Treatments for gastrointestinal stromal tumors that are resistant to standard therapies

RNA profiling and immunohistochemistry analyses of circRNAs in imatinib-resistant gastrointestinal stromal tumors

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal sarcomas of the upper digestive tract. Imatinib is the first-line therapy for patients with metastatic or unresectable GISTs. However, the majority of GIST patients eventually develop imatinib resistance.

METHODS

To identify the factors that are responsible for imatinib resistance, we investigated the differentially expressed mRNAs and circRNAs in imatinib-naïve and imatinib-resistant GISTs via ceRNA microarrays. The expression levels of circ-BRIP1, circ-EPHB4 and their host genes were validated via quantitative real-time PCR analyses and formalin-fixed and paraffin-embedded (FFPE) tissue microarrays (TMAs).

RESULTS

We found that 107 mRNAs and 521 circRNAs were differentially expressed between imatinib-resistant and imatinib-naïve GIST tissue samples. Among them, circ-BRIP1, circ-EPHB4 and their host genes were upregulated in imatinib-resistant GISTs and associated with imatinib resistance, tumor relapse and progression, and metastasis in GIST patients. The expression level of EPHB4 was significantly greater in high-grade GISTs than in low-grade GISTs and was correlated with imatinib resistance.

CONCLUSIONS

Our results demonstrated that the circRNA in situ hybridization-immunohistochemistry could not only be applied to FFPE-TMAs for high-throughput analysis of circRNA expression in tumors but also suggested a possible role for circ-BRIP1, circ-EPHB4, and their host genes in the progression of GISTs.

Radiotherapy in the Management of Gastrointestinal Stromal Tumors: A Systematic Review

Gastrointestinal stromal tumors (GISTs) are considered insensitive to radiotherapy. However, a growing number of case reports and case series have shown that some lesions treated by radiotherapy achieved an objective response. The aim of the study was to perform a systematic review of all reported cases, case series, and clinical studies of GISTs treated with radiotherapy to reevaluate the role of radiotherapy in GISTs. A systematic search of the English-written literature was conducted using PubMed, Web of Science, and Embase databases. Overall, 41 articles describing 112 patients were retrieved. The included articles were of low to moderate quality. Bone was the most common site treated by radiotherapy, followed by the abdomen. In order to exclude the influence of effective tyrosine kinase inhibitors (TKIs), a subgroup analysis was conducted on whether and which TKIs were concurrently applied with radiotherapy. Results showed that radiotherapy alone or combined with resistant TKIs could help achieve objective response in selected patients with advanced or metastatic GISTs; however, survival benefits were not observed in the included studies. Pain was the most common symptom in symptomatic GISTs, followed by neurological dysfunction and bleeding. The symptom palliation rate was 78.6% after excluding the influence of effective TKIs. The adverse reactions were mainly graded 1-2. Radiotherapy was generally well-tolerated. Overall, radiotherapy may relieve symptoms for GIST patients with advanced or metastatic lesions and even help achieve objective response in selected patients without significantly reducing the quality of life. In addition to bone metastases, fixed abdominal lesions may be treated by radiotherapy. Publication bias and insufficient quality of included studies were the main limitations in this review. Further clinical studies are needed and justified.

Adjunctive treatment of myxopapillary ependymoma

Myxopapillary ependymoma are rare tumors and optimal therapeutic strategy is remained controversial. The main treatments for myxopapillary ependymoma tumors include surgery and radiotherapy. Hence, the present study aimed to review adjuvant treatment of myxopapillary ependymoma, focusing on spinal myxopapillary ependymoma. The information sources of all articles were the English authoritative databases including PubMed, Web of science, Scopus, Science direct and Google scholar. In this review study, the keywords including adjuvant, treatment, myxopapillary and ependymoma were selected from MeSH medical library. Related articles were published from 2000 to 2020. Given radiation tolerance in the spinal cord is 10-15% lower than that of the brain, it also should be noted that with increased dose and scope of therapeutic field, the corresponding risks are increased, as well. Also, chemotherapy has never been used as the primary treatment approach. Radiotherapy's value is considered while involving with sensitive areas where chemotherapy is also recommended. Gross total resection is the preferred primary treatment. But the role of adjuvant radiotherapy is debated in different tumor and patient scenarios and no standard treatment strategy had been defined yet. The bottom line is that as long as cellular and molecular methods or gene therapy can be used in the treatment of myxopapillary ependymoma, all the studies confirm that the best treatment method is still wide surgical resection as much as possible.

Pimozide Inhibits the Human Prostate Cancer Cells Through the Generation of Reactive Oxygen Species

The United States Food and Drug Administration-approved antipsychotic drug, pimozide, has anticancer activities. However, the role of reactive oxygen species (ROS) in its effect on prostate cancer is not well-known. We examined cell proliferation, colony formation, migration, ROS production, and the expression of antioxidant-related genes after treatment of human prostate cancer PC3 and DU145 cells with pimozide. In addition, histopathology, ROS production, and superoxide dismutase (SOD) activity were analyzed after administering pimozide to TRAMP, a transgenic mouse with prostate cancer. Pimozide increased the generation of ROS in both cell lines and inhibited cell proliferation, migration, and colony formation. Oxidative stress induced by pimozide caused changes in the expression of antioxidant enzymes (SOD1, peroxiredoxin 6, and glutathione peroxidase 2) and CISD2. Co-treatment with glutathione, an antioxidant, reduced pimozide-induced ROS levels, and counteracted the inhibition of cell proliferation. Administration of pimozide to TRAMP mice reduced the progression of prostate cancer with increased ROS generation and decreased SOD activity. These results suggest that the antipsychotic drug, pimozide, has beneficial effects in prostate cancer in vivo and in vitro. The mechanism of pimozide may be related to augmenting ROS generation. We recommend pimozide as a promising anticancer agent.

The neuroleptic drug pimozide inhibits stem-like cell maintenance and tumorigenicity in hepatocellular carcinoma

Drug repurposing is currently an important approach for accelerating drug discovery and development for clinical use. Hepatocellular carcinoma (HCC) presents drug resistance to chemotherapy, and the prognosis is poor due to the existence of liver cancer stem-like cells. In this study, we investigated the effect of the neuroleptic agent pimozide to inhibit stem-like cell maintenance and tumorigenicity in HCC. Our results showed that pimozide functioned as an anti-cancer drug in HCC cells or stem-like cells. Pimozide inhibited cell proliferation and sphere formation capacities in HCC cells by inducing G0/G1 phase cell cycle arrest, as well as inhibited HCC cell migration. Surprisingly, pimozide inhibited the maintenance and tumorigenicity of HCC stem-like cells, particularly the side population (SP) or CD133-positive cells, as evaluated by colony formation, sphere formation and transwell migration assays. Furthermore, pimozide was found to suppress STAT3 activity in HCC cells by attenuating STAT3-dependent luciferase activity and down-regulating the transcription levels of downstream genes of STAT3 signaling. Moreover, pimozide reversed the stem-like cell tumorigenic phenotypes induced by IL-6 treatment in HCC cells. Further, the antitumor effect of pimozide was also proved in the nude mice HCC xenograft model. In short, the anti-psychotic agent pimozide may act as a novel potential anti-tumor agent in treating advanced HCC.

Genetic progression in gastrointestinal stromal tumors: mechanisms and molecular interventions

Gastrointestinal stromal tumors (GISTs) are the most common sarcomas in humans. Constitutively activating mutations in the KIT or PDGFRA receptor tyrosine kinases are the initiating oncogenic events. Most metastatic GISTs respond dramatically to therapies with KIT/PDGFRA inhibitors. Asymptomatic and mitotically-inactive KIT/PDGFRA-mutant "microGISTs" are found in one third of adults, but most of these small tumors never progress to malignancy, underscoring that a progression of oncogenic mutations is required. Recent studies have identified key genomic abnormalities in GIST progression. Novel insights into the genetic progression of GISTs are shedding new light on therapeutic innovations.

Molecular characterization of metastatic exon 11 mutant gastrointestinal stromal tumors (GIST) beyond KIT/PDGFRα genotype evaluated by next generation sequencing (NGS)

About 85% of GISTs are associated with KIT and PDGFRα gene mutations, which predict response to tyrosine kinase inhibitors. Although the outcomes in patients affected by GIST have dramatically improved, tumor progression control still remains a challenge. The aim of this study is the genomic characterization of individual metastatic KIT-exon 11-mutant GIST to identify additional aberrations and simultaneous molecular events representing potential therapeutic targets.Seven patients with metastatic GIST were studied with whole transcriptome sequencing and copy number analysis. Somatic single nucleotide variations were called; however, no shared mutated genes were detected except KIT. Almost all patients showed loss of genomic regions containing tumor suppressor genes, sometimes coupled with single nucleotide mutation of the other allele. Additionally, six fusion transcripts were found and three patients showed amplifications involving known oncogenes.Evaluating the concordance between CN status and mRNA expression levels, we detected overexpression of CCND2 and EGFR and silencing of CDKN2A, CDKN2C, SMARCB1, PTEN and DMD. Altered expression of these genes could be responsible for aberrant activation of signaling pathways that support tumor growth. In this work, we assessed the effect of Hedgehog pathway inhibition in GIST882 cells, which causes decrement of cell viability associated with reduction of KIT expression.Additional genomic alterations not previously reported in GIST were found even if not shared by all samples. This contributes to a more detailed molecular understanding of this disease, useful for identification of new targets and novel therapeutics and representing a possible point of departure for a truly individualized clinical approach.

miRNA profiling in gastrointestinal stromal tumors: implication as diagnostic and prognostic markers

MicroRNAs are a class of short noncoding RNAs, that play a relevant role in multiple biological processes, such as differentiation, proliferation and apoptosis. Gastrointestinal stromal tumors (GIST) are considered as a paradigm of molecular biology in solid tumors worldwide, and after the discovery of specific alterations in the KIT and PDGFRA genes, they have emerged from anonymity to become a model for targeted therapy. Epigenetics have an emerging and relevant role in different steps of GIST biology such as tumorigenesis, disease progression, prognosis and drug resistance. The aim of the present review was to summarize the current evidence about the role of microRNAs in GIST, including their potential application as well as their limits.

Sorafenib continuation or discontinuation in patients with unresectable hepatocellular carcinoma after a complete response

AIMS

To assess the efficacy of continued administration of sorafenib for patients with unresectable hepatocellular carcinoma (HCC) treated with local regional therapy (LRT) after a complete response (CR), also, the adverse events of sorafenib after discontinuation of administration were observed.

METHODS

Between April 2008 and May 2012, 956 consecutive patients with unresectable HCC treated with LRT (transarterial chemoembolization, radiofrequency ablation) combined with sorafenib were retrospectively investigated. Of these, 157 patients with a CR were enrolled: 102 of them continued to receive sorafenib (test group) and the other 55 stopped receiving sorafenib (control group).

RESULTS

The median recurrence-free survival (RFS), post-complete response overall survival (pOS) and overall survival (OS) in the test and control groups were 11 months (95% CI: 6.1, 15.9), 25 months (95% CI: 20.7, 29.3) and 33 months (95% CI: 29.2, 36.8) and 12 months (95% CI: 10.4, 13.6), 28 months (95% CI 24.2, 31.8) and 34 months (95% CI: 30.8, 37.2) respectively. The differences in RFS, pOS and OS between the groups were not significant (P = 0.768, 0.797 and 0.730, respectively). The adverse events related to sorafenib resolved after discontinuation of administration and the quality of life (QoL) scores improved.

CONCLUSIONS

Patients with unresectable HCC who achieved a CR did not benefit from continued sorafenib in terms of RFS, pOS or OS. The adverse events of sorafenib were reversible, and discontinuation of sorafenib may improve the QoL of patients who have achieved a CR.