Development of combination therapies with BTK inhibitors and dasatinib to treat CNS-infiltrating E2A-PBX1+/preBCR+ ALL.

ABSTRACT: The t(1;19) translocation, encoding the oncogenic fusion protein E2A (TCF3)-PBX1, is involved in acute lymphoblastic leukemia (ALL) and associated with a pre-B-cell receptor (preBCR+) phenotype. Relapse in patients with E2A-PBX1+ ALL frequently occurs in the central nervous system (CNS). Therefore, there is a medical need for the identification of CNS active regimens for the treatment of E2A-PBX1+/preBCR+ ALL. Using unbiased short hairpin RNA (shRNA) library screening approaches, we identified Bruton tyrosine kinase (BTK) as a key gene involved in both proliferation and dasatinib sensitivity of E2A-PBX1+/preBCR+ ALL. Depletion of BTK by shRNAs resulted in decreased proliferation of dasatinib-treated E2A-PBX1+/preBCR+ cells compared with control-transduced cells. Moreover, the combination of dasatinib with BTK inhibitors (BTKi; ibrutinib, acalabrutinib, or zanubrutinib) significantly decreased E2A-PBX1+/preBCR+ human and murine cell proliferation, reduced phospholipase C gamma 2 (PLCG2) and BTK phosphorylation and total protein levels and increased disease-free survival of mice in secondary transplantation assays, particularly reducing CNS-leukemic infiltration. Hence, dasatinib with ibrutinib reduced pPLCG2 and pBTK in primary ALL patient samples, including E2A-PBX1+ ALLs. In summary, genetic depletion and pharmacological inhibition of BTK increase dasatinib effects in human and mouse with E2A-PBX1+/preBCR+ ALL across most of performed assays, with the combination of dasatinib and BTKi proving effective in reducing CNS infiltration of E2A-PBX1+/preBCR+ ALL cells in vivo.

Sensitivity and Resistance of Oncogenic RAS-Driven Tumors to Dual MEK and ERK Inhibition.

Oncogenic mutations in RAS family genes arise frequently in metastatic human cancers. Here we developed new mouse and cellular models of oncogenic HrasG12V-driven undifferentiated pleomorphic sarcoma metastasis and of KrasG12D-driven pancreatic ductal adenocarcinoma metastasis. Through analyses of these cells and of human oncogenic KRAS-, NRAS- and BRAF-driven cancer cell lines we identified that resistance to single MEK inhibitor and ERK inhibitor treatments arise rapidly but combination therapy completely blocks the emergence of resistance. The prior evolution of resistance to either single agent frequently leads to resistance to dual treatment. Dual MEK inhibitor plus ERK inhibitor therapy shows anti-tumor efficacy in an HrasG12V-driven autochthonous sarcoma model but features of drug resistance in vivo were also evident. Array-based kinome activity profiling revealed an absence of common patterns of signaling rewiring in single or double MEK and ERK inhibitor resistant cells, showing that the development of resistance to downstream signaling inhibition in oncogenic RAS-driven tumors represents a heterogeneous process. Nonetheless, in some single and double MEK and ERK inhibitor resistant cell lines we identified newly acquired drug sensitivities. These may represent additional therapeutic targets in oncogenic RAS-driven tumors and provide general proof-of-principle that therapeutic vulnerabilities of drug resistant cells can be identified.

Glucagon-like peptide 2 for intestinal stem cell and Paneth cell repair during graft-versus-host disease in mice and humans.

Acute graft-versus-host disease (GVHD) is a life-threatening complication after allogeneic hematopoietic cell transplantation (allo-HCT). Although currently used GVHD treatment regimens target the donor immune system, we explored here an approach that aims at protecting and regenerating Paneth cells (PCs) and intestinal stem cells (ISCs). Glucagon-like-peptide-2 (GLP-2) is an enteroendocrine tissue hormone produced by intestinal L cells. We observed that acute GVHD reduced intestinal GLP-2 levels in mice and patients developing GVHD. Treatment with the GLP-2 agonist, teduglutide, reduced de novo acute GVHD and steroid-refractory GVHD, without compromising graft-versus-leukemia (GVL) effects in multiple mouse models. Mechanistically GLP-2 substitution promoted regeneration of PCs and ISCs, which enhanced production of antimicrobial peptides and caused microbiome changes. GLP-2 expanded intestinal organoids and reduced expression of apoptosis-related genes. Low numbers of L cells in intestinal biopsies and high serum levels of GLP-2 were associated with a higher incidence of nonrelapse mortality in patients undergoing allo-HCT. Our findings indicate that L cells are a target of GVHD and that GLP-2-based treatment of acute GVHD restores intestinal homeostasis via an increase of ISCs and PCs without impairing GVL effects. Teduglutide could become a novel combination partner for immunosuppressive GVHD therapy to be tested in clinical trials.

Mouse genetic background influences whether HrasG12V expression plus Cdkn2a knockdown causes angiosarcoma or undifferentiated pleomorphic sarcoma.

Soft tissue sarcomas are rare mesenchymal tumours accounting for 1% of adult malignancies and are fatal in approximately one third of patients. Two of the most aggressive and lethal forms of soft tissue sarcomas are angiosarcomas and undifferentiated pleomorphic sarcomas (UPS). To examine sarcoma-relevant molecular pathways, we employed a lentiviral gene regulatory system to attempt to generate in vivo models that reflect common molecular alterations of human angiosarcoma and UPS. Mice were intraveneously injected with MuLE lentiviruses expressing combinations of shRNA against Cdkn2a, Trp53, Tsc2 and Pten with or without expression of HrasG12V , PIK3CAH1047R or Myc. The systemic injection of an ecotropic lentivirus expressing oncogenic HrasG12V together with the knockdown of Cdkn2a or Trp53 was sufficient to initiate angiosarcoma and/or UPS development, providing a flexible system to generate autochthonous mouse models of these diseases. Unexpectedly, different mouse strains developed different types of sarcoma in response to identical genetic drivers, implicating genetic background as a contributor to the genesis and spectrum of sarcomas.

Oncogenic HrasG12V expression plus knockdown of Cdkn2a using ecotropic lentiviral vectors induces high-grade endometrial stromal sarcoma.

The uterine corpus represents the most common site for tumour development in the female genital system. Uterine neoplasms are categorised as epithelial, mesenchymal, mixed epithelial-mesenchymal or trophoblastic tumours. In this study we employed a mouse genetic approach using the MuLE lentiviral gene regulatory system to functionally test the ability of ecotropic lentiviruses to model epithelial and mesenchymal uterine malignancies ex vivo and in vivo. We discovered that MuLE lentiviruses efficiently infect uterine stromal cells but not endometrial epithelial cells when injected into the uterus of cycling, pseudopregnant or ovarectomized mice. Consistent with this cellular infection spectrum, we show that intra-uterine injection of ecotropic MuLE viruses expressing oncogenic HrasG12V together with knockdown of Cdkn2a induce high-grade endometrial stromal sarcomas. These findings establish this approach as an efficient method of generating autochthonous mouse models of uterine sarcomas and in general for performing genetic manipulations of uterine stromal cells in vivo.

Combined mutation in Vhl, Trp53 and Rb1 causes clear cell renal cell carcinoma in mice.

Clear cell renal cell carcinomas (ccRCCs) frequently exhibit inactivation of the von Hippel-Lindau tumor-suppressor gene, VHL, and often harbor multiple copy-number alterations in genes that regulate cell cycle progression. We show here that modeling these genetic alterations by combined deletion of Vhl, Trp53 and Rb1 specifically in renal epithelial cells in mice caused ccRCC. These tumors arose from proximal tubule epithelial cells and shared molecular markers and mRNA expression profiles with human ccRCC. Exome sequencing revealed that mouse and human ccRCCs exhibit recurrent mutations in genes associated with the primary cilium, uncovering a mutational convergence on this organelle and implicating a subset of ccRCCs as genetic ciliopathies. Different mouse tumors responded differently to standard therapies for advanced human ccRCC, mimicking the range of clinical behaviors in the human disease. Inhibition of hypoxia-inducible factor (HIF)-α transcription factors with acriflavine as third-line therapy had therapeutic effects in some tumors, providing preclinical evidence for further investigation of HIF-α inhibition as a ccRCC treatment. This autochthonous mouse ccRCC model represents a tool to investigate the biology of ccRCC and to identify new treatment strategies.

Finding of Anopheles (Anopheles) hyrcanus (Pallas, 1771) (Diptera, Culicidae) during the entomological surveillance for West Nile virus in Umbria, Italy.

This study reports the mosquito collections conducted in July-August 2013 in Castiglione del Lago (Umbria Region, Italy) during the entomological surveillance within the West Nile national control program. The mosquito collections showed the noteworthy occurrence of Anopheles hyrcanus s.l. (n = 156; 35.8% of the whole sample), a relatively rare mosquito species in Italy, with molecular analyses con rming that these mosquitoes belong to An. hyrcanus s.s. The same catching site was characterized by a relevant richness in mosquito species, in particular the following were found: Anopheles maculipennis s.l. (n = 146; 33.5% composed by 80% Anopheles melanoon, 13.3% Anopheles maculipennis s.s. and 6.7% Anopheles atroparvus), Culex pipiens s.l. (n = 116; 26.6% composed by 90% Cx. p. pipiens, 5% Cx. p. molestus and 5% Cx. p. pipiens/molestus), Culiseta annulata (n = 10; 2.3%), Aedes albopictus (n = 3; 0.7%), and Anopheles claviger (n = 5; 100%).

A versatile modular vector system for rapid combinatorial mammalian genetics.

Here, we describe the multiple lentiviral expression (MuLE) system that allows multiple genetic alterations to be introduced simultaneously into mammalian cells. We created a toolbox of MuLE vectors that constitute a flexible, modular system for the rapid engineering of complex polycistronic lentiviruses, allowing combinatorial gene overexpression, gene knockdown, Cre-mediated gene deletion, or CRISPR/Cas9-mediated (where CRISPR indicates clustered regularly interspaced short palindromic repeats) gene mutation, together with expression of fluorescent or enzymatic reporters for cellular assays and animal imaging. Examples of tumor engineering were used to illustrate the speed and versatility of performing combinatorial genetics using the MuLE system. By transducing cultured primary mouse cells with single MuLE lentiviruses, we engineered tumors containing up to 5 different genetic alterations, identified genetic dependencies of molecularly defined tumors, conducted genetic interaction screens, and induced the simultaneous CRISPR/Cas9-mediated knockout of 3 tumor-suppressor genes. Intramuscular injection of MuLE viruses expressing oncogenic H-RasG12V together with combinations of knockdowns of the tumor suppressors cyclin-dependent kinase inhibitor 2A (Cdkn2a), transformation-related protein 53 (Trp53), and phosphatase and tensin homolog (Pten) allowed the generation of 3 murine sarcoma models, demonstrating that genetically defined autochthonous tumors can be rapidly generated and quantitatively monitored via direct injection of polycistronic MuLE lentiviruses into mouse tissues. Together, our results demonstrate that the MuLE system provides genetic power for the systematic investigation of the molecular mechanisms that underlie human diseases.