Background Recent investigations in chronic myeloid leukemia (CML) have focused on the identification and characterization of leukemic stem cells (LSCs). These cells reside within the CD34+/CD38─/Lin─ fraction and score positive for CD26 (dipeptidylpeptidase IV) a marker, expressed in both bone marrow (BM) and peripheral blood (PB) samples, that discriminates CML cells from normal hematopoietic stem cells (HSCs) or from LSCs of other myeloid neoplasms. CD26 evaluation could be a useful tool to improve the identification of CML LCSs by using flow‐cytometry assay. Methods CD26+ LSCs have been isolated from EDTA PB and BM samples of patients with leucocytosis suspected for CML. Analysis of LSCs CML has been performed by using custom‐made lyophilized pre‐titrated antibody mixture test and control tube and a CD45+/CD34+/CD38−/CD26+ panel as a strict flow cytometric gating strategy. Results The expression of CD26 on CD34+/CD38− population was detectable in 211/211 PB and 84/84 BM samples of subsequently confirmed BCR‐ABL+ CP‐CML patients. None of the 32 samples suspicious for CML but scoring negative for circulating CD26+ LSCs were diagnosed as CML after conventional cytogenetic and molecular testing. To validate our results, we checked for PB CD26+ LSCs in patients affected by other hematological disorders and they all scored negative for CD26 expression. Conclusions We propose flow cytometry evaluation of CD26 expression on PB CD34+/CD38− population as a new rapid, reproducible, and powerful diagnostic tool for the diagnosis of CML. © 2019 The Authors. Cytometry Part B: Clinical Cytometry published by Wiley Periodicals, Inc. on behalf of International Clinical Cytometry Society.

Neutrophil gelatinaase-associated lipocalin (NGAL) is a glycoprotein bound with matrix metalloproteinase-9 (MMP-9) in human neutrophils, and elevated tissue NGAL expression has been documented in different infectious and inflammatory conditions. Recent evidence suggests that NGAL expression is induced in many types of human cancer. Moreover, NGAL is required for BCR-ABL-induced tumorigenesis. The aim of the present study was to measure serum levels of NGAL in patients with essential thrombocythemia (ET) and polycythemia vera (PV). We also evaluated NGAL levels in patients with ET and PV with and without thrombotic events, to explore a possible correlation of NGAL with platelet and leukocyte activation, and in patients with sepsis. Serum NGAL levels in the study population were significantly higher than in healthy adults and in subjects with sepsis. A correlation between NGAL and the number of white cells and neutrophils was found in patients with PV and ET. NGAL serum levels were not different depending on the presence or not of the JAK2 mutation, and a mutant allele dosage effect was not observed for NGAL levels. Patients with PV and ET with thrombosis did not have significantly higher levels of NGAL. We were unable to demonstrate a significant association between serum NGAL levels and CD11b or CD62 expression. In conclusion, our study reports evidence demonstrating that increased levels of NGAL appear to be a characteristic of patients with PV and ET.

The aim of the present study was to determine serum levels of neutrophil gelatinase-associated lipocalin (NGAL) and leptin in patients with chronic myeloid leukemia (CML) at diagnosis and after imatinib therapy when patients achieved a complete molecular remission. The study was conducted on 22 patients with CML in the chronic phase and 10 healthy subjects. The median serum NGAL levels in CML patients at diagnosis were significantly higher compared to age-matched controls. After imatinib therapy, all patients achieved complete molecular remission and NGAL levels decreased and were found significantly lower with respect to the baseline. No significant correlations were found between NGAL levels and other disease parameters. Before imatinib therapy, the median blood leptin levels were not significantly different from those of controls. After therapy with imatinib, all patients in molecular remission presented an increase in leptin levels. Future research is eagerly awaited as it may demonstrate the real role of NGAL and leptin in the onset and progression of CML.

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BCR-ABL1 kinase domain mutation testing in tyrosine kinase inhibitor (TKI)-resistant Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukaemia (ALL) patients is routinely performed by Sanger sequencing (SS). Recently, next-generation sequencing (NGS)-based approaches have been developed that afford greater sensitivity and straightforward discrimination between compound and polyclonal mutations. We performed a study to compare the results of SS and NGS in a consecutive cohort of 171 Ph+ ALL patients. At diagnosis, 0/44 and 3/44 patients were positive for mutations by SS and NGS respectively. Out of 47 patients with haematologic resistance, 45 had mutations according to both methods, but in 25 patients NGS revealed additional mutations undetectable by SS. Out of 80 patients in complete haematologic response but with BCR-ABL1 ≥0Á1%, 28 (35%) and 52 (65%) were positive by SS and NGS respectively. Moreover, in 12 patients positive by SS, NGS detected additional mutations. NGS resolved clonal complexity in 34 patients with multiple mutations at the same or different codons and identified 35 compound mutations. Our study demonstrates that, in Ph+ ALL on TKI therapy, NGS enables more accurate assessment of mutation status both in patients who fail therapy and in patients with minimal residual disease above 0Á1%.

Background We already showed that in CML pts peripheral blood CD34+/CD38-/CD26+ cell population represent a "CML specific" leukemia stem cell (LSC) circulating compartment. Indeed, we demonstrated that CD26+LSCs are measurable by flow-cytometry in 100% of CML pts at diagnosis the latter representing an alternative and rapid diagnostic tool. In addition, in a cross-sectional study we were able to spot peripheral blood CD26+LSCs also in about 65% of CML during TKI treatment regardless of type and length of TKI treatment and degree of molecular response. However, no prospective data are available regarding the behavior of PB CD26+LSCs in terms of rate and timing of reduction during TKI therapy and the correlation, if any, with the attainment of response according to ELN guidelines. Interestingly, even CML patients in stable TFR may harbor circulating CD26+LSCs thus suggesting a probable active role of the immune system in the control of residual disease. One hypothesis could reside in the presence or absence on the LSCs of molecules (such as PD-L1) able to hamper an anti-leukemic T cell response. From Jan 2018 we conducted a prospective multicenter Italian study including CML pts at diagnosis treated and managed by each of 15 participating center according to ELN guidelines. We here present the first interim analysis after a median time of treatment of 12 mos. Aims The main goals of this study were to prospectively monitoring PB CD26+LScs in CML pts during TKI treatment and to correlate the behavior of LSCs with molecular response. In a proportion of pts PD-L1 expression on CD26+ LSCs at diagnosis was also evaluated. Methods At diagnosis and during TKI treatment, pts have been centrally evaluated in Siena lab for flow-cytometry PB CD26+ LSCs (+3, +6, +12, +18, +24 mos) and PD-L1 expression (at diagnosis). At each time point molecular BCR-ABL/ABLIS ratio was monitored locally in each center. Results 176 consecutive CML pts (IMA 92; NILO 61; DASA 23) were enrolled in the study so far (table 1). PB CD26+LSCs were measured at time 0 (baseline) in all 176 CML pts and in 165/176 (94%), 142/176 (81%) and 112/176 (71%) at +3, +6, +12 mos of TKI treatment, respectively. Median CD26+LSCs absolute number/µL at baseline was 6.96/µL (range 0.0126-64429), at +3 mos 0.0137/µL (range 0-6,49), at +6 mos 0.0056/µL (range 0-1.188), and at +12 mos 0.0112/µL (range 0-0.1824). No significant correlation between number of CD26+LSC, degree of response and BCR-ABL copies was found (Table 2). Interestingly, median CD26+LSCs at diagnosis was found significantly higher in NILO and DASA treated pts (12, 48/µL and 17,48/µL, respectively) than in IMA pts (4,58/µL). So far, 20/176 (11.4%) pts switched to different TKIs, due to failure/suboptimal response: of note, median CD26+ LSCs of this cohort at diagnosis was the highest (23.12/µL). Starting from Jun 2019, 44/176 (25%) CML pts have been evaluated also for PD-L1 expression at diagnosis: of these, 23/44 (52%) resulted PD-L1 positive and 21/44 (48%) resulted negative with a median of CD26+LSCs of 15.39/µL (range 1.28-635.5) and 4.45/µL (range 0.234-113.9), respectively. Conclusions After a sensible drop observed at 3 mos of any TKI treatment, CD26+LSCs are fluctuating and measurable at low level in most of pts (> 65%) even at 18 and 24 mos. We confirmed no correlation between the absolute number of persisting CD26+LSCs and BCR-ABL copies. However, pts with failure or suboptimal response showed the highest level of CD26+ at diagnosis. CD26+LSCs were found PD-L1+ in about half of 44 pts tested. At diagnosis higher CD26+LSCs number, PD-L1 positivity or both may correlate with a lower probability to achieve an optimal response; interim data of this first report will be presented; enrolment and follow up are ongoing. Disclosures Bocchia: Incyte: Honoraria; CELGENE: Honoraria. Abruzzese:Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bms: Honoraria. Galimberti:Novartis: Speakers Bureau; Incyte: Honoraria. Pregno:Incyte-Italy,: Membership on an entity's Board of Directors or advisory committees, Other: conference reports; Novartis-Italy: Membership on an entity's Board of Directors or advisory committees, Other: conference reports; Pfizer-Italy: Membership on an entity's Board of Directors or advisory committees, Other: conference reports. Crugnola:BMS: Honoraria; Janssen: Honoraria; Celgene: Honoraria; Novartis: Honoraria. Liberati:MORPHOSYS: Honoraria, Research Funding; ONCONOVA: Honoraria, Research Funding; INCYTE: Honoraria; VERASTEM: Honoraria, Research Funding; ROCHE: Honoraria, Research Funding; PFIZER: Honoraria, Research Funding; ONCOPEPTIDES AB: Honoraria, Research Funding; TAKEDA: Honoraria, Research Funding; FIBROGEN: Honoraria; BIOPHARMA: Honoraria; ARCHIGEN: Honoraria; BEIGENE: Honoraria; BMS: Honoraria; AMGEN: Honoraria; CELGENE: Honoraria; JANSSEN: Honoraria; ABBVIE: Honoraria, Research Funding; NOVARTIS: Honoraria, Research Funding; KARYOPHARM: Honoraria, Research Funding.

Aims: The main goal was to describe CML pts in terms of pregnancy/ conceptions management and outcome. Secondary goals included demographics, characteristics of CML, management during pregnancy, pregnancy outcomes and characteristics of children. Methods: Adult pts aged ³18 years with Ph+ positive CML and pregnancy were included after signing a written informed consent. Data were collected either in the coordinating centers in Moscow (Russia) and Rome (Italy) followed by the analyses of the entire data set. A total 305 pregnancy cases in 234 CML female pts from 15 centers of 13 countries worldwide were analyzed (Table 1). Results: Chronic phase at diagnosis was in 217/221(98%) pts. In 50 (21%) pts CML was diagnosed during pregnancy, while 184 (67%) got pregnant after diagnosis. Median (Me) time from CML diagnosis to pregnancy was 59 months (range 1-203). The outcomes of 305 pregnancies were as follows: labor 234 (77%), induced abortion 42 (14%), spontaneous abortion 21 (7%) and ongoing pregnancy or unknown outcome 8 (2%). Labor at full term was in 141 (75%) of 187 cases fully reported (Table 2). Molecular response (MR) evaluations at the start of pregnancy were recorded in 249/305 cases. Deep MR (DMR or BCR-ABL£0,01% IS), major MR (MMR or BCR-ABL£0,1%> >0,01% IS), MR2 (BCR-ABL>0,1%> £1% IS) and no MR2 (BCR-ABL>1% IS) was observed in 80 (32%), 31 (12%), 32 (13%) and 106 (43%) cases respectively. In 182 (71%) of 257 pregnancies with known data pts conceived while on TKI: 77% under imatinib (IM) and 23% TKI 2nd/3rd generation. TKIs were usually stopped early in 1 st trimester (4-5 week of gestation) when the pregnancy was discovered. In 82 pregnancies pts were treated during 2 nd -3 rd trimester, after placental formation, until labor with IM: 33 (40%) of cases), nilotinib (NIL): 8 (9%), interferon (IFN): 23 (28%, 1 PEG-IFN), hydroxyurea: 6 (7%). IM was used throughout pregnancy in 13 (16%). One case of leukaferesis was recorded. The number of born children in 226 fully reported labors was 233 (including twins). Congenital abnormalities were recorded in 4 (1,7%) cases as follows: polydactyly (1), hypospadias (1) and non-closed foramen ovale of interatrial septum (2). None of the abnormalities were severe or life threatening, relationship to TKI use was considered unlikely by physicians. Low birth weight was recorded in 13 children with IM or NIL exposure at late pregnancy. The follow-up of all children was uneventful, with Me age at follow-up of 5 years (range 2 months-17 years). Summary/Conclusion: Most pregnancies in CML female pts resulted in normal childbirth with no increased rate of birth abnormalities in spite of TKI use at conception even if treatments were mostly early stopped at implant (4-5 weeks). Different therapies were used during pregnancy when needed. The results in terms of conception/pregnancy may be valuable for the development of CML treatment schemes particularly considering the variety of disease status.