Allogeneic Stem Cell Transplantation in Adult Patients with Acute Myeloid Leukemia and 17p Abnormalities in First Complete Remission: A Study from the Acute Leukemia Working Party (ALWP) of the European Society of Blood and Marrow Transplantation (EBMT)

Introduction: Acute myeloid leukemia (AML) with 17p abnormalities (abn(17p)), usually affecting TP53 locus, carries a very poor prognosis due to high refractoriness to conventional chemotherapy, with long-term survival of less than 5%. Allogeneic stem cell transplantation (SCT) appears as the only potential curative option in high-risk AML. To specifically address outcomes after SCT in patients with abn(17), we retrospectively analysed data from the EBMT registry.

Methods:De novo or secondary AML with abnormal karyotype transplanted between 2000 and 2013 have been allocated. From a dataset of 5495 patients with AML undergoing SCT, we included only those patients for whom data were sufficient to confirm the presence of abn(17p) resulting in a loss or a disruption of the TP53 locus.

Results: One hundred thirty-nine patients have been selected including 125 patients (90%) in first remission (CR1) and 14 (10%) in second remission. For further analysis, we focused on the 125 patients in CR1. Median age was 54 (range, 18-69) year-old and the median follow-up was 21 (range, 3-146) months. Eighty-five percent of the patients had a de novo AML, while 15% had a secondary AML. Abn(17p) was associated to a monosomal karyotype in 83% of patients, complex karyotype in 91%, monosomy 5 or 5q deletion (-5/5q-) in 55%, monosmy 7 (-7) in 39% and both -5/5q and -7 in 27%, respectively. Median time from diagnosis to CR1 was 57 (range, 18-170) days. Fifty-one (41%) of the patients received a myeloablative conditioning regimen and 73 (59%) had a reduced-intensity conditioning regimen. The vast majority of patients (70%) had a karnofsky performance status of more than 90% at the time of SCT. The 2-year overall survival (OS) and leukemia-free survival (LFS) were 28% and 24%, respectively. The 2-year non-relapse mortality (NRM) was 15%, and 2-yr relapse incidence (RI) was 61%. The cumulative incidence of grade II to IV acute graft-versus-host disease (GvHD) was 24% and that of chronic GvHD was 21%.

In multivariate analysis, the presence of a -5/5q- in addition to abn(17p) was significantly and independently associated with worse OS, LFS and higher RI. Age and donor type did not correlate with outcome. Conditioning intensity was not statistically associated with OS, LFS and NRM when adjusted for patients'age.

Conclusion: In contrast to the dismal prognosis reported for AML patients harboring abn(17p) undergoing conventional chemotherapy, allogeneic SCT provides long-term responses in about 25% of a selected group of patients harboring this cytogenetic abnormality at diagnosis and transplanted in CR1. Post and pre transplant targeted therapy may further improve results.