AML Patients In First CR with Intermediate Risk Cytogenetic and High Level of CD34+ Mobilization Have Better DFS After Allogeneic Transplantation.
Authors: Milone Giuseppe , Leotta Salvatore , Avola Giuseppe , Poidomani Massimo , Camuglia and Andrea Spadaro Maria Grazia 
Published: October 2019

Abstract
Abstract 4563
AML patients having a high apheretic yield in CD34+ cells during mobilization have a poor prognosis, independently from cytogenetic risk (Feller 2004, Keating 2004). It is however not known if prognostic value of PBSC mobilization is retained after different post remissional treatment and clinical usefullness of this prognostic information in dealing with intermediate cytogenetic group patients, the more represented AML subgroup in which post remissional therapy is still a controversial issue.

METHODS
A group of 64 AML adult patients in 1st CR was prospectively studied. PBSC mobilization was attempted following first consolidation course. Cytogenetic assessment at diagnosis was available in 95% of patients. Post remissional treatment was chosen based on cytogenetic risk, sibling donor availability and presence of others prognostic factors, MUD transplants were proposed in cytogenetic high risk patients or in selected young patients with intermediate cytogenetic, Autologous HSC Transplantation was proposed when allogeneic transplant was felt not indicated, no further therapy was administered in patients deemed ineligible for any kind of transplantation. Prognostic significance of CD34+ cells was evaluated measuring DFS in groups of patients identified from value of CD34+ peak in respect to 50th percentile (CD34 peak: 65×10e6/L) and 75th percentile (197×10e6/L). Those patients having a CD34+ cell peak below median value (65×10e6/L) were categorised as LOW MOBILIZER, those having a CD34+ peak between 65 and 197 ×10e6/L were categorised as GOOD MOBILIZER, and those having a CD34+ peak over 75th percentiles (197 ×10e6/L) were categorised as SUPERMOBILIZER.

RESULTS
In our serie 40% of patients received an Allogeneic transplant after a myeloablative treatment, 49% an autologous transplant while 11% no further chemotherapy. Disease Free Survival (DFS) was 60%. CD34+ peak during mobilization, evaluated as a continuous variable, in a Cox regression model resulted important for DFS (hazard ratio:1.001; p=0.01). Importance of CD34+ peak was maintained also when the stratum of patients with intermediate cytogenetic risk was analysed (DFS: p=0.002). POOR MOBILIZER, GOOD MOBILIZER and SUPERMOBILIZER patients had statistically different DFS when cases were analysed as a whole (DFS: POOR M.: 70%; GOOD M. 50%; SUPER M: 30%; log rank: p=0.05); mobilizing efficiency was important for DFS also in intermediate cytogenetic group (DFS: POOR M. 70%; GOOD M. 40% DFS; SUPER M. 28%; log rank p= 0.02), importance was maintained also in patients treated by allogeneic transplantation or with autologous transplantation (fig.1).
When allogeneic transplantation was compared to the group of patients receiving autologous transplantation or other post remissional strategies both in the cases as a whole and in the stratum of intermediate cytogenetic (table 1), the group of POOR mobilizer had after autologous transplants results non different from patients receiving allogeneic transplantation, however, the group of GOOD mobilizer patients had after allogeneic transplants a DFS significantly better compared to other treatment while SUPER mobilizer patients had poor results also when allogeneic transplantation was employed.
In conclusion in AML in 1st CR, evaluation of CD34 peak during mobilization is a parameter providing prognostic informations useful also within intermediate cytogenetic group.

Disclosures:
No relevant conflicts of interest to declare.