Germline DDX41 mutations are involved in familial myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML). We analyzed the prevalence and characteristics of DDX41-related myeloid malignancies in an unselected cohort of 1385 patients with MDS or AML. Using targeted next-generation sequencing, we identified 28 different germline DDX41 variants in 43 unrelated patients which we classified as causal (n=21) or unknown significance (n=7) variants. We focused on the 33 patients having causal variants, representing 2.4% of our cohort. Median age was 69 years, most patients were males (79%). Only 9 patients (27%) had a family history of hematological malignancy, while 15 (46%) had personal history of cytopenias years prior to MDS/AML diagnosis. Most patients had normal karyotype (85%) and the most frequent somatic alteration was a second DDX41 mutation (79%). High-risk DDX41 MDS/AML patients treated with intensive chemotherapy (n=9) or azacitidine (n=11) had an overall response rate of 100% and 73%, respectively, with a median overall survival of 5.2 years. Our study highlights that germline DDX41 mutations are relatively common in adult MDS/AML, often without known family history, arguing for systematic screening. Salient features of DDX41-related myeloid malignancies include male preponderance, frequent pre-existing cytopenias, additional somatic DDX41 mutation and relatively good outcome.

Early recognition of Ph-like acute lymphoblastic leukemia cases could impact on the management and outcome of this subset of B-lineage ALL. To assess the prognostic value of the Ph-like status in a pediatric-inspired, minimal residual disease (MRD)-driven trial, we screened 88 B-lineage ALL cases negative for the major fusion genes (BCR-ABL1, ETV6-RUNX1, TCF3-PBX1 and KTM2Ar) enrolled in the GIMEMA LAL1913 front-line protocol for adult BCR/ABL1-negative ALL. The screening - performed using the BCR/ABL1-like predictor - identified 28 Ph-like cases (31.8%), characterized by CRLF2 overexpression (35.7%), JAK/STAT pathway mutations (33.3%), IKZF1 (63.6%), BTG1 (50%) and EBF1 (27.3%) deletions, and rearrangements targeting tyrosine kinases or CRLF2 (40%). The correlation with outcome highlighted that: i) the complete remission (CR) rate was significantly lower in Ph-like compared to non-Ph-like cases (74.1% vs 91.5%, p=0.044); ii) at time point 2 (TP2), decisional for transplant allocation, 52.9% of Ph-like cases vs 20% of non-Ph-like were MRD-positive (p=0.025); iii) the Ph-like profile was the only parameter associated with a higher risk of being MRD-positive at TP2 (p=0.014); iv) at 24 months, Ph-like patients had a significantly inferior event-free and disease-free survival compared to non-Ph-like patients (33.5% vs 66.2%, p=0.005 and 45.5% vs 72.3%, p=0.062, respectively). This study documents that Ph-like patients have a lower CR rate, EFS and DFS, as well as a greater MRD persistence also in a pediatric-oriented and MRD-driven adult ALL protocol, thus reinforcing that the early recognition of Ph-like ALL patients at diagnosis is crucial to refine risk-stratification and to optimize therapeutic strategies.

Several papers authored by international experts have proposed recommendations on the management of BCR-ABL1+ chronic myeloid leukemia (CML). Following these recommendations, survival of CML patients has become very close to normal. The next, ambitious, step is to bring as many patients as possible into a condition of treatment-free remission (TFR). The Gruppo Italiano Malattie EMatologiche dell’Adulto (GIMEMA; Italian Group for Hematologic Diseases of the Adult) CML Working Party (WP) has developed a project aimed at selecting the treatment policies that may increase the probability of TFR, taking into account 4 variables: the need for TFR, the tyrosine kinase inhibitors (TKIs), the characteristics of leukemia, and the patient. A Delphi-like method was used to reach a consensus among the representatives of 50 centers of the CML WP. A consensus was reached on the assessment of disease risk (EUTOS Long Term Survival [ELTS] score), on the definition of the most appropriate age boundaries for the choice of first-line treatment, on the choice of the TKI for first-line treatment, and on the definition of the responses that do not require a change of the TKI (BCR-ABL1 ≤10% at 3 months, ≤1% at 6 months, ≤0.1% at 12 months, ≤0.01% at 24 months), and of the responses that require a change of the TKI, when the goal is TFR (BCR-ABL1 >10% at 3 and 6 months, >1% at 12 months, and >0.1% at 24 months). These suggestions may help optimize the treatment strategy for TFR.

It is judged safe to discontinue treatment with tyrosine kinase inhibitors for chronic myeloid leukemia in experimental trials on treatment free remission. We collected a total of 293 Italian patients with chronic phase chronic myeloid leukemia who discontinued tyrosine kinase inhibitors in deep molecular response. 72% of patients were on treatment with imatinib, 28% with second generation tyrosine kinase inhibitors at the time of discontinuation. Median duration of treatment with the last tyrosine kinase inhibitor was 77 months (IQR 54;111), median duration of deep molecular response was 46 months (IQR 31;74). Duration of treatment with tyrosine kinase inhibitors and duration of deep molecular response were shorter with 2nd generation tyrosine kinase inhibitors than with imatinib (p<0.001). 88% of the Italian patients discontinued per clinical practice and reasons for stopping treatment were: toxicity for 20% of patients, pregnancy for 6% patients and shared decision between treating physician and patient for 62% of cases. After a median follow-up of 34 months (Min-Max 12-161) overall estimated treatment free remission was 62% (95% CI 56;68). At 12 months treatment free remission was 68% (95% CI 62;74) for imatinib, 73% (95% CI 64;83) for 2nd generation tyrosine kinase inhibitors. Overall median time to restart treatment was 6 months (IQR 4;11). No progressions occurred. Although our study has the limitation of a retrospective study, our experience within the Italian population confirms that discontinuation of imatinib and 2nd generation tyrosine kinase inhibitors is feasible and safe in the clinical practice.