Early post-allogeneic hematopoietic stem cell transplantation (allo-HSCT) relapse in patients with acute myeloid leukemia (AML) has an almost invariably dismal prognosis.Recent studies have demonstrated that FLT3 inhibition enhances the graft-versus-leukemia effect in vitro and in vivo.Thus, FLT-3 inhibitors may be viable treatment options in this setting.Here, we report three patients with FLT3 and NPM1 mutated AML who relapsed early after allo-HSCT and were treated with gilteritinib (associated with donor lymphocyte Infusion in two patients) to achieve long-term remission without a second transplantation.
Abstract Combined therapy with venetoclax and hypomethylating agents has significantly improved the outcome of unfit patients ineligible for intensive chemotherapy. A recently published exploratory analysis of the VIALE-A trial reported that up to 51% of patients achieving remission survived more than 2 years. These data along with those from reallife settings, lead to questioning how long it is appropriate to continue treatment in long-term survivors. Accordingly, recent retrospective studies suggested the feasibility of suspending therapy in selected patients while maintaining prolonged responses. Also, these studies showed that retreatment may induce a second remission in almost a third of patients. We report the case of a patient who received salvage therapy with venetoclax and azacytidine, that was discontinued few cycles after blasts clearance because of severe hematological toxicity. Despite suspension, he maintained a sustained response lasting almost one year and was successfully retreated with the same combination when a second relapse occurred.
Abstract Graft-vs-host-disease (GvHD) is currently the main complication of allogeneic hematopoietic stem cell transplantation. Mortality and morbidity rates are particularly high, especially in steroid-refractory acute GvHD (aGvHD). Immune regulatory human bone marrow mesenchymal stromal cells (hMB-MSCs) represent a therapeutic approach to address this issue. Unfortunately, their effect is hardly predictable in vivo due to several variables, that is, MSC tissue origin, concentration, dose number, administration route and timing, and inflammatory status of the recipient. Interestingly, human bone marrow MSC-derived extracellular vesicles (hBM-MSC-EVs) display many of the hBM-MSC immunoregulatory properties due to their content in paracrine factors that greatly varies according to the collection method. In this study, we focused on the immunological characterization of hBM-MSC-EVs on their capability of inducing regulatory T-cells (T-regs) both in vitro and in a xenograft mouse model of aGvHD. We correlated these data with the aGvHD incidence and degree following hBM-MSC-EV intravenous administration. Thus, we first quantified the EV immunomodulation in vitro in terms of EV immunomodulatory functional unit (EV-IFU), that is, the lowest concentration of EVs leading in vitro to at least threefold increase of the T-regs compared with controls. Second, we established the EV therapeutic dose in vivo (EV-TD) corresponding to 10-fold the in vitro EV-IFU. According to this approach, we observed a significant improvement of both mouse survival and control of aGvHD onset and progression. This study confirms that EVs may represent an alternative to whole MSCs for aGvHD prevention, once the effective dose is reproducibly identified according to EV-IFU and EV-TD definition.
