Goetz, Matthew P.

Abstract Abstract 4259 Background: Patients with defective DNA repair mechanisms are at higher risk for developing cancer. BRCA1 and BRCA2 are proteins that coordinate DNA repair by homologous-recombination. Mutations in BRCA1 and BRCA2 are associated with an increased risk of cancers, namely breast, ovarian, and pancreatic, thus making these patients more likely to receive chemo- or radiation therapy. Additionally, secondary malignancies can be an unfortunate consequence of treatment with chemo- or radiation therapy. Although tumors with defective DNA repair mechanisms may be more susceptible to therapy, we hypothesized that patients with BRCA mutations that underwent chemotherapy or radiotherapy for treatment of breast or ovarian cancer would be at a higher risk of developing therapy- related myelodysplastic syndrome (t-MDS) or acute myeloid leukemia (t-AML). Methods: We accessed patient data from our institution maintained by the Mayo Clinic Life Sciences System using the Data Discovery and Query Builder. We searched for patients whose notes and diagnoses included the terms BRCA, and breast or ovarian cancer, and myelodysplastic syndrome or acute myeloid leukemia. We searched our records from 1/1/1995–7/15/2011. We cross-referenced our findings to a database of patients who were diagnosed with a BRCA mutation through our department of medical genetics. Secondly, we searched the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) database for female patients who developed AML after the diagnosis or breast or ovarian cancer from the years 1973–2008 using ratio and multiple primaries standardized incidence ratios sessions. Results: We identified 220 patients with a BRCA mutation, of which 73 received chemotherapy. There were two patients with BRCA mutations that developed t-AML following treatment for breast cancer, and one patient with a BRCA mutation who developed t-AML following treatment for ovarian cancer (Table 1). Manual data extraction from the list of patients with BRCA mutations diagnosed at our institution only identified one of these patients, as two obtained their testing through another institution. We did not identify any patients with BRCA mutations who developed t-MDS following treatment for breast or ovarian cancer. The latency between diagnosis of the primary cancer and the diagnosis or t-AML was 24 months for two patients, and 22 years for the other. From our search of the SEER database we found 649 patients who developed AML after a diagnosis of breast cancer, and 98 patients who developed AML after a diagnosis of ovarian cancer. These patients represented 0.1% and 0.2% of evaluable breast and ovarian cases respectively. The latency from time of diagnosis of the primary cancer to that of AML was 58 months (29–113 interquartile range) for breast cancer and 47 months (29–91) for ovarian cancer. The observed number of patients with AML following the diagnosis of breast or ovarian cancer was 1.68 and 4.74 times higher than that expected of the general population, respectively (both p<0.05). We were not able to stratify patients based on the presence of a BRCA mutation due to the limitations of the database. Conclusions: We identified three patients with confirmed BRCA mutations and t-AML at our institution. Although this does not represent a strong association, patients at risk for BRCA mutations do not always undergo testing. Thus, our results may not fully represent whether there is an association with BRCA mutations and t-MDS or t-AML. Using the SEER database, we confirmed that patients who were diagnosed with breast or ovarian cancer subsequently had a higher incidence of AML than the general population, although we were not able to test if patients with BRCA mutations are at higher risk of t-MDS or t-AML. Disclosures: No relevant conflicts of interest to declare.

Abstract Purpose: We hypothesized that integrated analysis of cancer types from different lineages would reveal novel molecularly defined subgroups with unique therapeutic vulnerabilities. On the basis of the molecular similarities between subgroups of breast and ovarian cancers, we analyzed these cancers as a single cohort to test our hypothesis. Experimental Design: Identification of transcriptional subgroups of cancers and drug sensitivity analyses were performed using mined data. Cell line sensitivity to Hsp90 inhibitors (Hsp90i) was tested in vitro. The ability of a transcriptional signature to predict Hsp90i sensitivity was validated using cell lines, and cell line- and patient-derived xenograft (PDX) models. Mechanisms of Hsp90i sensitivity were uncovered using immunoblot and RNAi. Results: Transcriptomic analyses of breast and ovarian cancer cell lines uncovered two mixed subgroups comprised primarily of triple-negative breast and multiple ovarian cancer subtypes. Drug sensitivity analyses revealed that cells of one mixed subgroup are significantly more sensitive to Hsp90i compared with cells from all other cancer lineages evaluated. A gene expression classifier was generated that predicted Hsp90i sensitivity in vitro, and in cell line- and PDXs. Cells from the Hsp90i-sensitive subgroup underwent apoptosis mediated by Hsp90i-induced upregulation of the proapoptotic proteins Bim and PUMA. Conclusions: Our findings identify Hsp90i as a potential therapeutic strategy for a transcriptionally defined subgroup of ovarian and breast cancers. This study demonstrates that gene expression profiles may be useful to identify therapeutic vulnerabilities in tumor types with limited targetable genetic alterations, and to identify molecularly definable cancer subgroups that transcend lineage.

Abstract INTRODUCTION: Breast cancer is the most common invasive cancer and the second leading cause of cancer death in women. Approximately 20% of breast cancer tumors overexpress human epidermal growth factor receptor 2 (HER2), which is associated with an aggressive clinical phenotype and with a poorer prognosis. The development of trastuzumab, an immunoglobulin G monoclonal antibody directed against HER2, has changed the treatment paradigm for this disease. However, approximately 15-20% still does not respond to anti-HER2 therapy. Furthermore, despite advances in the management of metastatic HER2-positive breast cancer, response rate varies greatly, with most patients eventually succumbing to their disease. It is crucial to develop additional therapeutic strategies to improve outcomes for HER2 positive patients, especially those with tumors that do not respond to anti-HER2 therapy. METHODS and RESULTS: Using HER2+ breast cancer cell lines, we found that an USP7 inhibitor, P5091, dramatically sensitized cancer cells to HER2 inhibitor, trastuzumab treatment. To confirm it in vivo, we tested the drug combination in BT474 xenografts and found P5091 and trastuzumab synergistically suppressed tumor growth. Furthermore, using trastuzumab resistant HER2+ breast cancer cell line, we found that USP7 inhibitor, P5091, can dramatically re-sensitize trastuzumab-resistant BT474 cell line to trastuzumab treatment both in vitro and in vivo. More importantly, using patient derived xenograft (PDX) HER2+ models, we confirmed the synergistic combination effect of P5091 and trastuzumab. Mechanistically, USP7 inhibitor, P5091 led to significantly increased degradation of all four HER family members (HER1-4). When we knocked down USP7 by RNA interference or small hairpin RNA (shRNA), we observed similar substantial decrease in HER family member proteins. CONCLUSIONS: We have demonstrated the feasibility of using USP7 inhibitor P5091 to sensitize HER2+ breast cancers to trastuzumab treatment. These results provide a rationale for the use of combination therapy of USP7 inhibitors and HER2 inhibitors to treat HER2+ breast cancer. This combination therapy might also be effective in other cancers with upregulated HER signaling, such as GI cancer, lung cancer or ovarian cancer. Citation Format: Jia Yu, Bo Qin, Judy Boughey, Matthew Goetz, Liewei Wang. The role of USP7 and USP7 inhibitor in HER2+ breast cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2980.

Abstract Chemotherapy resistant breast cancer is a major health challenge, resulting in high relapse rates and poor survival. Neoadjuvant chemotherapy (NACT) is a standard treatment for women with high-risk TNBC, HER2+, and locally advanced ER+ breast cancer. A completed course of NACT results in two possible outcomes: pathologic complete response (pCR) or residual disease. While pCR is a reliable clinical prognostic biomarker associated with excellent outcomes and prolonged survival, especially for TNBC and HER2+ cancers, patients with residual disease have a higher risk of recurrence. Patients with residual disease can be further stratified clinically using the Residual Cancer Burden (RCB) classification; however, patients with similar RCB classes may experience dramatically different clinical outcomes. Thus, additional precision biomarkers to stratify patients with residual disease after NACT are needed to identify patients at highest risk of recurrence, and to develop new therapeutic strategies to eradicate multidrug-resistant tumors. Supported by strong evidence in developmental, evolutionary and cancer biology, we found that K-RAS-SIAH pathway activation is a major tumor driver, and SIAH represents a key tumor vulnerability in breast cancer. Normal K-RAS/SIAH signaling pathway activation is indispensable for proper cell-cell communication, cell proliferation and tissue homeostasis in multicellular organisms. However, abnormal K-RAS/SIAH pathway activation is highly prevalent in high-risk and locally advanced breast cancer, and may confer chemo-resistance to these high-risk mammary tumors. Based on its evolutionary conservation and significance as the most downstream signaling module indispensable for K-RAS signal transduction, SIAHON/OFF expression is a reliable readout of K-RAS/EGFR/HER2 pathway activation/inactivation. We showed that SIAHON/OFF expression is a binary code in residual mammary tumors that can be used to stratify patients, augment RCB classification, forecast tumor relapse, and predict patient survival after 1st line NACT in a pilot retrospective study. Multidrug-resistant high-grade breast cancer is a genetically diverse, highly heterogeneous disease that challenges our ability to individualize and optimize precision therapy. Persistent K-RAS-SIAH-EGFR pathway activation endows TNBC with therapy resistance, and increases the risk of metastasis and early relapse. As such, we developed a K-RAS/SIAH-centered biomarker discovery program and a new anti-SIAH research initiative with the intended goal of designing novel and potentially life-saving anti-K-RAS targeted strategies to control and eradicate multidrug-resistant and intractable mammary tumors. Citation Format: Amy H. Tang, Lauren L. Siewertsz van Reesema, Vasilena P. Zheleva, Janet S. Winston, Rick J. Jansen, Emanuel F. Petricoin, Matthew P. Goetz, Matthew P. Goetz, Harry D. Bear, Richard A. Hoefer. Detect early tumor relapse in high-risk breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2145.

503 Background: TAILORx established that endocrine therapy (ET) alone is non-inferior to adjuvant chemotherapy (CT) plus ET in EBC and a 21-gene RS of 11-25, with some benefit if ≤50 years (y) with RS 16-25 (PMID: 29860917). We evaluated whether clinical risk (tumor size & histologic grade) provides additional prognostic information to RS, a secondary trial objective. Methods: Clinical risk by was assessed by Adjuvant! (version 8.0) using MINDACT criteria (PMID 27557300), defined as low clinical risk (LCR - tumor ≤3 cm and low grade, <2 cm and intermediate grade, or ≤1 cm and high grade) or high clinical risk (HCR -not meeting LCR criteria). Results: Of 9427 women with RS and clinical risk information, 70% were LCR and 30% HCR, with comparable distribution by age ( ≤50 vs. >50). The RS was 26-100 in 9% of LCR and 27% of HCR patients, with similar distributions by age. Although LCR/HCR provided additional prognostic information in each RS category for iDFS, including RS 0-10 (9-year rates 86.7% vs. 75.7% LCR vs. HCR), 11-25 (85.4% vs. 78.9%), and 26-100 (82.0% vs. 70.4%), iDFS rates were similar irrespective of CT (no vs. yes) in the entire RS 11-25 cohort whether LCR (85.8% vs. 85.1%) or HCR (79.8% vs. 77.9%). DRFI rates were also similar irrespective of CT in the RS 11-25 cohort or > 50y group whether LCR (96.0% vs. 96.1% overall; 96.5% vs. 96.0% > 50y) or HCR (92.3% vs. 89.9% overall; 91.7% vs. 90.7% >50y). For women ≤50y, the absolute reduction in distant recurrence from CT with a RS of 16-20 (N=923) was -0.2% (standard error [SE]±2.1%) for LCR vs. 6.5%(SE±4.9%) for HCR (vs. 1.6%[SE±1.9%] overall), whereas for a RS 21-25 (N=492) it was 6.4% (SE±4.9%) for LCR vs. 8.6% (SE±6.2%) for HCR (vs. 6.5%[SE±3.7%] overall). Conclusions: Clinical risk stratification provides additional prognostic information to the 21-gene RS, but not prediction of CT benefit in the overall TAILORx population or those > 50y, and facilitates more refined estimates of absolute CT benefit for women ≤50y with a RS 16-25. (Funded by National Cancer Institute, Komen Foundation, Breast Cancer Research Foundation). Clinical trial information: NCT00310180.