Frequency of genetic alterations differs in advanced breast cancer between metastatic sites.

About 20%-30% of breast cancer (BC) patients will develop distant metastases, preferentially in bones, liver, lung, and brain. BCs with different intrinsic subtypes prefer different sites for metastasis. These subtypes vary in the abundance of genetic alterations which may influence the localization of metastases. Currently, information about the relation between metastatic site and mutational profile of BC is limited. In this study, n = 521 BC metastases of the most frequently affected sites (bone, brain, liver, and lung) were investigated for the frequency of AKT1, ERBB2, ESR1, PIK3CA, and TP53 mutations via NGS and pyrosequencing. Somatic mutations were present in 64% cases. PIK3CA and TP53 were the most frequently mutated genes under study. We provide an analysis of the mutational profile of BCs and the affected metastatic site. Genetic alterations differed significantly depending on the organ site affected by metastases. TP53 mutations were mostly observed in brain metastases (51.0%), metastases outside of the brain revealed a much lower proportion of TP53 mutated samples. PIK3CA mutations are frequent in liver (40.6%), lung (36.8%), and bone metastases (35.7%), whereas less common in brain metastases (18.4%). The highest percentage of ESR1 mutations was observed in liver and lung metastases (about 30% each), whereas metastatic lesions in the brain showed significantly less ESR1 mutations, only in 2.0% of the cases. In summary, we found significant differences of mutational status in mBC depending on the affected organ and intrinsic subtype. Organotropism of metastatic cancer spread may be influenced by the mutational profile of individual BCs.

Integration of Pathological Criteria and Immunohistochemical Evaluation for Invasive Lobular Carcinoma Diagnosis: Recommendations From the European Lobular Breast Cancer Consortium.

Invasive lobular carcinoma (ILC) is the second most frequent type of breast cancer (BC) and its peculiar morphology is mainly driven by inactivation of CDH1, the gene coding for E-cadherin cell adhesion protein. ILC-specific therapeutic and disease-monitoring approaches are gaining momentum in the clinic, increasing the importance of accurate ILC diagnosis. Several essential and desirable morphologic diagnostic criteria are currently defined by the World Health Organization, the routine use of immunohistochemistry (IHC) for E-cadherin is not recommended. Disagreement in the diagnosis of ILC has been repeatedly reported, but interpathologist agreement increases with the use of E-cadherin IHC. In this study, we aimed to harmonize the pathological diagnosis of ILC by comparing 5 commonly used E-cadherin antibody clones (NCH-38, EP700Y, Clone 36, NCL-L-E-cad [Clone 36B5], and ECH-6). We determined their biochemical specificity for the E-cadherin protein and IHC staining performance according to type and location of mutation on the CDH1 gene. Western blot analysis on mouse cell lines with conditional E-cadherin expression revealed a reduced specificity of EP700Y and NCL-L-E-cad for E-cadherin, with cross-reactivity of Clone 36 to P-cadherin. The use of IHC improved interpathologist agreement for ILC, lobular carcinoma in situ, and atypical lobular hyperplasia. The E-cadherin IHC staining pattern was associated with variant allele frequency and likelihood of nonsense-mediated RNA decay but not with the type or position of CDH1 mutations. Based on these results, we recommend the indication for E-cadherin staining, choice of antibodies, and their interpretation to standardize ILC diagnosis in current pathology practice.

p53 Expression in Luminal Breast Cancer Correlates With TP53 Mutation and Primary Endocrine Resistance.

TP53 mutation is associated with primary endocrine resistance in luminal breast cancer (BC). Nuclear accumulation of p53, as determined by immunohistochemistry (IHC), is a surrogate marker for TP53 mutation. The immunohistochemical p53 index that defines a p53-positive status is not well established. This study determined the optimal p53 index cutoff to identify luminal BCs harboring TP53 mutations. In total, 364 luminal BCs from the West German Study Group ADAPT trial (NCT01779206) were analyzed for TP53 mutations by next-generation sequencing and for p53 expression by IHC (DO-7 antibody). P53 indices were determined by automated image analysis. All tumors were from patients treated with short-term preoperative endocrine therapy (pET; tamoxifen or aromatase inhibitor) before tumor resection. IHC evaluation included needle biopsies before therapy (baseline) and resections specimens after therapy (post-pET). Optimal p53 index cutoffs were defined with Youden statistics. TP53 mutations were detected in 16.3% of BC cases. The median p53 indices were significantly higher in TP53-mutated BCs compared to BCs harboring wild-type TP53 (baseline: 47.0% vs 6.4%, P < .001; post-pET: 50.1% vs 1.1%, P < .001). Short-term pET decreased p53 indices in BCs harboring wild-type TP53 (P < .001) but not in TP53-mutated BCs (P = .102). For baseline biopsies, the optimal p53 index cutoff was ≥34.6% (specificity 0.92, sensitivity 0.63, Youden index 0.54, accuracy: 0.87). For post-pET specimens, the optimal cutoff was ≥25.3% (specificity 0.95, sensitivity 0.65, Youden index 0.60, accuracy: 0.90). Using these cutoffs to define the p53 status, p53-positive BCs were >2-fold more common in pET nonresponders compared to pET responders (baseline: 37/162, 22.8% vs 18/162, 11.1%, P = .007; post-pET: 36/179, 20.1% vs 16/179, 8.9%, P = .004). In summary, IHC for p53 identifies TP53-mutated luminal BCs with high specificity and accuracy. Optimal cutoffs are ≥35% and ≥25% for treatment-naïve and endocrine-pretreated patients, respectively.

Evaluation of the routine use of E-cadherin immunohistochemistry in the typing of breast carcinomas: results of a randomized diagnostic study.

AIMS: Invasive lobular carcinoma (ILC) has distinct morphology and association with loss of E-cadherin function. It has special clinical and imaging features, and its proper recognition is important. Following a recent proposal, we tested the value of the routine use of E-cadherin immunohistochemistry (IHC) in recognizing ILC. METHODS AND RESULTS: Five pathologists with experience in breast pathology from four Hungarian institutions histotyped 1001 breast cancers from diagnostic core biopsies or excision specimens randomly assigned to haematoxylin and eosin (HE) diagnosis first, followed by E-cadherin IHC; or to immediate HE and E-cadherin-based diagnosis. Of 524 cases with HE diagnosis, 73(14%) were deemed uncertain. E-cadherin made the initial histological type change in 14/524 cases (2.7%), including three with confident HE-based type allocation. Use of E-cadherin immunostaining was considered useful in 88/477 cases (18%) with immediate dual assessment, and typing uncertainty went down to 5% (25/477 cases), but was not zero. Collective assessment of 171 uncertain, difficult, nonclassical cases resulted in consensus diagnosis in most cases, but 15 cases were still doubtful as concerns their proper histological type. CDH1 gene sequencing was attempted and successful in 13; pathogenic genetic alterations were identified in seven cases. CONCLUSIONS: The routine use of E-cadherin IHC decreases the uncertainty in typing and improves the typing accuracy at the cost of potentially redundant additional immunostains. Furthermore, this procedure does not exclude uncertainty due to E-cadherin-positive ILCs, which are occasionally difficult to confidently label as ILC, especially when the growth pattern is not classic.

De-escalated neoadjuvant pertuzumab plus trastuzumab therapy with or without weekly paclitaxel in HER2-positive, hormone receptor-negative, early breast cancer (WSG-ADAPT-HER2+/HR-): survival outcomes from a multicentre, open-label, randomised, phase 2 trial.

BACKGROUND: Several de-escalation neoadjuvant strategies have been investigated to reduce the use of chemotherapy in HER2-positive early breast cancer using pathological complete response as a surrogate endpoint; there are few survival data from these trials. Here, we report 5-year survival data in the WSG-ADAPT-HER2+/HR- trial and address the effect of pathological complete response, early therapy response, and molecular subtype. METHODS: WSG-ASAPT-HER2+/HR-, a part of the ADAPT umbrella trial performed in patients with different subtypes of early breast cancer, was an investigator-initiated, multicentre, open-label, randomised, phase 2 trial done at 40 Breast Cancer Centres in Germany. Eligible patients were aged 18 years or older with histologically confirmed, unilateral, primary invasive, non-inflammatory early breast cancer, hormone receptor-negative and HER2-positive status, and an Eastern Cooperative Oncology Group performance status of 0 or 1 or a Karnofsky performance status of at least 80%. Patients were randomly assigned (5:2, block size 21, stratified by centre and clinical nodal status) to 12 weeks of either trastuzumab (8 mg/kg loading dose, then 6 mg/kg every 3 weeks) plus pertuzumab (840 mg loading dose, then 420 mg every 3 weeks) or trastuzumab plus pertuzumab plus paclitaxel (80 mg/m2 weekly); all drugs were administered intravenously. The primary objective of the trial was to compare the number of patients with a pathological complete response at surgery (ie, no invasive tumour cells in breast and lymph nodes [ypT0/is ypN0], the primary endpoint) in early responders (ie, low cellularity or Ki67 decrease ≥30% after 3 weeks) in the trastuzumab plus pertuzumab group versus all patients (irrespective of an early response) in the trastuzumab plus pertuzumab plus paclitaxel group. Non-inferiority was defined as a pathological complete response no worse than 23% lower in the early-responder proportion of patients in the trastuzumab plus pertuzumab group than in the entire trastuzumab plus pertuzumab plus paclitaxel group. The primary endpoint has been reported previously. Additionally, the primary objective of the ADAPT umbrella trial was the evaluation of the effect of pathological complete response on invasive disease-free survival. At investigator's discretion, further chemotherapy could be omitted in patients with a pathological complete response. Secondary survival endpoints were 5-year invasive disease-free survival, relapse-free survival, locoregional relapse-free survival, distant disease-free survival, and overall survival. The effect of pathological complete response on survival was estimated by Cox regression analysis. All analyses are reported in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT01817452, and is closed to recruitment. FINDINGS: Between March 3, 2014, and Oct 6, 2015, 134 patients were recruited and randomly assigned to treatment, 92 to trastuzumab plus pertuzumab and 42 to trastuzumab plus pertuzumab plus paclitaxel. Median follow-up in survivors was 59·9 months (IQR 53·4-61·4). There were no significant differences between the treatment groups in invasive disease-free survival, relapse-free survival, locoregional relapse-free survival, distant disease-free survival, and overall survival. In the trastuzumab plus pertuzumab plus paclitaxel group and in the trastuzumab plus pertuzumab group, the proportions of patients achieving 5-year survival respectively were 98% (95% CI 84-100) and 87% (78-93) for invasive disease-free survival (hazard ratio [HR] 0·32, 95% CI 0·07-1·49; p=0·15); 98% (95% CI 84-100) and 89% (79-94) for relapse-free survival (HR 0·41, 95% CI 0·09-1·91; p=0·25); 100% (95% CI not estimable) and 95% (88-98) for locoregional relapse-free survival (HR 0·41, 95% CI 0·05-3·75; p=0·43); 98% (95% CI 84-100) and 92% (83-96) for distant disease-free survival (HR 0·35, 95% CI 0·04-3·12; p=0·36), and 98% (95% CI 84-100) and 94% (86-97) for overall survival (HR 0·41, 95% CI 0·05-3·63; p=0·43). Pathological complete response was associated with improved invasive disease-free survival (HR 0·14, 95% CI 0·03-0·64; p=0·011). Two invasive disease-free survival events occurred after a pathological complete response (one in each treatment group). INTERPRETATION: The WSG-ADAPT-HER2+/HR- trial showed good survival rates in patients with a pathological complete response after de-escalated 12-week trastuzumab plus pertuzumab with or without weekly paclitaxel. Omission of further chemotherapy did not affect invasive disease-free survival in patients with a pathological complete response. 12 weeks of weekly paclitaxel plus dual HER2 blockade could be an efficacious de-escalated neoadjuvant regimen in patients with hormone receptor-negative, HER2-positive early breast cancer with high pathological complete response rates and good 5-year outcomes. Further trials of this approach are ongoing. FUNDING: Roche, Bayer. TRANSLATION: For the German translation of the abstract see Supplementary Materials section.

Impact of stromal tumor-infiltrating lymphocytes (sTILs) on response to neoadjuvant chemotherapy in triple-negative early breast cancer in the WSG-ADAPT TN trial.

BACKGROUND: Higher density of stromal tumor-infiltrating lymphocytes (sTILs) at baseline has been associated with increased rates of pathological complete response (pCR) after neoadjuvant chemotherapy (NACT) in triple-negative breast cancer (TNBC). While evidence supports favorable association of pCR with survival in TNBC, an independent impact of sTILs (after adjustment for pCR) on survival is not yet established. Moreover, the impact of sTIL dynamics during NACT on pCR and survival in TNBC is unknown. METHODS: The randomized WSG-ADAPT TN phase II trial compared efficacy of 12-week nab-paclitaxel with gemcitabine versus carboplatin. This preplanned translational analysis assessed impacts of sTIL measurements at baseline (sTIL-0) and after 3 weeks of chemotherapy (sTIL-3) on pCR and invasive disease-free survival (iDFS). Predictive performance of sTIL-0 and sTIL-3 for pCR was quantified by ROC analysis and logistic regression; Kaplan-Meier estimation and Cox regression (with mediation analysis) were used to determine their impact on iDFS. RESULTS: For prediction of pCR, the AUC statistics for sTIL-0 and sTIL-3 were 0.60 and 0.63, respectively, in all patients; AUC for sTIL-3 was higher in NP/G. The positive predictive value (PPV) of "lymphocyte-predominant" status (sTIL-0 ≥ 60%) at baseline was 59.3%, though only 13.0% of patients had this status. To predict non-pCR, the cut point sTIL-0 ≤ 10% yielded PPV = 69.5% while addressing 33.8% of patients. Higher sTIL levels (particularly at 3 weeks) were independently and favorably associated with better iDFS, even after adjusting for pCR. For example, the adjusted hazard ratio for 3-week sTILs ≥ 60% (vs. < 60%) was 0.48 [0.23-0.99]. Low cellularity in 3-week biopsies was the strongest individual predictor for pCR (in both therapy arms), but not for iDFS. CONCLUSION: The independent impact of sTILs on iDFS suggests that favorable immune response can influence key tumor biological processes for long-term survival. The results suggest that the reliability of pCR following neoadjuvant therapy as a surrogate for survival could vary among subgroups in TNBC defined by immune response or other factors. Dynamic measurements of sTILs under NACT could support immune response-guided patient selection for individualized therapy approaches for both very low levels (more effective therapies) and very high levels (de-escalation concepts). TRIAL REGISTRATION: Clinical trials No: NCT01815242, retrospectively registered January 25, 2013.

The impact of anthracyclines in intermediate and high-risk HER2-negative early breast cancer-a pooled analysis of the randomised clinical trials PlanB and SUCCESS C.

BACKGROUND: Anthracycline/cyclophosphamide-taxane-containing chemotherapy (AC-T) is the standard of care in the adjuvant treatment of HER2-negative early breast cancer (EBC), but recent studies suggest omission of anthracyclines for reduced toxicity without compromising efficacy. METHODS: Based on individual patient data (n = 5924) pooled from the randomised Phase III trials PlanB and SUCCESS C, we compared disease-free survival (DFS) and overall survival (OS) between intermediate to high-risk HER2-negative EBC-patients treated with either six cycles of docetaxel/cyclophosphamide (TC6) or an AC-T regime using univariable and adjusted multivariable Cox regression models. RESULTS: AC-T conferred no significant DFS or OS advantage in univariable (DFS: hazard ratio (HR) for TC vs. AT 1.05, 95% confidence interval (CI): 0.89-1.24, P = 0.57; OS: HR 1.00, 95% CI: 0.80-1.26, P = 1.00) and adjusted multivariable analysis (DFS: HR 1.01, 95% CI: 0.86-1.19, P = 0.91; OS: HR 0.97, 95% CI: 0.77-1.22, P = 0.79). Patients receiving TC6 had significantly fewer grade 3-4 adverse events. Exploratory subgroup analysis showed that AC-T was associated with significantly better DFS and OS in pN2/3 patients, specifically in those with lobular histology. CONCLUSION: For most patients with HER2-negative EBC, AC-T is not associated with a survival benefit compared to TC6. However, patients with lobular pN2/pN3 tumours seem to benefit from anthracycline-containing chemotherapy.

ERBB2 mutation is associated with sustained tumor cell proliferation after short-term preoperative endocrine therapy in early lobular breast cancer.

Invasive lobular breast cancer (ILC) is a special breast cancer (BC) subtype and is mostly hormone receptor (HR)-positive and ERBB2 non-amplified. Endocrine therapy restrains tumor proliferation and is the mainstay of lobular BC treatment. Mutation of ERBB2 has been associated with recurrent ILC. However, it is unknown whether ERBB2 mutation impacts on the otherwise exquisite responsiveness of early ILC to endocrine therapy. We have recently profiled n = 622 HR-positive early BCs from the ADAPT trial for mutations in candidate genes involved in endocrine resistance, including ERBB2. All patients were treated with short-term preoperative endocrine therapy (pET, tamoxifen or aromatase inhibitors) before tumor resection. Tumor proliferation after endocrine therapy (post-pET Ki67 index) was determined prospectively by standardized central pathology assessment supported by computer-assisted image analysis. Sustained or suppressed proliferation were defined as post-pET Ki67 ≥10% or <10%. Here, we report a subgroup analysis pertaining to ILCs in this cohort. ILCs accounted for 179/622 (28.8%) cases. ILCs were enriched in mutations in CDH1 (124/179, 69.3%, P < 0.0001) and ERBB2 (14/179, 7.8%, P < 0.0001), but showed fewer mutations in TP53 (7/179, 3.9%, P = 0.0048) and GATA3 (11/179, 6.1%, P < 0.0001). Considering all BCs irrespective of subtypes, ERBB2 mutation was not associated with proliferation. In ILCs, however, ERBB2 mutations were 3.5-fold more common in cases with sustained post-pET proliferation compared to cases with suppressed post-pET proliferation (10/75, 13.3% versus 4/104, 3.8%, P = 0.0248). Moreover, ERBB2 mutation was associated with high Oncotype DX recurrence scores (P = 0.0087). In summary, our findings support that ERBB2 mutation influences endocrine responsiveness in early lobular BC.

Results of a worldwide survey on the currently used histopathological diagnostic criteria for invasive lobular breast cancer.

Invasive lobular carcinoma (ILC) represents the second most common subtype of breast cancer (BC), accounting for up to 15% of all invasive BC. Loss of cell adhesion due to functional inactivation of E-cadherin is the hallmark of ILC. Although the current world health organization (WHO) classification for diagnosing ILC requires the recognition of the dispersed or linear non-cohesive growth pattern, it is not mandatory to demonstrate E-cadherin loss by immunohistochemistry (IHC). Recent results of central pathology review of two large randomized clinical trials have demonstrated relative overdiagnosis of ILC, as only ~60% of the locally diagnosed ILCs were confirmed by central pathology. To understand the possible underlying reasons of this discrepancy, we undertook a worldwide survey on the current practice of diagnosing BC as ILC. A survey was drafted by a panel of pathologists and researchers from the European lobular breast cancer consortium (ELBCC) using the online tool SurveyMonkey®. Various parameters such as indications for IHC staining, IHC clones, and IHC staining procedures were questioned. Finally, systematic reporting of non-classical ILC variants were also interrogated. This survey was sent out to pathologists worldwide and circulated from December 14, 2020 until July, 1 2021. The results demonstrate that approximately half of the institutions use E-cadherin expression loss by IHC as an ancillary test to diagnose ILC and that there is a great variability in immunostaining protocols. This might cause different staining results and discordant interpretations. As ILC-specific therapeutic and diagnostic avenues are currently explored in the context of clinical trials, it is of importance to improve standardization of histopathologic diagnosis of ILC diagnosis.

Transcription factor AP-2beta in development, differentiation and tumorigenesis.

To date, the AP-2 family of transcription factors comprises five members. Transcription factor AP-2beta (TFAP2B)/AP-2ß was first described in 1995. Several studies indicate a critical role of AP-2ß in the development of tissues and organs of ectodermal, neuroectodermal and also mesodermal origin. Germline mutation of TFAP2B is known to cause the Char syndrome, an autosomal dominant disorder characterized by facial dysmorphism, patent ductus arteriosus and anatomical abnormalities of the fifth digit. Furthermore, single-nucleotide polymorphisms in TFAP2B were linked to obesity and specific personality traits. In neoplasias, AP-2ß was first described in alveolar rhabdomyosarcoma. Immunohistochemical staining of AP-2ß is a recommended ancillary test for the histopathological diagnosis of this uncommon childhood malignancy. In neuroblastoma, AP-2ß supports noradrenergic differentiation. Recently, the function of AP-2ß in breast cancer (BC) has gained interest. AP-2ß is associated with the lobular BC subtype. Moreover, AP-2ß controls BC cell proliferation and has a prognostic impact in patients with BC. This review provides a comprehensive overview of the current knowledge about AP-2ß and its function in organ development, differentiation and tumorigenesis.

Early response by MR imaging and ultrasound as predictor of pathologic complete response to 12-week neoadjuvant therapy for different early breast cancer subtypes: Combined analysis from the WSG ADAPT subtrials.

We evaluated the role of early response after 3 weeks of neoadjuvant treatment (NAT) assessed by ultrasound (US), magnetic resonance imaging (MRI) and Ki-67 dynamics for prediction of pathologic complete response (pCR) in different early breast cancer subtypes. Patients with HR+/HER2+, HR-/HER2- and HR-/HER2+ tumors enrolled into three neoadjuvant WSG ADAPT subtrials underwent US, MRI and Ki-67 assessment at diagnosis and after 3 weeks of NAT. Early response was defined as complete or partial response (US, MRI) and ≥30% proliferation decrease or <500 invasive tumor cells (Ki-67). Predictive values and area under the receiver operating characteristic (AUC) curves for prediction of pCR (ypT0/is ypN0) after 12-week NAT were calculated. Two hundred twenty-six had MRI and 401 US; 107 underwent both MRI and US. All three methods yielded a similar AUC in HR+/HER2+ (0.66-0.67) and HR-/HER2- tumors (0.53-0.63), while MRI and Ki-67 performed better than US in HR-/HER2+ tumors (0.83 and 0.79 vs 0.56). Adding MRI+/-Ki-67 increased AUC of US in HR-/HER2+ tumors to 0.64 to 0.75. MRI and Ki-67 demonstrated highest sensitivity in HR-/HER2- (0.8-1) and HR-/HER2+ tumors (1, both). Negative predictive value was similar for all methods in HR+/HER2+ (0.71-0.74) and HR-/HER2- tumors (0.85-1), while it was higher for MRI and Ki-67 compared to US in HR-/HER2+ subtype (1 vs 0.5). Early response assessed by US, MRI and Ki-67 is a strong predictor for pCR after 12-week NAT. Strength of pCR prediction varies according to tumor subtype. Adding MRI+/-Ki-67 to US did not improve pCR prediction in majority of our patients.

Association of TILs with clinical parameters, Recurrence Score® results, and prognosis in patients with early HER2-negative breast cancer (BC)-a translational analysis of the prospective WSG PlanB trial.

BACKGROUND: The presence of tumor-infiltrating lymphocytes has been associated with prognosis and chemotherapy response, particularly in high-risk breast cancer subtypes. There is limited data so far as to (i) how tumor-infiltrating lymphocyte (TIL) measurements correlate with genomic measurements such as the Oncotype DX Recurrence Score® and (ii) whether the survival impact of TIL measurements varies according to different adjuvant systemic therapies. METHODS: The WSG PlanB trial compared an anthracycline-free chemotherapy regimen (6x docetaxel/cyclophosphamide, TC) to an anthracycline-taxane sequence (4xEC followed by 4x docetaxel) in patients with intermediate-risk, HER2-negative early breast cancer (EBC). Patients with HR-positive HER2-negative EBC were further stratified to receive endocrine therapy alone vs. chemotherapy followed by endocrine therapy based on Recurrence Score results and nodal status. In this analysis, three independent observers quantified and categorized the presence of TILs among tumor samples from patients in PlanB. TIL measurements were correlated with clinical/pathological parameters and treatment outcome overall and according to the treatment arm. RESULTS: Disease-free survival (DFS) rates were significantly better (p = .04) in HR-negative patients with high vs. intermediate TIL levels and were higher in low vs. intermediate TIL patients, however with borderline significance only (p = .06). There were no significant differences among TIL categories in HR+ patients. High RS categories, HR-negative status, and high KI67 were independently and significantly associated with high TIL categories. There was no significant impact of TIL category on DFS in patients treated by endocrine therapy only; however, in patients receiving chemotherapy, DFS in the intermediate TIL category was lower than that in the other categories. CONCLUSION: Although the presence of high TILs is associated with negative prognostic parameters such as high KI67 and HR-negative status among patients with HR-positive HER2-negative EBC, patients with high TILs show a favorable 5-year DFS in both HR-positive/HER2-negative and triple-negative breast cancer.

Efficacy of deescalated chemotherapy according to PAM50 subtypes, immune and proliferation genes in triple-negative early breast cancer: Primary translational analysis of the WSG-ADAPT-TN trial.

In the neoadjuvant WSG-ADAPT-TN trial, 12-week nab-paclitaxel + carboplatin (nab-pac/carbo) was highly effective and superior to nab-paclitaxel + gemcitabine (nab-pac/gem) in triple-negative breast cancer regarding pathological complete response (pCR). Predictive markers for deescalated taxane/carbo use in TNBC need to be identified. Patients received 4 × nab-pac 125 mg/m2 (plus carbo AUC2 or gem 1,000 mg/m2 d1,8 q21). Expression of 119 genes and PAM50 scores by nCounter were available in 306/336 pretherapeutic samples. Interim survival analysis was planned after 36 months median follow-up. Basal-like (83.3%) compared to other subtypes was positively associated with pCR (38% vs. 20%, p = 0.015), as was lower HER2 score (p < 0.001). Proliferation biomarkers were positively associated with pCR, that is, PAM50 proliferation, ROR scores (all p < 0.004), higher Ki-67 (IHC; p < 0.001). For nab-pac/carbo, expression of immunological (CD8, PD1 and PFDL1) genes and proliferation markers (proliferation and ROR scores, MKI67, CDC20, NUF2, KIF2C, CENPF, EMP3 and TYMS) were positively associated with pCR (p < 0.05 for all). For nab-pac/gem, angiogenesis genes were negatively associated with pCR (ANGPTL4: p = 0.05; FGFR4: p = 0.02; VEGFA: p = 0.03). pCR after 12 weeks was strongly associated with favorable outcome (3y event-free survival: 92% vs. 71%, p < 0.001). In early TNBC, basal-like subtype, higher Ki-67 (IHC) and lower HER2 score were, associated with chemosensitivity. Chemoresistance pathways differed between the two taxane based combinations. Combination of proliferation/immune markers and PAM50 subtype could allow patient selection for further deescalated chemotherapy and/or immune treatment approaches.

Differential impact of prognostic parameters in hormone receptor-positive lobular breast cancer.

BACKGROUND: Invasive lobular breast cancer (BC) is the second most common BC subtype. Prognostic parameters (tumor classification, lymph node status, histologic grade, Oncotype DX recurrence score [RS], progesterone receptor status, and Ki67 index) were retrospectively studied in a large, prospective clinical trial encompassing 2585 patients who had hormone receptor-positive early BC (the West German Study Group PlanB trial). METHODS: BCs were centrally reviewed and classified as lobular (n = 353; 14%) or nonlobular (n = 2232; 86%). The median follow-up was 60 months. Five-year disease-free survival (DFS) estimates were obtained using the Kaplan-Meier method. Prognostic parameters were evaluated using Cox proportional hazard models. RESULTS: Lobular BC was associated with higher tumor classification, higher lymph node status, lower histologic grade, lower Ki67 index, and low or intermediate RS. The prevalence of high RS (RS range, 26-100) was 3-fold lower in patients who had lobular BC compared with those who had nonlobular BC (8% vs 24%; P < .001). However, 5-year DFS estimates for lobular and nonlobular BC were similar (92.1% and 92.3%, respectively; P = .673). In multivariate analyses, prognostic parameters for DFS in lobular BC included grade 3 (hazard ratio, 5.06; 95% CI, 1.91-13.39) and a pathologic lymph node status (pN) of pN3 (hazard ratio, 12.16; 95% CI, 3.87-38.24), but not RS. By contrast, prognostic parameters in nonlobular BC included grade 3 (hazard ratio, 1.65; 95% CI, 1.11-2.44), pN3 (hazard ratio, 3.68; 95% CI, 1.60-8.46), and high RS (hazard ratio, 2.49; 95% CI, 1.69-3.68). CONCLUSIONS: Lobular BC is associated with low and intermediate RS, although 5-year DFS is similar to that of nonlobular BC. The effect of the RS in lobular BC appears to be distinct from that in nonlobular BC. For risk assessment, the RS needs to be complemented by clinicopathologic parameters for therapy decision making.

E-cadherin to P-cadherin switching in lobular breast cancer with tubular elements.

Loss of E-cadherin expression due to mutation of the CDH1 gene is a characteristic feature of invasive lobular breast cancer (ILBC). Beta-catenin, which binds to the cytoplasmic domain of E-cadherin, is simultaneously downregulated, reflecting disassembly of adherens junctions (AJs) and loss of cell adhesion. E-cadherin to P-cadherin expression switching can rescue AJs and cell adhesion. However, P-cadherin has not been implicated in ILBC, so far. We aimed to characterize 13 ILBCs with exceptional histomorphology, which we termed ILBCs with tubular elements. The CDH1 mutational status was determined by next generation sequencing and whole-genome copy number (CN) profiling. Expression of cadherins was assessed by immunohistochemistry. ILBCs with tubular elements were ER-positive (13/13) and HER2-negative (13/13) and harbored deleterious CDH1 mutations (11/13) accompanied by loss of heterozygosity due to deletion of chromosome 16q22.1 (9/11). E-cadherin expression was lost or reduced in noncohesive tumor cells and in admixed tubular elements (13/13). Beta-catenin expression was lost in noncohesive tumor cells, but was retained in tubular elements (11/13), indicating focal rescue of AJ formation. N-cadherin and R-cadherin were always negative (0/13). Strikingly, P-cadherin was commonly positive (12/13) and immunoreactivity was accentuated in tubular elements. Adjacent lobular carcinoma in situ (LCIS) was always P-cadherin-negative (0/7). In a reference cohort of LCIS specimens, P-cadherin was constantly not expressed (0/25). In a reference cohort of invasive mammary carcinomas, P-cadherin-positive cases (36/268, 13%) were associated with triple-negative nonlobular breast cancer (P < 0.001). Compared with ILBCs from the reference cohort, P-cadherin expression was more common in ILBCs with tubular elements (12/13 versus 7/84, P < 0.001). In summary, E-cadherin to P-cadherin switching occurs in a subset of ILBCs. P-cadherin is the molecular determinant of a mixed-appearing histomorphology in ILBCs with tubular elements.

ERBB2 mutation frequency in lobular breast cancer with pleomorphic histology or high-risk characteristics by molecular expression profiling.

HER2-positive breast cancer is defined by amplification or overexpression of the HER2/ERBB2 oncogene and accounts for about 15% of breast cancer cases. Somatic mutation of ERBB2 is an alternative mechanism, by which activation of HER2 signaling can occur. ERBB2 mutation has been associated with invasive lobular breast cancer (ILBC). This study investigates the frequency and phenotype of ILBC harboring mutated ERBB2. The ERBB2 mutation status was determined by next generation sequencing and/or pyrosequencing in n = 106 ILBCs, including n = 86 primary or locally recurrent tumors and n = 20 metastases from visceral organs, soft tissue, or skin. Immunohistochemical characteristics were determined using tissue microarrays. This series was enriched for ILBCs with pleomorphic histology and/or high-risk expression profiles (Oncotype DX, recurrence score RS > 25). Nearly all specimens were E-cadherin-negative (99%), estrogen receptor (ER)-positive (92%), and lacked ERBB2 overexpression (96%). ERBB2 mutations (p.V777L, p.L755S, p.S310F) were identified in 5/106 (5%) cases. ERBB2-mutated cases included 2/86 (2%) primary tumors and 3/20 (15%) metastases (P = 0.045). ERBB2-mutated cases were associated with loss of ER (2/7, 29%, P = 0.035) and histological grade 3 (4/34, 12%, P = 0.023), but not with solid growth (3/31, 10%, P = 0.148) or pleomorphic histology (2/27, 7%, P = 0.599). No ERBB2 mutation was detected in ILBCs with RS > 25 (0/22, 0%). In 10 patients with multiple matched specimens (n = 25), the ERBB2 mutational status was always concordant. In summary, a small subset of ILBCs harbors potentially actionable ERBB2 mutations. In ERBB2-mutated ILBCs, no association with pleomorphic histology was found.

Correction to: Reducing chemotherapy use in clinically high-risk, genomically low-risk pN0 and pN1 early breast cancer patients: five-year data from the prospective, randomised phase 3 West German Study Group (WSG) PlanB trial.

The article Reducing chemotherapy use in clinically high-risk, genomically low-risk pN0 and pN1 early breast cancer patients: five-year data from the prospective, randomised phase 3 West German Study Group (WSG) PlanB trial, written by Ulrike Nitz, Oleg Gluz, Matthias Christgen, Ronald E. Kates, Michael Clemens, Wolfram Malter, Benno Nuding, Bahriye Aktas, Sherko Kuemmel, Toralf Reimer, Andrea Stefek, Fatemeh Lorenz-Salehi, Petra Krabisch, Marianne Just, Doris Augustin, Cornelia Liedtke, Calvin Chao, Steven Shak, Rachel Wuerstlein, Hans H. Kreipe, Nadia Harbeck, was originally published electronically on the publisher's internet portal (currently SpringerLink) on June 29, 2017 without open access.With the author(s)' decision to opt for Open Choice the copyright of the article changed on January 6, 2019 to © The Author(s) 2017 and the article is forthwith distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License ( http://creativecommons.org/licenses/by-nc/4.0/ ), which permits any noncommercial use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, a link is provided to the Creative Commons license and any changes made are indicated. The original article has been corrected.

CDKN2A loss and PIK3CA mutation in myoepithelial-like metaplastic breast cancer.

Metaplastic breast carcinoma comprises a heterogeneous group of tumours with poorly understood pathogenesis. A subset of metaplastic breast cancers show myoepithelial differentiation and constitute a morphological spectrum with ill-defined borders from fibromatosis-like spindle cell carcinoma to myoepithelial carcinoma. In a series of 34 metaplastic breast cancers with spindle cell and myoepithelial differentiation, we found recurrent genetic aberrations, which set them apart from other metaplastic breast cancers and suggest a unique pathogenesis. The majority of cases (28 of 34 patients; 82.4%) showed distinct chromosomal loss in the 9p21.3 region, including CDKN2A and CDKN2B. Biallelic loss of the CDKN2A/B region was found in 50% of deleted cases. Expression of the cyclin-dependent kinase inhibitor CDKN2A (p16) was missing in all samples affected by 9p21.3 loss. Other genomic alterations frequently occurring in triple-negative and metaplastic breast cancer were absent or found in only a minority of cases. Gains of whole chromosome 5 and chromosomal region 5p were observed in nine cases, and were associated with recurrences (p < 0.001). In 64.3% of cases, 9p21.3 loss was accompanied by concurrent PIK3CA mutation. Both genomic abnormalities were also detectable in adenomyoepitheliomas (4/12), which are considered to represent the precursor lesion of myoepithelial metaplastic breast cancer. In adenomyoepithelioma, PIK3CA mutation was present in both luminal epithelial and myoepithelial cells, whereas p16 loss was found only in the latter. We conclude that 9p21.3 (CDKN2A) loss and PIK3CA mutation characterize a subgroup of metaplastic breast cancers with myoepithelial and spindle cell differentiation. Myoepithelial cells in adenomyoepithelioma may show identical aberrations. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Lobular carcinoma in situ and invasive lobular breast cancer are characterized by enhanced expression of transcription factor AP-2ß.

Transcription factor AP-2ß (TFAP2B) regulates embryonic organ development and is overexpressed in alveolar rhabdomyosarcoma, a rare childhood malignancy. Gene expression profiling has implicated AP-2ß in breast cancer (BC). This study characterizes AP-2ß expression in the mammary gland and in BC. AP-2ß protein expression was assessed in the normal mammary gland epithelium, in various reactive, metaplastic and pre-invasive neoplastic lesions and in two clinical BC cohorts comprising >2000 patients. BCs from various genetically engineered mouse (GEM) models were also evaluated. Human BC cell lines served as functional models to study siRNA-mediated inhibition of AP-2ß. The normal mammary gland epithelium showed scattered AP-2ß-positive cells in the luminal cell layer. Various reactive and pre-invasive neoplastic lesions, including apocrine metaplasia, usual ductal hyperplasia and lobular carcinoma in situ (LCIS) showed enhanced AP-2ß expression. Cases of ductal carcinoma in situ (DCIS) were more often AP-2ß-negative (P<0.001). In invasive BC cohorts, AP-2ß-positivity was associated with the lobular BC subtype (P<0.001), loss of E-cadherin (P<0.001), a positive estrogen receptor (ER) status (P<0.001), low Ki67 (P<0.001), low/intermediate Oncotype DX recurrence scores (P<0.001), and prolonged event-free survival (P=0.003). BCs from GEM models were all AP-2ß-negative. In human BC cell lines, AP-2ß expression was independent from ER-signaling. SiRNA-mediated inhibition of AP-2ß diminished proliferation of lobular BC cell lines in vitro. In summary, AP-2ß is a new mammary epithelial differentiation marker. Its expression is preferentially retained and enhanced in LCIS and invasive lobular BC and has prognostic implications. Our findings indicate that AP-2ß controls tumor cell proliferation in this slow-growing BC subtype.