Concomitant Mutations G12D and G13D on the Exon 2 of the KRAS Gene: Two Cases of Women with Colon Adenocarcinoma

Next-Generation Sequencing Comparative Analysis of DNA Mutations between Blood-Derived Extracellular Vesicles and Matched Cancer Tissue in Patients with Grade 4 Glioblastoma

The biological heterogeneity of glioblastoma, IDH-wildtype (GBM, CNS WHO grade 4), the most aggressive type of brain cancer, is a critical hallmark, caused by changes in the genomic mutational asset and influencing clinical progression over time. The understanding and monitoring of the mutational profile is important not only to reveal novel therapeutic targets in this set of patients, but also to ameliorate the clinical stratification of subjects and the prognostic significance. As neurosurgery represents the primary technique to manage GBM, it is of utmost importance to optimize alternative and less invasive methods to monitor the dynamic mutation profile of these patients. Extracellular vesicles (EVs) are included in the liquid biopsy analysis and have emerged as the biological mirror of escaping and surviving mechanisms by many tumors, including glioblastoma. Very few studies have investigated the technical feasibility to detect and analyze the genomic profile by Next-Generation Sequencing (UMI system) in circulating EVs of patients with grade IV glioblastoma. Here, we attempted to characterize and to compare the corresponding matched tissue samples and potential variants with pathogenic significance of the DNA contained in peripheral-blood-derived EVs. The NGS analysis has revealed that patients with grade IV glioblastoma exhibited lesser DNA content in EVs than controls and that, both in EVs and matched cancer tissues, the NF1 gene was consistently mutated in all patients, with the c.2568C>G as the most common pathogenic variant expressed. This study supports the clinical utility of circulating EVs in glioblastoma as an eligible tool for personalized medicine.

Characterization of KRAS Mutational Regression in Oligometastatic Patients

Background

We previously reported rare regressive genetic trajectories of KRAS pathogenic mutations as a specific hallmark of the genuine oligometastatic status in colorectal cancer (CRC).

Methods

Survival and prognostic impact of disease extent in 140 metastatic CRC patients were evaluated through the Kaplan–Meyer curves and the Log-Rank test. KRAS mutations were assessed through the Illumina NovaSeq 6000 platform and TruSight™ Oncology 500 kit. HLA typing was carried out by PCR with sequence-specific oligonucleotides. Lymphocyte densities in tumors were expressed as cells per square millimeter. NKs isolated and CD8+ from NK-depleted PBMCs were characterized through flow cytometry. CD107a externalization was evaluated as NKs/CD8 cytotoxicity toward human colon cancer cells HT29, SW620, HCT116, and LS174T carrying different KRAS mutations.

Results

The oligometastatic status was a strong and independent variable for survival (HR: 0.08 vs. polymetastatic disease; 95% CI: 0.02–0.26; p < 0.001). Eighteen oligometastatic patients were selected. Twelve were alive at the last follow-up, and 9 were characterized. Genetic regression of KRAS was observed in 3 patients: patient (PAT)2, PAT5, and PAT8. PAT2 and PAT5 presented the highest levels of GrzB+ lymphocytes in the tumor cores of the metastases (120 ± 11.2 and 132 ± 12.2 cells/mm2, respectively). Six out of 9 patients (67%), including PAT2 and PAT5, expressed HLA-C7. Twopatients (PAT2 and PAT5) presented high CD3+/CD8+-dependent cytotoxicity against HLA-C7+ SW620 cells (p.G12V-mutated cells), which was consistent with their observed mutational regression (p.G12V/p.G13D in primary→p.G13D in metastatic tumor).

Conclusions

We provide evidence that CD3+/CD8+ lymphocytes from oligometastatic CRC patients display differential cytotoxicity against human colon cancer cells carrying KRAS mutations. This could provide an interesting basis for monitoring oligometastatic disease and developing future adoptive immunotherapies.

Coexistence of two missense mutations in the KRAS gene in adenocarcinoma of the lung: a possible indicator of poor prognosis

Background

KRAS mutations are present in up to 30% of patients with lung adenocarcinoma. The two most common KRAS mutations in non-small cell lung cancer (NSCLC) are G12C (~40%) and G12V (~22%). We describe the case of a 63-year-old Asian male patient with a very aggressive lung adenocarcinoma harbouring two coexisting missense mutations in the same exon.

Methods

The patient presented with a 6 cm spiculated lung mass and bilateral mediastinal lymphadenopathy on imaging. A cytology sample was obtained from EBUS-TBNA of mediastinal lymph nodes, and mutation screening was performed by next-generation sequencing using the Ion Torrent Cancer Hotspot panel.

Results

Cytological examination and immunocytochemistry confirmed the presence of metastatic lung adenocarcinoma. The molecular analysis revealed the coexistence of two missense mutations: c.34G > T; p.(Gly12Cys) and c.38G > T; A; p.(Gly13Asp) in exon 2 of the KRAS gene. The two independent variants were confirmed on Integrative Genomic Viewer (IGV), suggesting molecularly independent clones. The patient was treated with palliative care and died within two months of the diagnosis.

Conclusions

The present case showed aggressive clinical behaviour. It is questionable whether this aggressive course was due to the coexistence of multiple mutations or to a specific single mutation. Data in the literature regarding the outcome of polyclonal KRAS polyclonal lung adenocarcinomas are scarce, but some evidence seems to indicate that specific mutations may have prognostic value, possibly depending on the disease setting.

Concurrent RAS and RAS/BRAF V600E Variants in Colorectal Cancer: More Frequent Than Expected? A Case Report

The assessment of RAS and BRAF mutational status is one of the main steps in the diagnostic and therapeutic algorithm of metastatic colorectal cancer (mCRC). Multiple mutations in the BRAF and RAS pathway are described as a rare event, with concurrent variants in KRAS and BRAF genes observed in approximately 0.05% of mCRC cases. Here, we report data from a case series affected by high-risk stage III and stage IV CRC and tested for RAS and BRAF mutation, treated at our Medical Oncology Unit. The analysis of KRAS, NRAS (codons 12, 13, 59, 61, 117, 146), and BRAF (codon 600) hotspot variants was performed in 161 CRC tumors from August 2018 to September 2021 and revealed three (1.8%) patients showing mutations in both KRAS and BRAF (V600E), including two cases with earlier CRC and one with metastatic disease. We also identified one patient (0.6%) with a mutation in both KRAS and NRAS genes and another one (0.6%) with a double KRAS mutation. Notably, the latter was characterized by aggressive behavior and poor clinical outcome. The mutational status, pathological features, and clinical history of these five CRC cases are described. Overall, this study case series adds evidence to the limited available literature concerning both the epidemiological and clinical aspects of CRC cases characterized by the presence of concurrent RAS/BRAF variants. Future multicentric studies will be required to increase the sample size and provide additional value to results observed so far in order to improve clinical management of this subgroup of CRC patients.