Resection of metastases in patients with BRAF mutated metastatic colon cancer: results of a multicenter retrospective study

Introduction: local treatment of metastases is an integral part of colon cancer treatment. However, there is not enough data on the efficacy of surgical resection of metastases in patients with a BRAF gene mutation to recom‑mend this approach in routine practice. We initiated a retrospective multicenter study to assess the incidence of BRAF gene mutations in patients with metastatic colon cancer and to study the efficacy of metastasectomy in this group of patients.Materials and methods: we selected all patients who underwent surgical resection of metastases in various sites from the database of patients with BRAF gene mutations created as a result of a multicenter retrospective study with participation of 7 clinics in the Russian Federation. All 57 patients with RAS gene mutations and 43 patients with wild‑type RAS and BRAF genes who also underwent surgical resection of metastases at any stage of treatment were selected from the register of the Chemotherapy Department No. 2 of the NMRC of Oncology named after N. N. Blokhin for comparative analysis. Disease‑free survival and overall survival were used as primary efficacy criteria.Results: we found 26 patients with BRAF gene mutations who underwent surgical resection of metastases. When comparing disease‑free survival, the worst median was achieved in the group of patients with BRAF gene mutations: 7 months versus 14 months in patients with RAS gene mutations (HR 0.4, 94 % CI 0.23–0.7, P = 0.006); median disease‑free survival was not achieved in the wild‑type RAS and BRAF group (HR 0.2, 95 % CI 0.11–0.45, P <0.001).The median overall survival in the BRAF gene mutation group was 26 months versus 38 months in the RAS gene mutations group (HR 0.8, 95 % CI 0.33–1.98, P = 0.6) and 49 months in the wtRAS/wtBRAF group (RR 0.46, 95 % CI 0.17–1.24, P = 0.1). Resection of recurrent tumors in patients with metastases in retroperitoneal lymph nodes was associated with extremely low disease‑free survival (2 months); at the same time, disease‑free survival was 7 months after resection of isolated metastases in the liver and 8 months for metastases in the peritoneum.Conclusion: prognosis of patients with a BRAF gene mutation after surgical resection of metastases is worse than in patients with a different mutation phenotype. Nevertheless, literature data, as well as the results of our study, confirm the possibility of performing metastasectomy with careful selection of patients.

Development and Validation of a Targeted ‘Liquid’ NGS Panel for Treatment Customization in Patients with Metastatic Colorectal Cancer

The detection of actionable mutations in tumor tissue is a prerequisite for treatment customization in patients with metastatic colorectal cancer (mCRC). Analysis of circulating tumor DNA (ctDNA) for the identification of such mutations in patients’ plasma is an attractive alternative to invasive tissue biopsies. Despite having the high analytical sensitivity required for ctDNA analysis, digital polymerase chain reaction (dPCR) technologies can only detect a very limited number of hotspot mutations, whilst a broader mutation panel is currently needed for clinical decision making. Recent advances in next-generation sequencing (NGS) have led to high-sensitivity platforms that allow screening of multiple genes at a single assay. Our goal was to develop a small, cost- and time-effective NGS gene panel that could be easily integrated in the day-to-day clinical routine in the management of patients with mCRC. We designed a targeted panel comprising hotspots in six clinically relevant genes (KRAS, NRAS, MET, BRAF, ERBB2 and EGFR) and validated it in a total of 68 samples from 30 patients at diagnosis, first and second disease progression. Results from our NGS panel were compared against plasma testing with BEAMing dPCR regarding the RAS gene status. The overall percent of agreement was 83.6%, with a positive and negative percent agreement of 74.3% and 96.2%, respectively. Further comparison of plasma NGS with standard tissue testing used in the clinic showed an overall percent agreement of 86.7% for RAS status, with a positive and negative percent agreement of 81.2% and 92.8%, respectively. Thus, our study strongly supports the validity and efficiency of an affordable targeted NGS panel for the detection of clinically relevant mutations in patients with mCRC.

Targeted Long-Read Sequencing Decodes the Transcriptional Atlas of the Founding RAS Gene Family Members

The complicity of human RAS proteins in cancer is a well-documented fact, both due to the mutational hyperactivation of these GTPases and the overexpression of the genes encoding these proteins. Thus, it can be easily assumed that the study of RAS genes at the transcriptional and post-transcriptional level is of the utmost importance. Although previous research has shed some light on the basic mechanisms by which GTPases are involved in tumorigenesis, limited information is known regarding the transcriptional profile of the genes encoding these proteins. The present study highlights for the first time the wide spectrum of the mRNAs generated by the three most significant RAS genes (KRAS, NRAS and HRAS), providing an in-depth analysis of the splicing events and exon/intron boundaries. The implementation of a versatile, targeted nanopore-sequencing approach led to the identification of 39 novel RAS mRNA transcript variants and to the elucidation of their expression profiles in a broad panel of human cell lines. Although the present work unveiled multiple hidden aspects of the RAS gene family, further study is required to unravel the biological function of all the novel alternative transcript variants, as well as the putative protein isoforms.

Renin-Angiotensin System Single Nucleotide Polymorphisms Are Associated with Bladder Cancer Risk

The renin-angiotensin system (RAS), besides being a major regulator of blood pressure, is also involved in tumor angiogenesis. Emerging evidence suggests a correlation between the use of pharmacologic RAS inhibitors and a delay in urothelial bladder cancer (BC) progression. However, it is unknown whether RAS gene variants may predispose to the development of BC. This study examined the association of RAS single nucleotide polymorphisms (SNPs) including AT1R rs5186, AT2R rs11091046, REN rs12750834, ANG rs4762, and ANG rs699 with the risk of developing non-invasive BC. Peripheral blood samples from 73 patients with T1 urothelial BC (66 men, seven women) and an equal number of healthy subjects (control group) were collected. The TT genotype of the REN rs12750834 SNP (OR: 2.8 [1.3–6.05], p = 0.008) and to a lesser extent the presence of the T allele (OR: 2.3 [1.2–4.48], p = 0.01) conferred a higher risk of BC. The highest risk for BC within SNP carriers of the RAS system was associated with the presence of the CC genotype (OR: 17.6 [7.5–41.35], p < 0.001) and C allele (OR: 17.7 [8.8–35.9], p < 0.001) of the ANG rs699 SNP. The presence of the AT2R rs11091046 SNP, particularly the AA genotype, was associated with a protective effect against developing BC (OR: 0.268 [0.126–057], p < 0.001). In conclusion, these results support the clinical utility of RAS gene SNPs AT2R rs11091046, REN rs12750834, and ANG rs699 in the genetic cancer risk assessment of patients and families with BC.

Small-Molecule Inhibitors and Degraders Targeting KRAS-Driven Cancers

Drug resistance continues to be a major problem associated with cancer treatment. One of the primary causes of anticancer drug resistance is the frequently mutated RAS gene. In particular, considerable efforts have been made to treat KRAS-induced cancers by directly and indirectly controlling the activity of KRAS. However, the RAS protein is still one of the most prominent targets for drugs in cancer treatment. Recently, novel targeted protein degradation (TPD) strategies, such as proteolysis-targeting chimeras, have been developed to render “undruggable” targets druggable and overcome drug resistance and mutation problems. In this study, we discuss small-molecule inhibitors, TPD-based small-molecule chemicals for targeting RAS pathway proteins, and their potential applications for treating KRAS-mutant cancers. Novel TPD strategies are expected to serve as promising therapeutic methods for treating tumor patients with KRAS mutations.

Medulläres Schilddrüsenkarzinom

Was ist neu? Diagnose und Prognose Calcitonin ist ein sensitiver und spezifischer Tumormarker zur Früherkennung und Verlaufskontrolle des MTC. Daneben kommt dem Ultraschall der Schilddrüse eine entscheidende Rolle zu. Rolle des RET-Proto-Onkogens Das medulläre Schilddrüsenkarzinom (MTC) nimmt seinen Ursprung aus den parafollikulären Calcitonin-produzierenden C-Zellen. Es macht nur ca. 3–8 % aller Schilddrüsenkarzinome aus. Aktivierende Mutationen im RET (rearranged during transfection)-Gen liegen bei etwa 25 % der Patienten in der Keimbahn vor, werden aber auch beim sporadischen MTC als somatische Mutationen in ca. 60 % der Fälle beobachtet. Bei metastasierter Erkrankung findet sich in 90 % eine RET-Mutation. RET-Mutationen gelten als Treibermutationen und schließen weitere Treibermutationen weitestgehend aus. Seltener sind somatische Mutationen der RAS-Gene. Chirurgische Therapie Die chirurgische Resektion ist bis heute der einzige kurative Therapieansatz. Entscheidend für eine frühzeitige Diagnosestellung ist die Bestimmung des Serum-Calcitonins bei Nachweis von Schilddrüsenknoten. Die chirurgische Therapie steht auch bei der Behandlung lokoregionärer Rezidive oder lokal angehbarer Metastasen im Zentrum. Systemtherapie Bei irresektabel fortgeschrittener und progredienter Erkrankung mit signifikanter Tumorlast kann eine systemische Therapie erforderlich werden. Neuerdings ist die Kenntnis einer RET-Mutation im Tumorgewebe therapeutisch relevant, da mit den selektiven RET-Inhibitoren Selpercatinib und zukünftig Pralsetinib neue, effektive und gut verträgliche Systemtherapien zur Verfügung stehen. Ihr Einsatz ist nach Vortherapie mit einem der Multityrosinkinase-Inhibitoren Vandetanib oder Cabozantinib zugelassen und wird derzeit in der Erstlinientherapie in klinischen Studien untersucht.

THE IMPORTANCE OF CIRCULATING TUMOR DNA IN THE ASSESSMENT OF METASTATIC COLORECTAL CANCER TREATMENT EFFECTIVNE

Challenges in cancer detection, prognosis and management are currently being solved by determining circulating tumor DNA (ctDNA). The assessment of this marker has acquired particular importance in metastatic colorectal cancer (mCRC), the systemic treatment of which depends on the RAS gene status, which has prognostic and predictive value. However, the possibilities of taking samples from the primary or metastatic lesion for pathomorphological and molecular analysis in CRC are often limited. The determination of ctDNA using liquid biopsy has an advantage over standard biopsy due to its low invasiveness and high availability of the method. Analysis of mutations using ctDNA as well as changes in the level of this marker is a criterion for the effectiveness of systemic treatment, as well as a factor that determines the risk of disease progression. Currently, the potential of using ctDNA to monitor effectiveness of first-and second-line chemotherapy, as well as to predict the development of secondary resistance to EGFR inhibitors (cetuximab and panitumumab) in the first-line treatment and assessment of RAS status for returning to therapy with EGFR inhibitors in the third-line treatment of mCRC is being studied. Several pilot studies have provided evidence of the efficacy of EGFR re-treatment. The modern literature data published in leading peer-reviewed journals in Russian and international scientific citation databases, such as Medline, Elibrary, and PubMed were analyzed. Of the 138 analyzed publications, 56 were used to write this review.

Correlation of N-Ras Gene Expression in Hepatocellular Carcinoma with Color Doppler Ultrasound Findings

Objective: This study aims to study the N-ras gene expression in hepatocellular carcinoma (HCC) and its correlation with color Doppler imaging manifestations. Methods: The tumors of 145 HCC patients were evaluated via color Doppler ultrasonography before operation and N-ras level in tissue specimens obtained after operation were detected via RT-PCR, Western blotting and immunohistochemistry along with correlation analysis. Results: N-ras mRNA in para-carcinoma tissues was significantly reduced compared with carcinoma tissues (P < 0.05). Western blotting and immunohistochemistry showed a significant difference of N-ras protein level between para-carcinoma tissues and carcinoma tissues (P < 0.05). Moreover, N-ras gene expression was siginificantly correlated with the number of tumor nodules, the integrity of tumor capsule, vascular invasion, blood flow classification, RI (P < 0.05). Conclusion: Our data demonstrate the elevation of N-ras in the carcinoma tissues of HCC patients and its correlation with color Doppler imaging manifestations, which lays foundation for the development of the diagnosis of hepatocellular carcinoma.

Highlights on the Role of KRAS Mutations in Reshaping the Microenvironment of Pancreatic Adenocarcinoma

The most frequent mutated oncogene family in the history of human cancer is the RAS gene family, including NRAS, HRAS, and, most importantly, KRAS. A hallmark of pancreatic cancer, recalcitrant cancer with a very low survival rate, is the prevalence of oncogenic mutations in the KRAS gene. Due to this fact, studying the function of KRAS and the impact of its mutations on the tumor microenvironment (TME) is a priority for understanding pancreatic cancer progression and designing novel therapeutic strategies for the treatment of the dismal disease. Despite some recent enlightening studies, there is still a wide gap in our knowledge regarding the impact of KRAS mutations on different components of the pancreatic TME. In this review, we will present an updated summary of mutant KRAS role in the initiation, progression, and modulation of the TME of pancreatic ductal adenocarcinoma (PDAC). This review will highlight the intriguing link between diabetes mellitus and PDAC, as well as vitamin D as an adjuvant effective therapy via TME modulation of PDAC. We will also discuss different ongoing clinical trials that use KRAS oncogene signaling network as therapeutic targets.

Carcinogen-induced DNA structural distortion differences in the RAS gene isoforms; the importance of local sequence

Background Local sequence context is known to have an impact on the mutational pattern seen in cancer. The RAS genes and a smoking carcinogen, Benzo[a]pyrene diol epoxide (BPDE), have been utilised to explore these context effects. BPDE is known to form an adduct at the guanines in a number of RAS gene sites, KRAS codons 12, 13 and 14, NRAS codon 12, and HRAS codons 12 and 14. Results Molecular modelling techniques, along with multivariate analysis, have been utilised to determine the sequence influenced differences between BPDE-adducted RAS gene sequences as well as the local distortion caused by the adducts. Conclusions We conclude that G:C > T:A mutations at KRAS codon 12 in the tumours of lung cancer patients (who smoke), proposed to be predominantly caused by BPDE, are due to the effect of the interaction methyl group at the C5 position of the thymine base in the KRAS sequence with the BPDE carcinogen investigated causing increased distortion. We further suggest methylated cytosine would have a similar effect, showing the importance of methylation in cancer development.