Citations

Abstract Introduction: The programmed cell death-1 (PD-1) immune checkpoint is a normal regulator of the autoimmune response to inflammatory stimuli. Several cancers have taken advantage of this mechanism by harboring its ligand (PD-L1), thus activating the checkpoint to evade immune destruction. Increased expression of PD-L1 on tumor cells has been linked with worse outcomes in several cancers, including breast cancer. In triple-negative breast cancer (TNBC), expression of PD-L1 is increased compared to luminal cancers and as such, has become a favorable target for anti-tumor therapies. However, few studies evaluate the impact of PD-1 and PD-L1 expression on overall survival (OS) in TNBC. The aim of this study was to assess OS based on PD-1 and PD-L1 positivity and distribution in the tumor microenvironment. Methods: All patients with newly diagnosed TNBC from 1999 to 2015 with adequate pathologic specimen were identified for evaluation. Surgical pathology specimens were stained by immunohistochemistry (IHC) for PD-1 and PD-L1. Those considered PD-1+ or PD-L1+ had a staining score of 3, 4, or 5. Patient and clinical characteristics of the adjuvant group were compared by PD-1 and PD-L1 status with Chi-Square and ANOVA, as appropriate; characteristics of the neoadjuvant population were described. OS was calculated using Kaplan-Meier method and compared by Log Rank test for PD-1, PD-L1 positivity and tumor microenvironment status. Results: Fifty-two patients met inclusion; 38 had surgery prior to chemotherapy while 14 had neoadjuvant chemotherapy. There were 15 PD-1+ patients (39%) and 21 PD-L1+ (55%) patients in the treatment naive cohort. No significant difference was found in the treatment naive group between age, race, postmenopausal status, final stage, or pathologic characteristics (e.g. tumor size, mitotic rate, and grade) for all PD-1+ and PD-L1+ patients. Of the 21 PD-L1+ patients, staining was present in the tumor, tumor/non-tumor (mixed), and non-tumor microenvironment 42.9%, 33.3%, and 23.8% of the time, respectively (p=0.008). No significant difference was found in OS between PD-1+ and PD-1- patients (p=0.509) or PD-L1+ and PD-L1- patients (p=0.240). However, distribution of PD-L1 staining significantly associated with OS. Those demonstrating PD-L1 staining in the tumor had a significantly higher OS than those with PD-L1 staining in the non-tumor microenvironment (p=0.008). In the subset of PD-L1+ patients, those with staining in the tumor show a 10-year OS of 100% versus 60% for those with staining in non-tumor (p=0.006). In the neoadjuvant cohort, 14.3% of patients expressed PD-1 positivity, while 42.9% had PD-L1 positivity; the distribution of the PD-L1 staining in tumor 14%, mixed 29%, and non-tumor 50%. No difference in OS was found based on PD-1 or PD-L1 (p=0.660) positivity in the neoadjuvant cohort. Conclusion: A large number of TNBC stain for PD-1 and/or PD-L1. The implications of this are yet to be determined. In this small cohort, pattern of staining had a significant impact on overall survival in treatment naïve patients. This finding will need to be validated on a larger cohort but may have important implications for treatment by defining patients who may benefit by checkpoint inhibitor therapy. Citation Format: Linnaus ME, Kosiorek H, Barrett MT, Dueck A, Anderson KS, Ocal IT, McCullough AE, Annamalai L, Yearley JH, Pockaj BA. Effect of PD-1 and PD-L1 in the tumor microenvironment on overall survival of triple-negative breast cancer patients [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 PD5-03.

Abstract Estrogen receptor positive (ER+) breast cancer accounts for the majority of breast cancers diagnosed worldwide but fortunately, outcomes are markedly improved by pharmacological interventions that interrupt ER function. Unfortunately, suppression of relapse risk from early stage disease with endocrine therapy (anti-estrogens or aromatase inhibitors) is only ∼50%, and for advanced disease, pan endocrine therapy resistance is almost inevitable. While many mechanisms for intrinsic and acquired endocrine resistance have been explored, links between defects in DNA repair, the fundamental drivers of cancer pathogenesis, and endocrine therapy resistance have been understudied. Here we link mismatch repair (MMR) deficiency to poor clinical outcomes in ER+ breast cancer using whole exome DNA sequencing data and mRNA expression analysis. We subsequently demonstrate that MMR deficiency bypasses ER dependent cell cycle regulation through disruption of Chk2/p21-mediated feedback inhibition of CDK4 in breast cancer cell lines and tumor samples, as well as through correlations with human clinical data. We also show that pharmacological targeting of CDK4 significantly inhibits growth of MMR-deficient ER+ breast cancer cells in vitro and in vivo. This mechanism provides a new explanation for why endocrine therapy resistant ER+ breast cancers can respond to CDK inhibition and suggests that primary tumors exhibiting MMR deficiency are good candidates for adjuvant CDK4 inhibitor treatment. Citation Format: Haricharan S, Schmelz J, Schmidt C, Singh P, Holloway K, Anurag M, Suman V, Olson JA, Hunt K, Bainbridge MN, Ellis MJ. Mismatch repair deficiency induces endocrine therapy resistance in breast cancer [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 PD2-06.

Abstract Background. We previously reported an alternative ESR1 somatic gain-of-function chromosomal translocation event in a patient presenting with aggressive, endocrine therapy resistant estrogen receptor (ER) positive disease, producing an in-frame fusion gene consisting of N-terminal ESR1 and the C-terminus of the Hippo pathway coactivator YAP1 (ESR1-YAP1). We recently identified another ESR1 fusion through RNA sequencing (RNA-seq) in advanced stage ER+ disease from a chest wall recurrence in a male patient that was refractory to multiple lines of treatment. Two examples of fusions discovered in primary breast cancer samples include ESR1 fused in-frame to C-terminal sequences from NOP2 (ESR1-NOP2), identified in a resistant cohort from a RNA-seq screen focused on 81 primary breast cancers from aromatase inhibitor clinical trials, and a second ESR1 fusion, fused in-frame to the entire coding sequence of POLH (ESR1-POLH), that was identified from RNA-seq analysis of 728 Cancer Genome Atlas breast samples. This current study extends our previous characterization of ESR1-YAP1 by comparing functional and pharmacological properties of these three additional ESR1 gene fusion events of both early stage and advanced breast cancers. Methods. In vitro and in vivo experiments were conducted to test ESR1 fusions to induce therapeutic resistance, and metastasis. The transcriptional and binding properties of each fusion was also examined. Pharmacological inhibition with Palbociclib, a cyclin-dependent kinase 4/6 inhibitor, was utilized to assess drug sensitivity in ESR1 fusion containing breast cancer cells and in a patient derived xenograft (PDX) model expressing ESR1-YAP1 (WHIM18). Results. The YAP1 and PCDH11x fusions conferred estrogen-independent and fulvestrant-resistant growth. Immunohistochemistry revealed significantly higher numbers of ER+ cells in lungs of mice xenografted with T47D cells expressing the YAP1 and PCDH11x fusions compared to YFP control, NOP2 and POLH fusions. Results from ChIP-seq and microarray studies suggest that these two fusions promote proliferation and metastasis through genomic action by binding estrogen response elements (ERE) and subsequent gene activation. We thereby define these fusions as “canonical” fusions compared to “non-canonical” NOP2 and POLH fusions, which demonstrated dramatically decreased genomic binding ability. The non-canonical fusions induced genes associated with basal-like breast cancer and promoted HER2, EGFR, and MAPK gene expression signatures in contrast to genes associated with cell cycle/proliferation induced by canonical fusions. The proliferative ability of canonical fusion-containing ER+ cells was inhibited by Palbociclib in a dose-dependent manner. In vivo WHIM18 tumors in mice fed with Palbociclib-containing chow demonstrated significantly reduced tumor volume, growth rate, and weight compared to tumors in mice on control chow. Conclusions. In-frame ERE activating canonical fusions occur in end-stage drug resistant advanced breast cancer and can be added to ESR1 point mutations as a class of recurrent somatic mutation that may cause acquired resistance. Growth induced by these fusions can be antagonized by Palbociclib and is potentially clinically helpful. Citation Format: Lei JT, Shao J, Zhang J, Iglesia M, Cao J, Chan DW, He X, Kosaka Y, Schmidt C, Matsunuma R, Haricharan S, Crowder R, Hoog J, Phommaly C, Goncalves R, Ramalho S, Lai W-C, Hampton O, Rogers A, Tobias E, Parikh P, Davies S, Ma C, Suman V, Hunt K, Watson M, Hoadley KA, Thompson A, Chen X, Perou CM, Creighton CJ, Maher C, Ellis MJ. Recurrent functionally diverse in-frame ESR1 gene fusions drive endocrine resistance in breast cancer [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 PD2-03.

Abstract BACKGROUND: Based on prospective clinical trials, there is no evidence for differences in efficacy between the 3 aromatase inhibitors (AIs) anastrozole, exemestane, and letrozole. The purpose of this study was to identify germline genetic variants associated with response to AIs and to help identify novel mechanisms associated with drug disease efficacy. METHODS: A genome-wide association study (GWAS) was performed for 624 patients (Steroids 2015;99:32-38) to identify SNPs associated with estrogen level change in women with estrogen receptor (ER) positive breast cancer treated with anastrozole. Replication of associated SNPs was performed in a GWAS from the MA.27 trial that compared adjuvant anastrozole and exemestane treatment of post-menopausal women with ER+ breast cancer. Functional studies were subsequently performed to determine SNP effects and underlying mechanisms. RESULTS: Our initial GWAS identified SNPs within CSMD1 that were associated with changes in estrogen levels during anastrozole therapy. An additional SNP in CSMD1 was also associated with breast cancer events in CCTG MA.27. Functionally, we showed that CSMD1 regulates CYP19 expression in a SNP-, and in an anastrozole- dependent fashion. These phenomena were not observed for either letrozole or exemestane. In MA.27, an anastrozole- specific effect was also seen with the minor allele having a protective effect on time to distant metastasis (HR=0.49, p=0.00259), but this was not the case for exemestane (HR=0.71, p=0.111). Our in vitro functional studies indicated that overexpression of CSMD1 sensitized anastrozole or letrozole resistant cells to anastrozole but not to the other two AIs. The SNP in CSMD1 that was associated with increased CSMD1 and CYP19 expression levels increased anastrozole sensitivity, but not letrozole or exemestane in lymphoblastoid cell lines (LCLs) homozygous for either WT or variant CSMD1 SNP genotypes. Based on these observations, we explored whether anastrozole has additional mechanisms beyond its function as a CYP19 inhibitor. Utilizing an estrogen response element (ERE) luciferase reporter assay in a CYP19 CRISPR knockout breast cancer T47D cell line and a surface plasmon resonance (SPR) assay, we found that anastrozole can also function as an ERα agonist, and can bind to, and result in, proteasome dependent ERα degradation, especially in the presence of E2. Treatment of these CYP19 CRISPR knockout cells with anastrozole in the presence of increasing concentrations of E2 results in greater sensitivity compared with anastrozole alone, while the addition of E2, as expected, does not improve letrozole or exemestane sensitivity. These same observations were also seen in letrozole and anastrazole resistant cells. CONCLUSIONS: Our findings suggest that anastrozole might be more effective than letrozole or exemestane in patients with the CSMD1 SNP. Furthermore, anastrozole can function as an ERα agonist, binding to ERα and resulting in its degradation, especially in the presence of E2. These findings should help to make it possible to develop precision endocrine therapies for women who are candidates for AIs. Citation Format: Cairns J, Ingle J, Dudenkov T, Kalari K, Buzdar A, Kubo M, Robson M, Ellis M, Goss P, Shepherd L, Goetz M, Weinshilboum R, Wang L. CSMD1 SNPs selectively affect anastrozole response in postmenopausal breast cancer patients [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 PD1-04.

Abstract Background LIV-1, a transmembrane protein and downstream target of STAT3, is highly expressed in breast cancer cells. It is associated with lymph node involvement and metastatic progression. SGN-LIV1A is an anti-LIV-1 antibody conjugated via a protease-cleavable linker to monomethyl auristatin E (MMAE). Upon binding to cell-surface LIV-1, SGN-LIV1A is internalized and releases MMAE, which binds to tubulin and induces G2/M arrest and apoptosis. Methods This is an ongoing, phase 1 dose-escalation study evaluating safety, tolerability, pharmacokinetics, and antitumor activity of SGN-LIV1A (q3 wks IV) in women with LIV-1-positive, unresectable, locally advanced or metastatic breast cancer (LA/MBC) (NCT01969643). Patients (pts) with measurable disease and ≥2 prior cytotoxic regimens for LA/MBC were eligible. Pts with ≥Grade 2 neuropathy were excluded. Response was assessed per RECIST v1.1; pts with stable disease (SD) or better could continue treatment until disease progression or intolerable toxicity. At completion of dose escalation in hormone receptor-positive/HER2-negative (HR+/HER2–) and triple-negative (TN) pts, expansion cohorts were opened to further evaluate safety and antitumor activity of monotherapy in TN pts and combination therapy with trastuzumab (Tz) in HER2-positive (HER2+) pts. Pre- and post-treatment tumor biopsies were done to evaluate LIV-1 expression and other correlative endpoints. Results To date, 39 pts (18 HR+/HER2–, 21 TN) have received a median of 3 cycles (range, 1–10) of SGN-LIV1A monotherapy at doses of 0.5–2.8 mg/kg. Median age was 57 yrs (range, 33–79). At baseline, pts had a median of 4 prior cytotoxic regimens for LA/MBC (range, 2–8); 36 had visceral disease and 25 had bone involvement. No dose-limiting toxicities (DLT) occurred in 19 DLT-evaluable pts; maximum tolerated dose was not exceeded at 2.8 mg/kg. Treatment-emergent adverse events (AEs) reported in ≥30% of pts were: fatigue (64%), nausea (54%), alopecia (46%), decreased appetite (41%), constipation (39%), neutropenia (33%), and vomiting (31%). Peripheral neuropathy was reported in 9 pts (23%). Most AEs were Grade 1/2, except neutropenia (all ≥Grade 3). Four pts discontinued treatment due to AEs (acute respiratory distress syndrome, nausea, pneumonia, tachycardia). In dose escalation, modest activity was observed in 17 efficacy evaluable (EE) HR+/HER2- pts, with a disease control rate (DCR) of 59% (10 SD), including 1 pt with SD≥24 wks. Among the 17 EE TN pts (dose escalation plus cohort expansion), the overall response rate (ORR) was 41% (7 PR), DCR was 82% (7 PR, 7 SD) and clinical benefit rate (CBR=OR+SD≥24 wks) was 53% (9 pts). For TN pts, median PFS was 17.1 wks (95% CI: 6.0, 18.4); 6 pts remain on treatment. Of 281 MBC tumor samples evaluated for LIV-1, 93% were positive; 81% had moderate-to-high expression (H-score ≥100). Conclusions LIV-1 is expressed in almost all MBC tumors. SGN-LIV1A monotherapy has been generally well tolerated and shown encouraging antitumor activity in heavily pretreated TN MBC, with a PR rate of 41% and a CBR at ≥24 wks of 53%. Response duration data continue to evolve. Enrollment continues in the TN monotherapy expansion cohort and the HER2+ combination cohort with Tz. Citation Format: Forero-Torres A, Modi S, Specht J, Miller K, Weise A, Burris III H, Liu M, Krop I, Pusztai L, Kostic A, Li M, Mita M. Phase 1 study of the antibody-drug conjugate (ADC) SGN-LIV1A in patients with heavily pretreated metastatic breast cancer [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 P6-12-04.

Abstract 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 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 Background: Locoregional recurrence (LRR) is a concern after neoadjuvant chemotherapy. Absolute risk of LRR and risk factors associated with LRR among women with node positive breast cancer treated with neoadjuvant chemotherapy on ACOSOG Z1071 were examined. Methods: ACOSOG Z1071 (Alliance for Clinical Trials in Oncology) enrolled cT1-3, N1-2 breast cancer patients treated with neoadjuvant chemotherapy from 2009-2011. All patients underwent axillary dissection. Data was analyzed for locoregional recurrence-free survival (LR-RFS) and multivariable analysis performed to identify factors impacting locoregional recurrence. Results: Of 756 women enrolled, 701 patients were eligible. Median follow-up was 4.0 years (range 0.03–6.2). 39 pts (5.6%) experienced LRR (32 LRR alone and 7 LRR concurrent with metastatic disease) and 96 patients (13.7%) died. LR-RFS was lowest in patients with triple negative tumors (TNBC) (87.6% at 3 years), followed by HER2-positive tumors (94.1%) compared with Hormone Receptor (HR) positive/HER2-negative tumors (96.9%). Residual in-breast disease was present in 57% of patients undergoing BCT and 73% of patients undergoing mastectomy (p<0.0001). LRR was higher in BCT compared to mastectomy (p=0.018), however when evaluated by subtype there was no significant difference in LRR by BCT vs mastectomy. There was no difference in LRR by clinical T stage at presentation or pathologic N stage, however LRR increased with higher pathologic T stage (p=0.006). Overall LRR was lower in patients who achieved a pathologic complete response (pCR) across all tumor subtypes (0% in HR positive/HER2-negative, 2.1% in TNBC, 4% in HER2-positive at 3 years) than in non-pCR patients (HR=0.37, p=0.04). By tumor subtype, pCR was associated with a lower LRR in patients with TNBC (HR=0.17, p=0.019), but was not significantly different by pCR in HER2-positive (HR=0.50, p=0.31) or HR-positive/HER2-negative tumors (HR=inestimable). In the multivariable model, factors associated with increased LRR risk were tumor subtype (TNBC and HER2-positive tumors, p<0.0001), lack of pCR in the breast (p=0.013), breast conservation surgery (p=0.018) and omission of adjuvant radiation therapy (p=0.010). Predictors of locoregional recurrence UnivariableMultivariableVariableHR (95% CI)p-valueHR (95% CI)p-valueClinical T stageT0-T2REF0.34REF0.087T3-T41.38 (0.72-2.65) 1.87 (0.91-3.84) Tumor BiologyHR+/Her2-REF0.002REF<0.0001Her2+1.49 (0.65-3.45) 2.11 (0.89-5.00) Triple negative3.59 (1.68-7.68) 5.53 (2.53-12.13) Path CR breastNoREF0.019REF0.013Yes0.35 (0.15-0.84) 0.27 (0.09-0.76) Path CR breastNoREF0.064REF0.81Yes0.51 (0.25-1.04) 0.67 (0.29-1.59) SurgeryBCTREF0.067REF0.018Mastectomy0.55 (0.29-1.04) 0.43 (0.22-0.87) RadiationYesREF0.033REF0.010No2.18 (1.06-4.48) 2.60 (1.26-5.39) Conclusion: In patients with node-positive breast cancer treated with neoadjuvant chemotherapy, early LRR is higher in TNBC and HER2-positive tumors. In TNBC patients pCR is associated with lower LRR than residual disease. In this contemporary cohort of node-positive, HER2-positive tumors treated with anti-HER2 therapy, patients achieving a pCR had low LRR rate. Adjuvant radiation appears to be important for locoregional control regardless of pCR. Citation Format: Boughey JC, Ballman KV, McCall LM, Mittendorf EA, Hunt KK. Predictors of locoregional recurrence after neoadjuvant chemotherapy and surgery for node positive breast cancer: Results from ACOSOG Z1071 (Alliance) [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 P6-09-01.

Abstract Introduction: Previously, we detected amplification of chromosome 9p24.1 encoding PDL1, PDL2, and JAK2 (the PDJ amplicon) in up to 25% of triple negative breast cancers (TNBC) using oligonucleotide CGH arrays (aCGH). Amplification was associated with poor outcome and activation of the JAK/STAT pathway. Here, we have developed a novel fluorescence in situ hybridization (FISH) for detection of the JAK2/PDL1 amplification. Methods: We selected five 9p24.1-amplified and five non-amplified paraffin embedded TNBC tumor samples, defined by aCGH log2ratio>2.0 as amplified for FISH validation. 5' JAK2 DNA labeled with SpectrumGreen dUTP, 3' JAK2 DNA labeled in SpectrumOrange dUTP and a commercially available chromosome 9 centromeric probe (Spectrum Aqua) were combined as one probe set. The break-apart (BAP) probe set was applied to individual slides, hybridized, and washed, 50 events/sample were counted. We defined 9p24.1 amplification by FISH as the ratio of average JAK2 score/ average centromere 9 (CEN 9) score >1.1. Nonparametric student's t-test was used for statistical analysis. Results: In the amplified subgroup (n=5), JAK2 amplification was detected by FISH with the range from 1.89 to 21.0 (mean, 6.76). To adjust for aneuploidy, the ratio of JAK2 to CEN 9 was measured with the range from 1.02 to 9.21 (mean ratio, 2.9). The sample with highest level of amplification (aCGH log2ratio =4) detected by aCGH also scored highest by FISH (FISH ratio=9.21). One case with JAK2 amplification (aCGH log2ratio =3) was not detected by FISH (ratio, 1.02), but had low tumor cell content. In the non-amplification subgroup (n=5), JAK2 amplification was detected by FISH with the range from 0.98 to 3.54 (mean, 1.8), the ratio of JAK2 to CEN 9 was measured with the range from 0.48 to1.05 (mean, 0.73). Of note, two tumors with copy number loss by aCGH were confirmed by FISH (ratio 0.48, 0.56). In total, the 9p24.1 amplification was detected in 4 out 5 (80%) amplified samples defined by aCGH and 5 out 5 not amplified. A significant difference in JAK2: CEN 9 ratio (p=0.03) was observed between the amplified and non-amplified subgroups but not in JAK2 absolute scores (p=0.095). Conclusion: In this study, we have developed a novel FISH assay for detection of the 9p24.1 amplification in TNBC, encoding JAK2, PD-L1, and PD-L2. The FISH assay correlates with detection of the amplification by aCGH, but is less sensitive, in particular in tissue with lower tumor cell content. We predict that 9p24.1 amplification will be a clinically relevant biomarker in TNBC. Citation Format: Chen M, Andreozzi M, Pockaj B, Barrett MT, Ocal IT, McCullough AE, Anderson KS. A novel fluorescence in situ hybridization assay to detect 9p24.1 amplification in triple negative breast cancer [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 P6-07-17.

Abstract Clinical genetic testing of individuals with a personal or family history of breast and ovarian cancer using panels for BRCA1/2 and other candidate cancer predisposition genes has become routine clinical practice. Several of the genes on hereditary cancer testing panels have been strongly associated with specific subtypes of breast cancer. In particular, individuals with germline mutations in BRCA1 predominantly develop estrogen receptor (ER)-negative and triple negative (TN) (estrogen receptor negative, progesterone receptor negative, HER2 negative) breast tumors. In contrast, CHEK2 and ATM mutations have been associated with ER-positive breast cancer. In this study, associations between mutations in panel genes and breast cancer subtypes were evaluated. A cohort of 60,000 breast cancer patients tested for germline cancer predisposing mutations using hereditary cancer gene panels was utilized. Information on personal and family cancer history, age of diagnosis, tumor pathology, and ethnicity of patients was obtained from test requisition forms or by follow up with ordering health care providers. Mutations in each gene were combined into four histological subtypes (triple negative; HER2 positive; ER-positive,HER2-positive; and ER-positive,HER2 negative). Associations for each subtype were estimated by case-control analyses comparing the frequencies of pathogenic mutations in each subtype with frequencies from non-TCGA controls from the Exome Aggregation Consortium (ExAC) database. In addition, case-case analyses were conducted to assess enrichment of gene mutations in specific breast cancer subtypes. Among the observed associations between genes and breast cancer subtypes, mutations in CHEK2 and ATM were highly enriched in luminal breast cancers and BARD1 was specifically associated with TN breast cancer. Refining the spectrum of pathological correlates with mutations in hereditary breast cancer genes will aid gene specific cancer risk management, and may accelerate the development of novel gene-specific therapeutic interventions. Citation Format: Couch FJ, Lilyquist J, Na J, Hu C, Polley EC, Shimelis H, Akinhanmi M, McFarland R, LaDuca H, Goldgar DE, Dolinsky JS. Associations between breast cancer subtypes and mutations in cancer predisposition genes identified by clinical genetic testing of breast cancer patients [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 P5-09-03.