Search

We present a case of a patient with a three-month history of peripheral blood cytopenia without a confirmed diagnosis of myelodysplastic syndrome, who developed a favourable-risk acute myeloid leukemia (AML), according to the European Leukemia Net (ELN) criteria. The patient achieved a complete remission with incomplete platelet recovery (CRi) after induction. The patient achieved the morphological CR after the first consolidation and completed the first-line treatment with a syngeneic stem cell transplantation (SCT). A disease relapse occurred after one year of CR (blast cell count in the bone marrow 15%), and the patient was offered a haplo-SCT, which he refused due to personal reasons. In this paper, we discuss the interplay between clinical and biological risk factors in non-high-risk AML patients and speculate that some old clinical risk factors (e.g., age of the patient, achievement of CR after induction, and previous history of myelodysplastic syndrome) may still impact on the treatment decision algorithm of some of these patients.

Background We evaluated the incidence of proven/probable invasive aspergillosis (IA) and the role of antifungal prophylaxis (AP) in a 'real-life' setting of patients with AML receiving intensive consolidation therapy. Methods Cases of IA, observed during consolidation in adult/paediatric patients with AML between 2011 and 2015, were retrospectively collected in a multicentre Italian study. Results Of 2588 patients, 56 (2.2%) developed IA [43 probable (1.7%) and 13 proven (0.5%)]. IA was diagnosed in 34 of 1137 (2.9%) patients receiving no AP and in 22 of 1451 (1.5%) who were given AP (P = 0.01). Number-needed-to-treat calculation indicates that, on average, 71 patients should have received AP (instead of no AP) for one additional patient to not have IA. Initial antifungal therapy was 'pre-emptive' in 36 (64%) patients and 'targeted' in 20 (36%) patients. A good response to first-line therapy was observed in 26 (46%) patients, mainly those who received AP [16 of 22 (73%) versus 10 of 34 (29%); P = 0.001]. The overall mortality rate and the mortality rate attributable to IA by day 120 were 16% and 9%, respectively. In multivariate analysis, age ≥60 years (OR = 12.46, 95% CI = 1.13-136.73; P = 0.03) and high-dose cytarabine treatment (OR = 10.56, 95% CI = 1.95-116.74; P = 0.04) independently affected outcome. Conclusions In our experience, AP appears to prevent IA from occurring during consolidation. However, although the incidence of IA was low, mortality was not negligible among older patients. Further prospective studies should be carried out particularly in elderly patients treated with high-dose cytarabine to confirm our data and to identify subsets of individuals who may require AP.

Il trapianto di cellule ematopoietiche (HCT) rappresenta una terapia cardine per il trattamento delle neoplasie ematologiche altrimenti incurabili. Tuttavia, la procedura di trapianto può essere gravata dalla recidiva della malattia, dalla malattia del trapianto contro l'ospite (GVHD) e dalle infezioni. Le cellule T e NK che ricostituiscono dopo l'HCT proteggono da infezioni e recidive, ma sono anche coinvolte nella patogenesi della GVHD. Gli obiettivi del mio progetto di dottorato erano di migliorare la comprensione della ricostituzione delle cellule T e NK, utilizzando campioni di donatori sani e pazienti dopo il trapianto e diversi approcci tecnici (citometria a flusso, citometria di massa, sequenziamento dell'RNA e test funzionale ex vivo) e sviluppare nuove strategie immunoterapiche basate sui linfociti T e NK dopo HCT. In primo luogo, abbiamo dimostrato che un ritardo nel recupero dei linfociti T, un rapporto Treg/Tcon più elevato, un'aumentata espressione di PD-1 sui linfociti T di memoria e un arricchimento di cellule NK a fenotipo immaturo sono stati osservati dopo HCT aploidentico (aplo-HCT) con l’utilizzo di ciclofosfamide post-trapianto. Inoltre, la funzione delle cellule NK CD56brightCD16+ immature funzionalmente alterate dopo aplo-HCT può essere migliorata con l’utilizzo dell'interleuchina-15 in vitro. In secondo luogo, abbiamo avviato uno studio di fase I sulle cellule cytokine-induced memory-like (CIML) NK infuse da donatore haploidentico in pazienti con neoplasie mieloidi che hanno avuto una recidiva dopo aplo-HCT. Nei primi 6 pazienti arruolati, l'infusione di cellule CIML-NK ha portato a una rapida espansione in vivo da 10 a 50 volte, che è stata mantenuta per mesi. L'infusione è stata ben tollerata, con febbre e pancitopenia come eventi avversi più comuni. Sulla base di questi dati preliminari, le cellule CIML-NK possono fungere da piattaforma per il trattamento della recidiva post-trapianto delle patologie mieloidi. Infine, ci siamo concentrati sul bilanciamento della risposta dei linfociti T per controllare l’incidenza di GVHD. CD6, un recettore co-stimolatorio dei linfociti T, che aiuta a stabilizzare la sinapsi immunologica tra la cellula T e l'APC, dopo legame con il suo ligando, la molecola di adesione delle cellule leucocitarie attivate (ALCAM). In questo contesto, il legame CD6-ALCAM promuove l'attivazione, la proliferazione e la maturazione delle cellule T. Abbiamo dimostrato che le cellule T CD6 ricostituivano subito dopo il trapianto, con le cellule Treg che esprimono livelli inferiori di CD6 rispetto alle cellule Tcon e cellule T CD8+. Dopo l'insorgenza della aGVHD, l'espressione sia di CD6 che di ALCAM è stata mantenuta. Itolizumab ha inibito l'attivazione e la proliferazione delle cellule T CD4+ e CD8+ nell'ambito di aGVHD in esperimenti ex vivo, senza mediare l'attività citolitica diretta o la citotossicità anticorpo-dipendente. I nostri risultati identificano la via di CD6-ALCAM come potenziale bersaglio per il controllo dell'aGVHD. Uno studio di fase I/II che utilizza itolizumab come trattamento di prima linea in combinazione con steroidi per i pazienti con aGVHD è attualmente in corso. In conclusione, questi risultati evidenziano la necessità di bilanciare le proprietà effettrici e tolerogeniche del sistema immunitario che si ricostituisce dopo HCT e suggeriscono differenti strategie per promuovere o moderare le funzioni delle cellule T e NK. Hematopoietic cell transplantation (HCT) represents a cardinal therapy for hematological malignancy otherwise incurable. However, HCT can be complicated by disease recurrence, graft versus host disease (GVHD) and infections. After HCT, reconstituting T and NK cells protect against infection and relapse, but they are also involved in the pathogenesis of GVHD. The aims of my PhD project were to improve the understanding of T and NK-cell reconstitution, using samples from both healthy donor and patients after transplant and different technical approaches (flow cytometry, mass cytometry, RNA sequencing, and ex vivo functional assay) and to develop post-transplant T and NK cell-based immunotherapeutic strategies. First, we showed that delayed early T-cell recovery, a higher Treg/ Tcon ratio, an increased PD-1 expression on memory T cells, and an enriched immature NK phenotype were observed after haploidentical HCT (haplo-HCT) with post-transplant cyclophosphamide. In addition, the expansion of functionally impaired immature CD56brightCD16+ NK cells after haplo-HCT can be enhanced with in vitro interleukin-15 priming. Second, we initiated a phase I trial of adoptively transferred cytokine-induced memory-like (CIML) NK cells in patients with myeloid malignancies who relapsed after haplo-HCT. In the first 6 enrolled patients, infusion of CIML NK cells led to a rapid 10- to 50-fold in vivo expansion that was sustained over months. The infusion was well tolerated, with fever and pancytopenia as the most common adverse events. Based on these preliminary data, CIML NK cells may serve as a promising platform for the treatment of posttransplant relapse of myeloid disease. Finally, we focused on the balancing of T cell response to control GVHD occurrence. CD6, a pan-T cell co-stimulatory receptor, helps to stabilize the immunological synapse between the T cell and the APC, upon ligation, with its ligand, activated leukocyte cell adhesion molecule (ALCAM). In this context, CD6-ALCAM binding promotes T cell activation, proliferation, maturation. We showed that CD6 T cells reconstituted early after transplant with Treg expressing lower levels of CD6 compared to Tcon and CD8+ T cells. After onset of aGVHD, both CD6 and ALCAM expression was maintained. Itolizumab inhibited CD4+ and CD8+ T cell activation and proliferation in the setting of aGVHD in ex vivo experiments, without mediate direct cytolytic activity or antibody-dependent cytotoxicity. Our results identify the CD6-ALCAM pathway as a potential target for aGVHD control. A phase I/II study using itolizumab as first line treatment in combination with steroids for patients with aGVHD is currently ongoing. In conclusion, these results highlight the need of balancing the effector and tolerogenic properties of the immune system reconstituting after HCT and suggest different strategies to enhance or moderate the T and NK cells functions.

Until a few years ago, the onset of acute myeloid leukemia (AML) was entirely ascribed to genetic lesions in hematopoietic stem cells. These mutations generate leukemic stem cells, which are known to be the main ones responsible for chemoresistance and relapse. However, in the last years, increasing evidence demonstrated that dynamic interplay between leukemic cells and bone marrow (BM) niche is of paramount relevance in the pathogenesis of myeloid malignancies, including AML. Specifically, BM stromal niche components, such as mesenchymal stromal cells (MSCs) and their osteoblastic cell derivatives, play a key role not only in supporting normal hematopoiesis but also in the manifestation and progression of myeloid malignancies. Here, we reviewed recent clinical and experimental findings about how genetic and functional alterations in MSCs and osteolineage progeny can contribute to leukemogenesis and how leukemic cells in turn generate a corrupted niche able to support myeloid neoplasms. Moreover, we discussed how the newest single-cell technologies may help dissect the interactions between BM stromal cells and malignant hematopoiesis. The deep comprehension of the tangled relationship between stroma and AML blasts and their modulation during disease progression may have a valuable impact on the development of new microenvironment-directed therapeutic strategies, potentially useful for a wide cohort of patients.

Mesenchymal stromal cells (MSCs) represent an essential component of the bone marrow (BM) niche and display disease-specific alterations in several myeloid malignancies. The aim of this work was to study possible MSC abnormalities in Philadelphia-negative myeloproliferative neoplasms (MPNs) in relationship to the degree of BM fibrosis. MSCs were isolated from BM of 6 healthy donors (HD) and of 23 MPN patients, classified in 3 groups according to the diagnosis and the grade of BM fibrosis: polycythemia vera and essential thrombocythemia (PV/ET), low fibrosis myelofibrosis (LF-MF), and high fibrosis MF (HF-MF). MSC cultures were established from 21 of 23 MPN patients. MPN-derived MSCs did not exhibit any functional impairment in their adipogenic/osteogenic/chondrogenic differentiation potential and displayed a phenotype similar to HD-derived MSCs but with a decreased expression of CD146. All MPN-MSC lines were negative for the patient-specific hematopoietic clone mutations (JAK2, MPL, CALR). MSCs derived from HF-MF patients displayed a reduced clonogenic potential and a lower growth kinetic compared to MSCs from HD, LF-MF, and PV/ET patients. mRNA levels of hematopoiesis regulatory molecules were unaffected in MSCs from HF-MF compared to HD. Finally, in vitro ActivinA secretion by MSCs was increased in HF-MF compared to LF-MF patients, in association with a lower hemoglobin value. Increased ActivinA immunolabeling on stromal cells and erythroid precursors was also observed in HF-MF BM biopsies. In conclusion, higher grade of BM fibrosis is associated with functional impairment of MSCs and the increased secretion of ActivinA may represent a suitable target for anemia treatment in MF patients.

CMV represents one of the most serious life-threatening complications of allogeneic stem cell transplantaion (allo-SCT). Pre-emptive treatment is highly effective, but toxicity and repetitive reactivation of CMV represent a major challenge in the clinical practice. The use of anti-CMV specific immunoglobulins (Megalotect) is controversial. We retrospectively collected data on 92 patients submitted to allo-SCT for hematological malignancies, in whom Megalotect was used either for prophylaxis (n=14) or with pre-emptive therapy (n=78). All the patients were considered at high-risk of developing CMV reactivation and CMV disease. The treatment was well tolerated, with no reported infusion reactions, nor other adverse events. None of the 14 cases treated with Megalotect as prophylaxis developed CMV reactivation. 51/78 (65%) patients who received Megalotect during pre-emptive treatment achieved complete clearance of CMV viremia, and 14/51 patients (29%) developed a breakthroug CMV infection. 7/78 patients (9%) developed CMV disease. The projected 1-year OS, 1-year TRM and 1-year RR is 74%, 15% and 19%, respectively. No differences were observed in terms of OS, TRM and RR by comparing patients who achieved a complete response after treatment versus those who did not.. These retrospective data suggest that Megalotect is safe and well tolerated. When used as prophylaxis, no CMV reactivation was recorded. We have no conclusive data regarding its efficacy in reducing the cumulative dose of anti-CMV specific drugs in the pre-emptive setting. Further prospective trials are warrented to identify the best setting of patients who can benefit from Megalotect alone or in addition to anti-CMV specific drugs.

There is still an unmet need for xenotransplantation models that efficiently recapitulate normal and malignant human hematopoiesis. Indeed, there are a number of strategies to generate humanized mice and specific protocols, including techniques to optimize the cytokine environment of recipient mice and drug alternatives or complementary to the standard conditioning regimens, that can be significantly modulated. Unfortunately, the high costs related to the use of sophisticated mouse models may limit the application of these models to studies that require an extensive experimental design. Here, using an affordable and convenient method, we demonstrate that the administration of fludarabine (FludaraTM) promotes the extensive and rapid engraftment of human normal hematopoiesis in immunodeficient mice. Quantification of human CD45+ cells in bone marrow revealed approximately a 102-fold increase in mice conditioned with irradiation plus fludarabine. Engrafted cells in the bone marrow included hematopoietic stem cells, as well as myeloid and lymphoid cells. Moreover, this model proved to be sufficient for robust reconstitution of malignant myeloid hematopoiesis, permitting primary acute myeloid leukemia cells to engraft as early as 8 weeks after the transplant. Overall, these results present a novel and affordable model for engraftment of human normal and malignant hematopoiesis in immunodeficient mice.

Background aims: Cord blood (CB) and amniotic fluid (AF) could represent new and attractive mesenchymal stromal cell (MSC) sources, but their potential therapeutic applications are still limited by lack of standardized protocols for isolation and differentiation. In particular, chondrogenic differentiation has never been deeply investigated. Methods: MSCs were obtained from CB and AF samples collected during cesarean sections at term and compared for their biological and differentiation properties, with particular interest in cartilage differentiation, in which quantitative real-time polymerase chain reaction and immunohistochemical analyses were performed to evaluate the expression of type 2 collagen, type 10 collagen, SRY-box9 and aggrecan. Results: We were able to isolate MSCs from 12 of 30 (40%) and 5 of 20 (25%) CB and AF units, respectively. Fluorescence in situ hybridization analysis indicated the fetal origin of isolated MSC strains. Both populations expressed mesenchymal but not endothelial and hematopoietic markers, even though we observed a lower expression of human leukocyte antigen (HLA) I in CB-MSCs. No differences in proliferation rate and cell cycle analysis could be detected. After osteogenic induction, both populations showed matrix mineralization and typical marker expression. Under chondrogenic conditions, pellets derived from CB-MSCs, in contrast with AF-MSCs pellets, were significantly larger, showed cartilage-like morphology and resulted positive for chondrocyte-associated markers, such as type 2 collagen, type 10 collagen, SRY-box9 and aggrecan. Conclusions: Our results show that CB-MSCs and AF-MSCs collected at term differ from each other in their biological and differentiation properties. In particular, only CB-MSCs showed a clear chondrogenic potential and thus could represent an ideal candidate for cartilage-tissue engineering.

Human umbilical cord blood (CB) has attracted much attention as a reservoir for functional hematopoietic stem and progenitor cells, and, recently, as a source of blood-borne fibroblasts (CB-BFs). Previously, we demonstrated that bone marrow stromal cell (BMSC) and CB-BF pellet cultures make cartilage in vitro. Furthermore, upon in vivo transplantation, BMSC pellets remodelled into miniature bone/marrow organoids. Using this in vivo model, we asked whether CB-BF populations that express characteristics of the hematopoietic stem cell (HSC) niche contain precursors that reform the niche. CB ossicles were regularly observed upon transplantation. Compared with BM ossicles, CB ossicles showed a predominance of red marrow over yellow marrow, as demonstrated by histomorphological analyses and the number of hematopoietic cells isolated within ossicles. Marrow cavities from CB and BM ossicles included donor-derived CD146-expressing osteoprogenitors and host-derived mature hematopoietic cells, clonogenic lineage-committed progenitors and HSCs. Furthermore, human CD34+ cells transplanted into ossicle-bearing mice engrafted and maintained human HSCs in the niche. Our data indicate that CB-BFs are able to recapitulate the conditions by which the bone marrow microenvironment is formed and establish complete HSC niches, which are functionally supportive of hematopoietic tissue.

Neonatal bone marrow transplantation (nBMT) could offer a novel therapeutic opportunity for genetic disorders by providing sustainable levels of the missing protein at birth, thus preventing tissue damage. We tested this concept in Mucopolysaccharidosis type I (MPS IH, Hurler syndrome), a lysosomal storage disorder caused by deficiency of α-L-iduronidase (IDUA). MPS IH is characterized by a broad spectrum of clinical manifestations including severe progressive skeletal abnormalities. Although BMT increases the life span of MPS IH patients, musculoskeletal manifestations are only minimally responsive if the timing of BMT delays, suggesting already irreversible bone damage. In this study, we tested the hypothesis that transplanting normal bone marrow into newborn MPS I mice, soon after birth, can prevent skeletal dysplasia. 1- to 2-day-old mutant mice were conditioned using a single administration of 20 mg/kg busulfan and then injected via the superficial temporal vein with 2 x 106 bone marrow cells from wild type (WT) donors. Age-matched WT and untreated MPS I mice were used as controls. Transplantation of normal bone marrow cells into preconditioned MPS I and WT neonates led to a similar engraftment level at 37 weeks after nBMT (peripheral blood, median MPS I nBMT 81.30%, range from 0.80% to 95.80% vs. median WT nBMT 67.45%, range from 16.00% to 95.86%, p = 0.714). Spleen, PB and thymus cells of nBMT MPS I mice were repopulated with committed lymphoid and myeloid populations similar to the transplanted WT mice. The >50% replacement of the hematopoiesis resulted in a measurable increase in IDUA activity in visceral organs, especially in the spleen, showing a correlation between engraftment levels and enzyme activity with clearance of GAGs from blood and tissues. At the time of euthanasia (37-week-old), reconstitution of normal hematopoiesis in MPS I mice was associated with a consistent amelioration of bone pathology, as revealed by radiographic skeletal examination. Radiographic analysis has shown that the width of the humerus, radius/ulna, femur and tibia of untreated MPS I mice was significantly larger at comparison with WT littermates. For MPS I nBMT mice, long bone widths, including the humerus (p = 0.0014, vs. untreated MPS I mice), the radius/ulna (p = 0.0003, vs. untreated MPS I mice), the femur (p = 0.0003, vs. untreated MPS I mice), and the tibia (p = 0.0003, vs. untreated MPS I mice) significantly decreased, compared to untreated MPS I mice. Furthermore, several three-dimensional architectural parameters in femurs such as trabecular number and separation, cortical thickness and bone mineral volume were analyzed by micro-CT, resulting in a significant difference between untreated and nBMT MPS I mice. All examined nBMT MPS I mice displayed bone parameter values comparable to WT mice, confirming that nBMT mice had significant improvements in skeletal phenotype approaching complete normalization of each parameter tested. Histologically, in MPS I cortical bone, osteocytes were increased and contained vacuoles, likely reflecting GAGs storage. Histological amelioration of these features was consistently observed in femurs of all nBMT mice with a definite reduction in both hyperosteocytosis and lysosomal vacuolization, confirming that the perinatal treatment of the disease can positively impact the skeletal phenotype in MPS I. We also evaluated KS levels in the blood as a biomarker of MPS with skeletal dysplasia. Normalization of blood KS level strongly supports the notion that nBMT corrects the pathological and clinical bone lesions in nBMT MPS I mice. Our findings demonstrate that nBMT prevents some of the relevant abnormalities of the skeletal pathology in the MPS I mouse model. Moreover, improvements in bone parameters correlated with high levels of bone marrow-derived cell engraftment in multiple hematopoietic compartments, suggesting that the early and complete restoration of normal hematopoiesis can have significant impact on the bone development of newborn MPS I mice. Future clinical trials are needed to confirm our findings. Disclosures No relevant conflicts of interest to declare.