Nelarabine as salvage therapy and bridge to allogeneic stem cell transplant in 118 adult patients with relapsed/refractory T-cell acute lymphoblastic leukemia/lymphoma. A CAMPUS ALL study.

The outcome of relapsed or refractory (R/R) T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/T-LBL) in adults is poor, with less than 20% of patients surviving at 5 years. Nelarabine is the only drug specifically approved for R/R T-ALL/T-LBL, but the information to support its use is based on limited available data. The aim of this observational phase four study was to provide recent additional data on the efficacy and safety of nelarabine in adults with R/R T-ALL/T-LBL and to evaluate the feasibility and outcome of allogeneic hematopoietic stem cell transplant (SCT) after salvage with nelarabine therapy. The primary endpoints were overall response rate (ORR) and overall survival (OS). Additional endpoints were safety, SCT rate and post-SCT OS. Between May 2007 and November 2018, 118 patients received nelarabine salvage therapy at 27 Italian hematology sites. The median age was 37 years (range 18-74 years), 73% were male, 77 had a diagnosis of T-ALL and 41 of T-LBL, and 65/118 (55%) had received more than two lines of therapy. The median number of nelarabine cycles was two (range 1-4); 43/118 (36%) patients had complete remission (CR), 16 had partial remission (14%) and 59 (50%) were refractory, with an ORR of 50%. The probability of OS, from the first dose of nelarabine, was 37% at 1 year with a median survival of 8 months. The OS at 1 year was significantly better for the 47 patients (40%) who underwent SCT after nelarabine salvage therapy (58% vs 22%, log-rank P < .001). The probability of OS at 2 and 5 years from SCT was 46% and 38%, respectively. Seventy-five patients (64%) experienced one or more drug-related adverse events (AE). Grade III-IV neurologic toxicities were observed in 9/118 (8%) of cases and thrombocytopenia or/and neutropenia (grade III-IV) were reported in 41% and 43% of cases, respectively. In conclusion, this is one of the largest cohorts of adult patients with R/R T-ALL/T-LBL treated in real life with nelarabine. Taking into account the poor prognosis of this patient population, nelarabine represents an effective option with an ORR of 50% and a CR rate of 36%. In addition, 40% of cases following nelarabine salvage therapy could undergo SCT with an expected OS at 2 and 5 years of 46% and 38%, respectively. The safety profile of nelarabine was acceptable with only 8% of cases showing grade III-IV neurological AE.

A Comparison of the Conditioning Regimens BEAM and FEAM for Autologous Hematopoietic Stem Cell Transplantation in Lymphoma: An Observational Study on 1038 Patients From Fondazione Italiana Linfomi.

BEAM (carmustine [bis-chloroethylnitrosourea (BCNU)]-etoposide-cytarabine-melphalan) chemotherapy is the standard conditioning regimen for autologous stem cell transplantation (ASCT) in lymphomas. Owing to BCNU shortages, many centers switched to fotemustine-substituted BEAM (FEAM), lacking proof of equivalence. We conducted a retrospective cohort study in 18 Italian centers to compare the safety and efficacy of BEAM and FEAM regimens for ASCT in lymphomas performed from 2008 to 2015. We enrolled 1038 patients (BEAM = 607, FEAM = 431), of which 27% had Hodgkin lymphoma (HL), 14% indolent non-Hodgkin lymphoma (NHL), and 59% aggressive NHL. Baseline characteristics including age, sex, stage, B-symptoms, extranodal involvement, previous treatments, response before ASCT, and overall conditioning intensity were well balanced between BEAM and FEAM; notable exceptions were median ASCT year (BEAM = 2011 versus FEAM = 2013, P < .001), Sorror score ≥3 (BEAM = 15% versus FEAM = 10%, P = .017), and radiotherapy use (BEAM = 18% versus FEAM = 10%, P < .001). FEAM conditioning resulted in higher rates of gastrointestinal and infectious toxicities, including severe oral mucositis grade ≥3 (BEAM = 31% versus FEAM = 44%, P < .001), and sepsis from Gram-negative bacteria (mean isolates/patient: BEAM = .1 versus FEAM = .19, P < .001). Response status at day 100 post-ASCT (overall response: BEAM = 91% versus FEAM = 88%, P = .42), 2-year overall survival (83.9%; 95% confidence interval [CI], 81.5% to 86.1%) and progression-free survival (70.3%; 95% CI, 67.4% to 73.1%) were not different in the two groups. Mortality from infection was higher in the FEAM group (subhazard ratio, 1.99; 95% CI, 1.02 to 3.88; P = .04). BEAM and FEAM do not appear different in terms of survival and disease control. However, due to concerns of higher toxicity, fotemustine substitution in BEAM does not seem justified, if not for easier supply.

Endothelin-1 receptor blockade as new possible therapeutic approach in multiple myeloma.

New effective treatments are needed to improve outcomes for multiple myeloma (MM) patients. Receptors with restricted expression on plasma cells (PCs) represent attractive new therapeutic targets. The endothelin-1 (EDN1) axis, consisting of EDN1 acting through EDN-receptor A (EDNRA) and B (EDNRB), was previously shown to be overexpressed in several tumours, including MM. However, there is incomplete understanding of how EDN1 axis regulates MM growth and response to therapy. Besides EDNRA, the majority of MM cell lines and primary malignant PCs express high levels of EDNRB and release EDN1. Similarly, bone-marrow microenvironment cells also secrete EDN1. Investigating the extent of epigenetic dysregulation of EDNRB gene in MM, we found that hypermethylation of EDNRB promoter and subsequent down-regulation of EDNRB gene was observed in PCs or B lymphocytes from healthy donors compared to EDNRB-expressing malignant PCs. Pharmacological blockade with the dual EDN1 receptor antagonist bosentan decreased cell viability and MAPK activation of U266 and RPMI-8226 cells. Interestingly, the combination of bosentan and the proteasome inhibitor bortezomib, currently approved for MM treatment, resulted in synergistic cytotoxic effects. Overall, our data has uncovered EDN1-mediated autocrine and paracrine mechanisms that regulate malignant PCs growth and drug response, and support EDN1 receptors as new therapeutic targets in MM.

Multicentre survey to explore current survival of patients with acute myeloid leukaemia who failed induction chemotherapy.

BACKGROUND: Acute myeloid leukaemia not responsive to first induction chemotherapy (PIF-AML) still remains a challenge, and there are only few recent epidemiological data regarding the outcome of these patients. In this multicentre survey, we evaluate the prognosis and outcome of patients with PIF-AML, who were diagnosed and treated in the last 5 yrs in four Italian institutions. RESULTS: One hundred PIF-AML were recorded, 57 males and 43 females, with a median age of 63 yrs (19-79), 42% were younger than 60 yrs; 42% had a secondary AML and 40% had an adverse karyotype. According to cytogenetic/molecular risk stratification at diagnosis, 33% of patients were classified as favourable/intermediate-1 risk and 56% as intermediate-2/adverse risk. After a median follow-up of 11 months (1-49), 77% of patients died, while 23% were alive (with 12/23 in cCR). Thirty-six patients underwent allogeneic SCT, and of these, 11 of 36 (31%) were alive at last follow-up. The 12- and 24-month OS probability of the whole population was 45% and 21%, respectively. In multivariate analysis, the probability of OS of the whole population was significantly improved by Allo-SCT procedure (12-month OS probability 60% vs. 35%; P < 0.0001) and was better in patients with favourable/intermediate-1 risk at diagnosis (12-month OS probability 58% vs. 40%; P = 0.028). In transplanted cases, a pretransplant responsive disease was the only significant factor to predict a favourable outcome after Allo-SCT (P = 0.006). CONCLUSION: Treatment options of PIF-AML still are limited and the prognosis, even recently, remains extremely poor. This survey shows that PIF-AML is still rarely cured without Allo-SCT and confirms the importance of initiating an urgent unrelated donor search in cases without a matched sibling donor. Moreover, the outcome of Allo-SCT is better in patients who achieve a good AML debulking before transplant. To reach this goal, new predictive scores and new protocols of salvage therapy (with target drugs or combinations) need to be explored urgently in PIF-AML.

Complex karyotype, older age, and reduced first-line dose intensity determine poor survival in core binding factor acute myeloid leukemia patients with long-term follow-up.

Approximately 40% of patients affected by core binding factor (CBF) acute myeloid leukemia (AML) ultimately die from the disease. Few prognostic markers have been identified. We reviewed 192 patients with CBF AML, treated with curative intent (age, 15-79 years) in 11 Italian institutions. Overall, 10-year overall survival (OS), disease-free survival (DFS), and event-free survival were 63.9%, 54.8%, and 49.9%, respectively; patients with the t(8;21) and inv(16) chromosomal rearrangements exhibited significant differences at diagnosis. Despite similar high complete remission (CR) rate, patients with inv(16) experienced superior DFS and a high chance of achieving a second CR, often leading to prolonged OS also after relapse. We found that a complex karyotype (i.e., ≥4 cytogenetic anomalies) affected survival, even if only in univariate analysis; the KIT D816 mutation predicted worse prognosis, but only in patients with the t(8;21) rearrangement, whereas FLT3 mutations had no prognostic impact. We then observed increasingly better survival with more intense first-line therapy, in some high-risk patients including autologous or allogeneic hematopoietic stem cell transplantation. In multivariate analysis, age, severe thrombocytopenia, elevated lactate dehydrogenase levels, and failure to achieve CR after induction independently predicted longer OS, whereas complex karyotype predicted shorter OS only in univariate analysis. The achievement of minimal residual disease negativity predicted better OS and DFS. Long-term survival was observed also in a minority of elderly patients who received intensive consolidation. All considered, we identified among CBF AML patients a subgroup with poorer prognosis who might benefit from more intense first-line treatment.

Intracoronary delivery of autologous cardiac stem cells improves cardiac function in a porcine model of chronic ischemic cardiomyopathy.

BACKGROUND: Relevant preclinical models are necessary for further mechanistic and translational studies of c-kit+ cardiac stem cells (CSCs). The present study was undertaken to determine whether intracoronary CSCs are beneficial in a porcine model of chronic ischemic cardiomyopathy. METHODS AND RESULTS: Pigs underwent a 90-minute coronary occlusion followed by reperfusion. Three months later, autologous CSCs (n=11) or vehicle (n=10) were infused into the infarct-related artery. At this time, all indices of left ventricular (LV) function were similar in control and CSC-treated pigs, indicating that the damage inflicted by the infarct in the 2 groups was similar; 1 month later, however, CSC-treated pigs exhibited significantly greater LV ejection fraction (echocardiography) (51.7±2.0% versus 42.9±2.3%, P<0.01), systolic thickening fraction in the infarcted LV wall, and maximum LV dP/dt, as well as lower LV end-diastolic pressure. Confocal microscopy showed clusters of small α-sarcomeric actin-positive cells expressing Ki67 in the scar of treated pigs, consistent with cardiac regeneration. The origin of these cycling myocytes from the injected cells was confirmed in 4 pigs that received enhanced green fluorescent protein -labeled CSCs, which were positive for the cardiac markers troponin I, troponin T, myosin heavy chain, and connexin-43. Some engrafted CSCs also formed vascular structures and expressed α-smooth muscle actin. CONCLUSIONS: Intracoronary infusion of autologous CSCs improves regional and global LV function and promotes cardiac and vascular regeneration in pigs with old myocardial infarction (scar). The results mimic those recently reported in humans (Stem Cell Infusion in Patients with Ischemic CardiOmyopathy [SCIPIO] trial) and establish this porcine model of ischemic cardiomyopathy as a useful and clinically relevant model for studying CSCs.

The Immunotherapy of Acute Myeloid Leukemia: A Clinical Point of View.

The potential of the immune system to eradicate leukemic cells has been consistently demonstrated by the Graft vs. Leukemia effect occurring after allo-HSCT and in the context of donor leukocyte infusions. Various immunotherapeutic approaches, ranging from the use of antibodies, antibody-drug conjugates, bispecific T-cell engagers, chimeric antigen receptor (CAR) T-cells, and therapeutic infusions of NK cells, are thus currently being tested with promising, yet conflicting, results. This review will concentrate on various types of immunotherapies in preclinical and clinical development, from the point of view of a clinical hematologist. The most promising therapies for clinical translation are the use of bispecific T-cell engagers and CAR-T cells aimed at lineage-restricted antigens, where overall responses (ORR) ranging from 20 to 40% can be achieved in a small series of heavily pretreated patients affected by refractory or relapsing leukemia. Toxicity consists mainly in the occurrence of cytokine-release syndrome, which is mostly manageable with step-up dosing, the early use of cytokine-blocking agents and corticosteroids, and myelosuppression. Various cytokine-enhanced natural killer products are also being tested, mainly as allogeneic off-the-shelf therapies, with a good tolerability profile and promising results (ORR: 20-37.5% in small trials). The in vivo activation of T lymphocytes and NK cells via the inhibition of their immune checkpoints also yielded interesting, yet limited, results (ORR: 33-59%) but with an increased risk of severe Graft vs. Host disease in transplanted patients. Therefore, there are still several hurdles to overcome before the widespread clinical use of these novel compounds.

Notch-3 and Notch-4 signaling rescue from apoptosis human B-ALL cells in contact with human bone marrow-derived mesenchymal stromal cells.

Although many literature data are available on the role of Notch signaling in T-cell acute lymphoblastic leukemia (ALL) biology, the importance of this molecular pathway in the development of B-lineage ALL (B-ALL) cells in the BM microenvironment is unknown so far. In this study, we used anti-Notch molecules neutralizing Abs and γ-secretase inhibitor (GSI) XII to investigate the role of the Notch signaling pathway in the promotion of human B-ALL cell survival in presence of stromal cell support. The treatment with combinations of anti-Notch molecule neutralizing Abs resulted in the decrease of B-ALL cell survival, either cultured alone or cocultured in presence of stromal cells from normal donors and B-ALL patients. Interestingly, the inhibition of Notch-3 and -4 or Jagged-1/-2 and DLL-1 resulted in a dramatic increase of apoptotic B-ALL cells by 3 days, similar to what is obtained by blocking all Notch signaling with the GSI XII. Our data suggest that the stromal cell-mediated antiapoptotic effect on B- ALL cells is mediated by Notch-3 and -4 or Jagged-1/-2 and DLL-1 in a synergistic manner.

Toll-like receptor-3-activated human mesenchymal stromal cells significantly prolong the survival and function of neutrophils.

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are stromal precursors endowed with extensive immunomodulative properties. In this study, we aimed to assess whether Toll-like receptor-3 (TLR3)- and TLR4-activated BM-MSC influence human neutrophil (PMN) responses under coculture conditions. We show that TLR3 triggering by polyinosinic:polycytidylic acid dramatically amplifies, in a more significant manner than TLR4 triggering by lipopolysaccharide, the antiapoptotic effects that resting BM-MSC constitutively exert on PMN under coculture conditions, preserving a significant fraction of viable and functional PMN up to 72 hours. In addition, TLR3- and TLR4-activated BM-MSC enhance respiratory burst ability and CD11b expression by PMN. The coculture in the absence of cell contact and the incubation of PMN in supernatants harvested from TLR3- and TLR4-activated BM-MSC yield comparable results in terms of increased survival and immunophenotypic changes, thus suggesting the involvement of endogenous soluble factors. Neutralizing experiments reveal that the biological effects exerted on PMN by TLR3-activated BM-MSC are mediated by the combined action of interleukin 6, interferon-ß (IFN-ß), and granulocyte macrophage colony-stimulating factor (GM-CSF), while those exerted by TLR4-activated BM-MSC mostly depend on GM-CSF. MSC isolated from thymus, spleen, and subcutaneous adipose tissue behaves similarly. Finally, the effects exerted by TLR3- or TLR4-stimulated BM-MSC on PMN are conserved even after the previous priming of BM-MSC with IFN-γ and tumor necrosis factor-α. Our data highlight a novel mechanism by which MSC sustain and amplify the functions of PMN in response to TLR3- and TLR4-triggering and may consequently contribute to inflammatory disorders.

Neurological complications in adult allogeneic hematopoietic stem cell transplant patients: Incidence, characteristics and long-term follow-up in a multicenter series.

Neurological complications (NCs) represent a diagnostic and clinical challenge in allogeneic hematopoietic stem cell transplant (alloHSCT) patients. We retrospectively analyzed NC incidence, etiology, timing, characteristics, outcome, and long-term effects in 2384 adult patients transplanted in seven Italian institutions between January 2007 and December 2019. Ninety-three (3.9%) patients were affected by 96 NCs that were infectious (29.2%), immune/inflammatory (26%), drug-related (12.5%), cerebrovascular (5.2%), metabolic (3.1%), related to central nervous system disease relapse (11.5%) and malignancy (3.1%), or undefined (9.4%). Six patients (6.4%) had neurological manifestations of chronic graft-versus-host disease (GVHD). NCs occurred on average at day +128 (from -5 to +4063). Early (< day +120) and late NCs had similar frequencies (46.9% vs 53.1%, p = 0.39). Thirty-one patients (33.3%) were affected by acute or chronic GVHD at the NC onset. With a median follow-up of 25.4 (0.4-163) months, the overall mortality due to NCs was 22.6%. The median time between NC onset and death was 36 (1-269) days. Infectious NCs were the main cause (61.9%) of NC-related mortality. A persistent neurological impairment occurred in 20.4% patients, 57.9% of whom being affected by immune/inflammatory NCs. This study highlights the rare, yet severe impact of alloHSCT-associated NCs on patient survival and long-term functional ability.

Venetoclax in combination with hypomethylating agents in previously untreated patients with acute myeloid leukemia ineligible for intensive treatment: a real-life multicenter experience.

The addition of venetoclax to hypomethylating agents (HMA-V) improved the outcome of patients with newly diagnosed acute myeloid leukemia (AML) ineligible for intensive treatment. The aim of our study was to confirm data reported in literature, in a real-life multicenter experience. We retrospectively evaluated 56 naïve AML patients who received HMA-V at 8 different collaborating Hematology Units in the North-East of Italy, from September 2018 to October 2020. Patients received azacitidine or decitabine at standard dose, adding venetoclax starting from cycle 1-3. The median time-to-response was 2 cycles and composite complete remission rate (CCR) was 67.9%. Thirteen out of 38 responders (34.2%) relapsed, with a median response duration of 13.7 months. Transfusion independence (TI) was obtained in 27 (87.0%) and 28 (90.3%) out of 31 patients for red blood cells and platelets, respectively. Median OS was 12.3 months (95% CI, 8.1-16.5), and median PFS was 11.3 months (95% CI, 4.6-17.9). Cytogenetic risk was the only variable impacting on survival, while no differences were observed stratifying patients by age, bone marrow blasts, WHO classification or type of HMA. In conclusion, our real-life multicenter experience indicates that HMA-V treatment allows achieving good response rates in naïve AML patients, ineligible for intensive chemotherapy.

Progenitor cells from the explanted heart generate immunocompatible myocardium within the transplanted donor heart.

RATIONALE: Chronic rejection, accelerated coronary atherosclerosis, myocardial infarction, and ischemic heart failure determine the unfavorable evolution of the transplanted heart in humans. OBJECTIVE: Here we tested whether the pathological manifestations of the transplanted heart can be corrected partly by a strategy that implements the use of cardiac progenitor cells from the recipient to repopulate the donor heart with immunocompatible cardiomyocytes and coronary vessels. METHODS AND RESULTS: A large number of cardiomyocytes and coronary vessels were created in a rather short period of time from the delivery, engraftment, and differentiation of cardiac progenitor cells from the recipient. A proportion of newly formed cardiomyocytes acquired adult characteristics and was integrated structurally and functionally within the transplant. Similarly, the regenerated arteries, arterioles, and capillaries were operative and contributed to the oxygenation of the chimeric myocardium. Attenuation in the extent of acute damage by repopulating cardiomyocytes and vessels decreased significantly the magnitude of myocardial scarring preserving partly the integrity of the donor heart. CONCLUSIONS: Our data suggest that tissue regeneration by differentiation of recipient cardiac progenitor cells restored a significant portion of the rejected donor myocardium. Ultimately, immunosuppressive therapy may be only partially required improving quality of life and lifespan of patients with cardiac transplantation.

A proliferation-inducing ligand (APRIL) serum levels predict time to first treatment in patients affected by B-cell chronic lymphocytic leukemia.

PURPOSE: A proliferation-inducing ligand (APRIL), a tumor necrosis factor superfamily member involved in B-lymphocytes differentiation and survival, plays a role in protecting B-Cell Chronic lymphocytic leukemia (B-CLL) cells from apoptosis. Having observed that APRIL serum (sAPRIL) levels were higher in B-CLL patients with CLL at diagnosis as compared to healthy donors (14.61±32.65 vs. 4.19±3.42 ng/mL; P<0.001), we tested the correlation existing in these patients between sAPRIL, clinical-biological parameters and disease progression. EXPERIMENTAL DESIGN: sAPRIL levels were measured by ELISA in 130 patients with B-CLL at diagnosis and in 25 healthy donors. RESULTS: sAPRIL levels did not correlate with gender, age, clinical stage, blood cell counts, ß2-microglobulin (ß2M) levels, ZAP-70 and CD38 expression. Using median sAPRIL natural logarithm (ln) as cutoff, we distinguished two groups of patients (APRIL(LOW) and APRIL(HIGH) ) who were comparable with regard to clinical-biological parameters and overall survival, but different with regard to time to the first treatment (TTFT; P=0.035). According to univariate analysis, high lymphocyte count, high ß2M, Binet stage B-C, ZAP-70 expression and ln(sAPRIL) above median were associated with earlier TTFT. Advanced clinical stage, high ß2M, ZAP-70 expression and ln(sAPRIL) above median remained independently predictive of shorter TTFT at multivariate analysis. Moreover, sAPRIL increased its prognostic significance when patients were stratified according to independent favorable clinical-biological characteristics (low ß2M, stage A and lack of ZAP-70 expression). CONCLUSIONS: sAPRIL is a novel indicator of shorter TTFT in B-CLL and a predictor of progression especially in patients otherwise considered at low risk according to validated prognostic factors.

Adolescent feline heart contains a population of small, proliferative ventricular myocytes with immature physiological properties.

Recent studies suggest that rather than being terminally differentiated, the adult heart is a self-renewing organ with the capacity to generate new myocytes from cardiac stem/progenitor cells (CS/PCs). This study examined the hypotheses that new myocytes are generated during adolescent growth, to increase myocyte number, and these newly formed myocytes are initially small, mononucleated, proliferation competent, and have immature properties. Ventricular myocytes (VMs) and cKit(+) (stem cell receptor) CS/PCs were isolated from 11- and 22-week feline hearts. Bromodeoxyuridine incorporation (in vivo) and p16(INK4a) immunostaining were measured to assess myocyte cell cycle activity and senescence, respectively. Telomerase activity, contractions, Ca(2+) transients, and electrophysiology were compared in small mononucleated (SMMs) and large binucleated (LBMs) myocytes. Heart mass increased by 101% during adolescent growth, but left ventricular myocyte volume only increased by 77%. Most VMs were binucleated (87% versus 12% mononucleated) and larger than mononucleated myocytes. A greater percentage of SMMs was bromodeoxyuridine positive (SMMs versus LBMs: 3.1% versus 0.8%; P<0.05), and p16(INK4a) negative and small myocytes had greater telomerase activity than large myocytes. Contractions and Ca(2+) transients were prolonged in SMMs versus LBMs and Ca(2+) release was disorganized in SMMs with reduced transient outward current and T-tubule density. The T-type Ca(2+) current, usually seen in fetal/neonatal VMs, was found exclusively in SMMs and in myocytes derived from CS/PC. Myocyte number increases during adolescent cardiac growth. These new myocytes are initially small and functionally immature, with patterns of ion channel expression normally found in the fetal/neonatal period.

Induction of neural-like differentiation in human mesenchymal stem cells derived from bone marrow, fat, spleen and thymus.

Mesenchymal stem cells (MSCs) from bone marrow (BM) and sub-cutaneous fat are known to differentiate into neural cells under appropriate stimuli. We describe here the neural-like differentiation of human MSCs obtained from spleen and thymus, induced either with chemical factors or with co-culture with human Schwann cells (Sc). Under the effect of neural differentiation medium, most MSCs from BM, fat, spleen and thymus acquired morphological changes suggestive of cells of astrocytic/neuronal and oligodendroglial lineages with general up-regulation of neural molecules not correlated with morphological changes. The process was transient and reversible, as MSCs recovered basal morphology and phenotype, as well as their multilineage differentiation potential. Thus, we hypothesized that chemical factors may prime MSCs for neural differentiation, by inducing initial and poorly specific changes. By contrast, co-cultures of MSCs of different origin with Sc induced long-lasting and Sc differentiation, i.e., the expression of Sc myelin proteins for up to 12 days. Our results show that a MSC reservoir is present in tissues other than BM and fat, and that MSCs of different origin have similar neural differentiation potential. This evidence provides new insights into BM-like tissue plasticity and may have important implications for future therapeutic interventions in chronic neuropathies.

Immune regulation by mesenchymal stem cells derived from adult spleen and thymus.

We show here that human and mouse mesenchymal stem cells (MSCs) can be obtained not only from bone marrow (BM), but also from adult spleen and thymus. In vitro, both human and mouse spleen- and thymus-derived MSCs exhibit immunophenotypic characteristics and differentiation potential completely comparable to BM-MSCs. In addition, they can inhibit immune responses mediated by activated T lymphocytes with efficiency comparable to BM-MSCs. In vivo, mouse MSCs from BM, spleen, and thymus, if injected together with a genetically modified tumor cell vaccine, can equally prevent the onset of an anti-tumor memory immune response, thus leading to tumor growth in normally resistant mice. Our data suggest that not only do spleen and thymus have a stem cell reservoir to build up their stromal architecture, but also contain microenviromental immunoregulatory cells with the same properties of BM-MSCs.

Minimal Residual Disease in Acute Myeloid Leukemia: Still a Work in Progress?

Minimal residual disease evaluation refers to a series of molecular and immunophenotypical techniques aimed at detecting submicroscopic disease after therapy. As such, its application in acute myeloid leukemia has greatly increased our ability to quantify treatment response, and to determine the chemosensitivity of the disease, as the final product of the drug schedule, dose intensity, biodistribution, and the pharmakogenetic profile of the patient. There is now consistent evidence for the prognostic power of minimal residual disease evaluation in acute myeloid leukemia, which is complementary to the baseline prognostic assessment of the disease. The focus for its use is therefore shifting to individualize treatment based on a deeper evaluation of chemosensitivity and residual tumor burden. In this review, we will summarize the results of the major clinical studies evaluating minimal residual disease in acute myeloid leukemia in adults in recent years and address the technical and practical issues still hampering the spread of these techniques outside controlled clinical trials. We will also briefly speculate on future developments and offer our point of view, and a word of caution, on the present use of minimal residual disease measurements in "real-life" practice. Still, as final standardization and diffusion of the methods are sorted out, we believe that minimal residual disease will soon become the new standard for evaluating response in the treatment of acute myeloid leukemia.

Clinical outcome of myeloid sarcoma in adult patients and effect of allogeneic stem cell transplantation. Results from a multicenter survey.

INTRODUCTION: Myeloid Sarcoma (MS) is a rare hematologic myeloid neoplasm that can involve any site of the body. It can occur as an exclusively extramedullary form or it can be associated with an acute myeloid leukemia (AML), a chronic myeloproliferative neoplasm (MPN) or a myelodysplastic syndrome (MDS) at onset or at relapse. The rarity of MS does not enable prospective clinical trials and therefore a specific multicenter register can be useful for the clinical and biological studies of this rare disease. PATIENTS AND RESULTS: we report the clinical characteristics and outcome of 48 histologically confirmed MS, diagnosed and treated in 9 Italian Hematological Centers in the last 10 years. The patient's median age was 46 years. There were 9/48 de novo extramedullary MS, 24/48 de novo AML-related MS and 15/48 were secondary AML-related MS. The most common extramedullary anatomic sites of disease were: skin, lymph nodes and soft tissues. Forty-three patients (90%) underwent a program of intensive chemotherapy including FLAI, HDAC-IDA, HyperCVAD and MEC schemes, with a DDI of 5% and a CR Rate of 45%. Twenty-two (46%) patients underwent Allogeneic SCT, 13 from a MUD, 8 from an HLA-identical sibling donor and 1 from an haploidentical donor. The median OS of the whole population (48 pts) was 16.7 months. The OS probability at 1, 2 and 5 years was 64%, 39% and 33%, respectively. The OS was better in patients that underwent an intensive therapeutic program (median OS: 18 months vs 5 months). Among the intensively treated patients, in univariate analysis, the OS was better in young patients (P=0,008), in patients that underwent Allo-SCT (P=0,009) and in patients that achieved a CR during treatment (P=0,001), and was worse in pts with secondary AML-related MS (P=0,007). Age, response to intensive chemotherapy and Allo-SCT were the only three variables that significantly influenced DFS (P=0,02, P=0,01 and P=0,04, respectively). In multivariable analysis, Allo-SCT and response to intensive chemotherapy remained significant in predicting a better OS (P=0,04 and P=0,001, respectively), and response to intensive chemotherapy was the only significant variable in predicting DFS (P=0,01). After Allo-SCT we observe a survival advantage in patients who achieved a pre-transplant CR (P=0,008) and in those who developed a chronic GvHD (P=0,05). CONCLUSIONS: Patients with MS, both with de novo and secondary forms, still have a very unfavorable outcome and require an intensive therapeutic program, that includes Allo-SCT whenever possible. The outcome after Allo-SCT is positively influenced by the development of chronic GvHD suggesting a Graft versus MS effect.