ATRA plus arsenic trioxide is at least not inferior and may be superior to ATRA plus chemotherapy in the treatment of patients with low-to-intermediate-risk APL. (Funded by Associazione Italiana contro le Leucemie and others; ClinicalTrials.gov number, NCT00482833.).

Background Several small studies on patients with COVID-19 and haematological malignancies are available showing a high mortality in this population. The Italian Hematology Alliance on COVID-19 aimed to collect data from adult patients with haematological malignancies who required hospitalisation for COVID-19. Methods This multicentre, retrospective, cohort study included adult patients (aged ≥18 years) with diagnosis of a WHO-defined haematological malignancy admitted to 66 Italian hospitals between Feb 25 and May 18, 2020, with laboratory-confirmed and symptomatic COVID-19. Data cutoff for this analysis was June 22, 2020. The primary outcome was mortality and evaluation of potential predictive parameters of mortality. We calculated standardised mortality ratios between observed death in the study cohort and expected death by applying stratum-specific mortality rates of the Italian population with COVID-19 and an Italian cohort of 31 993 patients with haematological malignancies without COVID-19 (data up to March 1, 2019). Multivariable Cox proportional hazards model was used to identify factors associated with overall survival. This study is registered with ClinicalTrials.gov, NCT04352556, and the prospective part of the study is ongoing. Findings We enrolled 536 patients with a median follow-up of 20 days (IQR 10-34) at data cutoff, 85 (16%) of whom were managed as outpatients. 440 (98%) of 451 hospitalised patients completed their hospital course (were either discharged alive or died). 198 (37%) of 536 patients died. When compared with the general Italian population with COVID-19, the standardised mortality ratio was 2•04 (95% CI 1•77-2•34) in our whole study cohort and 3•72 (2•86-4•64) in individuals younger than 70 years. When compared with the non-COVID-19 cohort with haematological malignancies, the standardised mortality ratio was 41•3 (38•1-44•9). Older age (hazard ratio 1•03, 95% CI 1•01-1•05); progressive disease status (2•10, 1•41-3•12); diagnosis of acute myeloid leukaemia (3•49, 1•56-7•81), indolent non-Hodgin lymphoma (2•19, 1•07-4•48), aggressive non-Hodgkin lymphoma (2•56, 1•34-4•89), or plasma cell neoplasms (2•48, 1•31-4•69), and severe or critical COVID-19 (4•08, 2•73-6•09) were associated with worse overall survival. Interpretation This study adds to the evidence that patients with haematological malignancies have worse outcomes than both the general population with COVID-19 and patients with haematological malignancies without COVID-19. The high mortality among patients with haematological malignancies hospitalised with COVID-19 highlights the need for aggressive infection prevention strategies, at least until effective vaccination or treatment strategies are available. Funding Associazione italiana contro le leucemie, linfomi e mieloma-Varese Onlus.

Chromatin is a dynamic macromolecular structure epigenetically modified to regulate specific gene expression. Altered chromatin function can lead to aberrant expression of growth regulators and may, ultimately, cause cancer. That many human diseases have epigenetic etiology has stimulated the development of 'epigenetic' therapies. Inhibitors of histone deacetylases (HDACIs) induce proliferation arrest, maturation and apoptosis of cancer cells, but not normal cells, in vitro and in vivo, and are currently being tested in clinical trials. We investigated the mechanism(s) underlying this tumor selectivity. We report that HDACIs induce, in addition to p21, expression of TRAIL (Apo2L, TNFSF10) by directly activating the TNFSF10 promoter, thereby triggering tumor-selective death signaling in acute myeloid leukemia (AML) cells and the blasts of individuals with AML. RNA interference revealed that the induction of p21, TRAIL and differentiation are separable activities of HDACIs. HDACIs induced proliferation arrest, TRAIL-mediated apoptosis and suppression of AML blast clonogenicity irrespective of French-American-British (FAB) classification status, karyotype and immunophenotype. No apoptosis was seen in normal CD34(+) progenitor cells. Our results identify TRAIL as a mediator of the anticancer action of HDACIs.

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Many different molecular mechanisms have been associated with PML-RARalpha-dependent transformation of hematopoietic progenitors. Here, we identified high confidence PML-RARalpha binding sites in an acute promyelocytic leukemia (APL) cell line and in two APL primary blasts. We found colocalization of PML-RARalpha with RXR to the vast majority of these binding regions. Genome-wide epigenetic studies revealed that treatment with pharmacological doses of all-trans retinoic acid induces changes in H3 acetylation, but not H3K27me3, H3K9me3, or DNA methylation at the PML-RARalpha/RXR binding sites or at nearby target genes. Our results suggest that PML-RARalpha/RXR functions as a local chromatin modulator and that specific recruitment of histone deacetylase activities to genes important for hematopoietic differentiation, RAR signaling, and epigenetic control is crucial to its transforming potential.