant conflicts of interest to declare.