Non-interventional Study Evaluating the Mobilization of Stem Cells by Plerixafor Before Salvage Autologous Stem Cell Transplant in Relapsed Multiple Myeloma (IFM-2015-03).

Introduction: Despite the implementation of new therapeutic agents, management of relapsed multiple myeloma (MM) remains a challenge. Salvage autologous hematopoietic cell transplant (AHCT) remains a valid therapeutic option for eligible patients who achieve prolonged response after a first AHCT. However, a second graft is not always available, and these patients may need a second mobilization.

Patients and methods: This prospective, non-interventional, multicenter study aimed to collect data on the feasibility of salvage AHCT using a plerixafor-based hematopoietic cell mobilization in relapsed MM, according to the plerixafor label in France. Adult patients with relapsed MM eligible for a second AHCT and mobilized using granulocyte- colony stimulating factor (G-CSF) and plerixafor were included.

Results: Of the 23 patients, 17 achieved a successful hematopoietic cell mobilization and 13 were able to proceed to a second AHCT. Median age was 62.9 years (min-max 51-71). Ten patients (77%) were male. Eleven (85%) received AHCT as a third-line treatment or more. Median time between first and second AHCT was 5.4 years (range, 2.6-16.3). Among 18 evaluable patients, mobilization was successful for 17 (94%) of them [95% CI 84-100], with no reported side effects. Among the 13 patients who underwent salvage AHCT, the median time to engraftment was 14 days (min-max 11-29). One-year progression-free and overall survival were 88.9% [95% CI 43.3-98.4] and 100%, respectively.

Conclusion: This study demonstrated that plerixafor allows safe and efficient mobilization in relapsed MM patients who are candidates for a salvage AHCT.

Trial registration: NCT02439476 Registered 8 May 2015, https://clinicaltrials.gov/ct2/show/NCT02439476 .