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Background: MammaPrint (MP) is an FDA approved early breast cancer prognostic genomic assay that examines the expression levels of 70 genes and classifies clinically high-risk patients with early-stage breast cancer into low or high risk of distant metastasis. Current ASCO guidelines do not support using MP testing in clinically low-risk patients. Historically, assessing a patient’s clinical risk for breast cancer recurrence has relied on a subjective evaluation of histologic factors, immunohistochemical features, and clinical characteristics. Genomic assay testing provides more objective prognostic and predictive information than those more traditional methods; however, several studies have shown that statistical models using standard histologic variables can give valuable prognostic information, and might be used as an alternative approach to genomic assays for clinical risk-assessment and risk-stratification, particularly in lower risk breast cancer patients, potentially resulting in significant cost savings for health care systems. One of these statistical models, the average Modified Magee equation, has been shown to be prognostic for a low risk of recurrence in ER positive Her2 negative breast cancer patients who have an average Modified Magee score (aMMs) of ≤ 12. The aMMs has been shown to correlate well with the Oncotype DX recurrence score; however, there is limited data on the correlation between the aMMs and MP. In this study, we evaluated the concordance between the aMMs and the MP index (MPI). Methods: 222 consecutive patients with a new diagnosis of hormone receptor positive Her-2 negative breast cancer at the University of Rochester between April 2020 and December 2020 were sent for MP testing. The aMMs was determined for each patient based on the estrogen receptor status, progesterone receptor status, HER-2 status, Ki-67 proliferation index, Nottingham score, and tumor size. Based on the previous literature, patients were risk-stratified by the aMMs into three groups: 1) low risk (aMMs ≤ 12; n = 75); 2) low - intermediate risk (aMMs >12 and ≤ 18; n = 96); and, 3) high risk (aMMs >18, n = 51). Based on the previous literature, patients were risk-stratified by the MPI into two groups: 1) low risk (MPI 0 to +1); and, 2) high risk (MPI -1 to 0). The correlation between the aMMs and the MPI was evaluated using the Pearson correlation coefficient. Results: The aMMs showed a negative correlation (r= -0.55) with the MPI, consistent with a lower risk aMMs more likely being associated with a lower risk MPI. 92% of patients with an aMMs ≤ 12 (very low risk) were classified as low risk by MP. 72% of patients with an aMMs > 12 and ≤ 18 (low - intermediate risk) were classified as low risk by MP. 47% of patients with an aMMs > 18 (high risk) were classified as high risk by MP (Table 1). All patients with an aMMs ≥ 24.7 (n=8) were classified as high risk by MP. Conclusion: Our study suggests that hormone receptor positive, Her-2 negative breast cancer patients with a lower risk aMMs are likely to have a lower MPI, suggesting that these patients have a decreased risk for breast cancer recurrence. As the aMMs approaches higher risk, the concordance with the MPI decreases; however 100% of patients with an aMMs ≥ 24.7 were classified as high risk by MP. The aMMs can be helpful in clinical risk-assessment prior to making a decision about sending a patient specimen out for MP testing. Additional studies are warranted. Table 1.Risk of recurrence using the average Modified Magee score (aMMs) and the MammaPrint (MP) IndexaMMs Risk-stratification categoryMP Low risk n (%)MP High risk n (%)Very low (aMMs ≤ 12)69 (92%)6 (8%)Low - Intermediate (aMMs > 12 and ≤ 18)69 (72%)27 (28%)High (aMMs >18)27 (53%)24 (47%) Citation Format: Hani Katerji, Huina Zhang, David Hicks, Bradley M Turner. Clinical-risk assessment of ER positive, Her2 negative breast cancer patients: Correlation between the average modified magee score and mammaprint [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-06-03.

INTRODUCTION: In 2013, Klein and Dabbs et al. published three linear regression equations (the new Magee equations) using different combinations of standard histopathologic variables. In 2015, our group published a modification of the new Magee equations. Based on this modification, we published an algorithmic approach using an average Modified Magee equation. This algorithmic approach supported reflex Oncotype DX (ODX) testing based on several cutoff points using an average Modified Magee score. In 2019, we validated this algorithmic approach as the Rochester Modified Magee Algorithm (RoMMA) in a multi-institutional study, with outcome data in 247 patients, suggesting that ER positive breast cancer patients with an average Modified Magee score of ≤ 12 had a low risk of breast cancer recurrence. There has been limited published outcome data on the Magee equation since that 2019 study. We have further refined our risk-stratification approach, with additional outcome data in 416 ER positive breast cancer patients. METHODS: 416 patients with an ODX recurrence score who had at least five years of follow-up data or a breast cancer recurrence were included in the final outcome analysis (2008-2017). All patients received either Tamoxifen or an aromatase inhibitor. None of the patients received adjuvant systemic chemotherapy. The average Modified Magee score was calculated and patients were stratified into four risk-stratification categories: 1) very low, 2) low ≤ 50 years of age, 3) low > 50 years of age, and 4) high. We compared these four risk-stratification categories, with outcomes, between the average Modified Magee score and the ODX recurrence score. A p-value of < 0.05 was considered statistically significant. RESULTS: 27/416 (6.5%) patients had a recurrence of breast cancer. When comparing the same risk category groups, there was no significant difference between the average Modified Magee score and the ODX recurrence score (Table 1). CONCLUSION: Our study further reinforces that breast cancer patients can be confidently stratified into low and high risk recurrence groups using the average Modified Magee score. The average Modified Magee score may be an alternative to ODX for clinical risk-assessment and risk-stratification, particularly in lower risk patients, offering breast cancer patients increased access to clinical risk-assessment and risk-stratification, both domestically and internationally, with a potential significant cost savings for health care systems. A large prospective evaluation, similar to the studies done by ODX, using multi-institutional data or data from studies like the NSABP trial B-14 and the NSABP trial B-20, is necessary. Table 1.Risk-stratification categories and outcomes using the average Modified Magee score (aMMs) and the Oncotype DX recurrence score (ODXRS)RECURRENCENO RECURRENCEP-VALUEVERY LOW (N)aMMs ≤ 12 (76)1 (1.3)75 (98.7)0.65ODXRS < 11 (108)4 (3.7)104 (96.3)LOW ≤ 50 years of age (N)aMMs > 12, ≤ 18 (50)3 (6.0)47 (94.0)1.0ODXRS 11 - 15 (32)1 (3.1)31 (96.9)LOW >50 years of age (N)aMMs > 12, ≤ 18 (153)8 (5.2)145 (94.8)0.52ODXRS 11 - 25 (214)16 (7.5)198 (92.5)HIGH (N)aMMs > 18 (137)15 (10.9)122 (89.1)1.0ODXRS ≥ 16 - 25 (33)* and ODXRS > 25 (29)**6 (9.7)56 (90.3)* Patients ≤ 50 years of age with an ODXRS of ≥16 - 25. ** All patients with an ODXRS of > 25 Citation Format: Numbereye Numbere, Ioana Moisini, Ajay Dhakal, Kristin Skinner, Michelle Shayne, Mary Ann Gimenez Sanders, Huina Zhang, David Hicks, Bradley M Turner. Clinical risk-assessment, risk-stratification, and outcomes of ER positive, HER2 negative breast cancer patients using the Rochester modified Magee algorithm (RoMMA) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-06-07.

INTRODUCTION: There is dearth information on the long-term outcome and role of HER2 targeted therapy in breast cancer patients in the HER2 FISH group 3 category, which is defined as breast cancer with a HER2/CEP17 ratio < 2 and HER2 copy number ≥ 6 signals/cell. In this study, we report the clinicopathologic features and outcomes of breast cancer patients in the HER2 FISH group 3 category at our institution. METHODS: We identified 52/2,874 (1.8%) breast cancer patients with HER2 FISH group 3 results between 1/2007 and 3/2020. 28 of these 52 patients had available detailed clinicopathologic and follow-up data, with an average follow-up of 38.5 months. RESULTS: Most of the cases with group 3 FISH results were high grade ductal carcinomas with positive hormonal receptor expressions and equivocal HER2 expression by immunohistochemistry. Among all the clinicopathologic variables, only tumor size (p=0.048) significantly contributed to the poor clinical outcomes. HER2 copy number failed to show any significant association with histologic grade, tumor size, clinical stage, hormonal receptor status or disease outcomes. There was no statistically significant difference in disease outcome between patients who were treated with HER2 targeted therapy and patients who did not receive HER2 targeted therapy, regardless of the HER2 copy number or clinical stage (Table 1). CONCLUSION: Our preliminary findings suggest that certain patients with HER2 FISH group 3 category breast cancer may not need HER-2 targeted therapy. Larger-scale studies are needed to further evaluate which HER2 FISH group 3 results are more likely to benefit from the HER-2 targeted therapy. Table 1. Response to HER2 targeted therapy in HER2 FISH group 3 breast cancer patients based on HER2 copy numbers and clinical stageHER 2 targeted therapyp-valueGivenNot givenTotal populationGood outcome (n=21)1380.371Bad outcome (n=7)61HER2 copy number < 10Good outcome (n=16)1060.366Bad outcome (n=7)61HER2 copy number ≥ 10Good outcome (n=5)321.000Bad outcome (n=0)00Stage I-IIGood outcome (n=16)970.737Bad outcome (n=3)21Stage III-IVGood outcome (n=5)410.343Bad outcome (n=4)40*Good outcome = No evidence of disease**Bad outcome = Local recurrence, distant metastasis, and/or died of disease Citation Format: Huina Zhang, Rana Ajabnoor, David Hicks, Bradley Turner. Clinicopathologic features and follow-up outcomes of breast cancers with HER2 FISH group 3 Results: A single institution experience [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-48.

INTRODUCTION: Oncotype DX® (ODX) is a multigene assay estimating risk of distant recurrence and chemotherapy benefit in estrogen receptor (ER) positive breast cancer patients. Cost ($4,620.00) impedes its adoption in poorer countries, and the cost is unnecessary in certain patients. TAILORx results suggest that adjuvant endocrine therapy and chemoendocrine therapy had similar efficacy in women with hormone-positive, HER2-negative, node-negative invasive breast carcinomas with an ODX recurrence score < 26. Bhargava et al. and Turner et al. have suggested that a Magee scoreTM or a modified Magee score, respectively, of < 18 will identify patients who are highly likely to have an ODX recurrence score of < 26, and we previously presented data at SABCS 2019 (Abstract P3-07-06) that there is no significant difference in recurrence rate between patients with a modified Magee score of ≤ 18 and patients with an ODX recurrence score < 26 (in preparation for publication). We now present additional recurrence data on patients with a modified Magee score of > 18. METHODS: A total of 301 consecutive patients with ER+ invasive breast cancer from the University of Rochester and the University of Louisville were included in this study, with a mean of 6.6 years of follow-up. All patients had at least 5 years of follow-up (range 5-11 years) except for seven patients , who had a breast cancer recurrence prior to five years. Information on ER, PR, HER-2, Ki-67, Nottingham score , and tumor size were extracted from the pathology report in order to calculate the modified Magee score. Information, on hormone therapy, chemotherapy, radiation therapy, recurrence status, and mortality were extracted from the medical record. For all results, a p-value of < 0.05 was considered significant. RESULTS: 117/301 (39%) patients had a modified Magee score of > 18. The recuurence rate for patients with a modified Magee score > 18 was 11.1%. There was no significant difference in recurrence rate between patients with both a modified Magee score > 18 and ODX recurrence score < 26 compared to patients with both a modified Magee score >18 and ODX recurrence score ≥ 26 (p = 0.547, Table 1). CONCLUSIONS: Patients with a modified Magee score > 18 may be at increased risk for breast cancer recurrence, even if the ODX recurrence score is < 26. Additional studies are necessary to further evaluate these findings. Table 1: Modified Magee score > 18, Oncotype DX recurrence score (ODXRS), and outcomeRecurrenceNo recurrenceModified Magee score > 18 and ODXRS < 26870Modified Magee score > 18 and ODXRS ≥ 26633 Citation Format: Bradley M Turner, Mary Ann Gimenez-Sanders, Ioana Moisini, Huina Zhang, Xi Wang, Linda Schiffhauer, Hani Katerji, Kristin Skinner, Jessica Gooch, Michelle Shayne, Marilyn Ling, Carla Falkson, David Hicks. Are we missing something? Increased recurrence rates in patients with an oncotype DX score < 26 and a modified magee score > 18: A multi-institutional study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-24.

INTRODUCTION: The literature suggests that there is no difference in the Oncotype DX® (ODX) recurrence score between African American (AA) women and Caucasian (CA) women; however, an analysis of clinical outcomes in participants enrolled in the TAILORx trial found that AA women had worse clinical outcomes than CA women, despite similar ODX recurrence scores. The TAILORx trial suggested that chemoendocrine therapy may not be necessary in women with hormone-positive, HER2-negative, node-negative invasive breast carcinomas with an ODX recurrence score < 26. We examine Ki-67 (a marker of tumor proliferation) in relation to an ODX recurrence score of 26 in AA and CA women from two seperate institutions. METHODS: A total of 851 consecutive cases of AA (n = 78) and CA women (n = 773) with ER+ invasive breast cancer and available ODX recurrence scores from the University of Rochester and the University of Louisville were included in this study. For all results, a p-value of < 0.05 was considered significant. RESULTS: Consistent with the previous literatuere, there was no significant difference between the average ODX recurrence score of AA and CA women (p = 0.44, Table 1), and we found no significant difference in average ER, PR, Nottingham score, or tumor size between AA and CA patients; however, the Ki-67 was significantly higher in AA patients with an ODX recurrence score < 26 compared to CA patients with and ODX recurrence score < 26 (p = 0.002, Table 2). This significant difference in Ki-67 was not evident with an ODX recurrence score ≥ 26 (p = 0.98, Table 2). CONCLUSIONS: Our preliminary results suggest that compared to CA women, AA patients are more likely to have a higher Ki-67 if the ODX recurrence score is < 26. AA breast cancer patients with an ODX < 26 are at increased risk for recurrence compared to CA women with an ODX < 26. Ki-67 evaluation is not routinely done as part of the breast cancer workup in many institutions. Ki-67 evaluation may be helpful to help guide treatments decisions in AA patients with and ODX < 26. Additional investigation is warranted. Table 1: Oncotype DX and histopathologic variables for African American and Caucasian womenODXRS* (mean)ER** (mean)PR** (mean)NS***(mean)Ki-67 (mean)****Tumor size (mean)ODXRS < 26 (n) ODXRS ≥ 26 (n)ALL17.6255.3168.96.016.42.2713138AA18.3250.7175.96.321.42.26315CA17.5255.8168.26.015.92.2650123*Oncotype DX recurrence score** modified H-score*** Nottingham score****n = KI-67 available for 777 total patients (650 with ODXRS < 26 and 127 with ODXRS ≥ 26); KI-67 available for 71 AA patients (51 with ODXRS < 26 and 14 with ODXRS ≥ 26); KI-67 available for 706 CA patients (593 with ODXRS < 26 and 113 with ODXRS ≥ 26) Table 2: Oncotype DX < 26 and ≥ 26 and associated histopathologic variables for African American and Caucasian womenODXRS* (mean)ER** (mean)PR** (mean)NS*** (mean)Ki-67 (mean)****Tumor size (mean)ODXRS < 2614.5260.5189.15.813.72.2AA15.4262.8200.76.019.22.3CA14.4260.3188.05.813.12.2ODX ≥ 2633.8228.464.47.330.52.1AA30.3199.871.97.730.41.6CA34.2231.963.57.330.52.2*Oncotype DX recurrence score** modified H-score*** Nottingham score****n = KI-67 available for 777 total patients (650 with ODXRS < 26 and 127 with ODXRS ≥ 26); KI-67 available for 71 AA patients (51 with ODXRS < 26 and 14 with ODXRS ≥ 26); KI-67 available for 706 CA patients (593 with ODXRS < 26 and 113 with ODXRS ≥ 26) Citation Format: Bradley M Turner, Mary Ann Gimenez-Sanders, Huina Zhang, Ioana Moisini, Xi Wang, Linda Schiffhauer, Hani Katerji, Kristin Skinner, Jessica Gooch, Michelle Shayne, Marilyn Ling, Carla Falkson, David Hicks. Are we missing something? Ki-67 evaluation is important in African American women with an oncotype DX score< 26: A multi-institutional study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-18.

INTRODUCTION: The recent TAILORx results suggest that adjuvant endocrine therapy and chemoendocrine therapy had similar efficacy in women with hormone-positive, HER2-negative, node-negative invasive breast carcinomas with an Oncotype Dx® recurrence score < 26. Oncotype Dx® is an expensive test (current list price of $4,620.00). Although the Oncotype Dx® test has gained widespread acceptance, cost may be an impediment to its adoption in certain areas of the world, and it may not be the most cost-effective or cost-efficient option in certain subsets of breast cancer patients. Based on a modification of the new Magee equations, we published an algorithmic approach in 283 ER+ cases using an average modified Magee equation (Turner BM, et al. Mod Pathol. 2015;28(7):921-31), and subsequently published a validation of this algorithmic approach in an additional 620 ER+ cases (Cancer Med. 2019 Jun 14. doi: 10.1002/cam4.2323. [Epub ahead of print]), supporting only reflex Oncotype Dx® testing for certain subsets of breast cancer patients. We now have recurrence data and at least five years of outcome data on 310 cases. METHODS: A total of 310 cases with ER+ invasive breast cancer, all with Oncotype Dx® recurrence scores, were included in this study from the University of Rochester and the University of Louisville. The outcome analysis included all patients who had at least five years of follow-up data, and all patients who had a breast cancer recurrence. In order to calculate the average modified Magee score, information on the Nottingham score, ER, PR, Ki-67, HER-2, and tumor size was extracted from the pathology report. RESULTS: 255/310 cases had an Oncotype Dx® < 26, and 4% (10/255) of these cases were associated with a breast cancer recurrence. 187/310 cases had an average modified Magee score ≤ 18, and 184 of these 187 cases (98%) had an Oncotype Dx® recurrence score < 26. Only 2% (n = 4) of these 184 cases were associated with a breast cancer recurrence. On average, the Nottingham score and Ki-67 were lower for cases with an average modified Magee score ≤ 18 compared to cases with an Oncotype Dx® recurrence score < 26 (Table 1). On average, the modified ER and PR H-scores were higher for cases with an average modified Magee score ≤ 18 compared to cases with an Oncotype Dx® recurrence score < 26 (Table 1). CONCLUSION: If the average modified Magee score is ≤ 18, the patient has a low likelihood of recurrence, and the Oncotype Dx® recurrence score will likely be < 26. Given the recent TAILORx findings, we suggest that patients with an average modified Magee score ≤ 18 not be sent out for Oncotype Dx® testing if an Oncotype Dx® recurrence score < 26 is the basis on which the clinician will use to decide whether or not to give chemotherapy. The information needed to use the average modified Magee equation is already generated by many pathology laboratories during the initial assessment of breast cancer, and the Magee equations are free of charge (https://path.upmc.edu/onlineTools/mageeequations.html). Based on the Genomic Health 2017 Annual Report, our data suggests that not sending out cases with an average modified Magee score ≤ 18 would have resulted in a potential cost savings to the health-care system in 2018 of almost 300 million dollars. Table 1: Average Nottingham score, modified ER H-score, modified PR H-score, and Ki-67, with number and percent recurrence for cases with an average modified Magee score ≤ 18 and cases with an Oncotype Dx® recurrence score < 26AVERAGERecurrence Sore typeNNS**ER***PR***Ki-67Recurrence N (%)Average modified Magee score ≤ 18*1875.2262.3235.410.34 (2)Oncotype Dx® recurrence score < 262555.5253.2192.613.610 (4)*98% (184/187) of patients with an average modified Magee score ≤ 18 had an Oncotype Dx® recurrence score < 26**Nottingham score***modified H-score (Turner BM, et al. Mod Pathol. 2015;28(7):921-31) Citation Format: Hasan Khatib, Mary Ann G Sanders, Andrea Breaux, Armen Soukiazian, Nyrie Soukiazian, David Hicks, Bradley M Turner. ER+ patients with an average modified Magee score ≤ 18 have a low likelihood of breast cancer recurrence and a high likelihood of an Oncotype Dx® recurrence score < 26 [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-07-06.

INTRODUCTION: Breast cancer is the most prevalent non-skin cancer in women worldwide. Women with metastatic breast cancer to the liver have poor outcomes compared to metastases to other sites, frequently develop resistance to available hormonal and chemotherapeutic agents, and have poor overall survival. Conflicting evidence exists regarding the association of body mass index (BMI) with progression free and overall survival in patients with metastatic breast cancer. METHODS: A single institution retrospective study of women with breast cancer metastasis to the liver was conducted. The pathology reports and medical records from 2011 to 2017 were searched to identify cases with biopsy proven liver metastases. Several factors were considered including breast cancer histologic type and stage at diagnosis; estrogen receptor, progesterone receptor, and HER2-neu amplification status of the initially diagnosed breast cancer as well as the metastatic disease; patient age and ethnicity; BMI (kg/m2) at time of metastasis and at initial diagnosis; and, outcome to include survival after liver metastasis diagnosis. RESULTS: In our population, the BMI ranged from 21.2 kg/m2 to 56.3 kg/m2 (mean 28.4 kg/m2). Eighteen patients (62%) were either overweight or obese. Twenty-one patients (72.4%) were deceased at the time of the study with an average survival of 659 days after liver metastasis diagnosis (Table 1). Patients with a BMI > 30 (obese) had a significantly lower (p Table 1: Mean overall survival in patients with liver metastasisTotalER+ Liver MetastasisHER2+ Liver MetastasisBMI kg/m2N (%)Mean Survival (days)*N (%)Mean Survival (days)*N (%)Mean Survival (days)*Underweight ( 30)7 (33.3)3237 (43.7)3233 (60)315NA: not applicable*p-values Citation Format: Cynthia Reyes Barron, Maricarmen Planas-Silva, David G Hicks, Bradley M Turner. Body mass index and liver metastasis in women with invasive breast carcinoma [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-08-25.

Breast cancer is the most common invasive cancer in women, with most deaths attributed to metastases. Neoadjuvant chemotherapy (NACT) may be prescribed prior to surgical removal of the tumor for subsets of breast cancer patients but can have diverse undesired and off-target effects including increased appearance of the ‘tumor microenvironment of metastasis’ or TMEMs, image-based multicellular signatures which are prognostic of metastasis. In this study we explored whether NACT alters other image-based prognostic/predictive signatures, specifically second-harmonic generation (SHG) directionality, which is indicative of collagen fiber internal structure, as well as the disorganization in collagen fiber alignment. This was performed in paired biopsy/excision samples from 22 patients with HER2 overexpressing invasive ductal carcinoma as well as 22 patients with triple negative breast cancer (TNBC). We found that collagen fiber internal structure, measured using the SHG forward-to-backward-scattered ratio (F/B), is altered in the bulk of the tumor in both tumor types (p = 0.015 and 0.038, respectively), but not the adjacent tumor-stroma interface (p = 0.54 and 0.92, respectively), where F/B is prognostic of metastatic outcome. Overall disorganization in collagen fiber alignment was not significantly changed by NACT in HER2 overexpressing disease (p = 0.41) but was decreased in TNBC (p = 0.0051). These results suggest that NACT alters the collagenous extracellular matrix in diverse ways, with implications for the use of F/B and collagen fiber alignment as prognostic and predictive tools. Citation Format: Edward Brown, Danielle Desa, Robert M Brown, Edward B Brown, Robert L Hill, Bradley M Turner. Second-harmonic generation imaging reveals neoadjuvant chemotherapy-induced changes in breast tumor collagen [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-06-13.

Objectives: Recently-published phase I clinical trials have demonstrated promising efficacy of novel HER2-targeted therapy in advanced breast cancers with a HER2 immunohistochemistry (IHC) score of 1+, or 2+ with a non-amplified in-situ hybridization (ISH). This has raised the possibility for changing the categories for clinical interpretation of HER2 in breast cancers into: 1) HER2-negative (HER2 IHC score of 0+), 2) HER2-low (IHC score of 1+, or 2+ with a non-amplified ISH), and 3) HER2-positive (HER2 IHC score of 3+ and IHC score of 2+ with amplified ISH). Earlier studies on low HER2-expressing breast cancers focused on differences between HER2 2+ with negative ISH and HER2 0/1+. The aims of this study are to investigate the clinical, pathologic and molecular features of HER2-low breast cancers, in comparison to HER2-negative breast cancers. Methods: 281 breast cancers with HER2 IHC were diagnosed between 04/2020 and 12/2020 at our institution, including 164 HER2-negative, 87 HER2-low, and 30 HER2-positve cases. The clinicopathologic information and molecular subtyping (Agendia BluePrint) results of HER2-low breast cancers were retrospectively collected, and compared to those of HER2-negative cases. A p-value of < 0.05 was considered statistically significant. Results: HER2-low breast cancers accounted for 31% (87/281) of breast cancers in our study population. The majority of these HER2-low cases were clinical stage I-II, with 6 cases (6.9%) being stage IV. Most of the HER2-low cancers had a HER2 IHC score of 1+ (87%, 76/87), a ductal phenotype (82%, 71/87), histologic grades of 1 or 2 (94%, 82/87), were ER positive (94%, 81/86), PR positive (86%, 74/86), and had luminal molecular subtypes (96%, 83/87). Four patients received neoadjuvant chemotherapy and none of them achieved pathologic complete response. Compared to HER2-negative cancers, HER2-low breast cancers showed a lower Ki-67 (p Table 1. Comparison of clinicopathologic parameters and molecular subtypes between HER2-low and HER2-negative breast cancersHER2-Low (n=87)HER2-Negative (n=164)P valueAge (year)66.6264.380.22Tumor size (mm)21.4919.290.49Histologic typeDuctal711390.57Lobular1524Mixed11Histologic grade143640.156239813519pT Stage142880.0452817362Unknown2735PN stage036760.351613210300Unknown2353ER positivity94.2 % (81/86)82.9% (136/64)0.01PR positivity86% (74/86)76.8% (126/164)0.09Ki-67 (%)12.8118.290.03Molecular subtypeLuminal A571050.003Luminal B2630HER210Basal328 Citation Format: Huina Zhang, Hani Katerji, Bradley M Turner, David G Hicks. Clinicopathologic characteristics and molecular profiling of HER2-low breast cancer: A single academic institution experience [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-05-09.

Background: Over-expression of Human Epidermal Growth Factor receptor-2 (HER2) in breast cancer is associated with an aggressive clinical course and poor prognosis. Targeting HER2 over-expression has been shown to be a remarkably effective therapeutic modality in the metastatic, adjuvant and neoadjuvant setting and the pathologic response to neoadjuvant treatment in HER2-positive breast cancer has been shown to be an excellent surrogate for a good outcome. The stromal tumor microenvironment is implicated in fostering tumor growth, facilitating cell migration and ultimately resulting in metastatic disease. Specifically, the collagenous extracellular matrix, which includes fibrillar collagen, has been suggested to play a role in the migration of malignant breast epithelial cells within the surrounding stroma. We have developed a novel methodology which uses an intrinsic optical signature to quantitatively evaluate fibrillar collagen (Burke et al. BMC Cancer 15 (2015): 929). Here, we evaluate the ability of this quantitative methodology to predict the pathologic response after neoadjuvant HER2-targeted treatment as assessed by the Residual Cancer Burden score/class (RCB). This quantitative evaluation in pre-treatment biopsies is then correlated with the pathologic response to treatment in the post-therapy resection. Material and Methods: Clinical pathologic variables for 29 cases of HER2-positive breast cancer that had undergone neoadjuvant chemotherapy plus HER2-targeted therapy were retrieved from the medical record database at URMC, including the post-treatment RCB score and ER/PR/HER2 status. Second harmonic generation (SHG) is an intrinsic optical signal produced by fibrillar collagen. To quantify collagen microstructure in the pre-treatment core biopsy, we used SHG imaging to determine the average forward to backward-light scattering ratio (F/B). The F/B ratio is sensitive to structural properties of collagen fibers. Results: Logistic regression was used to assess the association between F/B and the binary response variable RCB class (0/1 or 2/3). A likelihood ratio test was used to calculate the p-value to test whether the regression coefficient for F/B was zero (i.e. no effect) in the tumor-stromal interface. The average F/B ratio at the leading edge of the tumor stratified by RCB class is shown in Table 1. When evaluated in the bulk of the tumor tissue, F/B was not correlated with RCB status; however, when evaluated at the leading edge of the tumor stromal interface, F/B was significantly correlated with RCB status (p=0.035). Table 1:RCB class and average F/BRCB class (n)Average F/B ± SEM0/1 (19)16.95 ± 1.062/3 (10)12.32 ± 1.84 Conclusions: We have previously shown that the measurement of F/B in the primary tumor after resection is an independent prognostic indicator of metastasis-free survival in breast cancer. Our results in the current study furthers these observations and suggests that the evaluations of the microstructure of collagen fibers by F/B measurement from the pre-treatment biopsy, specifically at the leading edge of the tumor-stroma interface, may be useful for predicting pathologic response to trastuzumab-based neoadjuvant therapy. Further studies in a larger patient cohort are warranted. Citation Format: Desa DE, Turner BM, Buscaglia B, Hill RL, Strawderman RL, Hicks DG, Brown EB. Using multiphoton laser scanning microscopy to assess neoadjuvant therapy outcome in core needle biopsies: A novel methodology [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-09-12.

Introduction: The recent TAILORx results suggests that adjuvant endocrine therapy and chemoendocrine therapy had similar efficacy in women with hormone–positive, HER2-negative, axillary node–negative breast cancer who had an Oncotype Dx recurrence score (ODXRS) between 11 and 25. These findings, along with updated results that patients with an ODXRS < 11 have a 9-year recurrence rate of only 3%, suggest that certain populations of patients with an ODXRS ≤ 25 may not benefit from additional systemic chemotherapy. Oncotype Dx is an expensive test (current list price of $4,650.00), and cost has been an impediment to its adoption in many centers throughout the United States, and internationally. The test can be performed only at a commercial specialized laboratory. Based on a modification of the new Magee equations (Klein ME, et al. Mod Pathol. 2013;26(5):658–664) we published an algorithm based on 283 patients with ODXRS's (Turner BM, et al. Mod Pathol. 28(7):921-31) that suggested our algorithm offered a less expensive alternative to Oncotype DX testing. We have validated this algorithm in a multi-institutional study on an additional 619 patients with ODXRS's (in preparation for publication). Our validation data, and our data from the original study, also suggests that the average modified Magee equation can reliably predict patients who will have an ODXRS ≤ 25. Methods: 903 cases with an available ODXRS (2006-2018) were identified from the pathology files at the University of Rochester Medical Center (n = 752) and the University of Louisville (n = 151). Information required to calculate the average modified Magee score, which includes estrogen receptor (ER) and progesterone receptor (PR) status, Her-2 status, Nottingham score, tumor size, and Ki-67 were also extracted from the medical record. 78 patients did not have an available Ki-67, leaving 825 patients for inclusion in this study. Results: 478/488 (98%) patients with an average Modified Magee score ≤ 18 had an ODXRS ≤ 25 (only 2% had an ODXRS > 25 - Table 1). 125/337 (37%) patients with an average Modified Magee score >18 had an ODXRS > 25 (Table 1) . Conclusions: The average Modified Magee Score can be helpful in predicting an ODXRS ≤ 25. Patients with an average Modified Magee score ≤ 18 may not need to be sent out for Oncotype Dx testing. The potential cost savings to the health care system would be enormous. Table 1:Average Modified Magee score and risk of an Oncotype Dx recurrence score (ODXRS) > 25Magee scorenAverage ODXRSMinimum ODXRS valueMaximum ODXRS valueCases with ODXRS > 25 [n (%)]≤ 91811.02190 (0)102110.90261 (4.8)113712.10250 (0)126012.00281 (1.7)136412.00230 (0)147012.90271 (1.4)156513.61313 (4.6)165614.12292 (3.6)175214.50272 (3.8)184514.30250 (0)195418.96379 (16.7)204319.30348 (18.6)215921.193715 (25.4)223819.32496 (15.8)232523.383811 (44)242920.83329 (31)252325.0144011 (47.8)> 25-272729.2174620 (74.1)> 27-301634.9225113 (81.3)> 302345.7317823 (100)≤ 1848812.903110 (2)> 1833723.7078125 (37) Citation Format: Turner BM, Sanders MA, Breaux A, Soukiazian A, Soukiazian N, Hicks DG. The average modified Magee score can be helpful in predicting an Oncotype DX recurrence score ≤ 25 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-24.

Introduction: The recent TAILORx results suggest that additional systemic chemotherapy may not be necessary in certain hormone +, HER2 -, node negative breast cancer patients with an Oncotype Dx recurrence score (ODXRS) ≤ 25. ODX is an expensive test (current list price of $4,650.00), and cost has been an impediment to its adoption in many centers throughout the world. Based on a modification of the new Magee equations (Klein ME, et al. Mod Pathol. 26[5]) we published data based on 283 patients with ODXRS's (Turner BM, et al. Mod Pathol. 28[7]), suggesting that the modified Magee equation (MME) offered a less expensive alternative to ODX testing in certain breast cancer patients. We now have outcome data suggesting that the MME along with progesterone receptor (PR), Ki-67, lymph node (LN) status, and lymphovascular invasion (LVI) status can be helpful in predicting which patients with an ODXRS ≤ 25 are more likely to recur. Methods: 248 patients with information on estrogen receptor (ER), PR, Ki-67, Her-2 status, Nottingham score, tumor size, LN status, LVI status, and an available ODXRS (2008-2018) were identified from the pathology files at the University of Rochester Medical Center. Results: All of the patients that recurred had an average modified Magee score (MMS) ≥ 14 (Table 1). Patients with LN involvement (5/43,12% ) or with LVI (5/27,19%) had a higher percentage of recurrence than patients without LN involvement (8/197, 4%) or without LVI (8/216, 4%). Patients that recurred had a significantly (p < 0.05) lower PR and higher Ki-67 than patients in the same risk class that did not recur (Table 2). Neither grade nor ER status was significantly different between patients that recurred and did not recur (Table 2). All of the patients that recurred had at least a lowered PR, higher Ki-67, LN involvement, or LVI, and most had some combination of these variables (Table 1). 8 of the 13 patients that recurred in our population (61.5%) had an ODXRS of ≤ 25. Conclusions: Risk stratification is still important in patients with an ODX score ≤ 25. The MMS along with PR, Ki-67, LN, and LVI status can be helpful in predicting patients with a higher risk of recurrence. Table 1:Recurrence dataODXRSMMSType of therapy*Nodal and LVI status**Nottingham scoreER-H score***PR-H score***Ki-671119.1NONENONE6240180271319.7HNONE530015201521.6HN51209051514HNONE5270210UNKNOWN1615HLVI527018051727.2HB62701601916.3HNONE428545UNKNOWN2424.5CLVI8240105352723.9BNONE7210100352821HN527021252823.4HB528530353128.7HB82701454432.3HNONE9210607021.4****21.4****--5.9****250.7****93.4****31.4*****H = Hormone only;C = Chemo only;B = Both; ** N = Nodal involvement;L = LVI;B = Both; ***modified (Turner BM, et al. Mod Pathol. 2015;28(7):921-31); **** average Table 2:Recurrence data in specific populationsPopulation typeNGradeER*PR*Ki-67≤ 25 no recurrence2165.4249.7185.712.8**≤ 25 recurrence85.5249.4103.325.3***> 25 no recurrence267.3211.776.834.1****> 25 recurrence56.8249.042.542.0* modified (Turner BM, et al. Mod Pathol. 2015;28(7):921-31); ** n = 181; *** n = 6; **** n = 23 Citation Format: Turner BM, Sanders MAG, Soukiazian A, Soukiazian N, Hicks DG. Reconsidering “at risk” criteria for breast cancer recurrence in hormone positive patients: Risk stratification is still important in patients with an Oncotype Dx recurrence score ≤ 25! [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-40.

Background: In 2013, the ASCO/CAP consensus panel published updated guidelines for HER2 testing in breast cancer that modified the definition of HER2 amplification by in situ hybridization (ISH), creating five new prognostic categories (group 1: classic amplified, group 2: monosomy, group 3: co-amplified (polysomy), group 4: equivocal, and group 5: classic non-amplified). Patients determined to be ISH amplified, were considered eligible for HER2-directed therapy. Concern over whether patients from non-classic groups 2-4 would benefit from treatment has led to the recent publication of the 2018 HER2 focused update. This update has modified the criteria for interpreting these ISH categories, recommending that the final diagnosis take into consideration a combination of HER2 immunohistochemistry (IHC) and ISH results. With increased emphasis on the HER2 protein assessment, it has prompted us to quantitatively examine HER2 protein expression in the ISH categories, using two different novel technologies. Materials & Methods: A cohort of 170 cases (URMC) and 102 cases (PSHMC) of invasive breast cancers, which had previously undergone HER2 IHC and ISH testing, were selected for this study. Cases were sorted and categorized into the HER2 ISH categories defined by ASCO/CAP. HER2 protein expression was quantitatively measured in the URMC and PSHMC cohorts using a novel immunodetection methodology (streptavidin-coated Phosphor-Integrated Dot (PID) fluorescent nanoparticles), and a novel dual-antibody, proximity-binding immunoassay (HERmark® Breast Cancer Assay, Monogram Biosciences, South San Francisco, California), respectively. HER2 protein expression was compared to the HER2 FISH and IHC results by ASCO/CAP category. Results: Cases in group 1 had a significantly (p < 0.01) higher average PID/cell and HERmark compared to cases in groups 2-5 (Table 1). Cases in groups 2-4 showed lower quantitative levels of HER2 protein expression, similar to the classic non-amplified cases (group 5). Group 1 was further divided into three subgroups (Table 2): Group A - ISH high-level amplified (ratio > 2, HER2 > 6, CEP17 < 2.7), Group B - amplified with elevated CEP17 (ratio > 2, CEP17 > 2.7), and Group C - low-level amplified (ratio > 2, HER2 > 4 and < 6). Group A and B had a significantly (p < 0.01) higher average PID/cell and HERmark compared to Group C. Group C was more comparable to cases in groups 2-5 (Table 1). Conclusion: Our results suggest that quantitative assessment of HER2 protein expression may help to further classify cases for HER2 status for targeted therapy, supporting the 2018 ASCO/CAP recommendation that non-classic ISH results might be resolved by evaluating protein expression. Follow up studies with a larger patient cohort and dual quantitative assessment are warranted. Average PID/cell and HERmark in ASCO category groupsASCO category groupN (URMC)PID/cell (URMC)*N (PSHMC)HERmark (PSHMC)*18888.07761.521011.20N/A32016.0213.84238.5315.95296.3208.3*averageTable 2:Average PID/cell and HERmark in subgroups of Group 1SubgroupN (URMC)PID/cell (URMC)*N (PSHMC)HERmark (PSHMC)*A24157.66465.7B34101.61044.1C3016.9329.8*average Citation Format: Buscaglia B, Turner B, Goda H, Huang W, Leitzel K, Natori T, Nakano Y, Okada H, Sperinde J, Ali S, Vasekar M, D'Aguiar M, McMahon L, Henry J, Lipton A, Hicks D. ASCO/CAP human epidermal growth factor receptor-2 (HER2) in situ hybridization (ISH) categories evaluated by quantitative HER2 protein diagnostic methodologies: A comparative analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-03-02.

Second harmonic generation (SHG) is an intrinsic optical signal that can be generated from fibrillar collagen. The directionality of SHG emission is influenced by the diameter and spacing of collagen fibrils, and the disorder in their packing within collagen fibers. One measure of SHG directionality is the ratio of forward- to backward-scattered SHG, or “F/B”. F/B has been used to assess healthy vs diseased tissue in breast, ovarian, and lung cancer, and is an independent prognostic indicator of metastasis free survival time in ER+, lymph node-negative (N0), invasive ductal carcinoma (IDC). Here we assess the heterogeneity in F/B within tumor sections from ER+ N0 IDC, and its effect on the use of F/B for metastatic risk prediction. We find that F/B of tumor collagen varies between the tumor/host interface and the more cellular tumor bulk (p Citation Format: Edward Brown, Danielle Desa, Wencheng Wu, Robert Hill, John Martens, Robert Strawderman, Bradley Turner. Intratumoral heterogeneity of second-harmonic generation scattering from tumor collagen and its effects on metastatic risk prediction [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-08.

INTRODUCTION: Oncotype DX (ODX) (Genomic Health, Redwood City, CA, USA) is a multigene quantitative reverse transcription-polymerase chain reaction-based assay used to estimate the risk of distant recurrence for ER-positive, node negative-breast cancer patients. The quoted list price for ODX is $4.175.00. ODX reports a recurrence score (RS) that is divided into low (< 18), intermediate (18-30), and high risk (≥ 30). The ODX RS has been shown to be prognostic and predict chemotherapy benefit in receptor positive breast cancer patients. The RS most highly weights genes related to proliferation (including Ki-67), HER-2, ER and PR. Klein et al. have previously shown that standard histological variables, in combination with semiquantitative ER, PR, HER-2, and Ki-67 results, can provide information similar to that found in the ODX RS using equations derived by linear regression analysis (Magee equations). In the current study, we have used a modification of these equations to validate their use in a cohort of breast cancer cases that were sent for ODX from our institution. MATERIALS AND METHODS: 233 cases (2009-present) with available ODX RS's (208 of these with Ki-67 results) were obtained from the pathology files at the University of Rochester Medical Center (URMC), and the histopathologic variables were extracted from the reports. Estimated RS's (URMC RS) were calculated by averaging results from the three published Magee equations, with a modification of the H-score for ER and PR. We estimated the H-score by multiplying the average intensity of staining by the% positive tumor cells. URMC RS's were compared with their paired ODX RS’s. RESULTS: The table shows the correlation between the ODX RS and URMC RS. 100% of cases with a high URMC RS also had a high ODX RS. There were no two step discordant results between a URMC RS and an ODX RS. A URMC RS correlated with an ODX RS of high, intermediate, and low in 7/12 (58%), 48/79 (61%) and 97/117 (83%) cases, respectively. Most of the discordant cases involved the intermediate/low groups, and the higher RS's in the discordant pairs were consistently close to the lower end cutoff point.The URMC RS and ODX RS would have resulted in similar treatment in 100% of patients. Comparison of ODX RS and URMC RS; n = number of cases (URMC median, URMC range) ODX RS ⇒URMC RS ⇓HIGHINTERMEDIATELOWHIGH7 (35,32-40)00INTERMEDIATE5 (25,22-28)48 (22,18-30)20 (20,18-27)LOW031 (15,9-18)97 (14,7-18) CONCLUSION: The modified Magee equations provide similar information as the ODX RS using information already generated by many laboratories, and may be a more cost-effective alternative than ODX in identifying breast cancer patients who might benefit from chemotherapy, or be spared its potential toxicity. If the estimated RS is clearly high or low, it is predictive of the ODX RS with a high degree of certainty. In our population a potential cost of $556,875.00 might have been avoided using the estimated RS. The estimated RS should not be dramatically different from the ODX RS. If there is a significant difference, this should be thoroughly investigated before decisions on adjuvant therapy are made. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-11-12.

Introduction: Neoadjuvant chemotherapy is used in locally advanced breast cancer to downstage the tumor, facilitating surgical management. Oncotype DX (ODX) is used to estimate the risk of distant recurrence for ER-positive breast cancers, allowing selected patients to avoid the toxicity of chemotherapy. ODX is often not possible on the small core biopsy samples. Klein et al. have shown that standard histological variables, combined with semiquantitative ER, PR, HER-2, and Ki-67 results, can provide information similar to that with ODX, using equations derived by linear regression analysis (Magee equations). We applied a modification of these equations to pretreatment core biopsies in women who received neoadjuvant chemotherapy to determine if the risk scores were predictive of pathologic response. Methods: 25 patients who received chemotherapy for receptor positive locally advanced(21), inflammatory(3), or metastatic(1) breast cancer followed by surgical treatment of the primary site were identified from a prospective breast cancer database. Pretreatment core biopsies were reviewed by a breast pathologist and Nottingham grade, ER and PR status (% of cells staining and intensity of staining), and Her-2 status by IHC and/or FISH were recorded. Clinical tumor size was defined as the average of sizes derived from mammogram, ultrasound, MRI, PET-CT and clinical breast examination. Using these data in a modified Magee equation, the patient's recurrence score was calculated. 0-18 was considered low risk (LR), >18- Results: Magee scores ranged from 13.8-41.6 (mean 27.4) and were significantly lower in the poor responders (mean = 23, range 13.8-41.6) compared to the good responders (mean = 33, range 22-41.3, p = 0.003). Table 1 shows the distribution of response by Risk Group (p = 0.018). Table 1: Response by Risk CategoryMagee Risk GroupLRIRHRPoor Response563Good Response038 73% of patients with high risk Magee scores had a good response to chemotherapy, compared to 21% of patient with low or intermediate scores (p = 0.01). Conclusions: Modified Magee equations applied to pretreatment core biopsies seem to predict pathologic response to neoadjuvant chemotherapy. Use of these equations to assign risk scores may be a useful tool in deciding which ER positive breast cancer patients are likely to benefit from preoperative chemotherapy for cytoreduction, and who should go directly to surgery. These findings need to be validated in larger studies. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-37.

Background: In the 2013 ASCO/CAP HER2 update, new recommendations for HER2 diagnostic criteria in breast cancer organized in situ hybridization (ISH) results into five categories; group1 (amplified), group 2 (monosomy), group 3 (co-amplified), group 4 (equivocal) and group 5 (non-amplified). Patients falling into groups 2, 3 and 4 were potentially eligible for HER2 targeted therapy, however, there is uncertainty from limited prospective clinical trials that show patients in these uncommon groups would receive the same benefit as group 1. Concern over whether the interpretation criteria should be modified for these uncommon groups led to the recent publication of the 2018 HER2 focused update. This update has modified ISH criteria for groups 2, 3 and 4, recommending the final diagnosis take into consideration both immunohistochemistry (IHC) and ISH results. The publication of this new guideline has prompted us to investigate what impact this would have on our institution. Materials & Methods: A retrospective review of the URMC pathology database revealed 2,281 cases that had undergone HER2 FISH analysis since the 2013 update. IHC for initial HER2 screening was used, followed by reflex testing of all 2+ results and cases with histopathologic discordance. All 2,281 FISH cases were sorted into their 5 HER2 categories based on the 2013 guidelines. The final HER2 diagnosis for groups 2, 3 and 4 were then re-determined after applying the new criteria presented in the 2018 focused update. Results: The results from the 2,281 HER2 FISH cases are shown in Tables 1 and 2. The results for group 1 and group 5 cases remained the same. However, for ISH cases in groups 2, 3 and 4, there were alterations in the final HER2 results. All 25 monosomy cases, originally interpreted as HER2 positive by the 2013 guidelines, were now considered HER2 negative. All group 3 (co-amplified) cases remained positive (due to IHC 2+ results). The largest change was that the original 199 equivocal cases, based on the 2013 guidelines, became split into 198 HER2 negative (99.5%) and 1 HER2 positive (0.5%). Conclusion: Comparison of the HER2 FISH cases between 2013 and 2018 revealed differences in the final HER2 status. Using the 2018 guideline, 13.72% (313 cases) of the 2281 cases were HER2 positive in contrast to 14.77% (337 cases) from 2013. While that is only a difference of 1.05%, the reclassification of 198 of 199 equivocal cases to negative indicates that 9.82% of the final HER2 results for the entire patient cohort was affected. With 266,000 new cases of breast cancer annually, the final HER2 status of approximately 26,000 patients and their potential eligibility for targeted-therapy would change. Further study of the clinical significance of these changes is warranted. Final ISH HER2 Status (2013)AmplifiedMonosomyCo-AmplifiedEquivocalNon-Amplified272 cases (11.93%)25 cases (1.10%)40 cases (1.75%)199 cases (8.72%)1,745 cases (76.50%) Citation Format: Hicks DG, D'Aguiar M, Henry J, McMahon L, Buscaglia B, Turner B. Impact of the 2018 ASCO/CAP HER2 focused update on human epidermal growth factor receptor-2 (HER2) testing in breast cancer: A retrospective review of a single institutional cohort [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-02-03.

Theranostics through the utilization of immunohistochemistry followed by radioimaging to determine if metastatic foci will react with a therapeutic antibody will allow for the selection of the patient population that will most benefit from this immunotherapy. The Thomsen-Friedenreich antigen (TF-Ag) has been shown to be involved in ∼90% of carcinomas, specifically breast carcinomas, making it a suitable target for radioimaging and therapy. The anti-TF-Ag antibody, JAA-F11, a mouse monoclonal antibody (mAb), has had success in localization, blocking metastasis, and inhibiting cell proliferation, and binds to ∼80% of breast cancer cell lines, without preference to receptor status. This is significant since the triple negative breast cancer (ER-/PR-/HER2-) has no current targeted treatment. Studies are extended to human breast cancer tissue microarray immunohistochemical (IHC) analysis, which was scored blindly by a pathologist on a semi- quantitative scale. JAA-F11 stained approximately 76% of all breast cancer specimens, which included cases of mucinous, medullary, invasive ductal and neuroendocrine carcinomas. The staining observed was irrespective of receptor status, whereas in normal breast tissue, staining was either absent or very weak/weak. In addition, all available matched lymph node metastasis stained, with greater intensity observed in 39% of cases. JAA-F11 IHC studies performed on human normal organ tissue arrays, showed staining that for the most part was not significantly different from staining obtained with isotype control antibody, or was observed in areas that would not be therapeutically accessible. Furthermore, in an additional IHC study, preliminary results suggest that JAA-F11 significantly stained other carcinomas including those of the colon, bladder, ovary and prostate. In vitro studies show that the humanized JAA-F11 (hJAA-F11) has similar chemical specificity and higher affinity towards the TF-Ag. Imaging studies were performed in a BALB/c mouse breast cancer model with the hJAA-F11 to determine biological reactivity and to predict the feasibility of theranostic imaging prior to therapy. After ∼10 days of tumor growth, mice pretreated with cold iodine water and rabbit IgG to inhibit binding to Fc receptors, were given tail vein injections of hJAA-F11 conjugated with [124]-I. Clear tumor images were obtained up to 144 hours post injection. Biodistribution analysis has provided further results indicating increased%ID/g (7.0±3.9%) in tumor tissue as compared to healthy tissues (brain%ID/g to be 0.21±.09, stomach 0.80±0.19%, and bone 0.90±2.4%). Results support that the hJAA-F11 antibody can be used in a multi-step theranostic approach, with analysis of tumor binding in IHC, followed by imaging to determine in vivo tumor targeting prior to direct immunotherapy or antibody drug conjugate therapy with hJAA-F11. Citation Format: Loukia Karacosta, Holly Johnson, Julia Abdullah, Taylor Chrisikos, Rachel Ludwig, Bradley Turner, Swetha Tati, Diala Ghazal, Munnawar Sajjad, Stephen Koury, Susan Morey, Julie Adams, Kate Rittenhouse-Olson. Immunohistochemistry and radioimaging with hJAA-11 antibody to the Thomsen-Friedenreich antigen: Potential theranostic application for breast cancer. [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 576.