Autologous hematopoietic cell transplants (auto-HCTs) remain the standard of care for transplant-eligible MM patients. The general practice has been to undergo upfront apheresis following induction to collect sufficient number of CD34+ cells to facilitate two auto-HCTs. However, 5-30% of MM patients do not initially mobilise a sufficient number of hematopoietic stem cells and are classified as poor mobilizers (PM). We compared the baseline characteristics and outcomes of 61 PMs and 816 non-PM patients who underwent a second auto-HCT and who were enrolled in the non-interventional CALM study (NCT01362972). Only patients who collected CD34+ prior to auto-HCT1 were included. Auto-HCT2 comprised both tandem and salvage transplants. PMs were re-mobilized with plerixafor (n = 24, 39.3%) or non-plerixafor-based regimens (n = 37, 60.7%). There were no significant differences in engraftment, progression-free survival (PFS) or overall survival (OS) after the second auto-HCT between PM and non-PM patients. There was a trend to shorter PFS in PM patients undergoing salvage auto-HCT (median 9.6 vs. 12.9 months; p = 0.08) but no significant difference in OS. The median OS was 41.1 months for PM and 41.2 months for non-PM patients (p = 0.86). These data suggest that salvage mobilization is effective and does not affect overall outcomes after a second auto-HCT.

ASST Papa Giovanni XXIII Bergamo Italy

Belfast City Hospital Belfast Northern Ireland

Charles University Hospital Prague Czech Republic

Department of Haematology Trinity College Dublin St James's Hospital Dublin Ireland

EBMT Leiden Statistical Unit Leiden the Netherlands

EBMT Leiden Study Unit Leiden the Netherlands

Faculty of Medicine Liv Hospital Ankara Turkey

George Papanicolaou General Hospital Thessaloniki Greece

Hannover Medical School Hannover Germany

Heinrich Heine Universitaet Duesseldorf Germany

Imperial College Hammersmith London UK

Karolinska University Hospital Stockholm Sweden

Klinikum Karlsruhe gGmbH Karlsruhe Germany

Kuopio University Hospital Kuopio Finland

Medizinische Klinik u Poliklinik 5 University of Heidelberg Heidelberg Germany

Nottingham City Hospital Nottingham UK

Programme de Transplantation and Therapie Cellulaire Marseille France

Skanes University Hospital Lund Sweden

Umea University Hospital Umeå Sweden

University Clinical Centre Medical University of Warsaw Warsaw Poland

University College London Hospitals NHS Trust London UK

University Hospital 1 Basel Basel Switzerland

University Hospital Brno Brno Czech Republic

University Medical Centre Ljubljana and Faculty of Medicine University of Ljubljana Ljubljana Slovenia

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