Monosomal Karyotype in Myeloid Malignancies Is Prognostically Worse Even After Allogeneic Hematopoietc Stem Cell Transplantaion; Results From Two Transplant Centers,
Authors: Koichiro Minauchi , Shigematsu Akio , Nakata Masanobu , Matsukawa Toshihiro , Ebata Koh , Yamakawa Tomohiro , Saga Tomoyuki , Shima Kanako , Ibata Makoto , Sugita Junichi , Ota Shuichi , Imai Kiyotoshi , Hirano Teiichi , Ogasawara Masahiro , Kiyama Yoshio , Imamura Masahiro , Kobayashi Naoki 
Published: October 2019

Abstract
Abstract 4154

Background:
Monosomal karyotype (MK) has been defined as the presence of two or more autosomal monosomies or of a single monosomy associated with at least one structural abnormality (Breems et al, JCO 2008). The presence of MK has been associated with extremely poor prognosis in patients with not only acute myeloid leukemia (AML) but myelodysplastic syndrome (MDS) (Patnaik et al, Leukemia 2011). Our goal was to investigate the efficacy of allogeneic hematopoietic stem cell transplantation (HSCT) for myeloid malignancies with MK.

Patients and methods:
We combined data from two transplant centers, Sapporo Hokuyu Hospital and Hokkaido University Hospital, and analyzed consecutive patients who underwent allogeneic transplantation for AML and MDS between January 2003 and July 2010. Patients were divided according to MK classification scheme into four groups (Oran et al, BBMT 2011), CN; cytogenetically normal, MK; monosomal karyotype, CBF; core binding factor abnormalities, Oth (Others); non-CBF and non-MK abnormalities. Patients with acute promyelocytic leukemia were excluded.

Resuts:
One-hundred eighty three out of 229 patients were analyzed with a median age of 48 years(15–68). Sixty one (33%) were from HLA-matched related donors, 86 (47%) from unrelated and 36 (20%) were cord blood.Conditioning regimens were myeloablative (MAC, n=102, 56%) or reduced intensity(RIC, n=81, 44%). Seventy patients (38%) were cytogenetically normal, 27 (15%)had CBF abnormalities, 70(38%) had non-CBF and non-MK abnormalities and 16(9%) had monosomal karyotype. There was no statistically difference between four groups in age, donor source and conditioning regimen. In the MK group, the proportion of MDS and non-remission state at stem cell transplantation were significantly higher than other groups (p=0.002, p<0.001). Four-year over all survival in patients with MK was 0%, which was significantly inferior to other groups; 50% for CN, 30.4% for CBF, 29.4% for Oth(p<0.001). Cox regression modeling showed that the disease status at stem cell transplantation (p=0.026) and the existence of MK (p=0.012) had prognostic value.
Seven of 16 patients with MK died within the first 50 days after transplantation, and 9 patients died within 120 days. Five patients died of infection and 2 died of complicated organ failure and 2 died of progression disease. Three patients who underwent transplantation at non-remission setting, survived more than 1-year experienced chronic graft-versus-host disease, suggesting the existence of GVL effect to myeloid malignancies with MK.

Conclusion:
This retrospective analysis revealed the dismal prognosis of myeloid malignancies with MK, even after allogeneic HSCT. Novel therapies and strategies are urgently needed for this very poor prognostic group.

Disclosures:
No relevant conflicts of interest to declare.