Unrelated-donor bone marrow transplantation for Philadelphia chromosome-positive chronic myelogenous leukemia in children: experience of eight European Countries. The EBMT Paediatric Diseases Working Party

: From September 1988 to December 1995 forty-four children (age < 17 years) with Ph1 Chronic Myelogenous Leukemia (CML) received unrelated donor marrow transplantation in 8 European Countries. Thirty-three evaluable children were typed by serological testing on HLA-A, B, and DR loci. Thirty of them were further DR subtyped by DNA techniques. Twenty-four pairs were 6 antigen matched. Seven were mismatched at 1 locus (2 pairs at A and B loci respectively and 3 at DR locus). Two out of 30 pairs evaluated by molecular biology had one antigen mismatched at DRB1 locus. Thirty-two (96%) out of 33 evaluable children reached a sustained granulocyte count higher than 0.5 x 10(9)/l at a median of 21 (range 14-88) days after transplantation. The remaining child failed to engraft. Two children developed secondary graft failure. A platelet count greater than 50 x 10(9)/l sustained for at least seven consecutive days without transfusion support was reached at a median of 25 (range: 20-144) days by 24 out of 33 evaluable children and 9 children never recovered to above 50 x 10(9)/l. Twenty-one out of 33 evaluable children developed grade I (n = 7), grade II (n = 8), grade III (n = 2) or grade IV (n = 4) acute GvHD (63%). Seven of the 30 evaluable children surviving more than 100 days developed chronic GvHD (20%) which was limited in 4 cases and extensive in 3. Relapse occurred in 3 of the 44 (7%) children at 2 to 24 months (median 14). Twenty-four month relapse rate was 14%. Seventeen out of 44 children (38%) died of transplant related mortality (TRM), 4 (9%) of secondary tumor, 4 (9%) of infections, 3 (7%) of organ failure, 1 (2%) of interstitial pneumonia, 5 (11%) of unknown causes. Actuarial TRM was 61% for children grafted before December 1991 and 33% for children grafted after January 1992 (p = .01). EFS was 49.7%; it was 65% for children receiving more than 3.5 x 10(9)/Kg MNC.