BMT from HLA haploidentical family members (hBMT), using either T-cell depleted or T-cell replete grafts, is increasingly employed in patients who urgently need (but lack) a donor. After the promising results in hBMT obtained by the Baltimore group (Luznik et al., Biol Blood Marrow Transplant 2008, Blood 2010) introducing post-transplant high-dose cyclophosphamide (PT-CY) following a non-myeloablative conditioning regimen, the Genoa group (Raiola et al., Biol Blood Marrow Transplant 2013) has shown, in the haploidentical setting that a myeloablative conditioning (MAC) with PT-CY (on day +3 and +5), cyclosporine from day zero and mycophenolate mofetil (MMF) from day +1, is associated with a high rate of engraftment, acceptable TRM and GVHD, and induces durable remission with low incidence of relapse in a high proportion of patients with high-risk hematologic malignancies. We now report a series of 13 heavly pretreated high-risk leukemia patients who underwent a MAC protocol consisted of TBF regimen: Thiotepa (10 mg/kg), Busulfan (9,6 mg/kg) and Fludarabine (150 mg/mq). As graft versus host disease (GVHD) prophylaxis, 2 patients received a 5 drugs combination (ATG-Fresenius, CSA, MTX, MMF and Basiliximab) and stem cells source was G-CSF-primed haploidentical bone marrow (hBM) cells (Di Bartolomeo et al., Blood 2013). In 11 patients stem cells source was non-primed unmanipulated hBM cells, and GVHD prophylaxis consisted of PT-CY (50mg/kg) iv on day +3 and +4, CSA 2.5 mg/kg/day and MMF 45 mg/kg/day from day +4.
From 2008 to 2013, 11 adult patients (M/F=8/3; median age 40 years, range 23 to 62) and 2 pediatric patients (M/F=1/1, age 4 and 7 years) with high risk ALL (1 pediatric; 2 adult), AML (1 pediatric; 8 adults) and one Richter evolution of CLL, underwent T replete hBMT. At time of transplant 10 patients were in CR (CR1=9, CR2=1), 1 in a good PR and 2 had refractory disease. Grafts contained a median of 5.68 x 108/kg nucleated BM cells (range 0.7-62.1), 2.14x106/kg CD34+ cells (range 0.55-7.09) and 34.7x106/kg CD3+ cells (range 16-93.4). 12 patients are evaluable for engraftment. This occurred in 100% for neutrophils and 93% for platelets, with a median time to neutrophil recovery (> 0.5 x 109/L) of 22.5 days (range, 13-40) and to platelet recovery (> 20.0 x 109/L) of 27.5 days (range, 17-49). All patients had full donor chimerism by day +30. Non relapse mortality (NRM) was 23%: 2 pt died for sepsis (one before engraftment), 1 for aGVHD. 4 patients had grade I and 3 grade II aGvHD, respectively. Only one patient had a grade III, and another had grade IV fatal GVHD. 3 patients had only limited chronic GvHD. Up to now, only 3 patients have relapsed and of these 2 have died. 8 patients (61.5%) are currently surviving, 7 of them are disease-free with median follow-up time of 165 days (range 32-896 days) from transplant.
Our preliminary results confirm that haplo-BMT following a MAC regimen, is a feasible treatment in pediatric and adult patients, and that PT-CY is highly effective as GVHD prophylaxis, producing a high rate of stable engraftment with encouraging non relapse mortality and relapse-free survival.
No relevant conflicts of interest to declare.