Leitch, A. Marilyn

504 Background: For PM patients (pts) with locally advanced ER+ HER2- BC, NET improves breast conservation surgery (BCS) rates, and modified preoperative endocrine prognostic index (mPEPI) 0, defined as pT1-2 pN0 Ki67< 2.7%, or pathologic complete response (pCR: no invasive disease in breast or lymph node) is associated with low risk of recurrence without adjuvant chemotherapy (CT). The ALTERNATE trial was initiated to assess if the endocrine-sensitive disease rate (ESDR: number of mPEPI 0 pts/number of eligible pts initiating NET) with fulvestrant (F) or F+anastrozole (A) is improved relative to A alone (reported here) and if the 5-year (yr) recurrence-free survival (RFS) rate for pts with mPEPI 0 on A alone without CT is ≥ 95% (awaits further follow-up). Methods: PM pts with clinical stage II/III ER+ HER2- BC were randomized 1:1:1 to 1 mg A po daily, 500 mg F IM every 4 week (wk)s after loading dose, or A+F for 6 months. Ki67 was tested centrally on biopsies acquired prior to NET, wk 4, wk 12 and at surgery. Pts with Ki67 >10% at wk 4 or 12 were recommended to go off protocol-directed ET and switch to CT. Pts with mPEPI 0 at surgery were recommended to continue assigned ET for 1.5 yrs followed by A for a total of 5 yrs ET (and not to receive CT). The primary endpoint of the neoadjuvant phase was ESDR. ESDR of each F arm was compared to that of the A alone arm. With 425 pts per arm, a one-tailed alpha = 0.025 chi-square test of two independent proportions has 84% power to detect an increase of ≥10% in ESDR for F or F+A compared to the A arm, assuming ESDR ≤30% in A. Results: 1362 pts (A 452; F 454; A+F 456) were enrolled Feb 2014 to Nov 2018. 63 pts were excluded (did not start NET). Of the remaining 1299 pts (A 434; F 431, A+F 434), 42% were cN1-3 and 73% were considered candidates for BCS. ESDR was 18.6% (95%CI: 15.1-22.7%) with A, 22.7% (95%CI: 18.9-27.0%) with F, and 20.5% (95%CI: 16.8-24.6%) with A+F. No significant difference in ESDR was found between A and F (p=0.15) or A and A+F (p=0.55). Among the 825 pts with wk 4 Ki67 < 10% who completed NET and surgery, ESDR and the BCS rate were 27.7% and 70.3% with A; 29.6% and 68.1% with F, and 26.8% and 69.9% with A+F, respectively. Conclusion: Neither F nor F+A significantly improved ESDR compared to A alone in PM pts with locally advanced ER+ HER2- BC. RFS data are awaited. Support: U10CA180821, U10CA180882, U24CA196171, https://acknowledgments.alliancefound.org ; NCI BIQSFP, BCRF, Genentech, AstraZeneca. Clinical trial information: NCT01953588 .

526 Background: Z1041 randomized women with HER2+ operable breast cancer to: FEC → P+T (Arm 1) or P+T → FEC+T (Arm 2). Treatment administered as 5-FU 500 mg/m2, epirubicin 75 mg/m2 and cyclophosphamide 500 mg/m2 day 1 of a 21-day cycle x 4; paclitaxel 80 mg/m2weekly x 12 and T 4 mg/kg once then 2 mg/kg weekly x 11. T was to continue q3 weeks post-op for 40 weeks. A secondary aim was to examine the cardiotoxicity (CE). Methods: Ejection fraction (EF) was measured at baseline (BL), between regimens (wk 12), prior to surgery (wk 24) and PRN. Eligibility: BL EF ≥ 55%. CEs included decline in EF of > 15%, or >10% points to a value < LLN. Reversibility was adjudicated by blinded investigators as reversible (R: recovery of EF to ≤ 5% below BL), partially reversible (PR: recovery of > 10% points from nadir, but ≤ 5% points below BL), indeterminate (IN: no additional EF data), or irreversible (IRR:follow-up EF studies showed no improvement). Results: Of the 280 patients (Arm 1: 138) who began treatment, 15 pts (Arm 1: 10; Arm 2: 5) did not receive T. The number of weeks of T was 13 (range: 1-18) in Arm 1 and 24 (range: 1-31) in Arm 2. Changes in EF and severe treatment related cardiac toxicities prior to surgery (sx) are tabled below. There were 271 pts (Arm 1: 131) who had post-BL EFs. Prior to sx, there were 11 CE (8.3%) in Arm 1 and 13 CE (9.2%) in Arm 2. CEs were R in 12 pts (Arm 1: 5; Arm 2: 7); PR in 6 pts (Arm 1: 4; Arm 2: 2); IN in 4 pts (Arm 1: 2; Arm 2: 3) and IRR in 1 Arm 2 pt. Conclusions: The number of CE events in arms 1 and 2 showed no significant difference; greater scatter was observed in arm 2 patients. While concern for late cardiac events makes ongoing cardiac surveillance prudent due to A, concomitant use of A and T appear to not be associated with increased cardiac risk. Clinical trial information: NCT00513292. [Table: see text]

502 Background: Neoadjuvant chemotherapy (NAC) and concomitant trastuzumab (T) have produced high pathologic complete response (pCR) rates in HER2+ breast cancers. Z1041 addresses the timing of initiation of T with NAC. Methods: Women with operable HER2+ invasive breast cancer were randomized 1:1 to: FEC → P+T (Arm 1) or P+T → FEC+T (Arm 2) where treatment was administered as 5-FU 500 mg/m2, epirubicin 75 mg/m2 and cyclophosphamide 500 mg/m2 day 1 of a 21-day cycle x 4 (FEC); paclitaxel 80 mg/m2 weekly x 12 and trastuzumab 4 mg/kg once then 2 mg/kg weekly x 11. Eligibility also included: tumor > 2 cm or a positive lymph node and left ventricular ejection fraction > 55%. The primary aim was to compare the pCR rates in the breast (pBCR) between the regimens. Secondary endpoints were pCR rate in the breast and lymph nodes (pBNCR) and safety profile. All pts who began study treatment were included in the analyses. With 128 pts per regimen, a two-sided alpha=0.05 test of proportions would have a 90% chance of detecting a difference of 20% or more in the pBCR rates, when the pBCR rate with the poorer regimen is ≤ 25%. Results: From September 15, 2007 to December 15, 2011, 282 women (Arm 1: 140 pts) were enrolled. Two pts (Arm 1) withdrew without receiving treatment. The two arms were similar in age, stage, and hormone receptor (HR) status (HR neg: 40%). The severe (grade 3+) treatment-related toxicities included: neutropenia (Arm 1: 24.6%; Arm 2: 32.4%), fatigue (Arm 1: 4.3%; Arm 2: 8.5%), and neurosensory problems (Arm 1: 3.6%; Arm 2: 4.9%). The pBCR rate and pBNCR rates (Table) were not found to differ between the two regimens (Fisher’s exact p values: 0.905 and 0.811, respectively). Conclusions: High pCR rates can be achieved with trastuzumab in combination with anthracyclines and taxanes. The pBCR or pBNCR was not different between regimens based on the timing of initiation of trastuzumab. Clinical trial information: NCT00513292. [Table: see text]

1107 Background: The role of axillary ultrasound (AUS) after neoadjuvant chemotherapy (NAC) to assess for residual nodal disease in patients presenting with node positive breast cancer remains unclear. ACOSOG Z1071 is a prospective multi-institutional trial evaluating sentinel node biopsy in patients with biopsy proven node positive breast cancer (T0-4, N1-2, M0) receiving NAC. Herein we report on the secondary objective evaluating the correlation of lymph node (LN) features on AUS with residual nodal disease. Methods: AUS images from diagnosis and after NAC were centrally reviewed for cortex size, LN size and LN morphology. Morphologic features were defined as: type I, no visible cortex, type II, < 3 mm hypoechoic cortex, type III, > 3mm hypoechoic cortex, type IV, generalized lobulated hypoechoic cortex, type V, focal hypoechoic cortical lobulation, and type VI, totally hypoechoic node with no hilum. Type I and II are considered normal. Results: Surgical and imaging data are available on 294 patients. Median age was 50 years (range 23-93 years), mean initial tumor size 3cm (0 to 15cm) and clinical stage II in 64.5% and III in 35.5%. The maximum LN diameter decreased after NAC (mean 22mm pre-NAC to 14mm post-NAC)(p<0.0001); however, there was no significant difference after NAC between the pathologically N+ (13mm, range 5-46mm) and N0 cases (12mm, range 3-32mm)(p=0.13). LN cortical thickness correlated with residual nodal disease after NAC (p-value = 0.04). Using a cutoff point of cortical thickness of 3 mm, the sensitivity was 33% (48/145) and specificity 80% (66/82). AUS morphological features after NAC was associated with false negative rate 62%, false positive rate 28%, sensitivity 38%, and specificity 72%. Conclusions: AUS after NAC is useful to assess nodal response. Cortical thickness was the best predictor of residual nodal metastasis. LN size and morphological features do not reliably exclude residual nodal metastasis in patients after NAC. [Table: see text]

503 Background: To correlate clinical features of estrogen receptor positive breast cancer with somatic mutations, massively parallel sequencing (MPS) was applied to tumor and normal DNAs accrued from patients treated with neoadjuvant aromatase inhibitors (AI). Methods: MPS was applied to 77 baseline tumor biopsy samples from the preoperative letrozole trial (JACS 2009: 208, 906) and the Z1031 trial (JCO 2011: 29, 2342) followed by targeted sequencing in another 240 trial samples. Standard statistical approaches were used to compare mutation status and clinical parameters and pathway-based correlation was used to assess interactions between signaling perturbations induced by gene mutations and response to neoadjuvant AI. Results: Eighteen genes were significantly mutated above background. Aside from PIK3CA mutations, the list is dominated by loss-of-function mutations in tumor suppressor genes. Five (RUNX1, CBFP, MYH9, MLL3 and SF3B1) have been previously linked to benign and malignant hematopoietic disorders. Clinical correlation revealed that TP53 mutation was associated with PAM50 LumB status, high-grade histology and high proliferation rates whereas loss-of-function mutations in MAP3K1 associate with PAM50 lumA status, low proliferation rates, and low grade histology. Mutations in GATA3 were associated with greater suppression of proliferation upon AI treatment suggesting mutGATA3 may predict endocrine response. Notably, mutations in MAP3K1 were more common in PIK3CA mutant cases, suggesting cooperation. Pathway analysis demonstrated that rare MAP2K4 mutations produce similar pathway perturbations as MAP3K1 mutation, a logical finding since MAP2K4 is a substrate for MAP3K1. Signaling network patterns driven by lncRNA MALAT1 mutations were associated with multiple poor clinical outcome features. Rare mutations in druggable kinases included two in the kinase domain of HER2. Conclusions: Tumor heterogeneity in luminal-type breast cancer is driven by specific patterns of somatic mutations, however most druggable or potentially prognostic mutations are infrequent. Prospective clinical trials based on these findings will require comprehensive genome sequencing approaches and large scale investigations.

CRA506 Background: Sentinel node biopsy (SNB) eliminates the need for axillary dissection (ALND) in patients whose sentinel node (SN) is tumor-free. However, completion ALND remains the gold standard for patients with a tumor-involved sentinel node. ALND achieves regional control, but its effect on survival remains controversial. The main objective of ACOSOG Z0011 was to compare outcomes of patients with hematoxylin and eosin (H&E) detected metastasis in SN managed with or without ALND and no axillary irradiation. Methods: Clinically node-negative patients who underwent SN biopsy and had 1 or 2 SN with metastases detected by H&E were randomized to ALND or no further axillary specific treatment. All patients were treated with lumpectomy and opposing tangential field irradiation. Adjuvant systemic therapy was at the discretion of their physicians. Overall survival (OS), disease-free survival (DFS), and locoregional control were evaluated. Results: 446 patients were randomized to SNB alone and 445 to SNB plus ALND. Patients treated with SNB alone were similar to those treated with SNB + ALND with respect to age, tumor size, Bloom-Richardson score, estrogen receptor status, adjuvant systemic therapy, tumor type, and T stage. Patients randomized to SNB alone had a median of two lymph nodes removed whereas patients randomized to ALND had a median of 17 lymph nodes removed. 17.6% of ALND patients had 3 or more involved nodes compared to 5.0% of SNB patients (p < 0.001). Median follow-up is 6.2 years. 5-year in breast recurrence after ALND was 3.7% compared to 2.1% for SNB (p = 0.16) while 5-year nodal recurrence was 0.6% compared to 1.3% (p = 0.44) respectively. The five-year OS for patients undergoing SNB + ALND is 91.9% compared to 92.5% for SNB alone (p = 0.24), and DFS is 82.2% compared to 83.8% respectively (p = 0.13). Conclusions: Despite the widely held belief that ALND improves survival, no significant difference was recognized by this study of SN node-positive women. Although the study closed early because of low accrual/event rate, it is the largest phase III study of ALND for node-positive women, and it demonstrates no trend toward clinical benefit of ALND for patients with limited nodal disease. [Table: see text]

CRA504 Background: SN biopsy (SNB) with immunohistochemistry (IHC) of histologically negative SN identifies metastases (mets) not seen by standard histology. The impact of IHC-detected BM mets has been reported in several large single-institution studies. 5,539 patients (pts) were entered into this prospective multicenter observational study to determine the clinical significance of SN and BM mets. Methods: Patients underwent lumpectomy and SNB with bilateral iliac crest BM aspiration. BM and histologically negative SN were evaluated with IHC in a central laboratory (results not clinically reported). Overall survival (OS), disease-free survival, and locoregional recurrence were determined. Results with OS (the primary endpoint) are reported here. Results: SN were successfully identified in 5,184 of 5,485 pts (94.5%). Histologic SN mets were found in 1,239 pts (23.9%). IHC detected an additional 350 pts (10.5%) with SN mets. BM mets were identified by IHC in 105 of 3491 examined (3.0%). 5-yr overall survival is shown in the Table . BM IHC positivity significantly predicted decreased OS (p=0.015). A multivariable analysis that included SN and BM status, ER, PR, grade, size, and age showed that neither IHC detected mets in SN (p=0.66) or BM (p=0.08) were independent predictors of OS, although BM status showed a strong trend. Conclusions: The detection of BM mets by IHC in pts with clinical T1/2 N0M0 breast cancer identifies those pts at significantly increased risk for death; the impact of BM mets on outcome supports and confirms prior studies. In this study, SN IHC-detected mets appear to have no significant impact on OS. The routine examination of SN by IHC is not supported in this patient population by this study. [Table: see text] [Table: see text]

Abstract Support: Alliance U10CA180821; Alliance Statistical Center grant U10CA180882; ACOSOG grant U10CA76001 HER2 gene amplification and its corresponding overexpression are present in approximately 12% of invasive breast cancers. While HER2-targeted agents (e.g. trastuzumab, pertuzumab, and lapatinib) are effective treatments, resistance remains a major cause of death from HER2-positive breast cancer. Mechanisms of resistance are poorly understood. Without a molecular understanding of these mechanisms, therapeutic advances will be delayed. We have generated molecular profiles of primary HER2-positive breast cancers treated on a neoadjuvant clinical trial, and compared features associated with response to treatment. The American College of Surgeons Oncology Group (ACOSOG) Z1041 trial in HER2-positive breast cancer was designed to compare the pathologic complete response (pCR) rate of a regimen of paclitaxel and trastuzumab, followed by trastuzumab administered with fluorouracil, epirubicin, and cyclophosphamide (FEC-75) to a regimen of FEC-75 alone followed by paclitaxel and trastuzumab. The trial identified no difference in pCR rates between the regimens (Buzdar et al., The Lancet Oncology 2013). In supplement to the tissues obtained from 37 of the patients enrolled in the Z1041 trial, an additional 11 cases were obtained from a single institution study (201101961) of patients treated with neoadjuvant trastuzumab that had pre-treatment core biopsies suitable for genomic studies. We have extracted genomic DNA from both pretreatment tumor biopsies and blood samples of these 48 patients and performed whole genome (WGS) and exome sequencing. Coincident with these efforts, we have extracted high quality RNA from 42 of the 48 biopsies, and have processed RNA-seq profiles of the tumors. Among patients in this cohort, 24 (50%) achieved a pCR. Because no difference was observed between arms of the Z1041 trial, patients with or without a pCR were directly compared without adjusting for treatment regimen. On average, each tumor and normal sample pair were sequenced to a depth of 49.4x and 32.5x by WGS respectively. In total, 15,027 candidate somatic variants were identified in known genes, including 11,606 missense, 860 nonsense, and 418 frameshift insertions or deletions. Preliminary results identified mutations in HER2 that were associated with the failure to achieve pCR in several cases. Furthermore, tumors assigned to the HER2-enriched subtype by RNA-seq analysis were more likely to achieve a pCR (19 compared to 8) than tumors with genomic features indicative of either the luminal or basal-like subtypes (3 compared to 12); a significant difference in the proportion of cases that achieve pCR (Fisher's exact test p-value = 0.0032). The identification of these features suggests that it may be possible to predict, at the time of diagnosis, those patients who will not respond to the current standard of care for HER2-positive breast cancer. Citation Format: Lesurf R, Griffith O, Griffith M, Watson MA, Hoog J, Ellis MJ, Ota D, Suman VJ, Meric-Bernstam F, Leitch AM, Boughey JC, Unzeitig G, Buzdar AU, Hunt KK, Mardis ER. The genomics of response to neoadjuvant trastuzumab and chemotherapy in HER2-positive breast cancer – Results from the ACOSOG Z1041 (Alliance) 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 PD6-02.

Abstract Background ACOSOG Z1041 (Alliance) found pathological complete response rates in women with operable HER2-positive breast cancer were similar with FEC → P+T (Arm 1) and P+T → FEC+T (Arm 2) where treatment was administered as 5-FU 500 mg/m2, epirubicin 75 mg/m2 and cyclophosphamide 500 mg/m2 day 1 of a 21-day cycle x 4; paclitaxel 80 mg/m2 weekly x 12 and trastuzumab 4 mg/kg once then 2 mg/kg weekly x 11. We now report DFS and OS results with a median follow up of 4.4 years (range: 26 days to 6.2 years). Methods All patients who began study treatment were included in the analyses. Stratified log rank tests and stratified proportional hazard models were used to assess differences in DFS and OS from randomization between treatment arms. Results From September 15, 2007 to December 15, 2011, 282 women with HER2-positive breast cancer were enrolled. Two patients randomized to arm 1 withdrew consent prior to treatment and are excluded from these analyses. Patient and disease characteristics of the remaining 280 women (arm 1, n=138; arm 2, n=142) were similar between treatment arms. Recurrences and deaths are shown in the table. DFS were not found to differ with respect to treatment arm (stratified logrank p=0.6870; HR stratified (Arm2/Arm1)=0.88; 95%CI: 0.48-1.61). Also, OS was not found to differ with respect to treatment arm (stratified logrank p=0.8790; HR stratified (Arm2/Arm1)=1.07; 95%CI: 0.43-2.69). Conclusions Concurrent administration of trastuzumab with anthracyclines offers no additional benefit in terms of achieving pathologic complete response or improving survival and is not needed. FEC → P+TP+T → FEC+T Arm 1Arm 2n138142Recurrences2022Deaths811 Grant Support: U10 CA76001 The study is registered with ClinicalTrials.gov, number NCT00513292. Citation Format: Buzdar AU, Suman VJ, Meric-Bernstam F, Leitch AM, Ellis MJ, Boughey JC, Unzeitig GW, Royce ME, Ewer MS, Hunt KK. Disease-free (DFS) and overall survival (OS) data from ACOSOG Z1041 (Alliance) a randomized neoadjuvant trial comparing FEC followed by paclitaxel plus trastuzumab (FEC → P+T) with paclitaxel plus trastuzumab followed by FEC plus trastuzumab (P+T → FEC+T) in HER2-positive operable 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 P1-14-02.