Satisfactory outcomes following a second autologous hematopoietic cell transplantation for multiple myeloma in poor stem cell mobilizers: a retrospective study on behalf of the Chronic Malignancies Working Party of the EBMT.

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.
Competing Interests: Competing interests JDS – honoraria AbbVie, Roche, Janssen, Astra Zeneca, SOBI, Takeda, BMS, Novartis, Swixx; Advisory board meetings organized by Janssen-Cilag, Sanofi, AstraZeneca, Roche, BeiGene; AP - honoraria from Behring and Abbvie, participation in scientific Advisory board meetings organized by Abbvie, Janssen-Cilag, Novartis, Pfizer, Sanofi and Takeda; none of COI directly related to the study. Ethics approval This retrospective study was approved by the Chronic Malignancies Working Party (CMWP) of the EBMT and was performed in accordance with the Declaration of Helsinki.
(© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)