High Prevalence of EGFR Mutations in Lung Adenocarcinomas From Brazilian Patients Harboring the TP53 p.R337H Variant

Molecular profile of driver genes in lung adenocarcinomas of Brazilian patients who have never smoked: implications for targeted therapies

INTRODUCTION

Lung cancer in never-smoker (LCINS) patients accounts for 20% of lung cancer cases, and its biology remains poorly understood, particularly in genetically admixed populations. We elucidated the molecular profile of driver genes in Brazilian LCINS.

METHODS

The mutational and gene fusion status of 119 lung adenocarcinomas from self-reported never-smoker patients, was assessed using targeted sequencing (NGS), nCounter, and immunohistochemistry. A panel of 46 ancestry-informative markers determined patients' genetic ancestry.

RESULTS

The most frequently mutated gene was EGFR (49.6%), followed by TP53 (39.5%), ALK (12.6%), ERBB2 (7.6%), KRAS (5.9%), PIK3CA (1.7%), and less than 1% alterations in RET, NTRK1, MET∆ex14, PDGFRA, and BRAF. Except for TP53 and PIK3CA, all other alterations were mutually exclusive. Genetic ancestry analysis revealed a predominance of European (71.1%), and a higher African ancestry was associated with TP53 mutations.

CONCLUSION

Brazilian LCINS exhibited a similar molecular profile to other populations, except the increased ALK and TP53 alterations. Importantly, 73% of these patients have actionable alterations that are suitable for targeted treatments.

Somatic mutational profiling and clinical impact of driver genes in Latin-Iberian medulloblastomas: Towards precision medicine

Medulloblastoma (MB) is the most prevalent malignant brain tumor in children, known for its heterogeneity and treatment-associated toxicity, and there is a critical need for new therapeutic targets. We analyzed the somatic mutation profile of 15 driver genes in 69 Latin-Iberian molecularly characterized medulloblastomas using the Illumina TruSight Tumor 15 panel. We classified the variants based on their clinical impact and oncogenicity. Among the patients, 66.7% were MBSHH, 13.0% MBWNT, 7.3% MBGrp3, and 13.0% MBGrp4. Among the 63 variants found, 54% were classified as Tier I/II and 31.7% as oncogenic/likely oncogenic. We observed 33.3% of cases harboring at least one mutation. TP53 (23.2%, 16/69) was the most mutated gene, followed by PIK3CA (5.8%, 4/69), KIT (4.3%, 3/69), PDGFRA (2.9%, 2/69), EGFR (1.4%, 1/69), ERBB2 (1.4%, 1/69), and NRAS (1.4%, 1/69). Approximately 41% of MBSHH tumors exhibited mutations, TP53 (32.6%) being the most frequently mutated gene. Tier I/II and oncogenic/likely oncogenic TP53 variants were associated with relapse, progression, and lower survival rates. Potentially actionable variants in the PIK3CA and KIT genes were identified. Latin-Iberian medulloblastomas, particularly the MBSHH, exhibit higher mutation frequencies than other populations. We corroborate the TP53 mutation status as an important prognostic factor, while PIK3CA and KIT are potential therapeutic targets.

Prevalence and clinical implications of germline pathogenic variants in cancer predisposing genes in young patients across sarcoma subtypes

BACKGROUND

Sarcomas are a rare and diverse group of cancers occurring mainly in young individuals for which an underlying germline genetic cause remains unclear in most cases.

METHODS

Germline DNA from 177 children, adolescents and young adults with soft tissue or bone sarcomas was tested using multigene panels with 113 or 126 cancer predisposing genes (CPGs) to describe the prevalence of germline pathogenic/likely pathogenic variants (GPVs). Subsequent testing of a subset of tumours for loss of heterozygosity (LOH) evaluation was performed to investigate the clinical and molecular significance of these variants.

RESULTS

GPVs were detected in 21.5% (38/177) of the patients (15.8% in children and 21.6% in adolescents and young adults), with dominant CPGs being altered in 15.2% overall. These variants were found in genes previously associated with the risk of developing sarcomas (TP53, RB1, NF1, EXT1/2) but also in genes where that risk is still emerging/limited (ERCC2, TSC2 and BRCA2) or unknown (PALB2, RAD50, FANCM and others). The detection rates of GPVs varied from 0% to 33% across sarcoma subtypes and GPV carriers were more likely to present more than one primary tumour than non-carriers (21.1%×6.5%; p=0.012). Loss of the wild-type allele was detected in 48% of tumours from GPV carriers, mostly in genes definitively associated with sarcoma risk.

CONCLUSION

Our findings reveal that a high proportion of young patients with sarcomas presented a GPV in a CPG, underscoring the urgency of establishing appropriate genetic screening strategies for these individuals and their families.

The Clinical and Molecular Profile of Lung Cancer Patients Harboring the TP53 R337H Germline Variant in a Brazilian Cancer Center: The Possible Mechanism of Carcinogenesis

In southern and southeastern Brazil, the TP53 founder variant c.1010G>A (R337H) has been previously documented with a prevalence of 0.3% within the general population and linked to a heightened incidence of lung adenocarcinomas (LUADs). In the present investigation, we cover clinical and molecular characterizations of lung cancer patients from the Brazilian Li-Fraumeni Syndrome Study (BLISS) database. Among the 175 diagnosed malignant neoplasms, 28 (16%) were classified as LUADs, predominantly occurring in females (68%), aged above 50 years, and never-smokers (78.6%). Significantly, LUADs manifested as the initial clinical presentation of Li-Fraumeni Syndrome in 78.6% of cases. Molecular profiling was available for 20 patients, with 14 (70%) revealing EGFR family alterations. In total, 23 alterations in cancer driver genes were identified, comprising 7 actionable mutations and 4 linked to resistance against systemic treatments. In conclusion, the carriers of TP53 R337H demonstrate a predisposition to LUAD development. Furthermore, our results indicate that environmental pollution potentially impacts the carcinogenesis of lung tumors in the carriers of TP53 R337H.

The Role of Germline Mutations in Thoracic Malignancies: Between Myth and Reality

Considering the established contribution of environmental factors to the development of thoracic malignancies, the inherited susceptibility of these tumors has rarely been explored. However, the recent introduction of next-generation sequencing-based tumor molecular profiling in the real-word setting enabled us to deeply characterize the genomic background of patients with lung cancer with or without smoking-related history, increasing the likelihood of detecting germline mutations with potential prevention and treatment implications. Pathogenic germline variants have been detected in 2% to 3% of patients with NSCLC undergoing next-generation sequencing analysis, whereas the proportion of germline mutations associated with the development of pleural mesothelioma widely varies across different studies, ranging between 5% and 10%. This review provides an updated summary of emerging evidence about germline mutations in thoracic malignancies, focusing on pathogenetic mechanisms, clinical features, therapeutic implications, and screening recommendations for high-risk individuals.

Disruptive and Truncating TP53 Mutations Are Associated with African-Ancestry and Worse Prognosis in Brazilian Patients with Lung Adenocarcinoma

INTRODUCTION

TP53 is the most frequently mutated gene in lung tumors, but its prognostic role in admixed populations, such as Brazilians, remains unclear. In this study, we aimed to evaluate the frequency and clinicopathological impact of TP53 mutations in non-small cell lung cancer (NSCLC) patients in Brazil.

METHODS

We analyzed 446 NSCLC patients from Barretos Cancer Hospital. TP53 mutational status was evaluated through targeted next-generation sequencing (NGS) and the variants were biologically classified as disruptive/nondisruptive and as truncating/nontruncating. We also assessed genetic ancestry using 46 ancestry-informative markers. Analysis of lung adenocarcinomas from the cBioportal dataset was performed. We further examined associations of TP53 mutations with patients' clinicopathological features.

RESULTS

TP53 mutations were detected in 64.3% (n = 287/446) of NSCLC cases, with a prevalence of 60.4% (n = 221/366) in lung adenocarcinomas. TP53 mutations were associated with brain metastasis at diagnosis, tobacco consumption, and higher African ancestry. Disruptive and truncating mutations were associated with a younger age at diagnosis. Additionally, cBioportal dataset revealed that TP53 mutations were associated with younger age and Black skin color. Patients harboring disruptive/truncating TP53 mutations had worse overall survival than nondisruptive/nontruncating and wild-type patients.

CONCLUSION

TP53 mutations are common in Brazilian lung adenocarcinomas, and their biological characterization as disruptive and truncating mutations is associated with African ancestry and shorter overall survival.

Case Report: A rare case of familial lung cancer requiring pneumonectomy in three male siblings

Lung cancer is a disease with a unique genetic pattern and is occasionally related to hereditary syndromes such as Lynch, Louis–Bar, and Li–Fraumeni. In some patients, germinal mutations may be discovered in combination with somatic alterations. For instance, Li–Fraumeni syndrome often reveals a mixture of TP53 and EGFR mutations. The development of new target therapies necessitates an extensive search for new pathogenic mutations. In this article, we present a rare case report of lung cancer, requiring a pneumonectomy, in three sibling brothers.

Lung cancer is also a hereditary disease

Pathogenic genetic variants (formerly called mutations) present in the germline of some individuals are associated with a clinically relevant increased risk of developing lung cancer. These germline pathogenic variants are hereditary and are transmitted in an autosomal dominant fashion. There are two major lung cancer susceptibility syndromes, and both seem to be specifically associated with the adenocarcinoma subtype. Li-Fraumeni syndrome is caused by variants in the TP53 tumour-suppressor gene. Carriers are mainly at risk of early-onset breast cancer, sarcoma, glioma, leukaemia, adrenal cortical carcinoma and lung cancer. EGFR variants, T790M in particular, cause the EGFR susceptibility syndrome. Risk seems limited to lung cancer. Emerging data suggest that variants in ATM, the breast and pancreatic cancer susceptibility gene, also increase lung adenocarcinoma risk. As for inherited lung disease, cancer risk is increased in SFTPA1 and SFTPA2 variant carriers independently of the underlying fibrosis. In this review, we provide criteria warranting the referral of a lung cancer patient to the cancer genetics clinic. Pathogenic variants are first identified in patients with cancer, and then in a subset of their relatives. Lung cancer screening should be offered to asymptomatic carriers, with thoracic magnetic resonance imaging at its core.

A proportion of lung cancers are hereditary. This includes patients with Li-Fraumeni syndrome and patients with EGFR-associated genetic susceptibility. They are mainly young patients with adenocarcinoma regardless of smoking history.https://bit.ly/2QAfjnB

Identification of the TP53 p.R337H Variant in Tumor Genomic Profiling Should Prompt Consideration of Germline Testing for Li-Fraumeni Syndrome

PURPOSE

Li-Fraumeni syndrome (LFS) is rare in the worldwide population, but it is highly prevalent in the Brazilian population because of a founder mutation, TP53 p.R337H, accounting for 0.3% of south and southeastern population. Clinical criteria for LFS may not identify all individuals at risk of carrying the Brazilian founder mutation because of its lower penetrance and variable expressivity. This variant is rarely described in databases of somatic mutations. Somatic findings in tumor molecular profiling may give insight to identify individuals who might be carriers of LFS and allow the adoption of risk reduction strategies for cancer.

MATERIALS AND METHODS

We determined the frequency of the TP53 p.R337H variant in tumor genomic profiling from 755 consecutive Brazilian patients with pan-cancer. This is a retrospective cohort from January 2013 to March 2020 at a tertiary care center in Brazil.

RESULTS

The TP53 p.R337H variant was found in 2% (15 of 755) of the samples. The mutation allele frequency ranged from 30% to 91.7%. A total of seven patients were referred for genetic counseling and germline testing after tumor genomic profiling results were disclosed. All the patients who proceeded with germline testing (6 of 6) confirmed the diagnosis of LFS. Family history was available in 12 cases. Nine patients (9 of 12) did not meet LFS clinical criteria.

CONCLUSION

The identification of the TP53 p.R337H variant in tumor genomic profiling should be a predictive finding of LFS in the Brazilian population and should prompt testing for germline status confirmation.

Prevalence of the Brazilian TP53 Founder c.1010G>A (p.Arg337His) in Lung Adenocarcinoma: Is Genotyping Warranted in All Brazilian Patients?

In Southern and Southeastern Brazil, there is a germline pathogenic variant with incomplete penetrance located in the oligomerization domain of TP53, c.1010G>A (p.Arg337His). Due to a founder effect, the variant is present in 0.3% of the general population of the region. Recently, this variant was identified in 4.4 and 8.9% of two apparently unselected, single center case series of Brazilian lung adenocarcinoma (LUAD) patients from the Southeastern and Central regions of the country, respectively. In the present study, our aim was to examine TP53 c.1010G>A allele and genotype frequencies in LUAD samples obtained from patients diagnosed in Southern Brazil. A total of 586 LUAD samples (tumor DNA) recruited from multiple centers in the region were tested, and the mutant allele was identified using TaqMan® assays in seven cases (7/586, 1.2%) which were submitted to next generation sequencing analyses for confirmation. Somatic EGFR mutations were more frequent in TP53 c.1010G>A carriers than in non-carriers (57.1 vs. 17.6%, respectively). Further studies are needed to confirm if TP53 c.1010G>A is a driver in LUAD carcinogenesis and to verify if there is a combined effect of EGFR and germline TP53 c.1010G>A. Although variant frequency was higher than observed in the general population, it is less than previously reported in LUAD patients from other Brazilian regions. Additional data, producing regional allele frequency information in larger series of patients and including cost-effectiveness analyses, are necessary to determine if TP53 c.1010G>A screening in all Brazilian LUAD patients is justified.

Comprehensive genomic profiling of Brazilian non-small cell lung cancer patients (GBOT 0118/LACOG0418)

Background

The aim of this study was to carry out a descriptive analysis of the somatic genetic profile and co‐occurring mutations of non‐small cell lung cancer (NSCLC) samples from patients tested with comprehensive genomic profiling (CGP).

Methods

This was a retrospective cross‐sectional study of patients diagnosed with NSCLC from 2013 to 2018 in Brazil and whose samples were submitted to CGP (FoundationOne or FoundationACT) using either tumor or circulating tumor DNA (ctDNA) from plasma.

Results

We recovered 513 CGP results from patients, 457 (89.1%) of which were from tumors and 56 (10.9%) from plasma. The median age of patients was 64 years old, of which 51.6% were males. TP53 mutations were identified in 53.6% of tumor samples, KRAS mutations in 24.2%, EGFR activating mutations were detected in 22.5%, STK11 mutations in 11.6%, PIK3CA mutations in 8.8%, ALK rearrangements in 5.4%, BRAF mutations in 5.2%, and ERBB2 alterations in 4.9%. The most commonly comutated gene was TP53. TP53 p.R337H was observed in 4.3% of samples and was associated with somatic mutations in EGFR and ERBB2 (P < 0.00001). Tumor mutational burden (TMB) analysis was available for 80.5% of samples tested, and 5.5% of samples had high TMB (≥ 20 mutations/Mb).

In conclusion, this retrospective analysis of genomic data from NSCLC patients obtained by CGP showed that common abnormalities such as EGFR mutations and ALK rearrangements had similar frequency to those previously described by other groups using others strategies. Additionally, our data confirm an association between TP53 p.R337H, supposedly germline in nature, and somatic mutations in genes of the HER family.

Key points

Significant findings of the study

This is the first report of the prevalence of driver mutations in Brazilian NSCLC patients using comprehensive genomic profiling (CGP).

The frequency of the most common driver mutations in this population was similar to that previously described in Brazil.

What this study adds

TP53 was the most commonly comutated gene across samples. TP53 p.R337H was associated with somatic mutations in EGFR and ERBB2.

Most samples had low TMB; only 5.5% of samples had high TMB.

What 20 years of research has taught us about the TP53 p.R337H mutation

The p53 tumor suppressor transcriptionally regulates a myriad of genes involved in cell cycle control, DNA repair, cell survival, and cell metabolism and represents one of the most well‐studied inhibitors of tumorigenesis. Since the discovery of TP53 in 1979, somatic mutations have been shown to be extremely common; more than 50% of human cancers carry loss‐of‐function mutations in TP53. Inherited or germline TP53 mutations are rare and are involved in complex hereditary cancer predisposition disorders, and affected family members can develop diverse tumor types and multiple primary cancers at young ages. In Brazil, a fascinating history of p53 and cancer predisposition began in the year 2000 with identification of the TP53 p.R337H mutation in close association with the development of adrenocortical tumors. In these past 20 years, much has been learned about the genetics and biochemistry of this mutation, which is widespread in Brazil because of a founder effect. This review highlights the contributions of TP53 p.R337H research over the last 20 years, the findings of which have sparked passionate debate among researchers worldwide, to understanding cancer predisposition in Brazilian individuals and families.

This review highlights the impact of TP53 p.R337H research in cancer predisposition studies in the Brazilian population. In addition, these studies serve as a model for carriers of hypomorphic TP53 alleles.

Mutational Portrait of Lung Adenocarcinoma in Brazilian Patients: Past, Present, and Future of Molecular Profiling in the Clinic

Objectives: Approximately 60% of lung adenocarcinomas (LAs) carry mutations that can guide treatment with tyrosine-kinase inhibitors (TKI) and other targeted therapies. Data on activating mutations in EGFR and other tyrosine-kinase receptor (TKR) genes in highly admixed populations, such as that of Brazil, are scarce. In this study, we comprehensively analyzed the actionable alteration profile of LA in Brazilian patients.

Materials and Methods:EGFR driver mutation data were collected from a large Brazilian LA cohort covering an 8-year period of molecular testing in a single institution. Tests were performed using three distinct methods, and demographic and histopathological data were analyzed. For a subset of patients, driver mutations in KRAS, NRAS, and BRAF and gene fusions involving TKR genes (before TKI treatment) and EGFR T790M (after TKI treatment) were assessed.

Results:EGFR mutations were detected in 25% of 1,316 LAs evaluated, with exon 19 deletions and exon 21 L858R TKI sensitizing mutations representing 72.5% of all mutations. Mutation rates were higher in women and non-smokers (p < 0.001). Next-generation sequencing was very sensitive, with a lower rate of inconclusive results compared with Sanger sequencing and pyrosequencing. EGFR/RAS/BRAF hotspot gene panels were applied in 495 LA cases and detected oncogenic mutations in 51.3% of samples, most frequently in EGFR (22.4%) and KRAS (26.9%). In subgroups of 36 and 35 patients, gene fusions were detected in 11.1% of tumors and EGFR T790M resistance mutations were detected in 59% of plasma samples from patients previously treated with TKI, respectively.

Conclusion: This report provides the first comprehensive actionable alteration portrait of LA in Brazil. The high rate of actionable alterations in EGFR and other driver genes in LA reinforces the need to incorporate TKI guided by molecular diagnostics into clinical routines for patients in both public and private healthcare systems.

High Prevalence of Somatic Oncogenic Driver Alterations in Patients With NSCLC and Li-Fraumeni Syndrome

INTRODUCTION

Actionable somatic molecular alterations are found in 15% to 20% of NSCLC in Europe. NSCLC is a tumor observed in patients with germline TP53 variants causing Li-Fraumeni syndrome (LFS), but its somatic molecular profile is unknown.

METHODS

Retrospective study of clinical and molecular profiles of patients with NSCLC and germline TP53 variants.

RESULTS

Among 22 patients with NSCLC and LFS (n = 23 lung tumors), 64% were women, median age was 51 years, 84% were nonsmokers, 73% had adenocarcinoma histological subtype, and 84% were diagnosed with advanced-stage disease. These patients harbored 16 distinct germline TP53 variants; the most common was p.R158H (5/22; three in the same family). Personal and family histories of cancer were reported in 71% and 90% of patients, respectively. In most cases (87%, 13/15), lung cancer was diagnosed with a late onset. Of the 21 tumors analyzed, somatic oncogenic driver mutations were found in 19 of 21 (90%), EGFR mutations in 18 (exon 19 deletion in 12 cases, L858R in three cases, and G719A, exon 20 insertion, and missing mutation subtype, each with one case), and ROS1 fusion in one case. A PI3KCA mutation was concurrently detected at diagnosis in three EGFR exon 19-deleted tumors (3/12). The median overall survival was 37.3 months in 14 patients treated with EGFR inhibitors; seven developed resistance, five (71%) acquired EGFR-T790M mutation, and one had SCLC transformation.

CONCLUSIONS

Driver oncogenic alterations were observed in 90% of the LFS tumors, mainly EGFR mutations; one ROS1 fusion was also observed. The germline TP53 variants and lung cancer carcinogenesis driven by oncogenic processes need further evaluation.