Outcome after Allogeneic Stem Cell Transplant for Patients with Hematological Malignancies and Associated Chromosome 7 Deletions

Chromosome 7 deletions are adverse prognostic factors associated with worse outcomes in patients with hematological malignancies. However there are few outcome data for hematopoietic stem cell transplant (HSCT) in pediatric patients with hematological malignancies and chromosome 7 deletions. We now describe the outcome in 40 patients with chromosome 7 abnormalities (ALL, n=13, AML, n=11, MDS, n=14 and JMML, n=2) who received an allogeneic HSCT at our institution between 2001-2013. The median age at the time of transplant was 9 years (range: 1-18 years). There were 23 patients with monosomy 7, 12 with 7q- and 5 with 7p-. At the time of transplant, 16 of the 24 patients with acute leukemia (ALL/AML) were in CR (9-CR1, 6-CR-2, 1-CR3) and 8/24 had active disease (3 with primary refractory disease, 5 in relapse). All patients with ALL (13/13), 10/11 patients with AML and 1 /2 patients with JMML received chemotherapy prior to transplant, while patients with MDS received no prior therapy. Patients received HSCT from MRD (10), MUD (17), MMUD (4) or haploidentical donors (9). The median time to engraftment was 19 days (95%CI: 17-20 days). With a median follow up of 857 days (range 5 -4099 days), the 3-year overall survival (OS) and disease free survival (DFS) for the entire cohort was 60% and 53%, respectively. The OS and DFS correlated with the underlying diagnosis with MDS patients having better 3-year OS and DFS (OS: MDS (77%), AML (36%), ALL (67%), JMML (50%) and DFS: MDS (64%), AML (36%), ALL (58%), JMML (50%) Outcome was not significantly affected by the type of chromosome 7 deletion (3-year OS: monosomy 7 (59%), 7q- (53%), 7p- (80%), p = 0.528). Upon further subdivision by diagnosis, patients with MDS that had associated monosomy 7 had significantly better OS compared to patients with AML and monosomy 7 as well as ALL and monosomy 7 (p = 0.014 and p = 0.029, respectively). Patients with MDS and associated chromosome 7 deletions, in particular monosomy 7, may achieve very good OS and DFS after HSCT. In contrast, patients with AML do not fare as well after HSCT.