Second haploidentical stem cell transplantation for primary graft failure

We report the outcome of 19 patients who experienced primary graft failure (PrGF) after a haploidentical (HAPLO), unmanipulated bone marrow transplant. The median age of patients was 52 years; the conditioning regimen of the first HAPLO transplant was either full dose total body irradiation (TBI) or fludarabine, busulfan, and thiotepa (TBF); PTCY was given to all patients together with cyclosporine and mycophenolate. All 19 patients with PrGF received a second HAPLO graft, at a median interval of 42 days (34-82) after HSCT, using the Baltimore protocol and G-CSF mobilized PB from the same (n = 13) or another HAPLO family donor (n = 6). GvHD prophylaxis was again PTCY-based; 14/19 patients had trilineage recovery (74%) and 1-year survival was 66%. Engraftment at second HAPLO was seen in 7/8 patient with, and in 5/7 patients without donor-specific antibodies (DSA). In a multivariate logistic regression analysis on the original group of 503 patients, there was a trend for a reduced dose of busulfan, to increase the risk of PrGF (p = 0.1). In conclusion, patients with PrGF following a HAPLO transplant, can be rescued with a second early HAPLO transplant, using the same or a different donor.