Salvage haploidentical or cord-blood allogeneic stem cell transplantation after a prior alternative allograft in hematologic malignancies: A retrospective study from the SFGM-TC.

Background: Haploidentical (haplo-) donors and cord-blood (CB) stem cells provide alternative transplant options in patients lacking an HLA-matched donor. In case of relapse or graft failure after a first alternative allogeneic hematopoietic stem cell transplant (HSCT), a second alternative HSCT (HSCT2) is rarely considered due to a high risk of toxicity.

Methods: A retrospective French multicentre study was performed, including patients with hematologic malignancies who underwent two consecutive HSCT from alternative donors. All data were exported from the national ProMISE database between 2000 and 2016.

Results: Forty-three patients (61.4%) received a CB-HSCT2 and 27 (38.6%) a haplo-HSCT2. Indications for HSCT were graft failure (51.4%) or disease progression (48.6%). Two-years probabilities of overall survival, progression-free survival and toxicity-related mortality were 18.5%, 17.8% and 55.8%, respectively. In multivariate analysis, complete remission status at HSCT2 and year of HSCT2 ≥ 2012 were significantly associated with a better outcome (with respectively hazard ratio [HR] = 0.42, p = .002 and HR = 0.5, p = .051).

Conclusions: Neither the indication of HSCT2 nor the source of stem cell was more advantageous towards overall patient survival. A salvage haploidentical or cord-blood stem cell transplantation is a high-risk procedure, that may be considered for patients achieving a complete remission before receiving the second HSCT.