Abstract P3-07-01: IRS1 expression is required for estrogen stimulated growth in breast cancer cells

Insulin receptor substrate (IRS) proteins are adaptor proteins phosphorylated by activated type I insulin-like growth factor receptor (IGF-1R) and insulin receptor (IR). In addition to their roles in normal cell physiology, we have shown IRS expression is required for breast cancer cell growth and motility. IRS1 plays a more important role in mitogenesis and survival while IRS2 in cancer cell metastasis. Moreover, this family of adaptor proteins is also involved in the signal transduction of many other transmembrane receptors. Thus, IRS proteins could be potential cancer therapeutic targets. We have previously shown that reduced IRS1 impairs IGF and insuliln stimulated cancer cell growth and tumorigenicity even when signaling is not affected due to possible compensation of IRS2 and other adaptor proteins. To further study the role of IRS-1 function in breast cancer, we created doxycycline inducible IRS-1 shRNA cells. We also found that IRS1 knockdown significantly reduced estradiol stimulated growth. To investigate if reduced IRS1 regulated E2 stimulated binding of ERa ChIP assay was performed using the pS2 promoter. Compared to parental MCF-7L cells, inducible IRS1 knock down clone 3G5 demonstrated significantly reduced promoter binding. Degradation of IRS-1 with a pharmacologic antagonist (NT-157) also diminished ERa binding to pS2 promoter. Further qRT-PCR analysis for mRNA levels of estrogen regulated genes, such as PGR, TFF1, etc. showed those genes were significantly down regulated. To evaluate effects of IRS-1 levels on estrogen stimulated growth, we evaluated 3G5-B12 (a subclone of 3G5) cell growth in a xenograft model. 3G5-B12 cells have similar levels of IGFIR and ERa expression compared to their parent cells. Estrogen dependent xenograft growth was similar to those of parent MCF-7L cells. After doxycycline was administered in the diet, 3G5-B12 tumor growth was significantly inhibited compared to those fed with normal mouse diet, and this inhibition was prolonged at least 2 and a half months. Parental MCF-7L tumor growth was not affected by the doxycycline diet. Doxycycline inducible IRS1 knock down significantly prolonged the time before tumors reached 1000mm3 compared with those tumors on a normal diet. In conclusion, IRS-1 is required for optimal estrogen receptor function as measured by promoter binding and xenograft growth. Our data suggested suppression of IRS-1 function may target several growth pathways in breast cancer cells and represents a new drug target.

Citation Format: Zhang X, Varma S, Yee D. IRS1 expression is required for estrogen stimulated growth in breast cancer cells [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 P3-07-01.

Abstract PD6-14: Analysis of DNA repair deficiency biomarkers as predictors of response to the PD1 inhibitor pembrolizumab: Results from the neoadjuvant I-SPY 2 trial for stage II-III high-risk breast cancer

Background: Pembrolizumab (P), an anti-PD-1 immune checkpoint inhibitor, has been approved for treatment of microsatellite instability-high and mismatch repair deficient cancers. In I-SPY 2, patients were randomized to receive standard chemotherapy alone or in combination with an experimental agent. P was one of the experimental agents evaluated in HER2- patients in I-SPY 2 and graduated in the TN, HR+HER2-, and HER2- signatures. We hypothesize that a combination of two signatures predicting response to veliparib/carboplatin therapy in I-SPY 2 [MammaPrint High2 (MP2)/PARPi7-high] and reflecting DNA damage repair deficiency, may also predict response to P. In addition, we also tested 9 gene expression signatures reflecting different aspects of DNA damage and repair: FA, MMR, BER, HR, TLS, NER, NHEJ, DR, and DNA damage sensing (DDS) pathways.

Methods: Data from 249 patients (P: 69 and controls: 180) were available. Pre-treatment biopsies were assayed using Agilent gene expression arrays. All I-SPY 2 qualifying biomarker analyses follow a pre-specified analysis plan. We used logistic modeling to assess biomarker performance. A biomarker is considered a specific predictor of P response if it associates with response in the P arm but not the control arm, and if the biomarker x treatment interaction is significant (likelihood ratio test, p<0.05). This analysis is also performed adjusting for HR status as a covariate, and within receptor subsets, sample size permitting. For successful biomarkers, we use Bayesian modeling to estimate the pCR rates of 'predicted sensitive' patients in each arm. Our statistics are descriptive rather than inferential and do not adjust for multiplicities of other biomarkers outside this study.

Results: MP2 status associates with pCR in P (OR=7.7; p=0.00021), but also to a lesser extent in the control arm (OR=2.4:p=0.045), with an OR ratio of 3.3 which trends toward significance, even after adjusting for HR status (LR p=0.083). A majority of TN patients are MP2; and TN/MP2 patients have an estimated pCR rate of 67% in P (vs. 23% in control). Although only ~30% of HR+HER2- patients were MP2, their estimated pCR rate in P is 61%, compared to 29% in unselected HR+/HER2- patients. PARPi7 predicted response in the P arm only in the HR+HER2- group (LR p= 0.025), but not in the population as a whole or the TN subtype. Combining MP2 and PARPi7 into MP2/PARPi7-high did not improve performance over MP2 as a single biomarker. Of the 9 DDR pathway signatures tested, both BER and DDS associate with pCR in P, but only DDS (which includes ATM, ATR, CHEK1-2) associates with pCR in the P arm (LR p=0.00029), and not the control arm (LR p=0.53), with a significant interaction with treatment (LR p=0.0064) that retains significance in a model adjusting for HR status. When dichotomized to optimize the biomarker x treatment interaction, the estimated pCR rate is 75% in P vs 18% in control, in the DDS+ subset.

Conclusion: In this small study, MP2 status and a DNA damage sensing pathway but not the PARPi7 or other repair pathways show promise as predictive biomarkers for immune checkpoint inhibition therapy in breast cancer.

Citation Format: Yau C, Wolf D, Brown-Swigart L, Hirst G, Sanil A, Singhrao R, I-SPY 2 TRIAL Investigators, Asare S, DeMichele A, Berry D, Esserman L, van 't Veer L, Nanda R, Liu M, Yee D. Analysis of DNA repair deficiency biomarkers as predictors of response to the PD1 inhibitor pembrolizumab: Results from the neoadjuvant I-SPY 2 trial for stage II-III high-risk breast cancer [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 PD6-14.

Abstract OT3-06-02: A phase Ib trial of xentuzumab and abemaciclib in patients with locally advanced or metastatic solid tumors, including hormone receptor-positive, HER2-negative breast cancer (plus endocrine therapy)

Background: Resistance to endocrine therapy remains an important clinical problem in hormone receptor-positive (HR+), HER2-negative (HER2-) breast cancer (BC), necessitating alternative treatment options. The insulin-like growth factor (IGF) axis and cyclin D-cyclin-dependent kinase (CDK) 4/6-retinoblastoma pathway have been implicated in the pathogenesis and resistance mechanisms of a variety of cancers, including BC. Binding of IGF-I and -II to the IGF receptor results in upregulation of cyclin D1, and subsequent progression through the cell cycle, thus providing rationale for the simultaneous inhibition of IGF-I and -II and CDK4/6. This Phase Ib trial assesses the maximum-tolerated dose (MTD)/recommended phase II dose (RP2D), safety and preliminary efficacy of the IGF-ligand-neutralizing antibody, xentuzumab, in combination with abemaciclib, a selective, small-molecule inhibitor of both CDK4 and 6, in patients (pts) with solid tumors. The trial includes four dose finding cohorts followed by two expansion cohorts. Only those cohorts that will include pts with postmenopausal HR+, HER2- BC will be presented here.

Trial design: In this phase Ib multicenter, non-randomized, open-label, dose escalation trial (BI 1280.18 [NCT03099174]), the key aims in the BC cohorts (Cohorts B–D, F) are to define the MTD or recommended phase 2 dose (RP2D), and to evaluate the preliminary efficacy, safety and tolerability of xentuzumab plus abemaciclib in combination with endocrine therapies. Eligible pts include adults ≥18 yrs (≥20 for Japan), with measurable or evaluable disease, adequate organ function, ECOG PS ≤1, and postmenopausal locally advanced or metastatic HR+, HER2- BC (Cohorts B–D, F). CDK4/6 inhibitor-naïve pts (Cohorts B–D) and pts who have received prior CDK4/6 inhibitors (palbociclib or ribociclib) plus aromatase inhibitors (Cohort F) are included. The MTD/RP2D of xentuzumab plus abemaciclib to be used in Cohorts B–D will be established in pts with solid tumors (Cohort A) who will receive xentuzumab (starting dose 1000mg weekly iv) plus abemaciclib (starting dose 150mg every 12 hours). CDK4/6 inhibitor-naïve pts with BC will receive xentuzumab plus abemaciclib at the RP2D determined in Cohort A in combination with letrozole (2.5mg/day; Cohort B), anastrozole (1mg/day; Cohort C), or fulvestrant (500mg/month; Cohort D). CDK4/6 inhibitor pre-treated pts with BC (Cohort F) will receive xentuzumab plus abemaciclib and fulvestrant at the RP2D determined in Cohort D. Primary endpoints in the BC cohorts are the MTD and/or RP2D of xentuzumab plus abemaciclib in combination with endocrine therapies, and the objective response (OR) in CDK4/6 inhibitor pre-treated pts with advanced BC (Cohort F); disease control (DC), duration of DC, time to OR, duration of OR, and progression-free survival (PFS) in Cohort F are secondary endpoints. Additionally, PK outcomes, safety and tolerability will be assessed in all cohorts. This study will be conducted in the US, Europe and Japan. Pt screening started in May 2017. Target enrolment is ˜88 pts, including ˜56 pts with advanced HR+, HER2- BC, of whom ˜20 had previously been treated with CDK 4/6 inhibitors.

Citation Format: Yee D, Sablin MP, Iwata H, Johnston EL, Bogenrieder T, Serra J, Hua H, Lo Russo P, Prat A. A phase Ib trial of xentuzumab and abemaciclib in patients with locally advanced or metastatic solid tumors, including hormone receptor-positive, HER2-negative breast cancer (plus endocrine therapy) [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 OT3-06-02.

Abstract P6-11-04: The evaluation of ganitumab/metformin plus standard neoadjuvant therapy in high-risk breast cancer: Results from the I-SPY 2 trial

Background: I-SPY 2 is a multicenter, phase 2 trial using response-adaptive randomization within biomarker subtypes to evaluate novel agents when added to standard neoadjuvant therapy for women with high-risk stage II/III breast cancer - investigational agent(I) +paclitaxel(T) qwk, doxorubicin & cyclophosphamide(AC) q2-3 wk x 4 vs. T/AC (control arm). The primary endpoint is pathologic complete response (pCR) at surgery. The goal is to identify/graduate regimens that have ≥85% Bayesian predictive probability of success (statistical significance) in a 300-patient phase 3 neoadjuvant trial defined by hormone-receptor (HR) & HER2 status & MammaPrint (MP). Regimens may also leave the trial for futility (< 10% probability of success) or following accrual of maximum sample size (10%< probability of success <85%). We report the results for experimental arm Ganitumab, a type I insulin-like growth factor receptor (IGF1R) inhibitor. IGF1R inhibitors are known to induce insulin resistance and all patients assigned to Ganitumab received metformin.

Methods: Women with tumors ≥2.5cm were eligible for screening. MP low/HR+ and HER2+ tumors were ineligible for randomization. Hemoglobin A1C≥ 8.0% were ineligible. MRI scans (baseline, 3 cycles after start of therapy, at completion of weekly T and prior to surgery) were used in a longitudinal statistical model to improve the efficiency of adaptive randomization. Ganitumab was given at 12mg/kg q2 weeks and metformin at 850mg PO BID, while receiving ganitumab. Analysis was intention to treat with patients who switched to non-protocol therapy counted as non-pCRs. Ganitumab/metformin was open only to HER2- patients, and eligible for graduation in 3 of 10 pre-defined signatures: HER2-, HR+HER2- and HR-HER2-.

Results: Ganitumab/metformin did not meet the criteria for graduation in the 3 signatures tested. When the maximum sample size was reached, accrual to this arm stopped. Ganitumab/metformin was assigned to 106 patients; there were 128 controls. We report probabilities of superiority for Ganitumab/metformin over control and Bayesian predictive probabilities of success in a neoadjuvant phase 3 trial equally randomized between Ganitumab/metformin and control, for each of the 3 biomarker signatures, using the final pathological response data from all patients. Safety data will be presented.

SignatureEstimated pCR Rate (95% probability interval)Probability Ganitumab/ Metformin Is Superior to ControlPredictive Probability of Success in Phase 3 Ganitumab/ Metformin N = 106Control N = 128  All HER2-22% (13%-31%)16% (10%-23%)89%33%HR+/HER2-14% (4%-24%)12% (4%-19%)66%21%HR-/HER2-32% (17%-46%)21% (11%-32%)91%51%

Conclusion: The I-SPY 2 adaptive randomization study estimates the probability that investigational regimens will be successful in a phase 3 neoadjuvant trial. The value of I-SPY 2 is to give insight about the performance of an investigational agent's likelihood of achieving pCR. For Ganitumab/metformin, no subtype came close to the efficacy threshold of 85% likelihood of success in phase 3, and this regimen does not appear to impact upfront reduction of tumor burden. Our data do not support its continued development for the neoadjuvant treatment of breast cancer.

Citation Format: Yee D, Paoloni M, van't Veer L, Sanil A, Yau C, Forero A, Chien AJ, Wallace AM, Moulder S, Albain KS, Kaplan HG, Elias AD, Haley BB, Boughey JC, Kemmer KA, Korde LA, Isaacs C, Minton S, Nanda R, DeMichele A, Lang JE, Buxton MB, Hylton NM, Symmans WF, Lyandres J, Hogarth M, Perlmutter J, Esserman LJ, Berry DA. The evaluation of ganitumab/metformin plus standard neoadjuvant therapy in high-risk breast cancer: Results from the I-SPY 2 trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-11-04.

Abstract P6-11-02: Efficacy of Hsp90 inhibitor ganetespib plus standard neoadjuvant therapy in high-risk breast cancer: Results from the I-SPY 2 trial

Background:Pathologic complete response(pCR) after neoadjuvant therapy is an established prognostic biomarker for high-risk breast cancer(BC). Improving pCR rates may identify new therapies that improve survival. I-SPY 2 uses response-adaptive randomization within biomarker subtypes to evaluate novel agents when added to standard neoadjuvant therapy for women with high-risk stage II/III breast cancer; the goal is to identify regimens that have ≥85% Bayesian predictive probability of success (statistical significance) in a 300-patient phase 3 neoadjuvant trial defined by hormone-receptor (HR), HER2 status and MammaPrint (MP). We report the results for Ganetespib, a selective inhibitor of Hsp90 that induces the degradation/deactivation of key drivers of tumor initiation, progression, angiogenesis, and metastasis.Ganetespib + taxanes previously have resulted in a superior therapeutic response compared to monotherapy in multiple solid tumor models including BC.

Methods:Women with tumors ≥2.5cm were eligible for screening and participation. MP low/HR+ tumors were ineligible for randomization. QTcF >470msec and HbA1C >8.0% were ineligible. MRI scans (baseline, +3 cycles, following weekly paclitaxel, T, and pre-surgery) were used in a longitudinal statistical model to improve the efficiency of adaptive randomization. Ganetespib was given with weekly T at 150 mg/m2 IV weekly (3 weeks on, 1 off). Patients were premedicated (dexamethasone 10mg and diphenhydramine HCl 25-50 mg, or therapeutic equivalents). Analysis was intention to treat with patients who switched to non-protocol therapy counted as non-pCRs. The Ganetespib regimen was open only to HER2- patients, and eligible for graduation in 3 of 10 pre-defined signatures: HER2-, HR+/HER2- and HR-/HER2-.

Results:Ganetespib did not meet the criteria for graduation in the 3 signatures tested. When the maximum sample size was reached, accrual stopped. Ganetespib was assigned to 93 patients; there were 140 controls. We report probabilities of superiority for Ganetespib over control and Bayesian predictive probabilities of success in a neoadjuvant phase 3 trial equally randomized between Ganetespib and control, for the 3 biomarker signatures, using the final pCR data from all patients. Safety data will be presented.

SignatureEstimated pCR Rate (95% probability interval)Probability Ganetespib Is Superior to ControlPredictive Probability of Ganetespib Success in a Phase 3 Trial Ganetespib N = 93Control N = 140  All HER2-26% (16%-37%)18% (8%-28%)91%47%HR+/HER2-15% (4%-27%)14% (4%-24%)60%19%HR-/HER2-38% (23%-53%)22% (9%-35%)96%72%

Conclusion:The I-SPY 2 adaptive randomization model efficiently evaluates investigational agents in the setting of neoadjuvant BC. The value of I-SPY 2 is that it provides insight as to the regimen's likelihood of success in a phase 3 neoadjuvant study. Although no signature reached the efficacy threshold of 85% likelihood of success in phase 3, we observed the most impact in HR-/HER2- patients, with a 16% improvement in pCR rate. While our data do not support the continued development of Ganetespib alone for neoadjuvant BC, combinations with Ganetespib, which could potentiate its effect, may be worth pursuing in I-SPY 2 or similar trials.

Citation Format: Forero A, Yee D, Buxton MB, Symmans WF, Chien AJ, Boughey JC, Elias AD, DeMichele A, Moulder S, Minton S, Kaplan HG, Albain KS, Wallace AM, Haley BB, Isaacs C, Korde LA, Nanda R, Lang JE, Kemmer KA, Hylton NM, Paoloni M, van't Veer L, Lyandres J, Perlmutter J, Hogarth M, Yau C, Sanil A, Berry DA, Esserman LJ. Efficacy of Hsp90 inhibitor ganetespib plus standard neoadjuvant therapy in high-risk breast cancer: Results from the I-SPY 2 trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-11-02.

Abstract S5-07: Aromatase inhibitors and endothelial function: Is there an association with early cardiovascular disease?

Background: As more women are cured from their breast cancer, survivors with early stage breast cancer are at greater risk of dying from cardiovascular disease than their breast cancer. Aromatase inhibitors (AI) have been shown to reduce breast cancer-related mortality in women with estrogen receptor (ER)-positive disease which makes up 75% of all breast cancer cases. The use of AIs has been associated with higher rates of hypertension, hypercholesterolemia, angina pectoris and ischemic cardiovascular disease. In the aging population taking AIs, little is known about the direct impact of AIs on endothelial function, a predictor of cardiovascular disease. Endothelial dysfunction identified by reactive hyperemia using Endo-PAT has been associated with an increased risk of cardiac adverse events, independent of Framingham risk score.

Methods: At the University of Minnesota in 2014-2015, 25 healthy postmenopausal women and 36 postmenopausal women with locally advanced breast cancer and prescribed an aromatase inhibitor were identified. Subjects with a history of hypertension or hyperlipidemia were excluded. Consented subjects underwent biomarker analysis and pulse wave analysis using the HDI/Pulse Wave CR-2000 Cardiovascular Profiling System and pulse contour analysis using the Endo-PAT2000 system. Biomarkers and functional test markers were compared between cases and controls using T-tests and Wilcoxon Rank-Sum tests.

Results: Mean age (61.7 vs 58.8 years), body mass index (27.4 vs 26.2 kg/m2), race (93% vs 92% Caucasian), and tobacco use (100% nonsmokers) were similar between cases and controls, respectively. Mean systolic blood pressure (BP) was elevated in cases (128.3 mmHg vs 114.5 mmHg, p=0.0006). There were no differences in lipid profiles. Median ultrasensitive estradiol levels were reduced in cases (2 vs 15 pg/mL, p<0.0001). Median high sensitive C-reactive protein was significantly elevated in cases (4146 vs 1406 ng/L, p=0.05). There were no differences seen in markers of hemostasis or endothelial damage, including circulating endothelial cells, vascular cell adhesion molecule, P-selectin. Median large artery elasticity (12.5 vs 15.1 ml/mmHg, p=0.02), small artery elasticity (5.2 vs 6.7 ml/mmHg, p=0.04), and endoPAT ratio (0.8 vs 2.6, p<0.0001) were significantly reduced in breast cancer survivors on AIs as compared to controls. There was no correlation between use of chemotherapy, radiation therapy, type of AI, or duration of AI use and endothelial function among the cases. When adjusting for differences in BP, endoPAT ratio continued to remain significantly decreased in breast cancer survivors (0.8 vs 2.6, p<0.0001).

Conclusion: Postmenopausal women with breast cancer on AIs have reductions in endothelial function, a predictor of adverse cardiovascular disease (acute coronary syndrome, chest pain, myocardial infarction, cardiac death). With the growing trend that longer duration of endocrine therapy is needed, further work is needed to confirm these findings.

Citation Format: Blaes AH, Beckwith H, Hebbel R, Solovey A, Potter D, Yee D, Vogel R, Luepker R, Duprez D. Aromatase inhibitors and endothelial function: Is there an association with early cardiovascular disease? [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S5-07.

Abstract P3-05-02: Quantitative ERα measurements in TNBC from the I-SPY 2 TRIAL correlate with HER2-EGFR co-activation and heterodimerization

Background: We have previously described that TNBC patients whose tumors have both HER2 Y1248 phosphorylation (pHER2) “high” and phospho-EGFR Y1173 (pEGFR) “high” have increased response (pCR) to neratinib in the I-SPY2 TRIAL. We hypothesize that the paradoxical finding of a response prediction signature comprised of HER2 activation in a HER2 IHC/FISH-negative population means there must be a ligand-driven biochemical event responsible for the HER2 phosphorylation because HER2 mutations were also not found to be significant. Exploratory analysis of additional cellular signaling events and protein expression levels in pre-treatment, LCM-purified tumor epithelium by reverse phase protein microarray (RPPA) included semi-quantitative measurement of total levels of estrogen receptor alpha (ERα), which has been previously shown to be able to act as a membrane non-genomic signaling molecule through direct interaction with various tyrosine kinases including EGFR and HER2. Since ERα has been previously shown to act as a ligand and co-stimulate (activate) HER2 and EGFR when present at low levels, we investigated whether or not RPPA-measured ERα levels in the TNBC cohort analyzed to date were higher in tumors with both pHER2 “high” and pEGFR “high” levels and thus provide evidence explaining how HER2-EGFR activation is occurring in TNBC.

Methods: Using RPPA analysis, we measured 118 analytes in lysates of LCM tumor epithelium obtained from the pre-treatment biopsy samples of 86 TNBC (Allred=0) patients in the I-SPY2 TRIAL analyzed to date. Cutpoints for pEGFR and pHER2 were determined previously by ROC analysis for pCR correlation in the neratinib treated TNBC population, and used here to dichotomize the pHER2 and pEGFR data in the larger TNBC population. Wilcoxon Rank Sum testing was performed using the continuous variable total ERα data and compared the TNBC that were both pHER2 and pEGFR “high” (N=39) to the rest of the TNBC population (N=47). Total ERα values were then divided into “high” and “low” groups based on the TNBC population median value in order to determine frequency/percentages within each class. Our study is exploratory with no claims for generalizability of the data, and calculations are descriptive (e.g. p-values are measures of distance with no inferential content).

Results: Total ERα values were obtained in 84/86 TNBC tumors analyzed. Total levels of ERα were higher (p< 0.006) in TNBC tumors with pHER2 and pEGFR “high” levels. 68% (26/38) of tumors in the pHER2 and pEGFR “high” group had ERα levels above the population median compared to 35% (16/46) in the rest of the TNBC population.

Conclusion: Our exploratory analysis reveals that ERα levels are significantly higher in TNBC with pHER2 and pEGFR activation and may be behaving as a direct signaling ligand in TNBC and driving HER2-EGFR signaling. This ERα-pHER2/pEGFR association was missed by current ER and HER2 clinical laboratory testing techniques, and if validated in larger independent study sets could suggest that utilization of new protein-based techniques defining ER more quantitatively could be helpful to understand tumor biology and therapeutic response prediction, especially in the context of TNBC that are ostensibly ER negative.

Citation Format: Gallagher RI, Yau C, Wolf DM, Dong T, Hirst G, Brown-Swigart L, ISPY-2 TRIAL Investigators, Buxton M, DeMichele A, van't Veer L, Yee D, Paoloni M, Esserman L, Berry D, Park J, Petricoin EF, Wulfkuhle JD. Quantitative ERα measurements in TNBC from the I-SPY 2 TRIAL correlate with HER2-EGFR co-activation and heterodimerization [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-05-02.

Abstract P2-11-02: A longitudinal look at toxicity management within a platform trial: Lessons from the I-SPY 2 TRIAL

Background: I-SPY 2 is a multicenter, phase 2 trial using response-adaptive randomization within biomarker subtypes to evaluate a series of investigational agents or regimens when added to standard neoadjuvant therapy for women with high-risk stage II/III breast cancer - investigational agent (I) +paclitaxel (T) qwk, doxorubicin & cyclophosphamide (AC) q2-3 wk x 4 vs. T+/-HP/AC (control arm(s)). Although the primary endpoint is pathologic complete response (pCR) at surgery, a key secondary aim is to evaluate the toxicity profiles of these investigational agents. Distinct aspects of safety monitoring in a platform trial, as well as the specificities of safety management in a potentially curative population make the experiences from I-SPY 2 valuable to the community.

Methods: Inclusion and exclusion criteria are uniformly applied to all women in I-SPY 2. When a new investigational agent/regimen is planned for the trial, agent specific laboratory/hematologic limits or additional required tests are added, as needed. Eligibility criteria remain in the trial for its duration and apply to all investigational and control arms. Laboratory and adverse event data are collected and monitored in real time. The lead investigator of the investigational agent/regimen who chaperones a specific agent/regimen through the trial (“Agent Chaperone”), Medical Monitor, I-SPY 2 Agents Committee, CRO safety group, and an active DSMB that meets monthly oversee the management of toxicities within each investigational agent/regimen of the trial. Toxicity profiles for an investigational agent/regimen are compared to their relevant control. Safety analyses are intention to treat.

Results: From March 2010-May 2016, eleven (11) investigational agents/regimens have opened (and 6 have completed evaluation) and 973 women have been randomized. These agents/regimens span a variety of mechanisms of action including targeted therapies such as small molecule inhibitors and antibodies, as well as immunotherapies. Additions to the trial's eligibility criteria have been made with new investigational arms. Adverse events of special interest have been monitored for each investigational arm and specific toxicities treated uniformly when applicable. A risk-based monitoring plan has been implemented that focuses on the collection and review of the trial's most critical data elements including serious adverse events and drug specific safety issues, allowing for a more efficient and focused effort. Safety issues have been quickly addressed and requirements updated, when needed, given the importance of limiting (or avoiding) long-term safety complications within this neoadjuvant patient population. Accrual to the trial has (been) maintained over time and the safety of trial participants has been well managed.

Conclusion: A platform trial requires an evolving, and focused safety-monitoring process that adapts as new investigational agents are included. I-SPY 2's infrastructure and team science approach has created a system to manage patients across multiple arms with different risk profiles. These practices will support the safe evaluation of additional new combinations and regimens and serves as a guide for safety management within standing platform trials.

Citation Format: Paoloni M, Lyandres J, Buxton MB, Berry DA, Esserman LJ, DeMichele A, Yee D. A longitudinal look at toxicity management within a platform trial: Lessons from the I-SPY 2 TRIAL [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-11-02.

Abstract P5-11-18: Trajectory of patient (Pt) reported physical function (PF) during and after neoadjuvant chemotherapy in the I-SPY 2 trial

Background

Patients (pts) receiving chemotherapy for breast cancer experience toxicities impacting short and long-term quality of life (QOL). Within I-SPY 2, a trial adaptively randomizing stage II/III breast cancer pts to neoadjuvant chemotherapy +/- an investigational agent, we are collecting pt reported outcome (PRO) data to understand the impact of investigational agents on QOL. This PRO sub-study provides a unique opportunity to study QOL longitudinally and explore how pt and tumor characteristics, exposure to investigational therapies, and surgical outcome impact QOL.

Methods

Pts enrolled in this trial receive paclitaxel (T) +/- an investigational agent for 12 weeks followed by 4 cycles of doxorubicin and cyclophosphamide (AC). Surveys include the EORTC QLQ-C30 and BR-23, and PROMIS measures for QOL metrics including but not limited to physical function (PF), anxiety, and depression. Surveys are administered pre-chemotherapy to 2 years post-surgery. PF data from the EORTC and PROMIS instruments was analyzed for 238 pts at 5 sites (UCSF, UCSD, U of Pennsylvania, U of Minnesota, and Swedish Cancer Center). 48 pts completed baseline, inter-regimen (between T and AC), pre-operative and post-surgery surveys. Of the 48 pts 32 completed a 6-month follow up (FUP) and 31 completed a 1-year FUP survey. A linear mixed effect model, adjusting for HER2 status and treatment type was used to evaluate changes in PF over time. Sample size is small and statistics are descriptive rather than inferential.

Results

Median age of pts in this analysis was 50 (range 27-72).

Table 1 shows PROMIS & EORTC PF scores in this cohort.Time Point  PROMISEORTC  nMeanSEMeanSEPre-TreatmentAll4852.51.092.02.0 HER2+1553.51.594.12.2 HER2-3352.11.391.12.8Inter-RegimenAll4845.51.282.22.7 HER2+1548.62.384.44.2 HER2-3344.11.381.23.4Pre-SurgeryAll4843.91.179.42.3 HER2+1545.12.275.34.1 HER2-3343.41.381.32.86-Month FUPAll3248.11.487.41.9 HER2+1247.52.285.03.3 HER2-2048.41.888.92.41 Year FUPAll3148.91.488.43.1 HER2+949.12.988.95.4 HER2-2248.81.788.33.8

At baseline, mean PROMIS PF scores were higher than the US average (mean = 50) but declined as expected throughout treatment. HER2+ patients experienced a similar degree of recovery as HER2- pts post-surgery despite adjuvant treatment with Herceptin. Analysis of post-operative PROMIS PF indicated an average score within the U.S. general population (mean =50) but did not return to higher functioning seen at baseline levels (mean 52.5, p-value < 0.05). Analysis of the EORTC PF sub-scale demonstrated a similar trend; however, the baseline and post-operative difference was not significant (p-value=0.15 for both FUP). Finding supports PROMIS PF ability to measure high functioning cancer patients.

Conclusions: Among a subset of pts who completed all surveys in the I-SPY 2 QOL substudy, PF did not return to baseline at 6-12 months post-operatively. Through transition to an electronic platform of data collection we hope to improve compliance with survey completion. We continue to analyze other QOL measures and plan to correlate QOL data with treatment arm, adverse events, comorbidities, and response to neoadjuvant treatment.

Citation Format: Shah M, Jensen R, Yau C, Straehley I, Berry DA, DeMichele A, Buxton MB, Hylton NM, Perlmutter J, Symmans WF, Tripathy D, Yee D, Wallace A, Kaplan HG, Clark A, Chien AJ, I-SPY 2 Investigators, Esserman LJ, Melisko ME. Trajectory of patient (Pt) reported physical function (PF) during and after neoadjuvant chemotherapy in the I-SPY 2 trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-11-18.

Intraoperative factors associated with stranded source placement accuracy in low-dose-rate prostate brachytherapy

PURPOSE

The quality of a low-dose rate prostate brachytherapy implant depends on the accurate placement of sources in their planned locations. This study investigates intraoperative factors that potentially contribute to stranded source placement inaccuracy in prostate brachytherapy.

METHODS AND MATERIALS

Intraoperative video images of the brachytherapist's hand motions and needle insertions during the implant procedure were acquired for analysis. Using video analysis software, maximum and average needle insertion velocities were determined. The number of needle insertion attempts and the use of the brachytherapist's other hand to manipulate the needle direction were also recorded. Sources misplacements were analyzed using an ultrasound-based method described elsewhere.

RESULTS

Fifteen patients agreed to undergo this study; 1619 ¹²⁵I seeds were inserted using 357 needles; 1197 seeds were confidently identified using ultrasound images and included in the analysis. The mean overall misplacement was 0.49 cm (0-2 cm, 95% CI = 0.47-0.51); 614 seeds were delivered with a single pass and 583 seeds with >1 passes (range 2-6). The mean maximum needle velocity was 12.34 cm s^-1 (range 4-28 cm s^-1) and mean average velocity was 4.76 cm s^-1 (range 0.4-17.4 cm s^-1); 747 seeds were delivered with manipulation of the needle. The generalized linear model test was used to analyze factors contributing to seed misplacement, and it was found that a maximum speed <12 cm s^-1 was associated with a decrease in seed misplacement by 0.049 cm vs. a maximum speed >12 cm s^-1, p = 0.0121). Other evaluated factors were found to have no statistically significant correlation with seed misplacement: average speed (p = 0.4947), manual manipulation of needle (p = 0.9264), and number of needle passes (p = 0.8907).

CONCLUSIONS

This study identified that needles inserted with lower maximum velocity were associated with less seed misplacement. Manual manipulation of the needle, number of passes, and average speed did not show statistically significant correlation with seed misplacement.

Abstract P1-14-03: The evaluation of trebananib plus standard neoadjuvant therapy in high-risk breast cancer: Results from the I-SPY 2 TRIAL

Background: I-SPY 2 is a multicenter phase 2 trial using response-adaptive randomization within biomarker subtypes to evaluate a series of novel agents when added to standard neoadjuvant therapy for women with high-risk stage II/III breast cancer. The primary endpoint is pathologic complete response (pCR). The goal is to identify/graduate regimens with ≥85% Bayesian predictive probability of success (statistical significance) in a 300-patient phase 3 neoadjuvant trial defined by hormone-receptor (HR), HER2 status & MammaPrint (MP). Regimens may also leave the trial for futility (&lt; 10% probability of success) or following accrual of maximum sample size (10%&lt; probability of success &lt;85%). We report the results for trebananib, an angiopoietin-1/2-neutralizing peptibody that inhibits interaction with the Tie2 receptor.

Methods: Women with tumors ≥2.5cm were eligible for screening. MP low/HR+/HER2- tumors were ineligible for randomization. Serial MRI scans (baseline, 2 during treatment and pre-surgery) were used in a longitudinal model to improve the efficiency of adaptive randomization. Participants are categorized into 8 subtypes based on: HR status, HER2 status and MP High 1 (MP1) or High 2 (MP2). MP1 and MP2 are determined by a predefined median cut-point of I-SPY 1 participants who fit the eligibility criteria for I-SPY 2. Trebananib was initially assigned to HER2- patients only; once safety data with trastuzumab (H) were obtained, it was also assigned to HER2+ patients. Analysis was intent to treat -- patients who switched to non-protocol therapy were designated non-pCRs.

Results: Trebananib +/-H did not meet the criteria for graduation in any of the 10 signatures tested. When the maximum sample size was reached, accrual ceased. We report probabilities of trebananib +/-H being superior to control and Bayesian predictive probabilities of success in a 1:1 randomized neoadjuvant phase 3 trial for the 10 biomarker signatures, using the final pCR data from all patients.

SignatureEstimated pCR Rate (95% probability interval)Probability Trebananib Is Superior to ControlPredictive Probability of Success in Phase 3Trebananib (n=134)Control (n=133)ALL0.259(0.16 -0.36)0.158(0.09-0.23)0.9860.564HR+0.157(0.05-0.26)0.115(0.03- 0.20)0.8050.281HR-0.378(0.22-0.53)0.207(0.11- 0.31)0.9910.784HER2+0.279(0.07-0.49)0.17(0.04-0.30)0.8790.553HER2-0.254(0.15-0.36)0.155(0.08-0.23)0.9810.555MP20.342 (0.19-0.49)0.177(0.07-0.28)0.9910.786HR-/HER2-0.368 (0.21-0.53)0.201(0.10-0.30)0.9880.771HR-/HER2+0.444(0.15-0.74)0.244(0.07-0.42)0.9260.739HR+/HER2+0.201(0.01-0.39)0.135(0.01-0.26)0.7750.41HR+/HER2-0.143(0.04-0.24)0.11(0.03-0.19)0.7580.248

Citation Format: Albain KS, Leyland-Jones B, Symmans F, Paoloni M, van 't Veer L, DeMichele A, Buxton M, Hylton N, Yee D, Lyandres Clennell J, Yau C, Sanil A, I-SPY 2 Trial Investigators, Berry D, Esserman L. The evaluation of trebananib plus standard neoadjuvant therapy in high-risk breast cancer: Results from the I-SPY 2 TRIAL. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-03.

Abstract ES9-1: Role for IGF/Insulin signaling in breast cancer

Because insulin regulates glucose homeostasis, there has been extensive study into the molecular mechanisms of action of the insulin signaling system. Besides insulin, additional ligands, insulin-like growth factor (IGF) – I and –II and specific receptors for these ligands regulate cellular biology. The receptors share a similar structure and function. Once ligand binds the extracellular domain, a conformational change occurs allowing autophosphorylation of the intracellular tyrosine kinase domains and subsequent activation of multiple signaling pathways that ultimately result in cellular glucose uptake. Type 2 diabetes mellitus (T2D) results from deficient insulin receptor (InsR) signaling and subsequent elevation of serum glucose with compensatory attempt at regulating this pathophysiology by increased insulin production by the pancreas. While the etiology of T2D is complex and multi-factorial, obesity and insulin resistance are epidemiologically and mechanistically linked. Insulin was one of the first peptide growth factors known to stimulate breast cancer proliferation. Epidemiological data link obesity, metabolic syndrome (hyperinsulinemia), and elevated levels of IGFs to breast cancer risk and poor outcome for women diagnosed with breast cancer. These data, in part, led to the development of multiple targeted therapies for breast cancer. Receptor targeting of IGF-receptor signaling was not successful in hormone receptor (HR) positive breast cancers possibly because drugs designed to target this receptor disrupted the negative feedback of this endocrine system and resulted in the elevation of serum insulin levels. Since InsR was not affected by anti-IGF receptor drugs, the potential that InsR was stimulated by these drug treatments could explain their failure. In contrast to receptor targeting strategies, the inhibition of downstream signaling pathways, such as mTORC1, have been successful in HR-positive breast cancer. Preclinical and clinical data have revealed complex intracellular and endocrine feedback pathways that affect the ability of any single targeted drug to effectively disrupt signals from this ligand-receptor family. This session will discuss combination strategies based on clinical and preclinical studies that could translate into effective drug therapies to disrupt this signaling system.

Citation Format: Yee D. Role for IGF/Insulin signaling in breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr ES9-1.

Abstract P3-08-03: Mobile phone multimedia messaging intervention for breast cancer screening

Background. Korean American women have one of the highest breast cancer mortality rates and lowest breast cancer screening rates among American women. In response to the need to enhance breast cancer screening, this study aims to develop and test a 7-day mobile phone application (app)-based Mammogram (mMammogram) intervention designed to promote breast cancer screening among Korean American women. To date, mobile app technology has not been used for mammogram promotion.

Methods. Using FBM Model, we developed a mammogram intervention designed to increase knowledge of breast cancer screening, intent to receive mammogram, and the receipt of a mammogram. A series of focus groups were conducted to inform the development of the intervention. A randomized controlled trial was conducted with baseline, one week post-intervention, and 6-month follow-up testing among 120 Korean American women who were aged 40 and older and had not had mammograms within the last 2 years. The intervention group (60) received an individually and culturally tailored text messages via mobile app with health navigation services. The control group (60) received a brochure including information on breast cancer, screening guidelines, and a list of clinics that offer low-cost or free mammography without health navigation services.

Results. At one week post-test, statistically significant between-group differences were found; intervention subjects reported higher scores of knowledge in breast cancer and screening guideline than subjects in control group (mean differences: 1.70, p &lt; 0.05). No statistical between group differences identified in intention to receive screening. However, significant between-group difference was found in the receipt of mammogram at 6-month follow-up test; 40.0% (24/60) of the intervention group received mammograms whereas 25.0% (15/60) of the brochure group received mammograms after intervention (p &lt; 0.05). 100% of the participants expressed satisfaction with the intervention and 98.3% reported that they would recommend the program to their friends.

Conclusions. This study provides evidence of the effectiveness and feasibility of the mammogram intervention with health navigation services in promoting breast cancer screening. Mobile application-based intervention is a promising tool to increase both knowledge and receipt of mammograms. Given the widespread usage of mobile phone among minority populations, a mobile phone-based health intervention could be an effective method of reaching hard-to-recruit populations with high breast cancer burden, using individually tailored messages that cover broad content areas and overcome restrictions to place and time of delivery.

Citation Format: Lee HY, Le C, Ghebre R, Yee D. Mobile phone multimedia messaging intervention for breast cancer screening. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-08-03.

Abstract S4-07: Tamoxifen resistance driven by the DNA cytosine deaminase APOBEC3B in recurrent estrogen receptor positive breast cancer

Recent studies have implicated the DNA cytosine deaminase APOBEC3B as a major source of mutation in breast cancer. APOBEC3B explains a large proportion of both dispersed and clustered cytosine mutations, the latter of which are also called kataegis. APOBEC3B expression levels correlate with poor outcomes for patients with estrogen receptor positive breast cancer. While targeted therapies, such as tamoxifen, are available to treat these tumors, secondary drug resistance often develops. Here we suppressed endogenous APOBEC3B in the estrogen receptor positive breast cell line MCF-7L with shRNA. Lowered levels of APOBEC3B did not affect in vitro growth or sensitivity to estradiol. In a xenograft model of tamoxifen therapy, suppression of APOBEC3B associated with prolonged responses to tamoxifen (p&lt;0.05). Furthermore, APOBEC3B over-expression did not affect in vitro cell growth but accelerated the development of tamoxifen-resistant tumors in vivo. In addition, we studied two separate cohorts of 285 breast cancer patients who received first line treatment with tamoxifen for recurrent disease. High APOBEC3B expression levels measured in the primary tumor associated significantly with unfavorable progression free survival in multivariate analysis that included the traditional predictive factors (age, dominant relapse site, disease-free interval, estrogen receptor and progesterone receptor, and adjuvant chemotherapy; HR=1.67, p=0.0001). The median period of progression free survival was 7.5 months for patients with APOBEC3B high primary tumors and 13.3 months for those with APOBEC3B low tumors (p&lt;0.0.0001). These studies demonstrate that APOBEC3B drives resistance to endocrine treatment with tamoxifen in recurrent disease.

Citation Format: Harris R, Law E, Sieuwerts A, LaPara K, Leonard B, Starrett G, Temiz NA, Sweep F, Span P, Foekens J, Martens J, Yee D. Tamoxifen resistance driven by the DNA cytosine deaminase APOBEC3B in recurrent estrogen receptor positive breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr S4-07.

Abstract PD2-07: Insulin receptor substrate (IRS) targeting by the tyrophostin NT157 inhibits breast cancer cell growth

Insulin and insulin-like growth factor (IGF) signaling systems regulate the malignant phenotype. However, targeting of the type I IGF receptor (IGF-IR) has shown little activity in clinical trials. One potential reason for these disappointing results is that activation of the closely related insulin receptor (InR) could compensate for IGF-IR blockade. Since both receptors phosphorylate the insulin receptor substrates (IRS), perhaps a better strategy would involving targeting of this key post-receptor protein. Two IRS proteins are expressed in breast cancer cells. IRS-1 is regulated by estradiol in breast cancer cell lines, while IRS-2 is the predominant IRS species in hormone receptor negative cells. NT157, a small-molecule tyrphostin, binds IGF-1R but does not affect receptor autophosphorylation. Instead, it downregulates IRS proteins in several model systems. In primary breast cancers, IRS-1 was positively correlated to ERα expression in the TCGA database. In ERα+ and basal-like breast cancer cell lines NT157 treatment suppressed IRS protein expression in a dose dependent manner. Short term exposure to NT157 treatment did not affect IGF-I, IGF-II, and insulin induced activation of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK), but longer exposure resulted in inhibition of these signaling pathways. NT157 resulted in serine phosphorylation of IRS proteins and was dependent on MAPK activation. Serine phosphorylation resulted in disassociation between IRS proteins and their receptors resulting in IRS degradation. NT157 decreased S phase fraction, monolayer, and anchorage independent growth after IGF/insulin treatment in ERα+ breast cancer cells. NT157 downregulation of IRS protein expression also sensitized ERα+ breast cancer cells to rapamycin. Moreover, NT157 inhibited the growth of tamoxifen resistant ERα+ breast cancer cells. In the basal-like breast cancer cells (MDA-MB-231), NT157 repressed the proliferation (G2/M abrogation) and migration through downregulation of IRS1/2 protein. Given that both IGF-IR and InR play a role in cancer biology, targeting of IRS adapter proteins could be a more effective inhibitory strategy compared to receptor-targeting approaches.

Citation Format: Yee D, Temiz NA, Levitzki A, Yang Y. Insulin receptor substrate (IRS) targeting by the tyrophostin NT157 inhibits breast cancer cell growth. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD2-07.

Estimation of Contaminant Loads from the Sacramento-San Joaquin River Delta to San Francisco Bay

Contaminant concentrations from the Sacramento-San Joaquin River watershed were determined in water samples mainly during flood flows in an ongoing effort to describe contaminant loads entering San Francisco Bay, CA, USA. Calculated PCB and total mercury loads during the 6-year observation period ranged between 3.9 and 19 kg/yr and 61 and 410 kg/yr, respectively. Long-term average PCB loads were estimated at 7.7 kg/yr and total mercury loads were estimated at 200 kg/yr. Also monitored were PAHs, PBDEs (two years of data), and dioxins/furans (one year of data) with average loads of 392, 11, and 0.15/0.014 (OCDD/OCDF) kg/yr, respectively. Organochlorine pesticide loads were estimated at 9.9 kg/yr (DDT), 1.6 kg/yr (chlordane), and 2.2 kg/yr (dieldrin). Selenium loads were estimated at 16 300 kg/yr. With the exception of selenium, all average contaminant loads described in the present study were close to or below regulatory load allocations established for North San Francisco Bay.