Toward more accurate preclinical glioblastoma modeling: Reverse translation of clinical standard of care in a glioblastoma mouse model.

Glioblastoma (GBM) is the deadliest of all brain cancers. GBM patients receive an intensive treatment schedule consisting of surgery, radiotherapy and chemotherapy, which only modestly extends patient survival. Therefore, preclinical studies are testing novel experimental treatments. In such preclinical studies, these treatments are administered as monotherapy in the majority of cases; conversely, in patients the new treatments are always combined with the standard of care. Most likely, this difference contributes to the failure of clinical trials despite the successes of the preclinical studies. In this methodological study, we show in detail how to implement the full clinical standard of care in preclinical GBM research. Systematically testing new treatments, including cellular immunotherapies, in combination with the clinical standard of care can result in a better translation of preclinical results to the clinic and ultimately increase patient survival.

Blood Mucorales PCR to track down Aspergillus and Mucorales co-infections in at-risk hematology patients: A case-control study.

Introduction: Serum Mucorales PCR can precede the final diagnosis of invasive mucormycosis by several days or weeks and could therefore be useful as a non-invasive screening tool. Methods: We assessed the performance of a commercial Mucorales PCR assay (MucorGenius®, PathoNostics, Maastricht, The Netherlands) on prospectively collected banked sera from hematology patients at risk for invasive mould infections. We evaluated if there is an underestimated incidence of missed Mucorales co-infections in patients with invasive aspergillosis (IA). We tested Mucorales PCR on the sera of all patients with a diagnosis of at least possible IA (EORTC-MSGERC consensus criteria) before the start of any antifungal therapy, and in a control group of similar high-risk hematology patients without IA (in a 1:4 ratio). When a positive Mucorales PCR was observed, at least 5 serum samples taken before and after the positive one were selected. Results: Mucorales PCR was performed in 46 diagnostic serum samples of cases and in 184 controls. Serum Mucorales PCR was positive in 4 cases of IA (8.7%; 12.9% of probable cases) and in 1 control case (0.5%) (p=0.0061, OR=17.43 (1.90-159.96). Post-mortem cultures of the positive control became positive for Rhizopus arrhizus. Mortality of IA cases with and without a positive Mucorales PCR was not significantly different. Only in the PCR positive control case, serial serum samples before and after the diagnostic sample were also positive. Discussion: It is not entirely clear what a positive Mucorales PCR in these cases implies since the 4 Mucorales PCR positive cases were treated with antifungals with activity against Mucorales. In addition, PCR was positive only once. This study does not provide enough evidence to implement Mucorales PCR screening. However, our findings emphasize once more the importance of considering the possibility of dual mould infections, even in patients with a positive galactomannan detection.

The Combination of the CDK4/6 Inhibitor, Palbociclib, With the Vitamin D3 Analog, Inecalcitol, Has Potent In Vitro and In Vivo Anticancer Effects in Hormone-Sensitive Breast Cancer, But Has a More Limited Effect in Triple-Negative Breast Cancer.

Active vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and its synthetically derived analogs possess potent anticancer properties. In breast cancer (BC) cells, 1,25(OH)2D3 blocks cell proliferation and induces apoptosis through different cell-type specific mechanisms. In this study, we evaluated if the combination of the potent vitamin D3 analog, inecalcitol, with a selective CDK4/6 inhibitor, palbociclib, enhanced the antiproliferative effects of both single compounds in hormone-sensitive (ER+) BC, for which palbociclib treatment is already approved, but also in triple-negative BC (TNBC). Inecalcitol and palbociclib combination treatment decreased cell proliferation in both ER+ (T47D-MCF7) and TNBC (BT20-HCC1143-Hs578T) cells, with a more pronounced antiproliferative effect in the former. In ER+ BC cells, the combination therapy downregulated cell cycle regulatory proteins (p)-Rb and (p)-CDK2 and blocked G1-S phase transition of the cell cycle. Combination treatment upregulated p-mTOR and p-4E-BP1 protein expression in MCF7 cells, whereas it suppressed expression of these proteins in BT20 cells. Cell survival was decreased after inecalcitol treatment either alone or combined in MCF7 cells. Interestingly, the combination therapy upregulated mitochondrial ROS and mitotracker staining in both cell lines. Furthermore, in vivo validation in a MCF7 cell line-derived xenograft mouse model decreased tumor growth and cell cycle progression after combination therapy, but not in a TNBC BT20 cell line-derived xenograft model. In conclusion, we show that addition of a potent vitamin D3 analog to selective CDK4/6 inhibitor treatment results in increased antiproliferative effects in ER+ BC both in vitro and in vivo.

Immunocompetent Mouse Models in the Search for Effective Immunotherapy in Glioblastoma.

Glioblastoma (GBM) is the most aggressive intrinsic brain tumor in adults. Despite maximal therapy consisting of surgery and radio/chemotherapy, GBM remains largely incurable with a median survival of less than 15 months. GBM has a strong immunosuppressive nature with a multitude of tumor and microenvironment (TME) derived factors that prohibit an effective immune response. To date, all clinical trials failed to provide lasting clinical efficacy, despite the relatively high success rates of preclinical studies to show effectivity of immunotherapy. Various factors may explain this discrepancy, including the inability of a single mouse model to fully recapitulate the complexity and heterogeneity of GBM. It is therefore critical to understand the features and limitations of each model, which should probably be combined to grab the full spectrum of the disease. In this review, we summarize the available knowledge concerning immune composition, stem cell characteristics and response to standard-of-care and immunotherapeutics for the most commonly available immunocompetent mouse models of GBM.