Jacqueline Lehmann-Che

A refined molecular taxonomy of breast cancer

The current histoclinical breast cancer classification is simple but imprecise. Several molecular classifications of breast cancers based on expression profiling have been proposed as alternatives. However, their reliability and clinical utility have been repeatedly questioned, notably because most of them were derived from relatively small initial patient populations. We analyzed the transcriptomes of 537 breast tumors using three unsupervised classification methods. A core subset of 355 tumors was assigned to six clusters by all three methods. These six subgroups overlapped with previously defined molecular classes of breast cancer, but also showed important differences, notably the absence of an ERBB2 subgroup and the division of the large luminal ER+ group into four subgroups, two of them being highly proliferative. Of the six subgroups, four were ER+/PR+/AR+, one was ER−/PR−/AR+ and one was triple negative (AR−/ER−/PR−). ERBB2-amplified tumors were split between the ER−/PR−/AR+ subgroup and the highly proliferative ER+ LumC subgroup. Importantly, each of these six molecular subgroups showed specific copy-number alterations. Gene expression changes were correlated to specific signaling pathways. Each of these six subgroups showed very significant differences in tumor grade, metastatic sites, relapse-free survival or response to chemotherapy. All these findings were validated on large external datasets including more than 3000 tumors. Our data thus indicate that these six molecular subgroups represent well-defined clinico-biological entities of breast cancer. Their identification should facilitate the detection of novel prognostic factors or therapeutical targets in breast cancer.

High Frequency of TP53 Mutation in BRCA1 and Sporadic Basal-like Carcinomas but not in BRCA1 Luminal Breast Tumors

Breast tumors with a germ-line mutation of BRCA1 (BRCA1 tumors) and basal-like carcinoma (BLC) are associated with a high rate of TP53 mutation. Because BRCA1 tumors frequently display a basal-like phenotype, this study was designed to determine whether TP53 mutations are correlated with the hereditary BRCA1 mutated status or the particular phenotype of these tumors. The TP53 gene status was first investigated in a series of 35 BRCA1 BLCs using immunohistochemistry, direct sequencing of the coding sequence, and functional analysis of separated alleles in yeast, and compared with the TP53 status in a series of 38 sporadic (nonhereditary) BLCs. Using this sensitive approach, TP53 was found to be frequently mutated in both BRCA1 (34 of 35, 97%) and sporadic (35 of 38, 92%) BLCs. However, the spectrum of mutation was different, particularly with a higher rate of complex mutations, such as insertion/deletion, in BRCA1 BLCs than in the sporadic group [14 of 33 (42%) and 3 of 34 (9%), [corrected] respectively; P = 0.002]. Secondly, the incidence of TP53 mutations was analyzed in 19 BRCA1 luminal tumors using the same strategy. Interestingly, only 10 of these 19 tumors were mutated (53%), a frequency similar to that found in grade-matched sporadic luminal tumors. In conclusion, TP53 mutation is highly recurrent in BLCs independently of BRCA1 status, but not a common feature of BRCA1 luminal tumors.

Resistance to therapy in acute promyelocytic leukemia.

Resistance to treatment in patients with acute promyelocytic leukemia is rare. The authors describe the development of resistance to arsenic through a mutation in the allele of PML that is not rearranged as the PML-RARA oncogenic driver.

Prognostic value of TP53 gene mutations in myelodysplastic syndromes and acute myeloid leukemia treated with azacitidine

TP53 mutations are found in 5-10% of MDS and AML, where they are generally associated with complex karyotype and an overall poor prognosis. However, the impact of TP53 mutations in MDS treated with azacitidine (AZA) remains unclear. We analyzed TP53 mutations in 62 patients with high risk MDS or AML treated with AZA. A TP53 mutation was found in 23 patients (37.1%), associated with complex karyotype in 18 (78.3%) of them. TP53 mutations had no significant impact on response or complete response to AZA (p=0.60 and p=0.26, respectively). By univariate analysis, OS was negatively influenced by the presence of TP53 mutation (median OS 12.4 months versus 23.7 months, p<10(-4)), abnormal cytogenetics (median OS 14.4 months vs 33 months, p=0.02) complex cytogenetics (median OS 12.7 months versus 23.7 months, p=0.0005), and a diagnosis of AML (median 14.5 months vs 21.2 months for MDS or CMML, p=0.02). By multivariate analysis, only TP53 mutational status (HR 2.89 (95% confidence interval 1.38-6.04; p=0.005) retained statistical significance for OS. Results were similar when the analysis was restricted to MDS and CMML patients, excluding AML (HR=2.46 (95% confidence interval: 1.1-6.4); p=0.04)). Thus, TP53 mutations strongly correlated with poorer survival in higher risk MDS and AML treated with AZA.

p53 in breast cancer subtypes and new insights into response to chemotherapy.

Despite an obvious central role of p53 in the hallmarks of cancer, TP53 status is not yet used for the management of breast cancer. Recent findings may lead to reconsider the role of p53 in breast cancer. TP53 mutations are the most frequent genetic alterations in breast cancer, observed in 30% of breast carcinomas. Their distribution is highly linked to molecular tumor subtypes found in 26% of luminal tumors (17% of luminal A, 41% of luminal B), in 50% of HER2 amplified tumors, in 69% of molecular apocrine breast carcinomas and in 88% of basal-like carcinomas. The type of mutation is linked to the tumor subtype with higher frequency of base-pair substitutions in luminal tumors, whereas molecular apocrine and basal-like tumors present much higher frequency of complex mutations (deletions/insertions). The timing of TP53 mutation also depends on the tumor subtype, being the first important event in luminal tumors but occurring after PTEN loss in basal-like tumors. Regarding response to cytotoxic chemotherapy, the situation is far from the p53-dependent apoptosis paradigm with subsequent clinical response. We reported that TP53 mutated non inflammatory locally advanced breast carcinomas had a high rate of complete pathological response to dose-dense doxorubicin-cyclophosphamide chemotherapy, while TP53 wild-type (WT) tumors never achieved complete response. Using human breast cancer xenograft models, we suggested that this could be due to the induction of senescence in TP53 WT tumor cells. A recent work confirmed these findings in MMTV-Wnt1 mammary tumors, showing that growth arrest and senescent phenotype, not apoptosis, were induced in TP53 WT tumors following doxorubicin treatment, while lack of arrest in mutant tumors resulted in aberrant mitoses, cell death and a superior clinical response. Furthermore, in ER positive (ER(+)) breast tumors, it has been recently reported that ER represses the p53-mediated apoptotic response induced by DNA damage. Taken together, these data can help to better understand p53-mediated response to doxorubicin-based chemotherapy in breast cancer: in ER(+) TP53 WT breast cancers, ER-induced inhibition of p53 apoptotic response would lead preferentially to tumor cell senescence and subsequent resistance to treatment. Conversely, in ER negative (ER(-)) TP53 mutated breast cancers, accumulation of genetic abnormalities would lead to mitotic catastrophe and subsequent better response. In view of these recent results, p53 impact in breast cancer should be reconsidered.

Hereditary Renal Cancer Syndromes: An Update of a Systematic Review

CONTEXT Hereditary renal cancers (HRCs) comprise approximately 3-5% of renal cell carcinomas (RCCs). OBJECTIVE Our aim was to provide an overview of the currently known HRC syndromes in adults. EVIDENCE ACQUISITION Data on HRC syndromes were analysed using PubMed and Online Mendelian Inheritance in Man with an emphasis on kidney cancer, clinical criteria, management, treatment, and genetic counselling and screening. EVIDENCE SYNTHESIS Ten HRC syndromes have been described that are inherited with an autosomal dominant trait. Eight genes have already been identified (VHL, MET, FH, FLCN, TSC1, TSC2, CDC73, and SDHB). These HRC syndromes involve one or more RCC histologic subtypes and are generally bilateral and multiple. Computed tomography and magnetic resonance imaging are the best imaging techniques for surveillance and assessment of renal lesions, but there are no established guidelines for follow-up after imaging. Except for hereditary leiomyomatosis RCC tumours, conservative treatments favour both an oncologically effective therapeutic procedure and a better preservation of renal function. CONCLUSIONS HRC involves multiple clinical manifestations, histologic subtypes, genetic alterations, and molecular pathways. Urologists should know about HRC syndromes in the interest of their patients and families.

Distinct tumor protein p53 mutants in breast cancer subgroups.

Tumor protein p53 (TP53) is mutated in approximately 30% of breast cancers, but this frequency fluctuates widely between subclasses. We investigated the p53 mutation status in 572 breast tumors, classified into luminal, basal and molecular apocrine subgroups. As expected, the lowest mutation frequency was observed in luminal (26%), and the highest in basal (88%) tumors. Luminal tumors showed significantly higher frequency of substitutions (82 vs. 65%), notably A/T to G/C transitions (31 vs. 15%), whereas molecular apocrine and basal tumors presented much higher frequencies of complex mutations (deletions/insertions) (36 and 33%, respectively, vs. 18%). Accordingly, missense mutations were significantly more frequent in luminal tumors (75 vs. 54%), whereas basal tumors displayed significantly increased rates of TP53 truncations (43 vs. 25%), resulting in loss of function and/or expression. Interestingly, as basal tumors, molecular apocrine tumors presented with a high rate of complex mutations, but paradoxically, these were not associated with increased frequency of p53 truncation. As in luminal tumors, this could reflect a selective pressure for p53 gain of function, possibly through P63/P73 inactivation. Collectively, these observations point not only to different mechanisms of TP53 alterations, but also to different functional consequences in the different breast cancer subtypes.

Two Mild Cystic Fibrosis-associated Mutations Result in Severe Cystic Fibrosis When Combined in Cis and Reveal a Residue Important for Cystic Fibrosis Transmembrane Conductance Regulator Processing and Function

The number of complex cystic fibrosis transmembrane conductance regulator (CFTR) genotypes identified as having double-mutant alleles with two mutations inheritedin cis has been growing. We investigated the structure-function relationships of a severe cystic fibrosis (CF)-associated double mutant (R347H-D979A) to evaluate the contribution of each mild mutation to the phenotype. CFTRmutants expressed in HeLa cells were analyzed for protein biosynthesis and Cl− channel activity. Our data show that R347H is associated with mild defective Cl− channel activity and that the D979A defect leads to misprocessing. The mutant R347H-D979A combines both defects for a dramatic decrease in Cl−current. To decipher the molecular mechanism of this phenotype, single and double mutants with different charge combinations at residues 347 and 979 were constructed as charged residues were involved in this complex genotype. These studies revealed that residue 979, located in the third cytoplasmic loop, is critical for CFTR processing and Cl− channel activity highlighting the role of charged residues. These results have also important implications for CF, as they show that two mutations in cis can act in concert to alter dramatically CFTR function contributing to the wide phenotypic variability of CF disease.

Estrogen receptor-positive/human epidermal growth factor receptor 2-negative breast tumors: Early prediction of chemosensitivity with (18) F-fluorodeoxyglucose positron emission tomography/computed tomography during neoadjuvant chemotherapy.

The objective of this prospective study was to evaluate the ability of 18F‐fluorodeoxyglucose (18F‐FDG) positron emission tomography/computed tomography (PET/CT) to predict chemosensitivity in patients with estrogen receptor (ER)‐positive/human epidermal growth factor receptor 2 (HER2)‐negative breast cancer.

SISH/CISH or qPCR as alternative techniques to FISH for determination of HER2 amplification status on breast tumors core needle biopsies: a multicenter experience based on 840 cases

BackgroundUntil now, FISH has been the gold standard technique to identify HER2 amplification status in ambiguous cases of breast cancer. Alternative techniques have been developed to increase the capacities of investigating HER2 amplification status. The aims of this multicenter study in a large series of breast cancer patients were to prospectively compare the level of performance of CISH, SISH, and qPCR alternative techniques on paraffin-embedded core biopsies with “gold standard FISH” for evaluation of HER2 amplification status.MethodsThis study was performed on 840 cases scored by immunohistochemistry (IHC): 0=317 (38%), 1+=183 (22%), 2+=109 (13%), 3+=231 (27%). Each of the 15 French centers participating in the study analyzed 56 breast carcinoma cases diagnosed on fixed paraffin-embedded core biopsies. HER2 amplification status was determined by commercially available FISH used as the reference technique with determination of the HER2/CEN17 ratio or HER2 copy number status. The alternative techniques performed on the same cases were commercially available SISH or CISH and a common qPCR method especially designed for the study including a set of 10 primer pairs: 2 for HER2 (exons 8 and 26), 5 to evaluate chromosome 17 polysomy TAOK1, UTP6, MRM1, MKS1, SSTR2 and 3 for diploidy control TSN, LAP3 and ADAMTS16.ResultsThe concordance between IHC and FISH was 96% to 95% based on the HER2/CEN17 ratio (n=766) or HER2 copy number (n=840), respectively. The concordance of the alternative techniques with FISH was excellent: 97% and 98% for SISH (498 and 587 cases), 98% and 75% for CISH (108 and 204 cases) and 95% and 93% (699 and 773 cases) for qPCR based on the HER2/CEN17 ratio or HER2 copy number, respectively. Similarly, sensitivity ranged from 99% to 95% for SISH, 100% to 99% for CISH and 89% to 80% for qPCR. The concordance with FISH (ratio) in the 2+ cases was 89% for SISH, 100% for CISH and 93% for qPCR.ConclusionThese alternative techniques showed an excellent concordance with FISH in core biopsies allowing their use in routine clinical practice. This newly designed qPCR on paraffin-embedded core biopsies deserves special attention, as it is reliable, easy to perform and less expensive than ISH tests.