Atypical teratoid/rhabdoid tumors (ATRTs) typically arise in the central nervous system (CNS) of children under 3 years of age. Despite intensive multimodal therapy (surgery, chemotherapy and, if age ...permits, radiotherapy), median survival is 17 months
. We show that ATRTs robustly express B7-H3/CD276 that does not result from the inactivating mutations in SMARCB1 (refs.
), which drive oncogenesis in ATRT, but requires residual SWItch/Sucrose Non-Fermentable (SWI/SNF) activity mediated by BRG1/SMARCA4. Consistent with the embryonic origin of ATRT
, B7-H3 is highly expressed on the prenatal, but not postnatal, brain. B7-H3.BB.z-chimeric antigen receptor (CAR) T cells administered intracerebroventricularly or intratumorally mediate potent antitumor effects against cerebral ATRT xenografts in mice, with faster kinetics, greater potency and reduced systemic levels of inflammatory cytokines compared to CAR T cells administered intravenously. CAR T cells administered ICV also traffic from the CNS into the periphery; following clearance of ATRT xenografts, B7-H3.BB.z-CAR T cells administered intracerebroventricularly or intravenously mediate antigen-specific protection from tumor rechallenge, both in the brain and periphery. These results identify B7-H3 as a compelling therapeutic target for this largely incurable pediatric tumor and demonstrate important advantages of locoregional compared to systemic delivery of CAR T cells for the treatment of CNS malignancies.
Primary Mediastinal large B-cell Lymphoma (PMLBL) is a rare entity predominantly affecting adolescents and young adults. Recently, an international phase 2 trial in pediatric patients using ...dose-adjusted etoposide, doxorubicin, and cyclophosphamide with vincristine and prednisone plus rituximab (DA-EPOCH-R) failed to reproduce excellent survival reported in some adult studies. The optimal therapy regimen needs to be determined in this disease. French prospective LMB2001 trial included all patients < 18 years with mature B-cell lymphoma treated in French centers. For patients with PMLBL, treatment included 4 to 8 courses of Lymphomes Malins B (LMB)-based chemotherapy without radiotherapy. From 2008, rituximab was added before each chemotherapy course. From 09/2001 to 03/2012, 42 patients with PMLBL were registered. The median age was 15 years (range 8-18). 21 patients were treated by chemotherapy plus rituximab. The median follow-up was 7.1 years (Interquartile range, 5.8-11.1). Five-year event-free (EFS) and overall survival (OS) were 88.1% (95%Confidence Interval (CI), 75.0%-94.8%) and 95.2% (95%CI, 84.0%-98.7%) for the whole population. The 5-year EFS was 81.0% (95%CI, 60.0%-92.3%) and 95.2% (95%CI, 77.3%-99.2%) (HR=0.24 (95%CI 0.03-2.2)) and 5-year OS was 90.5% (95%CI, 71.1%-97.3%) and 100% for patients treated without and with rituximab, respectively. Only 1/21 patients treated with rituximab and LMB-based chemotherapy had local early treatment failure but achieved prolonged complete remission with second-line chemotherapy and radiotherapy. Intensive LMB-based chemotherapy with rituximab achieved excellent survival in children/adolescents with PMLBL. Further international prospective studies are required to confirm these results in this population.
Rhabdoid tumors (RTs) are aggressive tumors of early childhood characterized by SMARCB1 inactivation. Their poor prognosis highlights an urgent need to develop new therapies. Here, we performed a ...high-throughput screening of approved drugs and identified broad inhibitors of tyrosine kinase receptors (RTKs), including pazopanib, and the potassium channel inhibitor clofilium tosylate (CfT), as SMARCB1-dependent candidates. Pazopanib targets were identified as PDGFRα/β and FGFR2, which were the most highly expressed RTKs in a set of primary tumors. Combined genetic inhibition of both these RTKs only partially recapitulated the effect of pazopanib, emphasizing the requirement for broad inhibition. CfT perturbed protein metabolism and endoplasmic reticulum stress and, in combination with pazopanib, induced apoptosis of RT cells in vitro. In vivo, reduction of tumor growth by pazopanib was enhanced in combination with CfT, matching the efficiency of conventional chemotherapy. These results strongly support testing pazopanib/CfT combination therapy in future clinical trials for RTs.
Display omitted
•High-throughput screening identifies pazopanib and clofilium tosylate for rhabdoid tumors•PDGFRα/β and FGFR2 are identified as targets of pazopanib•Pazopanib combined with clofilium tosylate induces apoptosis of RT cells•Reduction of PDX tumor growth by pazopanib is enhanced by the combination with CfT
Rhabdoid tumors (RTs) are aggressive pediatric tumors characterized by SMARCB1 inactivation. Chauvin et al. identify two SMARCB1-dependent targeted therapies for RT: pazopanib, which inhibits PDGFR and FGFR2, and the potassium channel inhibitor clofilium tosylate, which induces endoplasmic reticulum stress. Combining both drugs induces cell apoptosis and reduces PDX tumor growth.
BackgroundCAR T cells have been highly effective against refractory B cell malignancies but have not demonstrated sustained antitumor effects against solid tumors. Intense effort is underway to ...augment the potency of CAR T cells in order to overcome the suppressive tumor microenvironment, which is associated with T cell exhaustion. Adenosine is a major mediator of immune suppression. CD39 (ecto-ATP diphosphohydrolase-1) plays a central role in the generation of adenosine by catalyzing the metabolism of ATP into ADP/AMP. CD73 (5'-ectonucleotidase) subsequently metabolizes ADP/AMP into adenosine which mediates immune suppression through adenosine associated receptor signaling. CD39 is also expressed by exhausted CD8+ and tumor reactive T cells within the tumor microenvironment, where it is associated with tumor progression, but it remains unclear whether exhausted and/or tumor reactive CD39+CD8+ T cells mediate immune suppression via adenosine.MethodsWe developed a high affinity version of the disialoganglioside (GD2)-targeting CAR (HA-GD2) that spontaneously clusters on the surface of human T cells in the absence of antigen and mimics chronic antigen exposure leading to T cell exhaustion. Using this model, we demonstrate that exhausted CD39+CD8+ CAR T cells actively produce adenosine and mediate immune suppression through surface upregulation of CD39/73. In an attempt to generate adenosine resistance and enhance the function of exhausted CAR T cells, we knocked out CD39, CD73, or A2aR and overexpressed transmembrane-bound adenosine deaminase (ADA-TM).ResultsOnly overexpression of ADA-TM, which metabolizes adenosine to inosine, induced significant transcriptomic changes, higher frequency of stem- and central- like memory T cells, and a simultaneous decrease of exhausted T cell subpopulations. Direct exposure of HA-GD2 CAR T cells to high inosine concentration during cell manufacturing process, lead to a higher frequency of central-like memory cells and significant fitness enhancement associated with broad changes at the metabolic level. RNAseq and cyTOF analysis indicated decreased glycolytic flux, increased mitochondrial activity and glutamine and polyamine metabolism. Further, inosine altered the epigenetic state of HA-GD2 CAR T cells. We observed significant enrichment of IRF and NF-κB transcription factor motifs and motifs associated with memory differentiation in T cells grown in the presence of inosine. Finally, we showed that production of exhausted HA-GD2 and clinically-relevant version of GD2 CAR T cells in inosine-containing culture media enhances there in vivo efficacy, leading to improved survival of mice.ConclusionsWe propose introducing inosine during cell manufacturing process as a novel strategy for improving clinical outcomes of CAR T cell therapy.Ethics ApprovalImmunocompromised NOD-SCID-Il2rg−/− (NSG) mice were purchased from JAX and bred inhouse. All mice were bred, housed, and treated in ethical compliance with Stanford UniversityACUC (APLAC) approved protocolsProtocol ID 31287
Rhabdoid tumors (RTs) are genomically simple pediatric cancers driven by the biallelic inactivation of SMARCB1, leading to SWI/SNF chromatin remodeler complex deficiency. Comprehensive evaluation of ...the immune infiltrates of human and mice RTs, including immunohistochemistry, bulk RNA sequencing and DNA methylation profiling studies showed a high rate of tumors infiltrated by T and myeloid cells. Single-cell RNA (scRNA) and T cell receptor sequencing highlighted the heterogeneity of these cells and revealed therapeutically targetable exhausted effector and clonally expanded tissue resident memory CD8+ T subpopulations, likely representing tumor-specific cells. Checkpoint blockade therapy in an experimental RT model induced the regression of established tumors and durable immune responses. Finally, we show that one mechanism mediating RTs immunogenicity involves SMARCB1-dependent re-expression of endogenous retroviruses and interferon-signaling activation.
Display omitted
•Genomically simple RTs are infiltrated by T cell and myeloid populations•Clonally expanded T cell phenotypes suggest a tumor-specific response•Checkpoint blockade induces tumor regression and immune memory in vivo•Endogenous retrovirus expression is linked to the immunogenicity of RTs
Leruste et al. find that, despite their low mutation burden, rhabdoid tumors have a high rate of infiltration by T cells and myeloid cells, and the immunogenicity is linked to endogenous retrovirus expression. Immune checkpoint blockade induces tumor regression in a rhabdoid tumor mouse model.
Switch/sucrose nonfermentable–deficient cancers may respond to immune checkpoint blockade. Combinations with epidrugs or radiation therapies can offer new specific therapeutic vulnerabilities.
Chimeric Antigen Receptor T (CAR-T) cells are currently approved for B cell malignancies only, in children and adults. Despite a lack of robust evidence to approve such cellular immunotherapy for ...pediatric solid tumors, there is a growing interest for this approach in the treatment of pediatric brain tumors. Following the identification of tumor antigens as targets, the first clinical trials demonstrated some degree of clinical and biological responses to CAR-T cells for such tumor types. Additionaly, several preclinical studies have recently identified new attractive targets and antigen combination strategies, along with a superior tumor trafficking following locoregional administration. We review here the preclinical and clinical knowledge at the basis of the current clinical development of CAR-T cells for pediatric brain tumors.
Adenosine (Ado) mediates immune suppression in the tumor microenvironment and exhausted CD8+ CAR-T cells express CD39 and CD73, which mediate proximal steps in Ado generation. Here, we sought to ...enhance CAR-T cell potency by knocking out CD39, CD73, or adenosine receptor 2a (A2aR) but observed only modest effects. In contrast, overexpression of Ado deaminase (ADA-OE), which metabolizes Ado to inosine (INO), induced stemness and enhanced CAR-T functionality. Similarly, CAR-T cell exposure to INO augmented function and induced features of stemness. INO induced profound metabolic reprogramming, diminishing glycolysis, increasing mitochondrial and glycolytic capacity, glutaminolysis and polyamine synthesis, and reprogrammed the epigenome toward greater stemness. Clinical scale manufacturing using INO generated enhanced potency CAR-T cell products meeting criteria for clinical dosing. These results identify INO as a potent modulator of CAR-T cell metabolism and epigenetic stemness programming and deliver an enhanced potency platform for cell manufacturing.
Display omitted
•Exhausted CAR-T cells generate immunosuppressive adenosine through CD39/CD73•Increased inosine metabolism induces stemness•CAR-T cells cultured in inosine-containing media have increased effector function•Inosine supplementation is a novel strategy to improve CAR-T cell manufacturing
Klysz et al. show that targeting CD39, CD73, or A2aR does not reduce adenosine-mediated immunosuppression but increasing inosine levels, by direct supplementation or overexpression of adenosine deaminase, augments CAR-T cell function and stemness. Introduction of inosine during GMP cell manufacturing process is a feasible strategy to generate more potent CAR-T cells.
PDF
