EGFR analysis on scrapings from cytology smears in lung carcinoma, an effective alternative to testing on trucut biopsies

BACKGROUND

Lung carcinomas are a leading cause of cancer morbidity and mortality. Many cases present at an advanced stage of disease where definitive treatment by surgical resection is not feasible. Molecular testing using materials derived from minimally invasive procedures aid in targeted therapy with least iatrogenic burden to the patient.

METHODS

Cases diagnosed as non-small cell lung carcinoma (NSCLC) on cytology were included in the study. Scrapings from the smears with adequate tumor cell load were submitted for molecular testing. The DNA was extracted and quantified. Mutations in exons 18, 19, 20, and 21 of the EGFR gene were detected using Sanger sequencing. DNA quantity and EGFR mutation status on equal number of consecutive trucut biopsy specimens were also analyzed.

RESULTS

Seventy cases of NSCLC tested for EGFR mutation had a median DNA concentration of 40.2 ng/μl and 31% cases showed mutation. Majority of mutations (14/21, 66.66%) were identified in exon 19. Among 70 trucut biopsy samples, DNA concentration was 41.42 ng/μl and 30% cases showed mutation. No significant difference was seen in DNA quantity and EGFR mutation between cytology smears and trucut biopsies.

CONCLUSION

EGFR testing on cytology smears provides adequate DNA yield with minimal invasiveness and is equally effective as biopsies. Testing on samples like pleural effusion allows for concomitant diagnosis, staging, and molecular testing in one procedure. Tests done on the smears rather than on cell block or trucut biopsies ensures superior quality DNA from the tumor cells as they are unexposed to cross linking formalin fixative.

Dihydropyrimidine dehydrogenase deficiency in patients treated with 5FU or capecitabine based regimens: A single center experience from South India

e15517

Background: DPYD deficiency is present in 3-5% of patients. The risk of treatment-related death in DPYD mutation carriers who receive fluoropyrimidine chemotherapy has been estimated at 3-10%. There is growing data in support of widespread screening for DPYD deficiency prior to fluoropyrimidine chemotherapy. The purpose of our study was to identify the prevalence of DPYD deficiency among patients receiving 5-fluorouracil (5FU) or capecitabine based combination chemotherapy, and to analyse the toxicity profile among the DPYD deficient group. Methods: The study involved patients who have received 5FU and capecitabine based chemotherapy for the treatment for gastrointestinal, breast and head and neck cancers between 2019-2020. Four DPYD variants were checked using real-time PCR based Genotyping assay. Three common DPYD variants recommended by the CPIC guidelines (IVS14+1 G>A (*2A), c.1679T>G (*13), c.2846A>T) and a common variant in Asian population (c.496A>G), based on previous studies, was included in our analysis. These variants were assessed prior to the initiation of the chemotherapy and dose was modified based on the activity score and the toxicity profile was assessed. Descriptive statistics was performed using SPSS version 20. Results: 375 patients were included in this analysis. The median age of the cohort was 61years (21-84 years). 51.3% were males and 49.7% females. Among the 375 patients, 47 patients had DPYD mutation (12.5%). The median age of the DPYD mutated patients were 68 years; 29 (61.7%) males and 18 (38.2%) females. 32 (68.8%) had deleterious mutation in DPYD variant c.496A>G (rs2297595) and 15 (31.9%) showed mutation IVS14+1 G>A (rs3918290). 35 out 47 patients had grade II-III toxicity even after dose reduction during the first cycle of chemotherapy. The commonly seen adverse events were hand and foot syndrome in 18 (38.3%), mucositis in 7 (14.9%), diarrrhoea in 15 (31.9%) and neutropenia in 25 (31.9%) patients. Four patients had febrile neutropenia. One patient experience myocardial infarction. There was no mortality. Chi square analysis showed DPYD mutation had significant association with presence of severe adverse reaction (74.5%, p-value. 0.002). Conclusions: Prevalence of DPYD mutation in our patients was 12.5%. They experienced more toxicities while receiving 5-FU/Capecitabine even after dose modification. c.496A>G (rs2297595) was the most common variant seen in our patients. Screening of patients for DPYD mutations prior to administration of 5-FU/capecitabine using pharmacogenetic methods may help identify those patients who are at risk for adverse effects, allowing a more individualized approach to their chemotherapy management. c.496A>G (rs2297595) variant should also be in included routinely in DPYD screening among South Asian population.

Evaluation of molecular pathogenesis of colon cancer in Kerala using high-throughput expression, signaling pathways, and network analyses

e16065

Background: The molecular pathogenesis of colon adenocarcinoma (COAD) is attributed to large molecular changes such as Chromosomal Instability and high somatic copy number variation or defective DNA mismatch repair and consequent microsatellite instability (MSI). The prevalence of this type of cancer is increasing in the state of Kerala, India. A detailed study of the signaling pathways could lead to a better understanding of the central molecular pathological changes and potential biomarkers particular to this population. Methods: High throughput somatic expression analysis using Nanostring PanCancer pathway panel assay was performed. Differentially expressed (DE) genes were selected and KEGG pathway enrichment analysis was performed for assessment of canonical signaling pathways. Expression profiles were compared against the public database, Colon Adenocarcinoma cohort of the Cancer Genome Atlas (TCGA-COAD), using the Genome Expression Profiling Interactive Analysis (GEPIA). Protein-protein interaction network analysis was done using Cytoscape. DE genes were compared against immune cell infiltration in the TCGA-COAD from Tumor Immune Estimation Resource (TIMER) databases. Results: Nanostring assay was performed in 10 Tumor-Normal paired FFPE samples of stage II/III colon adenocarcinoma. Out of > 700 genes, significant difference in expression was found in 83 genes (FDR adjusted p -value < 0.01) with fold-change |fc(log2)| of at least one. Fold-change |fc(log2)| ≥ 2 was found in 19/83 genes. Network analysis clustered 13 out of 17 upregulated genes. Superimposition of the current data on TCGA study showed that among the three genes, four (MET, MCM2, ETV4 and MMP7), were common. DE Genes which were not significant in TCGA COAD study such as INHBA, COL1A1, COL11A1, COMP, SFRP4, SPP1, IL11, LIF, WT1 and DDIT4, were found to be significant in the current study. A few of the unique genes identified in the current study were found to have significant correlation with antigen presenting cells infiltration in the TCGA-COAD studies. Conclusions: Many DE genes from the study population were found to be different from previous large cohort studies in other population. This may suggest a different pathogenesis of COAD in this population, warranting a detailed study on the pathogenesis.

Exploring the role of defective fibronectin matrix assembly in the VHL-associated CNS hemangioblastoma

Background:

Central nervous system (CNS) hemangioblastoma (HB) is the most common tumor in the von Hippel Lindau (VHL) disorder, the hereditary tumor syndrome caused by the biallelic mutations of theVHLgene. The disrupted VHL and Elongin protein interaction on hypoxia-inducible factor-1α (HIF-1α) induces a set of hypoxia-inducible genes, resulting in an unchecked endothelial cell proliferation that then leads to hemangioblastoma formation. However, recent studies have shown that disruptive germline mutations ofVHLneed not result in hemangioblastoma, though it can cause other manifestations of the VHL syndrome. Similarly, sporadic hemangioblastoma can occur rarely without a somatic biallelicVHLmutation. The VHL protein was earlier found to be associated with the deposition of matrix fibronectin (FN) protein in the renal extracellular matrix.

Methods:

The present study was designed to investigate the deposition of the matrix FN protein in VHL-associated hemangioblastoma.

Results:

Seven HB tumor samples from the VHL syndrome had lower expressions of tissue FN compared to the control cerebellum samples or the control blood vessel sample. On comparing the VHL and FN protein expressions in a timed endothelial tube assay, the VHL protein expression was absent during the initial phase of tube formation but started expressing after 6 h. The levels of matrix form of FN gradually increased along with the VHL expression during the maturation of tube formation. Tube formation was found to be enhanced with extraneously added soluble FN and inhibited by matrix FN. Similarly, tube formation was inhibited by a modified tripeptide (RGD) inhibitor of integrin (-αVβ3), namely, Cyclo-Ala-Arg-Gly-Asp-3-aminomethylbenzoyl.

Conclusions:

Our study implicates that the extracellular deposition and matrix formation of FN is important for vascular endothelial proliferation, and that its absence has roles in the development of hemangioblastoma in the VHL syndrome.