Which Is the Best Mobilizing Regimen in POEMS Syndrome? a Retrospective Italian Study of Two Haematological Centres
Authors: Autore Francesco , Piccirillo Nicola , Nozza Andrea , Innocenti Idanna , Putzulu Rossana , Chiusolo Patrizia , Sora Federica , Zini Gina , Bacigalupo Andrea , Castagna Luca , Sica Simona , Bramanti Stefania , Laurenti Luca 
Published: October 2019

Abstract
Introduction. POEMS syndrome is a rare paraneoplastic condition associated to an underlying plasmacellular dyscrasia. The use of alkylating agents and autologous peripheral blood stem cell transplantation (aPBSCT) seem to be the best strategy.
At present aPBSCT should be considered the first line therapy in young patients with POEMS, eligible for high-dose Melphalan (HD-Mel), in absence of organ dysfunction. The best protocol to collect PBSC in patients affected by POEMS remains to be defined, because of the disease rarity and the heterogeneity of published case series.
We therefore decided to combine the case series of our two institutions to describe and compare results and outcomes in order to contribute to the definition of the best CD34+ cell mobilization strategy.
Patients and methods. We collected clinical and laboratory data of patients affected by POEMS syndrome undergoing hematopoietic stem cells (HSC) mobilization for aPBSCT from 2003 to 2018. Data were organized in order to perform a statistical analysis using "GraphPad Prism" GraphPad Software Inc., (5755 Oberlin Drive, #110, San Diego, CA 92121, USA). The COBE Spectra continuous flow cell separator (Terumo BCT, Shinagawa, Tokyo) was used for leukapheresis.
Results. Our data set consisted of 25 patients, of whom 11 were mobilized using cyclophosphamide (CY) 4 g/m2 followed by granulocyte colony-stimulating factor (G-CSF) 5 μg/kg and 14 patients were mobilized using G-CSF 10 μg/kg for 5 days. All patients submitted to mobilization underwent collection procedure. Three patients, because of low CD34+ cells after the administration of G-CSF alone, were submitted to plerixafor infusion achieving a median pre-apheresis CD34+cell count of 28 cells collecting a median of 4.5 CD34+cell/kg body weight. All patient underwent aPBSCT after HD-Mel conditioning regimen receiving an infusion of 4.7 CD34+cell/kg body weight (range 1.5-8.4) and achieved a successful engraftment. At present all the patients are alive and in remission.
In order to compare mobilization schedule we performed a comparison analysis between 11 patients receiving chemotherapy as mobilizing regimen versus 14 patients receiving only G-CSF. Data analysis according to mobilization schedule was reported in Table 1.
Analysing mobilization efficacy, chemo-mobilized patients achieved a higher pre-apheresis CD34+ cell count (57 vs 33 cells/µl, p<0.05). This result allowed a significantly shorter procedure (2.3 TBV vs 3 TBC, p<0001). Patients receiving only G-CSF showed a WBC count significantly higher than chemo-mobilized patients (40.000 vs 8.140, p<0.05). The incidence of poor mobilization was low (3 out of 25 patients, 12%) and not statistically different between the two mobilization schedules.
Discussion. The collection of these data allowed us to achieve one of the major series published in literature and to perform a comparison between two different approaches. The data suggest that both schemes (CY plus G-CSF vs. G-CSF alone) were able to harvest a sufficient CD34+ cell dose.

Disclosures
No relevant conflicts of interest to declare.