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Osteosarcoma (OS) remains a dismal malignancy in children and young adults, with poor outcome for metastatic and recurrent disease. Immunotherapies in OS are not as promising as in some other cancer types due to intra-tumor heterogeneity and considerable off-target expression of the potentially targetable proteins. Here we show that chimeric antigen receptor (CAR) T cells could successfully target an isoform of alkaline phosphatase, ALPL-1, which is highly and specifically expressed in primary and metastatic OS. The target recognition element of the second-generation CAR construct is based on two antibodies, previously shown to react against OS. T cells transduced with these CAR constructs mediate efficient and effective cytotoxicity against ALPL-positive cells in in vitro settings and in state-of-the-art in vivo orthotopic models of primary and metastatic OS, without unexpected toxicities against hematopoietic stem cells or healthy tissues. In summary, CAR-T cells targeting ALPL-1 show efficiency and specificity in treating OS in preclinical models, paving the path for clinical translation. Chimeric antigen receptor T (CAR-T) cells represent a breakthrough in the treatment of haematopoietic malignancies, however, in solid tumours this form of immune therapy is hampered by the scarcity of suitable targets showing high level tumour-restricted expression. Here authors generate CAR-T cells that target an osteosarcoma-specific isoform of alkaline phosphatase and show efficacy in orthotopic animal models while sparing healthy tissues.

Introduction: Previously, we found that intracellular calcium (Ca2+) homeostasis is altered in platelets from an experimental model of liver cirrhosis, namely the bile-duct-ligated (BDL) rat. These alterations are compatible with the existence of a hypercoagulable state. Objective: In the present study, we analyzed the role of nitric oxide in the abnormal calcium signaling responses of an experimental cirrhosis model, the bile duct-ligated rat. Methods: Chronic treatment with L-NAME was used to inhibit NO production in a group of control and BDL animals, and the responses compared to those obtained in a control and BDL untreated group (n = 6 each). The experiments were conducted on isolated platelets loaded with fura-2, using fluorescence spectrometry. Results: Chronic treatment with L-NAME increased thrombin-induced Ca2+ release from internal stores in both control and BDL rats. However, the effect was significantly greater in the BDL rats (p < 0.05). Thrombin-induced calcium entry from the extracellular space was also elevated but at lower doses and, similarly in both control and BDL platelets, treated with the NO synthesis inhibitor. Capacitative calcium entry was also enhanced in the control platelets but not in platelets from BDL rats treated with L-NAME. Total calcium in intracellular stores was elevated in untreated platelets from BDL rats, and L-NAME pretreatment significantly (p < 0.05) elevated these values both in controls and in BDL but significantly more in the BDL rats (p < 0.05). Conclusions: Our results suggest that nitric oxide plays a role in the abnormal calcium signaling responses observed in platelets from BDL rats by interfering with the mechanism that releases calcium from the internal stores.

Autophagy has been shown to be a key cellular event controlling tumor growth in different neoplasms including hepatocellular carcinoma (HCC). Although this biological role of autophagy has been clearly established, the mechanism underlying its regulation remains elusive. Here, we demonstrate a role of sulfatase 2 (SULF2), a 6‐O‐endosulfatase modulating various growth factors and cytokine‐related signaling pathways controlling tumor cell proliferation and survival, in the regulation of autophagy in HCC cells. SULF2 increased autophagosome formation, shown by increased LC3B‐II protein and green fluorescent protein–LC3 puncta. Increased fusion between autophagosomes and lysosomes/lysosomal enzymes, higher expression of lysosomal membrane protein, and an increase in autolysosomes were also shown by western blot, immunofluorescence, and electron microscopy of SULF2‐expressing cells, indicating enhanced autophagic flux. In contrast, RNA‐interference silencing of SULF2 in Huh7 cells induced lysosomal membrane permeabilization with diffuse cytosolic staining of cathepsin D and punctate staining of galectin‐3. Analysis of the mechanism showed that inhibition of lysosome‐associated protein transmembrane 4 beta (LAPTM4B), a gene induced by SULF2, resulted in decreased autophagosome formation, decreased fusion between autophagosomes and lysosomes, and increased lysosomal membrane permeabilization. Interestingly, down‐regulation of LAPTM4B also phenocopies the knockdown of SULF2, significantly reducing cell viability and colony formation. Conclusion: Our results demonstrate a role for SULF2 in the regulation of autophagic flux that is mediated through LAPTM4B induction in HCC cells, and provide a foundation for future translational efforts targeting autophagy in liver malignancies. High SULF2 expression was associated with enhanced autophagy, and SULF2 depletion showed lysosomal membrane permeabilization. Lysosomal protein transmembrane 4 beta (LAPTM4B) was positively correlated with SULF2 expression. Inhibition of LAPTM4B also resulted in decreased autophagy and increased lysosomal membrane permeabilization in SULF2‐positive HCC cells.

Relapse remains a major challenge in the clinical management of acute myeloid leukemia (AML) and is driven by rare therapy‐resistant leukemia stem cells (LSCs) that reside in specific bone marrow niches. Hypoxia signaling maintains cells in a quiescent and metabolically relaxed state, desensitizing them to chemotherapy. This suggests the hypothesis that hypoxia contributes to the chemoresistance of AML‐LSCs and may represent a therapeutic target to sensitize AML‐LSCs to chemotherapy. Here, we identify HIFhigh and HIFlow specific AML subgroups (inv(16)/t(8;21) and MLLr, respectively) and provide a comprehensive single‐cell expression atlas of 119,000 AML cells and AML‐LSCs in paired diagnostic‐relapse samples from these molecular subgroups. The HIF/hypoxia pathway signature is attenuated in AML‐LSCs compared with more differentiated AML cells but is more expressed than in healthy hematopoietic cells. Importantly, chemical inhibition of HIF cooperates with standard‐of‐care chemotherapy to impair AML growth and to substantially eliminate AML‐LSCs in vitro and in vivo. These findings support the HIF pathway in the stem cell‐driven drug resistance of AML and unravel avenues for combinatorial targeted and chemotherapy‐based approaches to specifically eliminate AML‐LSCs.

CD19‐directed chimeric antigen receptors (CAR) T cells induce impressive rates of complete response in advanced B‐cell malignancies, specially in B‐cell acute lymphoblastic leukemia (B‐ALL). However, CAR T‐cell‐treated patients eventually progress due to poor CAR T‐cell persistence and/or disease relapse. The bone marrow (BM) is the primary location for acute leukemia. The rapid/efficient colonization of the BM by systemically infused CD19‐CAR T cells might enhance CAR T‐cell activity and persistence, thus, offering clinical benefits. Circulating cells traffic to BM upon binding of tetrasaccharide sialyl‐Lewis X (sLeX)‐decorated E‐selectin ligands (sialofucosylated) to the E‐selectin receptor expressed in the vascular endothelium. sLeX‐installation in E‐selectin ligands is achieved through an ex vivo fucosylation reaction. Here, we sought to characterize the basal and cell‐autonomous display of sLeX in CAR T‐cells activated using different cytokines, and to assess whether exofucosylation of E‐selectin ligands improves CD19‐CAR T‐cell activity and BM homing. We report that cell‐autonomous sialofucosylation (sLeX display) steadily increases in culture‐ and in vivo‐expanded CAR T cells, and that, the cytokines used during T‐cell activation influence both the degree of such endogenous sialofucosylation and the CD19‐CAR T‐cell efficacy and persistence in vivo. However, glycoengineered enforced sialofucosylation of E‐selectin ligands was dispensable for CD19‐CAR T‐cell activity and BM homing in multiple xenograft models regardless the cytokines employed for T‐cell expansion, thus, representing a dispensable strategy for CD19‐CAR T‐cell therapy. Glyco‐engineered enforced sialofucosylation of E‐selectin ligands was dispensable for CD19‐CAR T‐cell activity and BM homing in multiple xenograft models, thus representing an unnecessary strategy for CD19‐CAR T‐cell therapy

Acute myeloid leukemia (AML) is the most common acute leukemia in adults. Patients with AML harboring a constitutively active internal tandem duplication mutation (ITDMUT) in the FMS-like kinase tyrosine kinase (FLT3) receptor generally have a poor prognosis. Several tyrosine kinase/FLT3 inhibitors have been developed and tested clinically, but very few (midostaurin and gilteritinib) have thus far been FDA/EMA-approved for patients with newly diagnosed or relapse/refractory FLT3-ITDMUT AML. Disappointingly, clinical responses are commonly partial or not durable, highlighting the need for new molecules targeting FLT3-ITDMUT AML. Here, we tested EC-70124, a hybrid indolocarbazole analog from the same chemical space as midostaurin with a potent and selective inhibitory effect on FLT3. In vitro, EC-70124 exerted a robust and specific antileukemia activity against FLT3-ITDMUT AML primary cells and cell lines with respect to cytotoxicity, CFU capacity, apoptosis and cell cycle while sparing healthy hematopoietic (stem/progenitor) cells. We also analyzed its efficacy in vivo as monotherapy using two different xenograft models: an aggressive and systemic model based on MOLM-13 cells and a patient-derived xenograft model. Orally disposable EC-70124 exerted a potent inhibitory effect on the growth of FLT3-ITDMUT AML cells, delaying disease progression and debulking the leukemia. Collectively, our findings show that EC-70124 is a promising and safe agent for the treatment of AML with FLT3-ITDMUT.

BackgroundAlthough adoptive transfer of CD19-directed chimeric antigen receptor (CAR) T-cells (CD19-CAR T-cells) achieves high rates of complete response in patients with B-cell acute lymphoblastic leukemia (B-ALL), relapse is common. Bone marrow (BM) mesenchymal stem/stromal cells (BM-MSC) are key components of the hematopoietic niche and are implicated in B-ALL pathogenesis and therapy resistance. MSC exert an immunosuppressive effect on T-cells; however, their impact on CD19-CAR T-cell activity is understudied.MethodsWe performed a detailed characterization of BM-MSC from pediatric patients with B-ALL (B-ALL BM-MSC), evaluated their immunomodulatory properties and their impact on CD19-CAR T-cell activity in vitro using microscopy, qRT-PCR, ELISA, flow cytometry analysis and in vivo using a preclinical model of severe colitis and a B-ALL xenograft model.ResultsWhile B-ALL BM-MSC were less proliferative than those from age-matched healthy donors (HD), the morphology, immunophenotype, differentiation potential and chemoprotection was very similar. Likewise, both BM-MSC populations were equally immunosuppressive in vitro and anti-inflammatory in an in vivo model of severe colitis. Interestingly, BM-MSC failed to impair CD19-CAR T-cell cytotoxicity or cytokine production in vitro using B-ALL cell lines and primary B-ALL cells. Finally, the growth of NALM6 cells was controlled in vivo by CD19-CAR T-cells irrespective of the absence/presence of BM-MSC.ConclusionsCollectively, our data demonstrate that pediatric B-ALL and HD BM-MSC equally immunosuppress T-cell responses but do not compromise CD19-CAR T-cell activity.

Background The treatment of extensive and/or chronic skin wounds is a widespread and costly public health problem. Mesenchymal stem cells (MSCs) have been proposed as a potential cell therapy for inducing wound healing in different clinical settings, alone or in combination with biosynthetic scaffolds. Among them, silk fibroin (SF) seeded with MSCs has been shown to have increased efficacy in skin wound healing experimental models. Methods In this report, we investigated the wound healing effects of electrospun SF scaffolds cellularized with human Wharton’s jelly MSCs (Wj-MSCs-SF) using a murine excisional wound splinting model. Results Immunohistopathological examination after transplant confirmed the presence of infiltrated human fibroblast-like CD90-positive cells in the dermis of the Wj-MSCs-SF-treated group, yielding neoangiogenesis, decreased inflammatory infiltrate and myofibroblast proliferation, less collagen matrix production, and complete epidermal regeneration. Conclusions These findings indicate that Wj-MSCs transplanted in the wound bed on a silk fibroin scaffold contribute to the generation of a well-organized and vascularized granulation tissue, enhance reepithelization of the wound, and reduce the formation of fibrotic scar tissue, highlighting the potential therapeutic effects of Wj-MSC-based tissue engineering approaches to non-healing wound treatment.

BackgroundChimeric antigen receptor (CAR)-T cells have emerged as a breakthrough treatment for relapse/refractory hematological tumors, showing impressive complete remission rates. However, around 50% of the patients relapse before 1-year post-treatment. T-cell ‘fitness’ is critical to prolong CAR-T persistence and activity. Allogeneic T cells from healthy donors are less dysfunctional or exhausted than autologous patient-derived T cells; in this context, Delta One T cells (DOTs), a recently described cellular product based on MHC/HLA-independent Vδ1+γδ T cells, represent a promising allogeneic platform.MethodsHere we generated and preclinically validated, for the first time, 4-1BB-based CAR-DOTs directed against the interleukin-3α chain receptor (CD123), a target antigen widely expressed on acute myeloid leukemia (AML) blasts.ResultsCD123CAR-DOTs showed vigorous, superior to control DOTs, cytotoxicity against AML cell lines and primary samples both in vitro and in vivo, even on tumor rechallenge.ConclusionsOur results provide the proof-of-concept for a DOT-based next-generation allogeneic CAR-T therapy for AML.