Long-Term Follow-up of Hematopoietic Stem Cell Transplantation with the Modified Peking Regimen for the Treatment of Acute Leukemia

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative treatment strategy for patients with acute leukemia. The ATG-based transplantation system initiated by Peking University people's hospital, known as the Peking regimen, has become a mainstream transplant system worldwide. Here, based on the Peking regimen, we report a modified protocol:(1)add Fludarabine and replace ATG with ATG-F in the conditioning regimen; (2)transfuse higher-dose cell collections from granulocyte-colony stimulating factor(G-CSF) primed bone marrow and peripheral blood samples; (3) add Basiliximab (a CD25-antibody) on day +3 for acute GVHD prophylaxis. In this study, 265 patients (158 patients with haplo-SCT and 107 patients with sibling-SCT) underwent allo-HSCT with our modified protocols. All patients achieved sustained full-donor chimerism. The incidence of grade II-IV and III-IV acute GVHD in haplo-SCT comparing with sibling-SCT was 36.1%(57/158) vs 17.8%(19/107)(P=0.001) and 13.3% (21/158) vs 9.3%(10/107)(P>0.05) respectively. The 2-year cumulative incidence of total chronic GVHD and extensive chronic GVHD in haplo-SCT was 41% (65/158) and 15% (24/158) respectively. The 3-year cumulative incidence of non-relapse mortality (NRM) in haplo-SCT and sibling-SCT was 6.3% (10/158) and 4.7%(5/107) respectively(P>0.05). The 100-day cumulative incidence of CMV viremia in haplo-SCT and sibling-SCT was 35.5% (56/158) and 23.4%(25/107) respectively(P=0.036). A total of 36 patients in haplo-SCT group and 24 patients in haplo-SCT group had recurrent disease, reaching a cumulative incidence of relapse of 20.8% in haplo-SCT and 23.4% in sibling-SCT at 3 years respectively(P>0.05). The relapse ratio of haplo-SCT and sibing-SCT in the 1st year, between the 1st and the 2nd year and after 2 years was 21.5% vs 14.1%(P>0.05), 1.3%(2/158) vs 0%(P>0.05) and 0% vs 6.5%(P=0.009) respectively. The 3-year overall survival(OS) and leukemia-free survival(LFS) rates in haplo-SCT and sibling-SCT was 78.8% vs 74.2% and 76.8% vs 75.04% respectively(P>0.05) by the Kaplan-Meier estimate. The 3-year GVHD-free and leukemia-free survival rates (GRFS) in haplo-SCT and sibling-SCT were 43.4% vs 69.5%(P=0.045) respectively. Lower OS in haplo-SCT was associated with III-IV aucte GVHD and lower MNC(<19×10^8/L) in grafts by Cox regression analysis. In a word, the results from our experience showed that the modified protocol based on the Peking Regimen is safe and reliable for acute leukemia patients and brings on a long-stage survival post transplantation.