relA over-expression reduces tumorigenicity and activates apoptosis in human cancer cells

We previously demonstrated that bcl-2 over-expression increases the malignant behaviour of the MCF7 ADR human breast cancer cell line and enhances nuclear factor-kappa B (NF-k B) transcriptional activity. Here, we investigated the direct effect of increased NF-k B activity on the tumorigenicity of MCF7 ADR cells by over-expressing the NF-k B subunit relA/p65. Surprisingly, our results demonstrated that over-expression of relA determines a considerable reduction of the tumorigenic ability in nude mice as indicated by the tumour take and the median time of tumour appearance. In vitro studies also evidenced a reduced cell proliferation and the activation of the apoptotic programme after relA over-expression. Apoptosis was associated with the production of reactive oxygen species, and the cleavage of the specific substrate Poly-ADP-ribose-polymerrase. Our data indicate that there is no general role for NF-k B in the regulation of apoptosis and tumorigenicity. In fact, even though inhibiting NF-k B activity has been reported to be lethal to tumour cells, our findings clearly suggest that an over-induction of nuclear NF-k B activity may produce the same effect. © 2001 Cancer Research Campaign http://www.bjcancer.co

Post-Marketing Surveillance of CAR-T-Cell Therapies: Analysis of the FDA Adverse Event Reporting System (FAERS) Database

Introduction As chimeric antigen receptor T-cell therapies are becoming increasingly available in the armamentarium of the hematologist, there is an emerging need to monitor post-marketing safety. Objective We aimed to better characterize their safety profile by focusing on cytokine release syndrome and identifying emerging signals. Methods We queried the US Food and Drug Administration Adverse Event Reporting System (October 2017-September 2020) to analyze suspected adverse drug reactions to tisagenlecleucel (tisa-cel) and axicabtagene ciloleucel (axi-cel). Disproportionality analyses (reporting odds ratio) were performed by comparing chimeric antigen receptor T-cell therapies with (a) all other drugs (reference group 1) and (b) other onco-hematological drugs with a similar indication, irrespective of age (reference group 2), or (c) restricted to adults (reference group 3). Notoriety was assessed through package inserts and risk management plans. Adverse drug reaction time to onset and cytokine release syndrome features were investigated. Results Overall, 3225 reports (1793 axi-cel; 1433 tisa-cel) were identified. The reported toxicities were mainly: cytokine release syndrome (52.2%), febrile disorders (27.7%), and neurotoxicity (27.2%). Cytokine release syndrome and neurotoxicity were often co-reported and 75% of the events occurred in the first 10 days. Disproportionalities confirmed known adverse drug reactions and showed unexpected associations: for example, axi-cel with cardiomyopathies (reporting odds ratio = 2.3; 95% confidence interval 1.2-4.4) and gastrointestinal perforations (2.9; 1.2-7.3), tisa-cel with hepatotoxicity (2.5; 1.1-5.7) and pupil disorders (15.3; 6-39.1). Conclusions Our study confirms the well-known adverse drug reactions and detects potentially emerging safety issues specific for each chimeric antigen receptor T-cell therapy, also providing insights into a stronger role for tisa-cel in inducing some immunodeficiency-related events (e.g., hypogammaglobulinemia, infections) and coagulopathies, and for axi-cel in neurotoxicity

Bcl-2 Regulates HIF-1α Protein Stabilization in Hypoxic Melanoma Cells via the Molecular Chaperone HSP90

Hypoxia-Inducible Factor 1 (HIF-1) is a transcription factor that is a critical mediator of the cellular response to hypoxia. Enhanced levels of HIF-1alpha, the oxygen-regulated subunit of HIF-1, is often associated with increased tumour angiogenesis, metastasis, therapeutic resistance and poor prognosis. It is in this context that we previously demonstrated that under hypoxia, bcl-2 protein promotes HIF-1/Vascular Endothelial Growth Factor (VEGF)-mediated tumour angiogenesis.By using human melanoma cell lines and their stable or transient derivative bcl-2 overexpressing cells, the current study identified HIF-1alpha protein stabilization as a key regulator for the induction of HIF-1 by bcl-2 under hypoxia. We also demonstrated that bcl-2-induced accumulation of HIF-1alpha protein during hypoxia was not due to an increased gene transcription or protein synthesis. In fact, it was related to a modulation of HIF-1alpha protein expression at a post-translational level, indeed its degradation rate was faster in the control lines than in bcl-2 transfectants. The bcl-2-induced HIF-1alpha stabilization in response to low oxygen tension conditions was achieved through the impairment of ubiquitin-dependent HIF-1alpha degradation involving the molecular chaperone HSP90, but it was not dependent on the prolyl hydroxylation of HIF-1alpha protein. We also showed that bcl-2, HIF-1alpha and HSP90 proteins form a tri-complex that may contribute to enhancing the stability of the HIF-1alpha protein in bcl-2 overexpressing clones under hypoxic conditions. Finally, by using genetic and pharmacological approaches we proved that HSP90 is involved in bcl-2-dependent stabilization of HIF-1alpha protein during hypoxia, and in particular the isoform HSP90beta is the main player in this phenomenon.We identified the stabilization of HIF-1alpha protein as a mechanism through which bcl-2 induces the activation of HIF-1 in hypoxic tumour cells involving the beta isoform of molecular chaperone HSP90

Vemurafenib treatment of pleomorphic xanthoastrocytoma in a child with Down syndrome

Brain tumors are the most common solid neoplasms of childhood, but they are very rarely reported in children with Down Syndrome (DS), who develop more commonly different types of malignancies. In particular, we hereby report the case of an 8-years-old child with DS that presented to our attention for neurological and endocrinological issues. Brain imaging revealed the presence of a mass that was partially resected revealing a histological diagnosis of Pleomorphic Xanthoastrocytoma (PXA), a rare WHO grade II tumor extending from the diencephalic region into the surrounding brain tissue. These tumors can harbor the BRAF mutation p.V600E, targetable by the specific inhibitor Vemurafenib. After confirming the presence of the mutation in the tumor, the patient was treated with Vemurafenib. The treatment proved to be effective, leading to a partial response and a stabilization of the disease. Usually, in patients with DS a reduction of the dose of chemotherapeutic drugs is necessary. Vemurafenib was instead well-tolerated as the only observed adverse effect was grade I skin toxicity. This is, to our knowledge, the first case of a PXA reported in a child with DS and the first DS patient treated with Vemurafenib

GD2 redirected CAR T and activated NK-cell-mediated secretion of IFNγovercomes MYCN-dependent IDO1 inhibition, contributing to neuroblastoma cell immune escape

Immune escape mechanisms employed by neuroblastoma (NB) cells include secretion of immunosuppressive factors disrupting effective antitumor immunity. The use of cellular therapy to treat solid tumors needs to be implemented. Killing activity of anti-GD2 Chimeric Antigen Receptor (CAR) T or natural killer (NK) cells against target NB cells was assessed through coculture experiments and quantified by FACS analysis. ELISA assay was used to quantify interferon-gamma (IFN gamma) secreted by NK and CAR T cells. Real Time PCR and Western Blot were performed to analyze gene and protein levels modifications. Transcriptional study was performed by chromatin immunoprecipitation and luciferase reporter assays on experiments of mutagenesis on the promoter sequence. NB tissue sample were analyzed by IHC and Real Time PCR to perform correlation study. We demonstrate that Indoleamine-pyrrole 2,3-dioxygenase1 (IDO1), due to its ability to convert tryptophan into kynurenines, is involved in NB resistance to activity of immune cells. In NB, IDO1 is able to inhibit the anti-tumor effect displayed by of both anti-GD2 CAR (GD2.CAR) T-cell and NK cells, mainly by impairing their IFN gamma production. Furthermore, inhibition of MYCN expression in NB results into accumulation of IDO1 and consequently of kynurenines, which negatively affect the immune surveillance. Inverse correlation between IDO1 and MYCN expression has been observed in a wide cohort of NB samples. This finding was supported by the identification of a transcriptional repressive role of MYCN on IDO1 promoter. The evidence of IDO1 involvement in NB immune escape and its ability to impair NK and GD2.CAR T-cell activity contribute to clarify one of the possible mechanisms responsible for the limited efficacy of these immunotherapeutic approaches. A combined therapy of NK or GD2.CAR T-cells with IDO1 inhibitors, a class of compounds already in phase I/II clinical studies, could represent a new and still unexplored strategy capable to improve long-term efficacy of these immunotherapeutic approaches

Choice of costimulatory domains and of cytokines determines CAR T-cell activity in neuroblastoma

Chimeric antigen receptor (CAR) T-cell therapy has been shown to be dramatically effective in the treatment of B-cell malignancies. However, there are still substantial obstacles to overcome, before similar responses can be achieved in patients with solid tumors. We evaluated both in vitro and in a preclinical murine model the efficacy of different 2nd and 3rd generation CAR constructs targeting GD2, a disial-ganglioside expressed on the surface of neuroblastoma (NB) tumor cells. In order to address potential safety concerns regarding clinical application, an inducible safety switch, namely inducible Caspase-9 (iC9), was also included in the vector constructs. Our data indicate that a 3rd generation CAR incorporating CD28.4-1BB costimulatory domains is associated with improved anti-tumor efficacy as compared with a CAR incorporating the combination of CD28.OX40 domains. We demonstrate that the choice of 4-1BB signaling results into significant amelioration of several CAR T-cell characteristics, including: 1) T-cell exhaustion, 2) basal T-cell activation, 3) in vivo tumor control and 4) T-cell persistence. The fine-tuning of T-cell culture conditions obtained using IL7 and IL15 was found to be synergic with the CAR.GD2 design in increasing the anti-tumor activity of CAR T cells. We also demonstrate that activation of the suicide gene iC9, included in our construct without significantly impairing neither CAR expression nor anti-tumor activity, leads to a prompt induction of apoptosis of GD2.CAR T cells. Altogether, these findings are instrumental in optimizing the function of CAR T-cell products to be employed in the treatment of children with NB