Second-harmonic generation directionality is associated with neoadjuvant chemotherapy response in breast cancer core needle biopsies.

Neoadjuvant chemotherapy (NACT) is routinely administered to subsets of breast cancer patients, including triple negative (TN) or human epidermal growth factor receptor 2-positive (HER2+) cancers. After NACT and subsequent surgical resection, 5% to 30% of patients have no residual invasive carcinoma, termed pathological complete response. Unfortunately, many patients experience little-to-no response after NACT and unnecessarily suffer its side effects. Methods are needed to predict an individual patient's response to NACT. Core needle biopsies, taken before NACT, consist of tumor cells and the surrounding extracellular matrix. We performed second-harmonic generation (SHG) imaging of fibrillar collagen in core needle biopsy sections as a possible predictor of response to NACT. The ratio of forward-to-backward scattering (F/B) SHG was assessed in the "tumor bulk" and "tumor­host interface" in HER2+ and TN core needle biopsy sections. Patient response was classified post-treatment using the Residual Cancer Burden (RCB) score. In HER2+ biopsies, RCB class was associated with F/B derived from the tumor­stromal interface, but not tumor bulk. F/B was not associated with RCB class in TN biopsies. These findings suggest that F/B from needle biopsy sections may be a useful predictor of which patients will respond favorably to NACT, with the potential to help reduce overtreatment.

Impact of Specimen Type and Specimen Number on HER2 Status in Gastroesophageal Junction and Gastric Adenocarcinoma.

OBJECTIVES: Human epidermal growth factor receptor 2 (HER2) is expressed in some gastric and gastroesophageal junction adenocarcinomas. There were two goals: assess the impact of specimen type on HER2 status and evaluate HER2 concordance with multiple specimens. METHODS: All cases were evaluated by immunohistochemistry (IHC) for HER2 and interpreted using established criteria. Fluorescence in situ hybridization (FISH) was performed on a subset. RESULTS: Of 460 specimens, 83.9% were IHC negative, 5.4% were equivocal, and 10.7% were IHC positive. Of those with FISH testing, 78.5% were FISH negative, and 21.5% were FISH positive. IHC-FISH concordance for biopsy specimens, resections, and metastases was 82%, 84%, and 86%, respectively. With one vs two vs three or more specimens, the HER2-positive rate increased from 10.5% to 18.1% to 24.1%, respectively. CONCLUSIONS: HER2 testing may be performed on biopsy specimens with a relatively high concordance rate with resection specimens, and if multiple samples are analyzed from a single patient, the HER2-positive rate increases over twofold.

A novel detection methodology for HER2 protein quantitation in formalin-fixed, paraffin embedded clinical samples using fluorescent nanoparticles: an analytical and clinical validation study.

BACKGROUND: Clinical assays for the assessment of the human epidermal growth factor receptor-2 (HER2) status in breast cancer include immunohistochemistry (IHC) and in situ hybridization (ISH), both of which have limitations. Recent studies have suggested that a more quantitative approach to the measurement of HER2 protein expression may improve specificity in selecting patients for HER-2 targeted therapy. In the current study, we have used HER2 expression in breast cancer cell lines and clinical samples as a model to explore the potential utility of a novel immunodetection technique, using streptavidin coated Phosphor Integrated Dot fluorescent nanoparticles (PID), which can be quantitatively measured using computer analysis. METHODS: The expression of HER2 protein in cell lines was evaluated with antibody-binding capacity using fluorescence-activated cell sorting (FACS) for comparison with PID measurements to test for correlations with existing quantitative protein analysis methodologies. Various other analytic validation tests were also performed, including accuracy, precision, sensitivity, robustness and reproducibility. A methods comparison study investigated correlations between PID versus IHC and ISH in clinical samples. Lastly, we measured HER2 protein expression using PID in the pretreatment biopsies from 34 HER2-positive carcinomas that had undergone neoadjuvant trastuzumab-based chemotherapy. RESULTS: In the analytic validation, PID HER2 measurements showed a strong linear correlation with FACS analysis in breast cell lines, and demonstrated significant correlations with all aspects of precision, sensitivity, robustness and reproducibility. PID also showed strong correlations with conventional HER2 testing methodologies (IHC and ISH). In the neoadjuvant study, patients with a pathologic complete response (pCR) had a significantly higher PID score compared with patients who did not achieve a pCR (p = 0.011), and was significantly correlated to residual cancer burden (RCB) class (p = 0.026, R2 = 0.9975). CONCLUSIONS: Analytic testing of PID showed that it may be a viable testing methodology that could offer advantages over other experimental or conventional biomarker diagnostic methodologies. Our data also suggests that PID quantitation of HER2 protein may offer an improvement over conventional HER2 testing in the selection of patients who will be the most likely to benefit from HER2-targeted therapy. Further studies with a larger cohort are warranted.