Ki67 represents an immunohistochemical nuclear localized marker that is widely used in surgical pathology. Nuclear immunoreactivity for Ki67 indicates that cells are cycling and are in G1- to ...S-phase. The percentage of Ki67-positive tumor cells (Ki67 index) therefore provides an estimate of the growth fraction in tumor specimens. In breast cancer (BC), tumor cell proliferation rate is one of the most relevant prognostic markers and Ki67 is consequently helpful in prognostication similar to histological grading and mRNA profiling-based BC risk stratification. In BCs treated with short-term preoperative endocrine therapy, Ki67 dynamics enable distinguishing between endocrine sensitive and resistant tumors. Despite its nearly universal use in pathology laboratories worldwide, no internationally accepted consensus has yet been achieved for some methodological details related to Ki67 immunohistochemistry (IHC). Controversial issues refer to choice of IHC antibody clones, scoring methods, inter-laboratory reproducibility, and the potential value of computer-assisted imaging analysis and/or artificial intelligence for Ki67 assessment. Prospective clinical trials focusing on BC treatment have proven that Ki67, as determined by standardized central pathology assessment, is of clinical validity. Clinical utility has been demonstrated in huge observational studies.
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.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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.
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.
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.
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.
Invasive lobular breast cancer (ILC) is the most common special histological type of breast cancer (BC). This review recapitulates developments in the histomorphologic assessment of ILC from its ...beginnings with the seminal work of Foote and Stewart, which was published in 1941, until today. We discuss different concepts of ILC and their implications. These concepts include (i) BC arising from mammary lobules, (ii) BC growing in dissociated cells and single files, and (iii) BC defined as a morpho-molecular spectrum of tumors with distinct histological and molecular characteristics related to impaired cell adhesion. This review also provides a comprehensive overview of ILC variants, their histomorphology, and differential diagnosis. Furthermore, this review highlights recent advances which have contributed to a better understanding of the histomorphology of ILC, such as the role of the basal lamina component laminin, the molecular specificities of triple-negative ILC, and E-cadherin to P-cadherin expression switching as the molecular determinant of tubular elements in CDH1-deficient ILC. Last but not least, we provide a detailed account of the tumor microenvironment in ILC, including tumor infiltrating lymphocyte (TIL) levels, which are comparatively low in ILC compared to other BCs, but correlate with clinical outcome. The distinct histomorphology of ILC clearly reflects a special tumor biology. In the clinic, special treatment strategies have been established for triple-negative, HER2-positive, and ER-positive BC. Treatment specialization for patients diagnosed with ILC is just in its beginnings. Accordingly, ILC deserves greater attention as a special tumor entity in BC diagnostics, patient care, and cancer research.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Invasive lobular carcinoma (ILC) is a common breast cancer subtype that is often diagnosed at advanced stages and causes significant morbidity. Late-onset secondary tumor recurrence affects up to 30% ...of ILC patients, posing a therapeutic challenge if resistance to systemic therapy develops. Nonetheless, there is a lack of preclinical models for ILC, and the current models do not accurately reproduce the complete range of the disease. We created clinically relevant metastatic xenografts to address this gap by grafting the triple-negative IPH-926 cell line into mouse milk ducts. The resulting intraductal xenografts accurately recapitulate lobular carcinoma in situ (LCIS), invasive lobular carcinoma, and metastatic ILC in relevant organs. Using a panel of 15 clinical markers, we characterized the intratumoral heterogeneity of primary and metastatic lesions. Interestingly, intraductal IPH-926 xenografts express low but actionable HER2 and are not dependent on supplementation with the ovarian hormone estradiol for their growth. This model provides a valuable tool to test the efficiency of potential new ILC therapeutics, and it may help detect vulnerabilities within ILC that can be exploited for therapeutic targeting.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Summary Therapeutic decision-making in breast cancer depends on histopathologic biomarkers and is influenced by the Ki67 proliferation index. Computer-assisted image analysis (CAIA) promises to ...improve Ki67 quantification. Several commercial applications have been developed for semiautomated CAIA-based Ki67 quantification, many of which rely on measurements in user-defined regions of interest (ROIs). Because of intratumoral proliferative heterogeneity, definition of the ROI is an important step in the analytical procedure. This study explores the ROI size impacts on Ki67 quantification. Whole-slide sections of 100 breast cancers were immunostained with the anti–Ki67 antibody 30-9 and were analyzed on the iScan Coreo digital pathology platform using a Food and Drug Administration–cleared Ki67 quantification software version v5.3 (Virtuoso; Ventana, Tucson, TX). For each case, the Ki67 labeling index (LI) was determined in multiple ROIs of gradually increasing size centered around a high-proliferation area. The spatial Ki67 decline was modeled with nonlinear regression. Depending on the ROI size, the median Ki67 LI varied between 55% and 15%. The proportion of tumors classified as Ki67 low according to the St Gallen 2013/2015 cutoff increased from 2% to 56%, as the ROI size increased from 50 to 10 000 cells captured. The interrater reliability of conventional Ki67 assessment versus CAIA-based Ki67 quantification was also dependent on the ROI size and varied between slight and almost perfect agreement (Cohen κ = 0.06-0.85). In conclusion, the ROI size is a critically important parameter for semiautomated Ki67 quantification by CAIA. Ki67 LIs determined on platforms like iScan Coreo/Virtuoso require an ROI size adjustment, for which we offer a downloadable data transformation tool.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Abstract
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.
Invasive lobular carcinoma (ILC) accounts for up to 15% of all breast cancer (BC) cases and responds well to endocrine treatment when estrogen receptor α-positive (ER
) yet differs in many biological ...aspects from other ER
BC subtypes. Up to 30% of patients with ILC will develop late-onset metastatic disease up to ten years after initial tumor diagnosis and may experience failure of systemic therapy. Unfortunately, preclinical models to study ILC progression and predict the efficacy of novel therapeutics are scarce. Here, we review the current advances in ILC modeling, including cell lines and organotypic models, genetically engineered mouse models, and patient-derived xenografts. We also underscore four critical challenges that can be addressed using ILC models: drug resistance, lobular tumor microenvironment, tumor dormancy, and metastasis. Finally, we highlight the advantages of shared experimental ILC resources and provide essential considerations from the perspective of the European Lobular Breast Cancer Consortium (ELBCC), which is devoted to better understanding and translating the molecular cues that underpin ILC to clinical diagnosis and intervention. This review will guide investigators who are considering the implementation of ILC models in their research programs.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Background:
Endocrine sensitivity, as determined by response of the proliferation marker Ki-67 to short-term preoperative endocrine therapy (ET), is currently not included in adjuvant treatment ...decisions in hormone receptor (HR)+/human epidermal growth factor receptor 2 (HER2)− breast cancer (BC).
Methods:
The prospective WSG-ADAPT HR+/HER2− trial included patients with N0/N1 early BC who were candidates for adjuvant chemotherapy based on clinical–pathological criteria alone. The trial utilized a genomic assessment the Recurrence Score (RS) plus endocrine sensitivity testing to guide treatment. All patients received 3 (±1) weeks of preoperative induction ET. According to protocol, patients with RS 0–11 or RS 12–25 plus endocrine proliferation response (EPR, post-induction Ki-67 ⩽ 10%) were to be spared adjuvant chemotherapy.
Results:
The ADAPT HR+/HER2− trial run-in phase included 407 patients with baseline RS, of whom 386 (median age: 54 years) had complete data for Ki-67 at both baseline and post-induction. RS distribution: 23.1% RS 0–11, 58.3% RS 12–25, and 18.7% RS 26–100. EPR occurred in 84.3%, 76.0%, and 36.1% of these RS groups, respectively. Differences in EPR proportions (RS 26–100 versus others, RS 0–11 versus others) were significant (both p < 0.001); Ki-67 quotients were higher for RS 26–100 (p = 0.02, Mann–Whitney). In premenopausal women (n = 146, mostly tamoxifen-treated), median quotient of Ki-67 level (post/pre) was significantly higher than in postmenopausal women (n = 222, mostly aromatase-inhibitor treated; 0.67 versus 0.25, p < 0.001). EPR was significantly associated with baseline estrogen-receptor status as determined by immunohistochemistry (p = 0.002) or real-time polymerase chain reaction (p < 0.001). Also, a strong correlation was observed between RS measured pre- and post-ET (RS = 0.7, n = 181).
Conclusions:
This phase of the WSG-ADAPT HR+/HER2− trial confirms trial design estimates of RS and EPR. It indicates that the ADAPT concept of combining static and dynamic biomarker assessment for individualized therapy decisions in early BC is feasible using the EPR criterion post-induction Ki-67 ⩽ 10%.
Clinicaltrials.gov identifier:
NCT01779206.
Most breast cancers depend on estrogenic growth stimulation. Functional genetic screenings in in vitro cell models have identified genes, which override growth suppression induced by anti-estrogenic ...drugs like tamoxifen. Using that approach, we have previously identified Breast Cancer Anti-Estrogen Resistance 4 (BCAR4) as a mediator of cell proliferation and tamoxifen-resistance. Here, we show high level of expression and function of BCAR4 in human breast cancer.
BCAR4 mRNA expression was evaluated by (q)RT-PCR in a panel of human normal tissues, primary breast cancers and cell lines. A new antibody raised against C78-I97 of the putative BCAR4 protein and used for western blot and immunoprecipitation assays. Furthermore, siRNA-mediated gene silencing was implemented to study the function of BCAR4 and its downstream targets ERBB2/3.
Except for placenta, all human normal tissues tested were BCAR4-negative. In primary breast cancers, BCAR4 expression was comparatively rare (10%), but associated with enhanced proliferation. Relative high BCAR4 mRNA expression was identified in IPH-926, a cell line derived from an endocrine-resistant lobular breast cancer. Moderate BCAR4 expression was evident in MDA-MB-134 and MDA-MB-453 breast cancer cells. BCAR4 protein was detected in breast cancer cells with ectopic (ZR-75-1-BCAR4) and endogenous (IPH-926, MDA-MB-453) BCAR4 mRNA expression. Knockdown of BCAR4 inhibited cell proliferation. A similar effect was observed upon knockdown of ERBB2/3 and exposure to lapatinib, implying that BCAR4 acts in an ERBB2/3-dependent manner.
BCAR4 encodes a functional protein, which drives proliferation of endocrine-resistant breast cancer cells. Lapatinib, a clinically approved EGFR/ERBB2 inhibitor, counteracts BCAR4-driven tumor cell growth, a clinical relevant observation.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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