Contributions
Type: Publication Only
Background
T cell replete haploidentical stem cell transplantation with post-transplantation cyclophosphamide (PTCy) has shown encouraging results for the treatment of hematologic malignancies; its main advantage is that almost every patient will have a donor. But this technique has been explored mainly in adults and using bone marrow as a cellular source
Aims
To present our experience using T cell replete haploidentical peripheral blood stem cell transplantation (TCR-Haplo-PBSCT) with PTCy for high risk pediatric acute leukemia
Methods
Donors were mobilized with filgrastim 5 ucg/kg/BID for five days, the PBSC were collected with one large volume apheresis procedure. The conditioning consisted of fludarabine 150 mgs/m2, busulfan 4-8 mgs/kg and Total Body Irradiation 400 cGy (Flu Bu TBI) or fludarabine 150 mgs/m2, melfalan 100-140 mgs/m2 and TBI 200 cGy(Flu Mel TBI); on days +3 and +4 PTCy 50 mgs/kg/day was given followed by cyclosporin and mycophenolate starting day + 5. All patients received post transplant filgrastim beginning on d + 6
Results
After a signed informed consent, 18 patients, were transplanted; median age was 11.5 years (range 6-16), 8 were girls, the diagnosis were: acute lymphoblastic leukemia 8 patients, acute myeloid leukemia 9 and blastic phase of chronic myeloid leukemia one. 22% were in CR1, 39% in CR2 and 39% in CR3 or with refractory disease. Flu Bu TBI conditioning was given in 14 cases while Flu Mel TBI in 4. A median of 10 million/kg of CD34+ cells were infused.
The engraftment rate was 100%, median time to achieve 500 neutrophil or more was 15 days (range 14-20), 1 patient out of 18 died without platelet recovery, the remaining had a self- sustained platelet count of 20.000 or more at a median of 14 days (range 10-21). Chimerism at day + 100 was available in 14 cases, all of them had full donor hematopoiesis. The cumulative incidence of aGVHD II-III and extensive cGVHD was 37.5% and 27% respectively.
The median follow-up is 13.5 months (range 1-24), 4 patients have died, the causes were; pneumonia (n:1) and relapse of leukemia( n:3), other 2 have relapsed but are alive receiving low intensity chemotherapy. The cumulative incidence of transplantation related mortality is 5.6% and the 2 years actuarial overall survival and event free survival are 79.8% and 58.7% respectively
Summary
The use of TCR-Haplo-PBSCT with PTCy for treating pediatric acute leukemia is promising; it is associated with low transplantation related mortality, very good engraftment rate, acceptable incidence of GVHD, despite the use of peripheral blood, and encouraging leukemia free survival. It deserve more studies
Keyword(s): Acute leukemia, Haploidentical stem cell transplantation, Pediatric
Session topic: Publication Only
Type: Publication Only
Background
T cell replete haploidentical stem cell transplantation with post-transplantation cyclophosphamide (PTCy) has shown encouraging results for the treatment of hematologic malignancies; its main advantage is that almost every patient will have a donor. But this technique has been explored mainly in adults and using bone marrow as a cellular source
Aims
To present our experience using T cell replete haploidentical peripheral blood stem cell transplantation (TCR-Haplo-PBSCT) with PTCy for high risk pediatric acute leukemia
Methods
Donors were mobilized with filgrastim 5 ucg/kg/BID for five days, the PBSC were collected with one large volume apheresis procedure. The conditioning consisted of fludarabine 150 mgs/m2, busulfan 4-8 mgs/kg and Total Body Irradiation 400 cGy (Flu Bu TBI) or fludarabine 150 mgs/m2, melfalan 100-140 mgs/m2 and TBI 200 cGy(Flu Mel TBI); on days +3 and +4 PTCy 50 mgs/kg/day was given followed by cyclosporin and mycophenolate starting day + 5. All patients received post transplant filgrastim beginning on d + 6
Results
After a signed informed consent, 18 patients, were transplanted; median age was 11.5 years (range 6-16), 8 were girls, the diagnosis were: acute lymphoblastic leukemia 8 patients, acute myeloid leukemia 9 and blastic phase of chronic myeloid leukemia one. 22% were in CR1, 39% in CR2 and 39% in CR3 or with refractory disease. Flu Bu TBI conditioning was given in 14 cases while Flu Mel TBI in 4. A median of 10 million/kg of CD34+ cells were infused.
The engraftment rate was 100%, median time to achieve 500 neutrophil or more was 15 days (range 14-20), 1 patient out of 18 died without platelet recovery, the remaining had a self- sustained platelet count of 20.000 or more at a median of 14 days (range 10-21). Chimerism at day + 100 was available in 14 cases, all of them had full donor hematopoiesis. The cumulative incidence of aGVHD II-III and extensive cGVHD was 37.5% and 27% respectively.
The median follow-up is 13.5 months (range 1-24), 4 patients have died, the causes were; pneumonia (n:1) and relapse of leukemia( n:3), other 2 have relapsed but are alive receiving low intensity chemotherapy. The cumulative incidence of transplantation related mortality is 5.6% and the 2 years actuarial overall survival and event free survival are 79.8% and 58.7% respectively
Summary
The use of TCR-Haplo-PBSCT with PTCy for treating pediatric acute leukemia is promising; it is associated with low transplantation related mortality, very good engraftment rate, acceptable incidence of GVHD, despite the use of peripheral blood, and encouraging leukemia free survival. It deserve more studies
Keyword(s): Acute leukemia, Haploidentical stem cell transplantation, Pediatric
Session topic: Publication Only