Poor mobilizer: a retrospective study on proven and predicted incidence according to GITMO criteria

The Italian Group for Bone Marrow Transplantation (Gruppo Italiano Trapianto di Midollo Osseo, GITMO) recently formalized criteria for a shared definition of poor mobilizer in order to facilitate randomized clinical trials and study comparison focusing on the efficacy of current mobilizing regimens. The availability of a standardized tool for poor mobilizer definition suggested us to retrospectively test GITMO criteria feasibility and applicability. Therefore we analyzed medical and laboratory records of adult patients affected by myeloma (MM) or lymphoma undergoing mobilization for autologous peripheral blood HSC collection from January 2010 to June 2011, at Servizio di Emotrasfusione, Istituto di Ematologia, Università Cattolica Del Sacro Cuore, Roma, UOC SIMT AO S. Camillo Forlanini Roma and SIMT Fondazione Policlinico Tor Vergata Roma. We collected data about 227 patients (134 male, 93 female) affected by MM (31.3%) NHL (58.6%) e HD (10.1%). Thirty-nine patients, 21 male and 18 female met proven poor mobilizer criteria definition resulting in a incidence of 17.2% (12.7% in MM, 21.8% in NHL and 4.3% in HD). Eleven patients, seven affected by lymphoma and four affected by myeloma, were defined predicted PM according to major criteria. Eight patients, seven affected by lymphoma and one affected by myeloma, were define predicted PM according to minor criteria. Sixteen out of 39 patients defined as poor mobilizer either according to major or minor criteria underwent collection procedures and eight (20.5%) achieved a cell dose ⩾2×10(6)/kg CD34(+) cells. GITMO criteria application was easy and resulted in poor mobilizer incidence comparable to current literature. Definitions of proven poor mobilizer and predicted poor mobilizer according to major criteria were very effective while minor criteria were less predictive. These results came from a retrospective analysis and therefore should be validated in future prospective trial. On the other hand these data could be an early overall view of the foreseeable future of peripheral blood stem cell collection. In conclusion we believe that these criteria will be able to better characterize poor mobilizer phenomenon and, consequently, to identify patients taking advantage from new mobilizing agents.