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Background The crucial point in making treatment decisions for breast cancer patients is the assessment of tumour aggressiveness. The established prognostic markers may be insufficient to stratify cancer patients into treatment relevant risk groups. Emerging evidence indicates that mechanical properties of cancer cells and their microenvironment that occur on a nanometre scale play a critical role in cancer invasion and metastases. Therefore, detecting these nanomechanical changes could serve as biomarker of cancer aggressiveness. Trial design We conduct a prospective, blinded study in a routine clinical setting. Using minimal invasive breast biopsies we measure the nanomechanical (stiffness) properties of human breast tissue with our atomic force microscope (AFM) based method known as ARTIDIS (Automated and Reliable Tissue Diagnostics). These properties can only be measured using fresh (non-fixed) tissue under physiological conditions (Custodiol transplant buffer). This novel method is based on the use of a micro-fabricated 20nm-sharp tip that indents several thousand individual locations across tissue specimens within 60-180 minutes. Each indentation effectively measures the stiffness of local structures (e.g. cancer cells, extracellular matrix) located under the tip. Thus we obtain a quantitative, biopsy-wide, nanomechanical profile. Post-AFM the same biopsy is used for routine histopathological diagnosis, the current diagnostic gold standard to which the nanomechanical profile is then correlated. Eligibility criteria All women undergoing a minimal invasive breast biopsy (core needle or vacuum assisted biopsy) at the breast centre of the University of Basel. Exclusion criteria: age younger than 18years, necrotic/disintegrated biopsy, and technical limitations Specific aims Our primary endpoint is to differentiate benign from cancerous breast lesions based on their nanomechanical properties. Our secondary endpoint is to subclassify biopsies with cancerous lesions into the current four main breast cancer subgroups (Luminal A, Luminal B, HER2+ and basal-like). Statistical analysis The full dataset will include all patients with valid AFM measurements. Primary analysis: the proportion of true positive results divided by the total number of patients with malignant tumour (sensitivity) will be estimated and presented together with its 95% confidence interval. The histological diagnosis of the same biopsy as analysed by AFM will serve as gold standard. Present accrual and target accrual Present accrual as of June 12, 2017: 200 breast tissue biopsies. Target accrual is 508 biopsies. This will allow for a power of 0.8 and a sensitivity of 90%. Contact information: Rosemarie.Burian@usb.ch Citation Format: Burian R, Appenzeller T, Oertle P, Raez C, Lim R, Forte S, Dellas S, Münst S, Obermann E, Plodinec M. Atomic force microscopy (AFM) - a novel nanotool for cancer diagnostics: A prospective, blinded study of nanomechanical profiling of human breast tissue as a potential biomarker for stratifying low- and high-risk breast cancer subtypes [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT1-06-05.

Clinical treatment of breast cancer is successful. What remains a challenge for individualized therapy is the prediction of which cancer responds to which treatment. Emerging evidence indicates that mechanical alterations on a (sub-) cellular level are markers of cancer aggressiveness. Detecting these could serve as biomarker and help optimize cancer diagnosis, therapy choice, and patient follow-up. We developed a diagnostic platform called ARTIDIS (Automated and Reliable Tissue Diagnostics) based on atomic force microscopy (AFM)-type nanomechanical testing. ARTIDIS uses a 20-nanometer-sharp tip measuring 10'000 miniscule indentation across the biopsy's surface and quantifies stiffness on a molecular level. The relative size and distribution of stiffness values is integrated into a data analytics tool that systematically analyses tissue biomechanics in correlation to clinical parameters, histological prognostic markers, and treatment yielding prognostic and predictive value. To demonstrate ARTIDIS' clinical utility for diagnosis and development of prognostic and predictive biomarkers we conducted a prospective blinded clinical study on 545 patients. All patients undergoing a core needle or vacuum biopsy of the breast qualified. Within the routine clinical workflow, ARTIDIS analyzed fresh biopsies in a physiological solution preserving the biopsy's viability for histological and genetic analysis. Per patient, one representative biopsy was measured, marked and reunited with the patient's other biopsies for standard histological procedure. In total, 583 biopsies from N=545 patients were analyzed: 62.1% were B1-B4 (normal, benign, of uncertain malignant potential, or suspicious); a third (36.9%) malignant (B5a-B5d), and six specimens (1%) not assignable. Half of all B5b lesions were Luminal B, followed by Luminal A, Luminal B-like, HER2-positive or triple negative. The analysis of the primary endpoint (N=520 patients qualified, N=3 were excluded due to missing information) demonstrated ARTIDIS' ability to detect cancer in all samples including lesions with We could separate more aggressive cases within the Luminal B subtype (CI 95%; sensitivity 83%, specificity 82%, AUC = 0.86). Secondary analysis also indicated a similarity between the majority of B3 (uncertain) and B2 (benign) lesions and distinct differences from all B5a and B5b, which could help reduce overtreatment of B3 lesions. This large prospective single center study demonstrated ARTIDIS' ability to differentiate benign from malignant lesions and to further subclassify specific breast cancer subtypes. In addition, Luminal B cancers exhibited nanomechanical profiles associated with better or worse prognosis and treatment outcome. The final analysis results provide cutoffs that will be assessed in the upcoming large multicenter prospective trial. Finally, this study helped to determine clinical utility of nanomechanical characterization of breast and other solid cancers for prediction and treatment optimization. Citation Format: Rosemarie Burian, Ahmed Jizawi, Flora Scott, Sabine Schädelin, Christian Raez, Simone Muenst-Soysal, Tatjana Vlaijnic, Ellen Obermann, Sophie Dellas, Serafino Forte, Zlatko Marušić, Tobias Appenzeller, Philipp Oertle, Nam Seung-Zln, Gregory Zaugg, Milan Liepelt, Gabriel Zihlman, Roderick Lim, Marko Loparic, Marija Plodinec. First clinical validation of the physical biomarker based on the nanomechanical tissue profiling for rapid breast cancer diagnosis, prognosis and predication of treatment outcome [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-273.

The onset of metastasis occurs when cancer cells invade and breach the basement membrane (BM) that provides mechanical support to epithelial tissues. Yet, it remains unclear what triggers cancer cells to breach the BM, and how ‘triggered’ cells in fact breach the BM. We have established an in vitro assay using native BM interface for culturing epithelial cells. Using atomic force microscopy (AFM) with other high-resolution microscopies and TER (trans-epithelial resistance), we have correlated the mechano-cellular attributes of the BM/epithelium interface to its biochemical and structural properties. We demonstrated that the internal limiting membrane (ILM) isolated from human retinas acts as a native substrate for culturing epithelial cells in terms of BM composition, architecture and stiffness. These are required to act jointly in order to achieve apico-basal polarity, tissue barrier formation and stiffness properties of the epithelial layer similarly to secretory epithelia in vivo. The native BM serves several advantageous over reconstituted Matrigel, an ECM extracts that originates from mouse tumor ascites. Besides variations in thickness and biochemical composition, we find that Matrigel is mechanically 100-fold more compliant (i.e., softer) than native BMs. When tumorigenic variants of cells are used, we demonstrated that cancer cell invasion is associated with a decrease in cellular stiffness correlated to changes in cell and BM morphology. In addition, we showed that activation of ß1 integrin by the stiffness and architecture of the native alpha - 5 laminin chain has a key role, not only as previously thought for maintenance of cell polarity but also for the establishment of a physiological mechanophenotype. On the other hand it is well know that during cancer progression in vivo, cancer cells can perforate the BM using proteolysis. Whether stromal cells also play a role and what kind of role in this process is unclear. Therefore, we asked if carcinoma-associated fibroblasts (CAFs) isolated from cancer patients promote cancer cell invasion through a BM. In the presence of CAFs, moderately invasive cancer cells invade in a matrix metalloproteinase-independent manner. Using live imaging and atomic force microscopy, we showed that CAFs actively pull, stretch and soften the BM, forming gaps through which cancer cells can migrate. By exerting contractile forces, CAFs alter the organization and the physical properties of the BM, making it permissive for cancer cell invasion. Finally, we propose that, in addition to proteolysis, mechanical interactions between CAFs and BM represent an alternative mechanism of BM breaching. Given their mechano-biological relevance, native BMs allow us to further understand how mechanosignaling occurs between the epithelia and the surrounding stromal layers at the BM interface during cancer invasion and progression. Note: This abstract was not presented at the meeting. Citation Format: Marija Plodinec, Philipp Oertle, Daphne Assgeirson, Willi Halfter, Serenella Eppenberger Castori, Ellen C. Obermann, Alexandre Glentis, Roderick Y. LIM. Mechanobiology of epithelia on native basement membrane and relevance for cancer invasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2962. doi:10.1158/1538-7445.AM2017-2962

A crucial point in making treatment decisions for cancer patients is the assessment of tumor aggressiveness. Currently, for breast cancer, established prognostic markers exist that are routinely assessed by standard pathological examination. However, these parameters are often not sufficient to stratify patients, especially those with early stages of breast cancer and adjuvant therapy is frequently administered to patients who might have been cured by surgery and anti-hormonal treatment alone. The goal to avoid over- and under-treatment has led to an intensive search for prognostic and predictive markers in early breast cancer. Physical interactions between cancer cells and the extracellular matrix (ECM) that occur at the molecular (nanometer) scale are crucial for the metastatic process. Consequently, nanomechanical alterations of cells and ECM due to cancer progression can serves as potentially suitable markers of cancer aggressiveness that may help to optimize treatment strategies. This motivated us to develop an atomic force microscope (AFM)-based method for measuring nanomechanical (stiffness) profiles of unadulterated tissues in native physiological buffer conditions with an unprecedented stiffness sensitivity resolved at nanometer-scale spatial resolution. An AFM utilizes a ∼10 nm-sharp stylus or tip that makes ∼10’000 miniscule indentations across tissue. In our initial study using transgenic mouse model of human breast cancer we could show that the “softest” nanomechanical phenotype (∼0.4 - 0.8 kPa) present at the primary tumor site closely corresponded to the stiffness of the metastatic lesions obtained from the lungs of the same mouse (Plodinec et. al; Nature Nanotech. 2012). In this study, we have analyzed human 187 breast cancer samples from breast biopsies and tumor resections including primary breast cancers of various stage and grade, lymph node metastases, and non-neoplastic breast parenchyma. Post-AFM samples were fixed, paraffin embedded in an oriented manner and used for routine histology. Data showed for all human breast cancer samples, distinct stiffness phenotypes in comparison to the surrounding non-neoplastic and morphologically normal breast tissue and revealed specific nanomechanical profiles of phenotypes that lead to metastases. Interestingly, patients presenting nanomechanical changes in the adjacent tissue, which was histologically characterized as tumor free, typically exhibited local and/or distant metastases. Overall, our findings demonstrate the first application of nanomechanical profiling in a clinical setting that allows for fast, on-site assessment of specimen and does not suffer from inter-observer variability such as other markers (Obermann et al, Pathologe, 2012). The relative size and distribution of nanomechanical profiles can provide an indicator of cancer aggressiveness, and therefore orientate therapy choice, and support patient follow-up. Citation Format: Marija Plodinec, Christian Raez, Philipp Oertle, Adrian Hodel, Maja Fünfschilling, Roderick YH Lim, Ellen C. Obermann. Nanomechanical profiling of breast cancer: A novel tool for cancer diagnostics and prognostics. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3926.