Multi-center analysis of the effect of T-cell acute lymphoblastic leukemia subtype and minimal residual disease on allogeneic stem cell transplantation outcomes.

This study aims to provide a detailed analysis of allogeneic stem cell transplantation (allo-SCT) outcomes in a large T-cell acute lymphoblastic leukemia (T-ALL) cohort with a specific emphasis on the effects of pre-transplant minimal residual disease (MRD) and disease subtype, including the aggressive early-thymic precursor (ETP) subtype. Data from 102 allo-SCT patients with a diagnosis of T-ALL from three centers were retrospectively analyzed. Patients were grouped into four T-ALL subtypes: ETP, early, cortical and mature. At 3 years, overall survival (OS), PFS, non-relapse mortality and cumulative incidence (CI) progression were 35, 33, 11 and 55%, respectively. Patients transplanted in first complete remission (CR1) had a 3-year OS of 62% versus those transplanted in CR2 or greater (24%) (hazards ratio 1.6, P=0.2). Patients with MRD positivity at the time of transplant had significantly higher rates of progression compared with those with MRD negativity (76 vs 34%, hazards ratio 2.8, P=0.006). There was no difference in OS, PFS or cumulative incidence (CI) progression between disease subtypes, including ETP (n=16). ETP patients transplanted in CR1 (n=10) had OS of 47%, comparable to other disease subtypes, suggesting that allo-SCT can overcome the poor prognosis associated with ETP. MRD status at transplant was highly predictive of disease relapse, suggesting novel therapies are necessary to improve transplant outcomes.

Romidepsin targets multiple survival signaling pathways in malignant T cells.

Romidepsin is a cyclic molecule that inhibits histone deacetylases. It is Food and Drug Administration-approved for treatment of cutaneous and peripheral T-cell lymphoma, but its precise mechanism of action against malignant T cells is unknown. To better understand the biological effects of romidepsin in these cells, we exposed PEER and SUPT1 T-cell lines, and a primary sample from T-cell lymphoma patient (Patient J) to romidepsin. We then examined the consequences in some key oncogenic signaling pathways. Romidepsin displayed IC50 values of 10.8, 7.9 and 7.0 nm in PEER, SUPT1 and Patient J cells, respectively. Strong inhibition of histone deacetylases and demethylases, increased production of reactive oxygen species and decreased mitochondrial membrane potential were observed, which may contribute to the observed DNA-damage response and apoptosis. The stress-activated protein kinase/c-Jun N-terminal kinase signaling pathway and unfolded protein response in the endoplasmic reticulum were activated, whereas the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) and ß-catenin pro-survival pathways were inhibited. The decreased level of ß-catenin correlated with the upregulation of its inhibitor SFRP1 through romidepsin-mediated hypomethylation of its gene promoter. Our results provide new insights into how romidepsin invokes malignant T-cell killing, show evidence of its associated DNA hypomethylating activity and offer a rationale for the development of romidepsin-containing combination therapies.