Constantine Alifrangis

BRAF inhibitor resistance mediated by the AKT pathway in an oncogenic BRAF mouse melanoma model.

Significance Using Sleeping Beauty transposon mutagenesis in a melanoma model driven by oncogenic BRAF (B-Raf proto-oncogene, serine/threonine kinase), we identified both known and novel candidate genes that mediate resistance to the BRAF inhibitor PLX4720. We validate ES-cell expressed Ras as a novel promoter of BRAF inhibitor resistance and propose that AKT (v-akt murine thymoma viral oncogene homolog 1)-mediated inactivation of BAD (BCL2-associated agonist of cell death) constitutes a pathway that may contribute to hepatocyte growth factor-mediated therapy resistance. Our work establishes Sleeping Beauty mutagenesis as a powerful tool for the identification of novel resistance genes and mechanisms in genetically modified mouse models. BRAF (v-raf murine sarcoma viral oncogene homolog B) inhibitors elicit a transient anti-tumor response in ∼80% of BRAFV600-mutant melanoma patients that almost uniformly precedes the emergence of resistance. Here we used a mouse model of melanoma in which melanocyte-specific expression of BrafV618E (analogous to the human BRAFV600E mutation) led to the development of skin hyperpigmentation and nevi, as well as melanoma formation with incomplete penetrance. Sleeping Beauty insertional mutagenesis in this model led to accelerated and fully penetrant melanomagenesis and synchronous tumor formation. Treatment of BrafV618E transposon mice with the BRAF inhibitor PLX4720 resulted in tumor regression followed by relapse. Analysis of transposon insertions identified eight genes including Braf, Mitf, and ERas (ES-cell expressed Ras) as candidate resistance genes. Expression of ERAS in human melanoma cell lines conferred resistance to PLX4720 and induced hyperphosphorylation of AKT (v-akt murine thymoma viral oncogene homolog 1), a phenotype reverted by combinatorial treatment with PLX4720 and the AKT inhibitor MK2206. We show that ERAS expression elicits a prosurvival signal associated with phosphorylation/inactivation of BAD, and that the resistance of hepatocyte growth factor-treated human melanoma cells to PLX4720 can be reverted by treatment with the BAD-like BH3 mimetic ABT-737. Thus, we define a role for the AKT/BAD pathway in resistance to BRAF inhibition and illustrate an in vivo approach for finding drug resistance genes.

EMA/CO for High-Risk Gestational Trophoblastic Neoplasia: Good Outcomes With Induction Low-Dose Etoposide-Cisplatin and Genetic Analysis

PURPOSE Patients with high-risk (International Federation of Gynecology and Obstetrics score ≥ 7) gestational trophoblastic neoplasia (GTN) frequently receive etoposide, methotrexate, and dactinomycin alternating weekly with cyclophosphamide and vincristine (EMA/CO). Between 1979 and 1995, overall survival (OS) with this regimen at our institute was 85.4% with a significant proportion of early deaths (< 4 weeks). Here, we determine whether survival rates have improved in a more recent patient cohort (1995 to 2010). PATIENTS AND METHODS Patients receiving EMA/CO were identified using the Charing Cross GTN database. Genetic analysis identified nongestational trophoblastic tumors (nGTTs). The use of induction low-dose etoposide 100 mg/m(2) and cisplatin 20 mg/m(2) (EP; days 1 and 2 every 7 days) since 1995 to reduce early deaths before commencing EMA/CO was noted. RESULTS Four hundred thirty-eight patients received EMA/CO between 1995 and 2010. Six patients had nGTTs, 140 had high-risk disease, and 250 had relapsed/resistant low-risk GTN. OS was 94.3% in high-risk patients (90.4% including nGTTs) and 99.6% in the low-risk group, with a median follow-up time of 4.2 years. All patients with nGTT and seven patients with high-risk GTNs died as a result of drug-resistant disease. EP induction chemotherapy was given to 23.1% of high-risk patients (33 of 140 patients) with a large disease burden, and the early death rate was only 0.7% (n = 1; 95% CI, 0.1% to 3.7%) compared with 7.2% (n = 11 of 151 patients; 95% CI, 4.1% to 12.6%) in the pre-1995 cohort. CONCLUSION OS after EMA/CO for high-risk GTN has increased by nearly 9%. This reflects a more accurate estimate of OS by excluding nGTTs (3.9%) in patients with atypical presentations using genetic diagnosis. Low-dose induction EP in selected individuals also allows near complete elimination of early deaths. The latter should be considered routinely in high-risk GTN.

Inactivating CUX1 mutations promote tumorigenesis

A major challenge in cancer genetics is to determine which low-frequency somatic mutations are drivers of tumorigenesis. Here we interrogate the genomes of 7,651 diverse human cancers and find inactivating mutations in the homeodomain transcription factor gene CUX1 (cut-like homeobox 1) in ∼1–5% of various tumors. Meta-analysis of CUX1 mutational status in 2,519 cases of myeloid malignancies reveals disruptive mutations associated with poor survival, highlighting the clinical significance of CUX1 loss. In parallel, we validate CUX1 as a bona fide tumor suppressor using mouse transposon-mediated insertional mutagenesis and Drosophila cancer models. We demonstrate that CUX1 deficiency activates phosphoinositide 3-kinase (PI3K) signaling through direct transcriptional downregulation of the PI3K inhibitor PIK3IP1 (phosphoinositide-3-kinase interacting protein 1), leading to increased tumor growth and susceptibility to PI3K-AKT inhibition. Thus, our complementary approaches identify CUX1 as a pan-driver of tumorigenesis and uncover a potential strategy for treating CUX1-mutant tumors.

Extracellular vesicles swarm the cancer microenvironment: from tumor–stroma communication to drug intervention

Intercellular communication sets the pace for transformed cells to survive and to thrive. Extracellular vesicles (EVs), such as exosomes, microvesicles and large oncosomes, are involved in this process shuttling reciprocal signals and other molecules between transformed and stromal cells, including fibroblasts, endothelial and immune cells. As a result, these cells are adapted or recruited to a constantly evolving cancer microenvironment. Moreover, EVs take part in the response to anticancer therapeutics not least by promoting drug resistance throughout the targeted tumor. Finally, circulating EVs can also transport important molecules to remote destinations in order to prime metastatic niches in an otherwise healthy tissue. Although the understanding of EV biology remains a major challenge in the field, their characteristics create new opportunities for advances in cancer diagnostics and therapeutics.

Langerhans cell histiocytosis: old disease new treatment

Langerhans cell histiocytosis (LCH) has been previously thought of as a rare illness, but is now increasingly diagnosed as a result of the more intensive investigations of patients with cystic pulmonary disease. In recent years, treatments developed from our new understanding of the molecular biology of malignant disease have been applied to patients with LCH, and responses seen. In this review, we describe the origins, presentation and modern treatment of LCH, showing that there is new hope for patients with this condition.

Reading between the lines; understanding drug response in the post genomic era

Following the fanfare of initial, often dramatic, success with small molecule inhibitors in the treatment of defined genomic subgroups, it can be argued that the extension of targeted therapeutics to the majority of patients with solid cancers has stalled. Despite encouraging FDA approval rates, the attrition rates of these compounds remains high in early stage clinical studies, with single agent studies repeatedly showing poor efficacy In striking contrast, our understanding of the complexity of solid neoplasms has increased in huge increments, following the publication of large‐scale genomic and transcriptomic datasets from large collaborations such as the International Cancer Genome Consortium (ICGC http://www.icgc.org/) and The Cancer Genome Atlas (TCGA http://cancergenome.nih.gov/). However, there remains a clear disconnect between these rich datasets describing the genomic complexity of cancer, including both intra‐ and inter‐tumour heterogeneity, and what a treating oncologist can consider to be a clinically “actionable” mutation profile. Our understanding of these data is in its infancy and we still find difficulties ascribing characteristics to tumours that consistently predict therapeutic response for the majority of small molecule inhibitors. This article will seek to explore the recent studies of the patterns and impact of mutations in drug resistance, and demonstrate how we may use this data to reshape our thinking about biological pathways, critical dependencies and their therapeutic interruption.

Anti Ma2-associated myeloradiculopathy: expanding the phenotype of anti-Ma2 associated paraneoplastic syndromes

Anti-Ma2 associated paraneoplastic syndrome usually presents as limbic encephalitis in association with testicular tumours.1 2 Only four patients have been reported with involvement outside the CNS, two of whom also had limbic or brainstem encephalitis.2 3 We report a man with anti-Ma2 associated myeloradiculopathy and previous testicular cancer whose neurological syndrome stabilised and anti-Ma2 titres fell following orchidectomy of a microscopically normal testis. A 46-year-old dentist noticed weakness of pincer movement in the left hand. Six weeks later he developed sequential finger drop of the 4th, 5th and 3rd fingers of the left hand over days. During the subsequent weeks the fingers of his right hand also dropped. He had a prior history of left orchidectomy for stage I testicular seminoma and had been well on surveillance for 5 years. MRI brain, cervical spine and brachial plexii were normal. A diagnosis of multifocal motor neuropathy with conduction block was considered. Neurophysiology of the upper limbs demonstrated reduced motor amplitudes and acute and chronic denervation but no conduction block. Neurophysiology of the lower limbs was normal. He was given a trial of intravenous immunoglobulin without response. Some weeks later he developed an unusual itchy sensation spreading across his back and shoulders. On examination there was head drop with weakness of neck flexion. There was wasting of both forearms and intrinsic hand muscles, with some fasciculations in the biceps and triceps. Tone was normal. There was asymmetric patchy proximal and distal weakness of both arms with finger drop. Reflexes were brisk …

Genome-wide chemical mutagenesis screens allow unbiased saturation of the cancer genome and identification of drug resistance mutations

Drug resistance is an almost inevitable consequence of cancer therapy and ultimately proves fatal for the majority of patients. In many cases, this is the consequence of specific gene mutations that have the potential to be targeted to resensitize the tumor. The ability to uniformly saturate the genome with point mutations without chromosome or nucleotide sequence context bias would open the door to identify all putative drug resistance mutations in cancer models. Here, we describe such a method for elucidating drug resistance mechanisms using genome-wide chemical mutagenesis allied to next-generation sequencing. We show that chemically mutagenizing the genome of cancer cells dramatically increases the number of drug-resistant clones and allows the detection of both known and novel drug resistance mutations. We used an efficient computational process that allows for the rapid identification of involved pathways and druggable targets. Such a priori knowledge would greatly empower serial monitoring strategies for drug resistance in the clinic as well as the development of trials for drug-resistant patients.

New drugs for prostate cancer

Whats known on the subject? and What does the study add?

Genetics of gestational trophoblastic neoplasia: an update for the clinician

Gestational trophoblastic disease is a spectrum of disorders ranging from premalignant hydatidiform moles through to malignant invasive moles, choriocarcinoma and rare placental site trophoblastic tumor. The latter are often collectively referred to as gestational trophoblastic tumors or neoplasia (GTN). Although most women can expect to be cured of their disease, many interesting questions arise in the management of gestational trophoblastic disease. Current issues pertain to diagnosis of GTN, predicting progression from hydatidiform moles to GTN and the emergence of drug resistance in GTN. Our understanding of the genetics of GTN has helped us answer some of these questions but many remain unresolved. This article seeks to address recent advances in the genetics of GTN in relation to diagnosis, etiology, prognosis and treatment.