Vallow, LA

614 Background: An analysis of preoperative bilateral breast MRI at our institution suggests that approximately 1/3 of patients with newly diagnosed breast cancer may have a mammographically occult, but MRI-evident, contralateral breast abnormality. A number of these patients will have pathologic confirmation of carcinoma in the contralateral breast. Identification of risk factors to predict which patients are at high risk for having a mammographically occult contralateral carcinoma was performed. Methods: MRI results of 401 women with newly diagnosed breast carcinoma who underwent MRI were reviewed (overall group; OG). Patients with a contralateral abnormality identified only by MRI were analyzed to determine the incidence of contralateral carcinoma. In addition, the following risk factors were evaluated: Age at diagnosis, menopausal status, tumor size, nodal status, ipsilateral tumor histology, tumor grade, hormone receptor status, Her-2/neu receptor status, and whether the patient had a palpable vs. mammographically detected abnormality. Results: Pathologically confirmed contralateral carcinoma (CC) was found in 13 patients (3.2%). Similar percentages of patients in both groups (OG and CC) were noted in regard to tumor size, histology, grade, nodal status, Her-2/neu receptor status, and method of detection (palpable vs. mammographic). However, median patient age was 71 (CC) vs. 62(OG); 92% (12/13) were postmenopausal (CC) compared to 75% (OG); and 100% were ER positive (CC) vs. 81% percent (OG). Conclusions: Older, postmenopausal women who have ER + tumors may have a higher likelihood of having synchronous, contralateral, mammographically occult, MRI-detected breast carcinoma. Preoperative MRI may be beneficial in patients with similar risk factors; however, further follow up and additional experience is needed for confirmation of these findings. No significant financial relationships to disclose.

Abstract Background: Conventional WBI after lumpectomy for early-stage breast cancer decreases ipsilateral breast tumor recurrence (IBTR), yielding comparable results to mastectomy. Accelerated PBI appears effective in reducing IBTR by treating only the tumor bed area. As the majority of IBTR occur at or in the vicinity of the tumor bed, we hypothesized that PBI would be as effective as WBI in controlling IBTR. The primary aim of NSABP B-39/RTOG 0413 was to determine if PBI provides equivalent local tumor control post lumpectomy compared to WBI in pts with early-stage breast cancer. The equivalency test was based on a 50% margin of increase in the hazard ratio (HR=1.5). Secondary endpoints included: overall survival (OS), recurrence-free interval (RFI), distant disease-free interval (DDFI), and toxicity. Methods: Eligible pts had lumpectomy with histologically-free margins and 0-3 positive axillary nodes. Pts were stratified by stage, menopausal status, hormone receptor status, and intent to receive chemotherapy and then randomized to PBI or WBI. PBI was 10 fractions of 3.4-3.85 Gy, given twice daily with either brachytherapy or 3D external beam radiation. WBI was 50 Gy in 2 Gy fractions given daily with a sequential boost to the surgical cavity. Follow-up was every 6 mos for 5 yrs and then annually. All analyses were by intent-to-treat. Results: From 3-21-05 to 4-16-13, 4216 pts were randomized: 2107 PBI; 2109 WBI. 61% were postmenopausal; 81% were hormone receptor-positive; 29% intended to receive chemotherapy. Stage distribution was: DCIS, 24%; invasive pN0, 65%; invasive pN1, 10%. As of 7-31-18, median follow-up was 10.2 yrs. There were 161 IBTRs as first events: 90 PBI v 71 WBI (HR 1.22; 90%CI 0.94-1.58). Per protocol-defined margin, to declare PBI and WBI equivalent regarding IBTR risk, the 90% CI for the observed HR had to lie entirely between 0.667 and 1.5. The percent of pts IBTR-free at 10 yrs was 95.2% PBI v 95.9% WBI. A statistically significant difference in the 10-yr RFI rate favored WBI (91.9% PBI v 93.4% WBI; HR 1.32; 95%CI 1.04-1.68; p=0.02). No statistically significant differences existed between PBI and WBI in DDFI (HR 1.31; 95%CI 0.91-1.91; p=0.15), OS (HR 1.10; 95%CI 0.90-1.35; p=0.35), or DFS (HR 1.12; 95%CI 0.98-1.29; p=0.11). Grade 3 toxicity was 9.6% PBI v 7.1% WBI, and grade 4-5 toxicity was 0.5% v 0.3%, respectively. Discussion: PBI did not meet the criteria for equivalence to WBI in controlling IBTR based on the upper limit of the hazard ratio confidence interval. However, the absolute difference in 10-yr rate of IBTR was <1% (4.8% PBI v 4.1% WBI). The risk of an RFI event was statistically significantly higher for PBI compared to WBI, but the absolute difference in 10-yr RFI rate was also small (8.1% PBI v 6.6% WBI). DDFI, OS, and DFS were not statistically different for PBI v WBI. Grade 3-5 toxicities, although low, were more common for PBI than WBI. The trial population was heterogeneous, ranging from Stage 0-2 breast cancer, and outcome by risk categories are being analyzed. Support: U10CA180868, -180822, UG1CA189867. Citation Format: Vicini FA, Cecchini RS, White JR, Julian TB, Arthur DW, Rabinovitch RA, Kuske RR, Parda DS, Ganz PA, Scheier MF, Winter KA, Paik S, Kuerer HM, Vallow LA, Pierce LJ, Mamounas EP, Costantino JP, Bear HD, Germaine I, Gustafson G, Grossheim L, Petersen IA, Hudes RS, Curran, Jr. WJ, Wolmark N. Primary results of NSABP B-39/RTOG 0413 (NRG Oncology): A randomized phase III study of conventional whole breast irradiation (WBI) versus partial breast irradiation (PBI) for women with stage 0, I, or II breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS4-04.

Abstract Background The clinical results of NSABP B-35, phase III trial comparing 1 mg/day A to 20 mg/day tam, each given for 5 years, were reported at ASCO 2015. B-35 demonstrated a statistically significant benefit in breast cancer free interval for women assigned to A, primarily in women <60 years. A secondary endpoint of B-35 was quality of life (QOL) and symptom (SX) outcomes in the two treatment groups. The primary hypotheses of the PRO study were that there would be no differences in QOL between the two treatments, and that patients receiving A would report higher rates of hot flashes compared to patients receiving tam. Other SX comparisons were secondary endpoints. Methods QOL and SX were assessed at baseline (prior to randomization), and every 6 months thereafter for 5 years of treatment and in the following 12 months. QOL was measured with the SF-12 Physical Component Summary (PCS) and Mental Component Summary (MCS). SX were measured with selected scales from the BCPT symptom-checklist, and other standardized instruments. Stratification was by age (<60 v ≥60) as in the main trial. Study hypotheses and endpoints were examined by comparing PROs in the two treatment arms using a mixed model for repeated measures analysis with adjustment for the baseline scores, time point and age category, using an intention-to-treat principle and including only patients who completed the baseline and at least one follow-up questionnaire. Patients with protocol events were censored. Only data through 60 months are reported here. The accrual goal for the sub-study was 1,150 consecutive patients. Results Between January 6, 2003 and June 15, 2006, a total of 3,104 patients were entered and randomly assigned to NSABP Protocol B-35. Accrual to the PRO study of B-35 closed on December 28, 2004, at which time 1,275 patients were entered, with 1,193 patients included in this analysis. There were no medical or demographic differences between patients assigned to A or tam in the PRO sub-study, and they reflected the characteristics of the parent trial. Adherence to data collection across the 60 months was 87%. There were no significant differences in QOL outcomes by treatment for the PCS (p=0.16) or the MCS (p=0.38). SX subscales: hot flash scale was greater in tam group and this difference varied over time (p=0.001); musculoskeletal pain was significantly greater in A group for time points 6-24 months (all p<.001); vaginal problems were greater in A group (p=0.03). Hot flash and vaginal problems were significantly worse in women <60 years. Additional SX outcomes (depression, fatigue, sexual function) will be reported at presentation. Conclusion In this large, double-blind, placebo-controlled trial comparing A to tam in patients with DCIS, there was no significant difference in QOL between the two treatments. However, there were important treatment differences in SX outcomes, which should be considered as part of treatment decision-making discussions, along with the clinical breast cancer outcome results. Support: CA-180868, 180822, 189867, 196067, 114732; AstraZeneca Pharmaceuticals LP. Citation Format: Ganz PA, Cecchini RS, Julian TB, Margolese RG, Costantino JP, Vallow LA, Albain KS, Whitworth PW, Cianfrocca ME, Brufsky A, Gross HM, Soori GS, Hopkins JO, Fehrenbacher L, Sturtz K, Wozniak TF, Seay TE, Mamounas EP, Wolmark N. Patient-reported outcome (PRO) results, NRG Oncology/NSABP B-35: A clinical trial of anastrozole (A) vs tamoxifen (tam) in postmenopausal patients with DCIS undergoing lumpectomy plus radiotherapy. [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 S6-04.

Abstract Background: Targeting immune checkpoint programmed death receptor 1 (PD-1)/PD-L1 pathway has shown promising clinical activity with some preliminary association of clinical benefit with PD-L1 expression on tumors. Recent preclinical and clinical studies highlight the beneficial immunomodulatory potential of epigenetic therapy. Entinostat is a class I specific histone deacetylase inhibitor (HDACi). A promising preclinical study showed that entinostat in combination with immune checkpoint blockade agent can eradicate modestly immunogenic breast tumors in mice via reduction in immunosuppressive myeloid-derived suppressor cells. In this study, we investigated the effects of entinostat on expression of immune-related genes in breast cancer cells to further explore the potential mechanism of its combined activity. Method: Gene expression was assessed on Nanostring platform using the nCounter GX Human ImmunologyV2 panel comprised of 594 immune-related and 15 reference genes. Gene expression was normalized to the internal positive controls and reference genes using nSolver2.0 software. Hormone receptor-positive (HR+) breast cancer (MCF-7 and T47D) and triple negative breast cancer (TNBC) cell lines (MDA-MB-231 and Hs578T) were used for the analysis. Gene expression analysis was performed on control and after 24-hour treatment of entinostat at clinically relevant 125 and 500 nM concentrations. Results: Overall, a greater number of immune-related genes were induced > 2 fold with entinostat at 125 and 500 nM in TNBC compared to HR+: 77 and 118 genes in MDA-MB-231, 80 and 147 genes in Hs578T, 20 and 64 genes in MCF-7, and 73 and 72 genes in T47D, respectively. In particular, MHC class I (HLA-A, HLA-B, HLA-C) and II (HLA-DMA, HLA-DMB, HLA-DOA, HLA-DOB, HLA-DPA1, HLA-DPB1, HLA-DQA1, HLA-DQA2, HLA-DQB1, HLA-DQB2, HLA-DRA, and HLA-DRB1) genes were induced by entinostat in a dose dependent manner (range 1.5-22.44 fold). These inductions were observed in both HR+ and TNBC cell lines. Interestingly, we found higher baseline expression and a several fold increase in PD-L1 expression in TNBC. PD-L1 mRNA expression increased by 1.74 and 2.14 fold in MDA-MB-231 and 3 and 9.6 fold in Hs578T with 125 and 500 nM treatment, respectively. Corresponding increase in PD-L1 protein expression after entinostat treatment was also observed. In contrast, there appeared to be no significant changes in PD-L1 expression after entinostat treatment in MCF-7 and T47D. Furthermore, we also identified 21 genes that were differentially induced by entinostat in TNBC but not in HR+. These genes include PTPN22, ARG2, CISH, IL17A, ICAM2, KIR3DL1, CXCR3, TLR2, CFD, CCR5, IL13, LILRA3, IL8, TNFRSF9, DPP4, MR1, SELPLG, PTGS2, IL1B, CD3D, and MBL2. No significant change in PDL2 expression was observed in any of the cell lines. Conclusion: Our data suggest that entinostat induces immune-related genes involved in antigen presentation in both ER+ and TNBC cells, potentially increasing the immunogenicity of these tumors. Given the significant induction of PD-L1 expression with entinostat in TNBC, our preclinical data provides support for further investigation of entinostat in combination with anti-PD1 or anti-PD-L1 in this subtype of breast cancer. Citation Format: Chumsri S, Necela BM, Ordentlich P, Advani P, Moreno-Aspitia A, McLaughlin SA, Geiger X, McDonough M, Vallow LA, Perez EA, Thompson EA. Immunomodulatory effects of entinostat on PD-L1 and MHC class I and II in different subtypes of 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 P2-04-02.

Abstract Abstract #4020 Background: HER2 positive (HER2+) breast cancer accounts for 20% of all breast cancer and is an independent adverse prognostic factor. Breast magnetic resonance imaging (MRI) has been shown to identify additional mammographically occult ipsilateral (I/L) and contralateral (C/L) disease, however indications for preoperative MRI in patients with newly diagnosed breast cancer are not standardized. While invasive lobular cancer, younger patient age, and increased breast density have been suggested as routine indications, the role of preoperative MRI according to HER2 status has not been evaluated.
 Methods: All patients with invasive breast cancer who underwent preoperative MRI between January 2003 and December 2007 were reviewed. Retrospective chart review was performed to collect clinical, radiographic, and pathologic data. The incidence of additional I/L or C/L malignacy was calculated. Additionally, changes in surgical management because of MRI findings were recorded.
 Results: Of the 401 women with invasive breast cancer undergoing preoperative breast MRI, 51 (13%) had HER2+ tumors. The average age at the time of MRI was similar in both groups. HER2+ patients were more likely to have nodal disease, and tumors with higher rates of lymphovascular invasion or extensive intraductal components.
 
 When compared to HER2- patients, more HER2+ patients had additional ipsilateral MRI abnormalities. A second ipsilateral cancer was found in 31% of HER2+ patients compared to 25% of HER2- patients. When analyzed according to ER status, HER2+/ ER- patients were more likely to have an additional site of cancer compared to HER2+/ER+ patients (42% vs 23%). Conversely, among HER2- patients, rates of additional ipsilateral cancer were similar for HER2-/ER+ (26%) and HERr2-/ER- (23%) patients. Of the 216 patients (HER2+ and HER2-) with additional ipsilateral MRI findings (benign or malignant), 125/216 (58%) patients were deemed appropriate breast conservation (BCT) candidates after MRI. However, BCT was only chosen in 84/125 (67%) patients. Additional contralateral disease was documented in 8% of HER2+ versus 5% of HER2- patients.
 Conclusions: HER2 positivity remains and important prognostic factor for women with breast cancer. Indications for routine preoperative MRI are unclear. In patients with newly diagnosed Her2+ invasive breast cancer routine preoperative MRI may be valuable in the subset of patients who are also ER-. Further study is needed to determine the influence of MRI on patient decisions for surgical therapy. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4020.

Abstract Abstract #4014 Background
 Preoperative magnetic resonance imaging (MRI) of the breasts in women with breast cancer (BC) has improved the detection of occult ipsilateral (I/L) and contralateral (C/L) malignancies. Breast MRI findings in patients with estrogen receptor (ER), progesterone receptor (PR), and HER2 negative (triple negative (TN)) disease have not been previously reported. Women with TN BC are at increased risk of distant metastases and a reduced survival vs. BC patients as a whole. One potential explanation may be the presence of occult disease. The role of bilateral breast MRI in these patients remains to be determined.
 Hypothesis
 Patients with TN BC are more likely to have occult malignancy identified by preoperative MRI vs. those with non-TN BC.
 Methods
 All newly diagnosed BC patients from 2003-2007 were reviewed. Information on age, race, histology, ER, PR, HER2, staging, treatment, MRI findings, subsequent investigations, and additional cancer diagnoses was recorded. The incidence of additional I/L or C/L malignany was calculated. The percentage of total patients initially felt to be candidates for partial breast irradiation who required a change in their cancer management was calculated.
 Results
 55 (11%) were diagnosed with TN BC, of whom 52 women completed preoperative MRI. 456 (89%) had non-TN BC; 421 completed preoperative MRI. The median age among TN and non-TN patients was 62 years (Table 1). A majority of women in both groups were Caucasian. African-American women were more likely to be diagnosed with TN vs. non-TN disease (11% vs. 6%).
 
 I/L BC was documented in 13/52 (25%) of TN patients vs. 25% of non-TN patients. No C/L cancers were detected in the TN group (6% in the non-TN group). Of the TN group, 15 patients required a change in their treatment (29%) based on findings from MRI vs. 32% of non-TN patients.
 Conclusions
 Patients with a new diagnosis of TN BC are not at increased risk of occult malignancy than those with non-TN BC. 25% of patients with TN BC had additional I/L disease not previously detected on clinical examination, mammogram, or ultrasound. Of those with non-TN BC, 25% were diagnosed with an additional I/L and 6% with C/L malignancy. The benefit of MRI was limited by false positives, with a number of patients in both groups undergoing a benign biopsy.
 These results suggest that patients with TN BC are not more likely than those with non-TN disease to have additional occult I/L or C/L cancer. The incidence of additional disease remains high and preoperative MRI may be beneficial. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4014.