Homologous recombination deficiency and platinum rechallenge in platinum-resistant ovarian cancer patients

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Background: Ovarian carcinomas show homologous recombination deficiency (HRD) in up to 50% of cases and in 15 to 20% of cases occur due to germline BRCA1 or BRCA2 mutations. BRCA mutated tumors are more sensitive to PARP inhibitors and platinum based chemotherapy. The objective of this study was to characterize a cohort of ovarian cancer patients regarding HRD and to evaluate the impact of these scores in prolonged platinum sensitivity. Methods: Thirty one ovarian cancer patients with platinum resistant recurrence reexposed to platinum based chemotherapy were selected. Paraffin embedded tumor samples from 14 patients were analyzed using ONCOSCAN assay (Affymetrix) to evaluate HRD scores. The association of the scores with response rate to platinum rechallenge, overall survival and clinical pathologic factors was evaluated. Results: From the cohort of 31 patients, 15 samples from 14 patients were analyzed for genomic alterations. Median scores were 19.5 for TAI, 12.5 for cnLOH+L, 26.0 for LST and 6.3 for HRD. High scores were found in 10 out of 14 (for cnLOH+L score) and 9 out of 14 (for LST score) patients. Seven of the 14 patients analyzed analyzed for genomic alterations had response, which suggested homologous recombination deficiency. No significant differences were observed between response rates for high versus low scores. Numerically, cnLOH+L, LST and HDR scores were higher in patients with response to treatment compared to those without response. Median overall survival was 13.4 months from the beginning of platinum rechallenge and no difference in survival according to scores was observed. Among the clinical pathologic factors, family history of breast or ovarian cancer or personal history of breast cancer was associated to higher response rate to platinum rechallenge. Conclusions: In conclusion,HRD scores showed to be potential markers of response to platinum rechallenge in the platinum resistant setting. Further studies are necessary to clarify the best cutoffs for each score, the impact of tumor heterogeneity and the analysis of tumor samples in the moment of treatment. Positive family history of cancer is a clinical factor predictvie of platinum rechallenge response.

Oral and maxillofacial considerations in Gardner's syndrome: a report of two cases

Gardner's syndrome (GS) is a genetic disorder characterised by intestinal polyps, multiple osteomas, and soft-tissue tumours. Dentists play an important role in the syndrome diagnosis considering that craniomaxillofacial osteomas are a major criteria for Gardner's syndrome diagnosis. This study aimed to describe the main stomatological manifestation of GS and the importance of dentists in its diagnosis. Two patients presenting GS were evaluated. The first one had two osteomas in the mandible and GS was suspected. The colonoscopy confirmed the presence of polyposis and a prophylactic proctocolectomy was performed. The other patient had a late-stage diagnosis of GS and developed a rectum adenocarcinoma. The presence of craniomaxillofacial osteomas are a hallmark of the disease. Early-stage GS diagnosis may enable early diagnosis and preventive strategies in carriers. Other dental abnormalities, such as supernumerary teeth, hypercementosis and odontomas, can also be observed.

(18)F-FDG PET-CT for Surveillance of Brazilian Patients with Li-Fraumeni Syndrome

PURPOSE

To evaluate the effectiveness of (18)F-Fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG-PET/CT) for detecting early cancer in carriers of germline TP53 mutation, the genetic defect underlying Li-Fraumeni and related syndromes, which predisposes to many forms of cancer throughout life.

PATIENTS AND METHODS

A total of 30 adult patients from six families with germline TP53 mutations were recruited. These patients did not have a diagnosis of cancer in the 24 months preceding the study. Anomalous concentrations from whole-body (18)F-FDG-PET/CT were assessed by two independent experts. Suspicious lesions were excised and subjected to pathological examination.

RESULTS

A total of 6/30 patients showed abnormal (18)F-FDG-concentration. Confirmation studies revealed three cases of cancer, including one lung cancer, one ovarian cancer, and one disseminated breast cancer. Three patients had non-malignant lesions (one Bartholin's cyst and two cases of reactive lymph nodes).

CONCLUSION

(18)F-FDG-PET/CT is effective in detecting cancer in subjects who are asymptomatic according to current screening guidelines. These results further suggest that (18)F-FDG-PET/CT is an appropriate method for surveillance of cancer risk in TP53 mutation carriers.

Germline CDKN2A mutations in Brazilian patients of hereditary cutaneous melanoma

Approximately 10 % of all cutaneous melanoma cases occur in a familial context. The major susceptibility gene for familial melanoma is CDKN2A. In Latin America, genetic studies investigating melanoma predisposition are scarce. The aim of this work was to investigate germline CDKN2A point mutations and genomic rearrangements in a cohort of 59 Brazilian melanoma-prone patients. Screening of CDKN2A alterations was performed by sequencing and multiplex ligation probe amplification. Germline CDKN2A mutations affecting p16(INK4a) were detected in 8 unrelated probands (13.6 %), including 7 familial cases and one patient with multiple melanomas; 4 out of 8 mutation carriers met the criteria for familial melanoma and had multiple primary lesions. Although this study adds to the literature on melanoma susceptibility in Latin America, it is limited by the small size of the cohort. Our findings suggest that stringent inclusion criteria led to a substantially increased rate of CDKN2A mutation detection. This consideration should be taken into account when referring patients for genetic screening in a setting of limited budget, such as in developing countries.

Abstract A025: Screening for genomic rearrangements and germline mutations in BRCA1 and BRCA2 genes in hereditary breast cancer unrelated Brazilian families

Breast cancer (BC) is one of the most important causes of mortality within women worldwide. About 90% of breast cancer cases are sporadic and 5 to 10% are due to hereditary predisposition. Hereditary Breast Cancer (HBC) is an autosomal dominant disease, characterized by germline mutations in BRCA1 and BRCA2 genes that confers high risk of developing breast and ovarian cancers. Large genomic rearrangements (LGRs), including deletions and duplications, are responsible for up to 27% in BRCA1 gene and are less common in the BRCA2 gene, depending on the population. The aim of the present study was to evaluate BRCA1 and BRCA2 germline mutations and the prevalence of LGRs in Brazilian families that fulfilled clinical criteria for HBC. In total, 128 unrelated families were evaluated, from which 108 fulfilled clinical criteria for hereditary breast and ovary cancer (HBOC), 20 for hereditary breast and colon cancer (HBCC) and 32 met both clinical criteria. DNA samples from peripheral blood were used to evaluate by direct sequencing the complete coding sequences and exon-intron boundaries of BRCA1 and BRCA2, and also the CHEK2 1100delC variant. To determine pathogenicity of variants of uncertain significance (VUS), Breast Cancer Information Core, IARC-LOVD database and web-based protein prediction algorithms such as SIFT, PolyPhen and align-GVGD were used. The non-carriers of BRCA1/2 mutations were selected for MLPA (multiplex ligation-dependent probe amplification) analysis for the evaluation of large genomics rearrangements. The prevalence of pathogenic mutations in this study was: 22.5% including 21 in BRCA1 (2 splice site, 2 missense, 9 frame shift, 6 nonsense and 2 LGR) and 7 in BRCA2 (3 frameshift and 4 nonsense) and one proband harbored CHEK2 1100delC variant. Seven (25%) pathogenic mutations were firstly described, including a novel splice-site BRCA1 mutation, whose pathogenicity was confirmed by transcriptional analysis. Among the VUS carriers, 19 variants were distinct and two of them were described for the first time. The VUS evaluation by three protein prediction algorithms (Polyphen, SIFT and GVGD-Align) showed that seven were classified as likely pathogenic by at least one of them (four in one algorithm, two in two algorithms and one in all three algorithms). In our series, we have detected 2 LGR (1,56%) in BRCA1 gene in HBOC patients. One of the large rearrangement, an amplification of exon 24 in BRCA1, apparently not reported previously, was confirmed by duplex quantitative PCR and array-CGH analysis. Our results, showed that mutations BRCA1 (75%) are more prevalent than BRCA2 (25%) in the Brazilian population. In summary, we reported a comprehensive analysis of the genetic and clinical basis of HBC families in Brazil, which revealed to be highly complex. Currently, a screening for new susceptibility genes using exome sequencing in SOLID platform is under process in 11 non-carriers young (<36 yo) women [5 from this study and 6 from a previous study (Carraro et al., 2013)] revealing new candidates involved in HBC.

Citation Format: Marcia Cristina Pena Figueiredo, Felipe Carneiro Silva, Bianca Cristina Garcia Lisboa, Giovana Tardin Torrezan, Elisa Napolitano e Ferreira, Erika Maria Monteiro Santos, Ana Cristina Krepischi, Maria Isabel Waddington Achatz, Benedito Mauro Rossi, Dirce Maria Carraro. Screening for genomic rearrangements and germline mutations in BRCA1 and BRCA2 genes in hereditary breast cancer unrelated Brazilian families. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A025.

Association between the founder brazilian TP53 p.R337H mutation and HER2-positive status

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Background: Recent studies in North American and British series have suggested an association between germline TP53 mutations and early onset HER2-positive breast cancer (BC). Mutations in the TP53 gene are estimated to occur in 1:2,000-1:5,000 individuals of the general population. Among women with BC who are unselected for family history they occur in up to 0.25%. In women with early-onset BC (<30 years) they occur in up to 7%. A specific germline TP53 mutation (c.1010G>A; p.R337H) has been encountered in 0.3% of the general population, in 13.3% of Li-Fraumeni-like families and in 0.5-2.4% of BC-affected women in Brazil. In an exploratory approach, the aim of this study was to investigate, in our series, if there is an association between human epidermal growth factor receptor 2 (HER2) amplification and the germline TP53 p.R337H mutation in a series of BC-affected women. Methods: A series of 718 Brazilian BC-affected women was genotyped in our previous study and 64 (8.9%) were mutation carriers. These cases were recruited from 3 centers and HER2 analysis was performed by immunohistochemistry (IHC) in each center according to validated protocols. Statistical analysis was done using SPSS software. Results: In 47 of 64 mutation carriers (73.5%), BC showed HER expression (either 1+, 2+ or 3+) while among 654 non-carriers, this immunophenotype was observed in 320 (48.9%) (p<0.001). This pattern was still observed after stratification of groups according to age at diagnosis (≤45 and ≥55 years) (p<0.001 and 0.03, respectively) and was independent of recruiting center. Conclusions: These results indicate that BC developing on a background of the founder Brazilian TP53 p.R337H mutation shows more frequently some amplification of HER2, consistent with recent studies showing an association between germline TP53 mutations and BC with HER2 hyperexpression. These findings should be confirmed in larger series to understand the significance of the association. If confirmed, this finding may justify germline TP53 p.R337H mutation testing in all HER2-positive Brazilian BC patients and would have a significant impact on patient and family counseling as well as on treatment.

Mutational spectrum of the APC and MUTYH genes and genotype-phenotype correlations in Brazilian FAP, AFAP, and MAP patients

Background

Patients with multiple colorectal adenomas are currently screened for germline mutations in two genes, APC and MUTYH. APC-mutated patients present classic or attenuated familial adenomatous polyposis (FAP/AFAP), while patients carrying biallelic MUTYH mutations exhibit MUTYH-associated polyposis (MAP). The spectrum of mutations as well as the genotype-phenotype correlations in polyposis syndromes present clinical impact and can be population specific, making important to obtain genetic and clinical data from different populations.

Methods

DNA sequencing of the complete coding region of the APC and MUTYH genes was performed in 23 unrelated Brazilian polyposis patients. In addition, mutation-negative patients were screened for large genomic rearrangements by multiplex ligation-dependent probe amplification, array-comparative genomic hybridization, and duplex quantitative PCR. Biallelic MUTYH mutations were confirmed by allele-specific PCR. Clinical data of the index cases and their affected relatives were used to assess genotype–phenotype correlations.

Results

Pathogenic mutations were identified in 20 of the 23 probands (87%): 14 in the APC gene and six in the MUTYH gene; six of them (30%) were described for the first time in this series. Genotype-phenotype correlations revealed divergent results compared with those described in other studies, particularly regarding the extent of polyposis and the occurrence of desmoid tumors in families with mutations before codon 1444 (6/8 families with desmoid).

Conclusions

This first comprehensive investigation of the APC and MUTYH mutation spectrum in Brazilian polyposis patients showed a high detection rate and identified novel pathogenic mutations. Notably, a significant number of APC-positive families were not consistent with the predicted genotype-phenotype correlations from other populations.

Abstract 1837: Clinical diversity and tumor spectrum in Xeroderma Pigmentosum Brazilian patients

Xeroderma Pigmentosum (XP) is a rare autossomic recessive hereditary disorder in which normal ability to repair DNA damage caused by ultraviolet light (UV) is deficient due to the presence of mutations in nucleotide excision repair pathway genes (XPA, ERCC3, XPC, ERCC2, DDB, ERCC4 and ERCC5) or in POLH gene, responsible for the replication of damaged DNA on the leading strand. These different genetic alteration result in distict phenotypes classifified into eight genetic complementation sub groups, XP-A to XP-G and a variant group XP-V. Clinical characteristics of the syndrome include skin poikiloderma and eye hypersensibility to UV radiation. Carriers have an increased risk of early onset multiple cutaneous, mucocutaneous and ophthalmologic malignancies when compared with normal population. Occasionally neurological impairment is observed in certain variations of the syndrome. Given the paucity of specific literature data about the incidence and clinical profile of the disease in Brazilian population, this study was conducted to describe clinical diversity and tumor spectrum of XP syndrome in Brazilian population. Twenty-nine XP patients from 19 non-related families from Hospital A.C. Camargo (São Paulo, Brazil), Hospital Universitário Alcides Carneiro (Campina Grande, Paraíba) and Hospital de Clínicas de Porto Alegre (Rio Grande do Sul, Brazil). Data collection was performed after genetic counseling and signed informed consent. Clinical characteristics were obtained through medical ascertainment. The median age was 24 (4 to 61 years) in a predominant female population (19/29). Basal cell carcinomas (BCC) were the most frequent neoplasm, present in 86,20% (25/29) of all patients, with the occurrence of up to 60 BCCs in a same patient. Squamous cell carcinomas and melanoma were present in 66,7% and 37,5% respectively. Six patients developed the first malignant tumor before the age of six and four patients developed the first tumor in early adulthood. One male patient developed a diffuse gastric cancer at 50 years old. Visual impairment occurred in 45,83% of the patient. Despite the unknown frequency of affected patients, the Brazilian population of XP cases seems to be underestimated. Genetic counseling is fundamental to provide information to carriers and family members and enable preventive measurements.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1837. doi:10.1158/1538-7445.AM2011-1837

Highly prevalent TP53 mutation predisposing to many cancers in the Brazilian population: a case for newborn screening?

The unusually high population frequency of a germline TP53 mutation (R337H) predisposing to early cancer has led to mass newborn testing for this mutation in the State of Paraná, southern Brazil. Newborn screening for inherited cancer risk is complex and controversial. In this paper, we discuss the justifications for this screening by considering the medical and scientific evidence for this mutation. R337H has been identified in Brazilian families with Li-Fraumeni or related syndromes predisposing to cancers in childhood (ie, brain, renal, and adrenocortical carcinomas), adolescence (ie, soft tissue and bone sarcomas), and young adulthood (ie, breast cancer). R337H has also been detected in children with adrenocortical carcinoma without a documented family history of cancer. The mutation is estimated to occur in about 0.3% of the population in southern Brazil and is associated with increased cancer risk throughout life. Cancer patterns in families positive for R337H suggest strong genetic modifying effects, making it difficult to predict individual risk. Because protocols for cancer-risk management in Li-Fraumeni or related syndromes are debatable, extreme care should prevail in predictive testing of children for R337H. A detailed assessment of the risks, benefits, and costs is needed to ensure that medical, social, and ethical justifications for newborn screening are met.

TP53 mutations in human cancers: functional selection and impact on cancer prognosis and outcomes

A large amount of data is available on the functional impact of missense mutations in TP53 and on mutation patterns in many different cancers. New data on mutant p53 protein function, cancer phenotype and prognosis have recently been integrated in the International Agency for Research on Cancer TP53 database (http://www-p53.iarc.fr/). Based on these data, we summarize here current knowledge on the respective roles of mutagenesis and biological selection of mutations with specific functional characteristic in shaping the patterns and phenotypes of mutations observed in human cancers. The main conclusion is that intrinsic mutagenicity rates, loss of transactivation activities, and to a lesser extent, dominant-negative activities are the main driving forces that determine TP53 mutation patterns and influence tumor phenotype. In contrast, current experimental data on the acquisition of oncogenic activities (gain of function) by p53 mutants are too scarce and heterogenous to assess whether this property has an impact on tumor development and outcome. In the case of inherited TP53 mutations causing Li-Fraumeni and related syndromes, the age at onset of some tumor types is in direct relation with the degree of loss of transactivation capacity of missense mutations. Finally, studies on large case series demonstrate that TP53 mutations are independent markers of bad prognosis in breast and several other cancers, and that the exact type and position of the mutation influences disease outcome. Further studies are needed to determine how TP53 haplotypes or loss of alleles interact with mutations to modulate their impact on cancer development and prognosis.

The TP53 mutation, R337H, is associated with Li-Fraumeni and Li-Fraumeni-like syndromes in Brazilian families

A TP53 germline mutation, R337H, has been previously described in children from southern Brazil with adrenocortical tumours but no documented familial history of other cancers. Here, we have screened for TP53 mutation 45 Brazilian unrelated individuals with family histories fulfilling the clinical definitions of Li-Fraumeni (LFS) or Li-Fraumeni-like (LFL) syndromes. Mutations were found in 13 patients (28.9%), including six (46.1%) R337H mutations, and four novel germline mutations (V173M, V197M, G244D and IVS6+1G>T). Families with the R337H mutation presented a wide spectrum of tumours, including breast cancers (30.4%), brain cancers (10.7%), soft tissue sarcomas (10.7%) and adrenocortical carcinomas (8.9%). Testing of 53 Brazilian subjects with no cancer history showed that R337H was not a common polymorphism in that population. Moreover, loss of heterozygocity with retention of the R337H allele was observed in a breast adenocarcinoma, supporting a role for this mutation in breast tumorigenesis. These results show that the TP53 R337H germline mutation predisposes to a larger spectrum of tumours, similar to the one reported for other TP53 mutations.