Effect of Metformin Versus Placebo on New Primary Cancers in Canadian Cancer Trials Group MA.32: A Secondary Analysis of a Phase III Randomized Double-Blind Trial in Early Breast Cancer

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned coprimary or secondary analyses are not yet available. Clinical trial updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Metformin has been associated with lower cancer risk in epidemiologic and preclinical research. In the MA.32 randomized adjuvant breast cancer trial, metformin (v placebo) did not affect invasive disease-free or overall survival. Here, we report metformin effects on the risk of new cancer. Between 2010 and 2013, 3,649 patients with breast cancer younger than 75 years without diabetes with high-risk T1-3, N0-3 M0 breast cancer (any estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2) were randomly assigned to metformin 850 mg orally twice a day or placebo twice a day for 5 years. New primary invasive cancers (outside the ipsilateral breast) developing as a first event were identified. Time to events was described by the competing risks method; two-sided likelihood ratio tests adjusting for age, BMI, smoking, and alcohol intake were used to compare metformin versus placebo arms. A total of 184 patients developed new invasive cancers: 102 metformin and 82 placebo, hazard ratio (HR), 1.25; 95% CI, 0.94 to 1.68; P = .13. These included 48 contralateral invasive breast cancers (27 metformin v 21 placebo), HR, 1.29; 95% CI, 0.72 to 2.27; P = .40 and 136 new nonbreast primary cancers (75 metformin v 61 placebo), HR, 1.24; 95% CI, 0.88 to 1.74; P = .21. Metformin did not reduce the risk of new cancer development in these nondiabetic patients with breast cancer.

Metformin, placebo, and endocrine therapy discontinuation among participants in a randomized double-blind trial of metformin vs placebo in hormone receptor-positive early-stage breast cancer (CCTG MA32)

BACKGROUND

The MA32 study investigated whether 5 years of metformin (versus placebo) improves invasive disease-free survival in early-stage breast cancer (BC). Non-adherence to endocrine therapy (ET) and medications for chronic conditions is common and increases with drug toxicity and polypharmacy. This secondary analysis evaluates rates and predictors of early discontinuation of metformin, placebo, and ET among participants with HR-positive BC.

METHODS

Patients with high-risk non-metastatic BC were randomized to 60 months of metformin (850 mg BID) or placebo BID. Patients were administered bottles of metformin/placebo every 180 days. Metformin/placebo adherence was defined as a bottle dispensed at month 48 or later. The ET adherence analysis included patients with HR-positive BC who received ET with start and stop date reported, with adherence defined as > 48 months of use. Associations of covariates with study drug and ET adherence were examined using multivariable models.

RESULTS

Among the 2521 HR-positive BC patients, 32.9% were non-adherent to study drug. Non-adherence was higher among patients on metformin vs placebo (37.1% vs 28.7%, p < 0.001). Reassuringly, ET discontinuation rates were similar between treatment arms (28.4% vs 28.0%, p = 0.86). Patients who were non-adherent to ET were more likely to discontinue study therapy (38.8% vs 30.1%, p < 0.0001). In a multivariable analysis, study drug non-adherence was increased with metformin vs placebo (OR: 1.50, 95% CI 1.25-1.80; p < 0.0001); non-adherence to ET (OR: 1.47, 95% CI 1.20-1.79, p < 0.0001); grade 1 or greater GI toxicity during the first 2 years; lower age; and higher body mass index.

CONCLUSION

While non-adherence was higher among patients on metformin, it was still considerable among patients on placebo. Reassuringly, treatment arm allocation did not impact ET adherence. Attention to global medication adherence is needed to improve BC and non-oncological outcomes in cancer survivors.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01.

Effect of Metformin vs Placebo on Invasive Disease-Free Survival in Patients With Breast Cancer: The MA.32 Randomized Clinical Trial

Importance

Metformin, a biguanide commonly used to treat type 2 diabetes, has been associated with potential beneficial effects across breast cancer subtypes in observational and preclinical studies.

Objective

To determine whether the administration of adjuvant metformin (vs placebo) to patients with breast cancer without diabetes improves outcomes.

Design, Setting, and Participants

MA.32, a phase 3 randomized, placebo-controlled, double-blind trial, conducted in Canada, Switzerland, US, and UK, enrolled 3649 patients with high-risk nonmetastatic breast cancer receiving standard therapy between August 2010 and March 2013, with follow-up to October 2020.

Interventions

Patients were randomized (stratified for hormone receptor [estrogen receptor and/or progesterone receptor {ER/PgR}] status, positive vs negative; body mass index, ≤30 vs >30; human epidermal growth factor receptor 2 [ERBB2, formerly HER2 or HER2/neu], positive vs negative; and any vs no chemotherapy) to 850 mg of oral metformin twice a day (n = 1824) or oral placebo twice a day (n = 1825) for 5 years.

Main Outcomes and Measures

The primary outcome was invasive disease-free survival in hormone receptor-positive breast cancer. Of the 8 secondary outcomes, overall survival, distant relapse-free survival, and breast cancer-free interval were analyzed.

Results

Of the 3649 randomized patients (mean age, 52.4 years; 3643 women [99.8%]), all (100%) were included in analyses. After a second interim analysis, futility was declared for patients who were ER/PgR-, so the primary analysis was conducted for 2533 patients who were ER/PgR+. The median duration of follow-up in the ER/PgR+ group was 96.2 months (range, 0.2-121 months). Invasive disease-free survival events occurred in 465 patients who were ER/PgR+. The incidence rates for invasive disease-free survival events were 2.78 per 100 patient-years in the metformin group vs 2.74 per 100 patient-years in the placebo group (hazard ratio [HR], 1.01; 95% CI, 0.84-1.21; P = .93), and the incidence rates for death were 1.46 per 100 patient-years in the metformin group vs 1.32 per 100 patient-years in the placebo group (HR, 1.10; 95% CI, 0.86-1.41; P = .47). Among patients who were ER/PgR-, followed up for a median of 94.1 months, incidence of invasive disease-free survival events was 3.58 vs 3.60 per 100 patient-years, respectively (HR, 1.01; 95% CI, 0.79-1.30; P = .92). None of the 3 secondary outcomes analyzed in the ER/PgR+ group had statistically significant differences. Grade 3 nonhematological toxic events occurred more frequently in patients taking metformin than in patients taking placebo (21.5% vs 17.5%, respectively, P = .003). The most common grade 3 or higher adverse events in the metformin vs placebo groups were hypertension (2.4% vs 1.9%), irregular menses (1.5% vs 1.4%), and diarrhea (1.9% vs 7.0%).

Conclusions and Relevance

Among patients with high-risk operable breast cancer without diabetes, the addition of metformin vs placebo to standard breast cancer treatment did not significantly improve invasive disease-free survival.

Trial Registration

ClinicalTrials.gov Identifier: NCT01101438.

The Futility of Futility Analyses in Adjuvant Trials in Hormone Receptor Positive Breast Cancer

An interim analysis is commonly used in phase III superiority trials to compare treatment arms, with the goal of terminating exposure of patients to ineffective or unsafe drugs, or to identify highly effective therapies for earlier public disclosure. Traditionally, interim analyses have been designed to identify early evidence of extremely large benefit of the experimental approach, potentially leading to early dissemination of effective treatments. Increasingly, interim analysis has also involved analysis of futility which may lead to early termination of a trial that will not yield additional useful information This presents an important challenge in early-stage hormone receptor positive breast cancer, where recurrence often occurs late, with a steady annual event rate up to 20 years. Early analysis of events may miss late treatment effects that can be observed only with longer follow-up. We discuss approaches to futility analysis in adjuvant clinical trials in hormone receptor positive breast cancer, the role of the Data Safety Monitoring Committee in such analyses, considerations of the potential harms versus benefits of treatment, and the risks of continuing versus early stopping of a trial.

A scalable serology solution for profiling humoral immune responses to SARS-CoV-2 infection and vaccination

Objectives

Antibody testing against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has been instrumental in detecting previous exposures and analyzing vaccine‐elicited immune responses. Here, we describe a scalable solution to detect and quantify SARS‐CoV‐2 antibodies, discriminate between natural infection‐ and vaccination‐induced responses, and assess antibody‐mediated inhibition of the spike‐angiotensin converting enzyme 2 (ACE2) interaction.

Methods

We developed methods and reagents to detect SARS‐CoV‐2 antibodies by enzyme‐linked immunosorbent assay (ELISA). The main assays focus on the parallel detection of immunoglobulin (Ig)Gs against the spike trimer, its receptor binding domain (RBD) and nucleocapsid (N). We automated a surrogate neutralisation (sn)ELISA that measures inhibition of ACE2‐spike or ‐RBD interactions by antibodies. The assays were calibrated to a World Health Organization reference standard.

Results

Our single‐point IgG‐based ELISAs accurately distinguished non‐infected and infected individuals. For seroprevalence assessment (in a non‐vaccinated cohort), classifying a sample as positive if antibodies were detected for ≥ 2 of the 3 antigens provided the highest specificity. In vaccinated cohorts, increases in anti‐spike and ‐RBD (but not ‐N) antibodies are observed. We present detailed protocols for serum/plasma or dried blood spots analysis performed manually and on automated platforms. The snELISA can be performed automatically at single points, increasing its scalability.

Conclusions

Measuring antibodies to three viral antigens and identify neutralising antibodies capable of disrupting spike‐ACE2 interactions in high‐throughput enables large‐scale analyses of humoral immune responses to SARS‐CoV‐2 infection and vaccination. The reagents are available to enable scaling up of standardised serological assays, permitting inter‐laboratory data comparison and aggregation.

Abstract GS1-08: CCTGMA.32, a phase III randomized double-blind placebo controlled adjuvant trial of metformin (MET) vs placebo (PLAC) in early breast cancer (BC): Results of the primary efficacy analysis (clinical trials.gov NCT01101438)

Background: MET has been associated with beneficial anti-cancer effects in epidemiologic and preclinical research. It may act indirectly by reversing obesity associated physiologic changes or directly via mitochondrial mediated effects on LKB1/AMPK/mTOR and other mechanisms. MA.32 investigated the effect of MET vs PLAC (in addition to standard therapy) on adjuvant BC outcomes. Design: Randomized, placebo-controlled double-blind Phase III clinical trial conducted within the NCI US National Clinical Trials Network, NCRI (UK) BG, IBCSG. Methods: Between 2010-2013 BC patients &lt; 75 yo without diabetes (DM) with high risk T1-3, N0-3 M0 BC regardless of ER, PgR, HER2 and with adequate cardiac, renal and hepatic function were randomized (stratified for ER/PgR + vs -, BMI &lt; vs &gt; 30 kg/m2, HER2 +ve vs -ve, any vs no chemo) within 1 year of BC diagnosis to MET 850 mg po bid or PLAC bid for 5 years. Dose was reduced for toxicity with re-escalation when possible. Subjects were followed for Invasive Disease-Free Survival (IDFS primary outcome; events included invasive local/regional recurrences, distant recurrences, new ipsilateral/contralateral invasive BCs, new non-breast primary cancers, any death), Overall Survival (OS), Distant Relapse Free Survival (DRFS), BC Specific Survival (BCSS), BC Free Interval (BCFI), contralateral BC and cardiovascular (CV) events/new DM. 3582 subjects were required for 80% power to detect HR 0.76 (431 events). In 2011, entry was restricted to higher risk BC, leading to 80% power to detect HR 0.785 (544 events). In 2016, after the 2nd interim analysis at 29.5 months median F/U, the DSMB recommended (i) the intervention be continued with primary analysis triggered at 544 events be conducted in ER/PgR +ve (any HER2) subjects only and (ii) ER/PgR -ve subjects stop study drug for futility but blinding and follow-up continue. In 2021, a time driven analysis in ER/PgR +ve BC was approved (465 events providing 80% power to detect the original HR 0.76). Time to event survival described by the Kaplan-Meier method. Two-sided log-rank tests adjusting for stratification factors were primarily used to compare IDFS between arms. Cox proportional hazards models were used to identify and adjust for factors significantly related to IDFS. Results: 3649 subjects were enrolled. In the 2533 ER/PgR +ve subjects included in the primary analysis, baseline mean (± SD) age was 52.7 (±9.9 yrs); mean BMI 28.8 (±6.4) kg/m2. Baseline tumor characteristics were balanced: T stage 1/2/3/4 = 832/1351/349/1; N stage 0/1/2/3 = 964/1097/449/23; HER2+ 429. 1901 (75%) received XRT. 2150 (84.9%) received (neo)adj chemo, 2223 (87.8%) (neo)adj hormones and 434 (17.1%) HER2 targeted therapy. Any Grade ≥ 3 toxicity was similar in MET and PLAC arms (21.7% and 18.7%, P = 0.06). Median follow-up was 96.2 (range 0.2-121.0) months with 465 IDFS events (234 MET, 231 PLAC, 76% due to BC). Efficacy results are shown below.

MET vs PLACMET vs PLACIDFSOSPopulation Included# subjectsHR (95% CI)HR (95% CI)PRIMARY ANALYSISER/PgR +ve (any HER2)*25331.01 (0.84-1.21). P=0.920.89 (0.64-1.23). P=0.46ER/PgR -ve (any HER211161.01 (0.79-1.30. P=0.92)0.89 (0.64-1.23). P=0.46Exploratory. AnalysisHER2 +ve (any ER/PgR)6200.64 (0.43-0.95. P=0.0260.53 (0.30-0.98. P=0.0398**in ER/PgR pos BC HRs were similar for BCFI, DRFS, BCSS (ranging from 0.98-1.09)Conclusions: MET did not improve IDFS or other BC outcomes in ER/PgR positive or ER/PgR negative BC and should not be used as adjuvant treatment. Exploratory findings suggesting benefit in HER2+ve BC should be further investigated. Funded by: CCSRI, NCI (US), CBCF, BCRF, CRUK, Hold’Em for Life Charity, Apotex (Canada)

Citation Format: Pamela J. Goodwin, Bingshu E Chen, Karen A Gelmon, Timothy J Whelan, Marguerite Ennis, Julie Lemieux, Jennifer A Ligibel, Dawn L Hershman, Ingrid A Mayer, Timothy J Hobday, Judith M Bliss, Priya Rastogi, Manuela Rabaglio-Poretti, Som D. Mukherjee, Robert R Mackey, Vandana G Abramson, Conrad Oja, Robert Wesolowski, Alastair M Thompson, Daniel W Rea, Paul M Stos, Lois E Shepherd, Vuk Stambolic, Wendy R Parulekar. CCTGMA.32, a phase III randomized double-blind placebo controlled adjuvant trial of metformin (MET) vs placebo (PLAC) in early breast cancer (BC): Results of the primary efficacy analysis (clinical trials.gov NCT01101438) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr GS1-08.

The Breast Cancer Weight Loss trial (Alliance A011401): A description and evidence for the lifestyle intervention

The Breast Cancer Weight Loss (BWEL) trial is a randomized controlled trial designed to determine whether weight loss after a breast cancer diagnosis can reduce the risk of cancer recurrence in women with overweight or obesity. The BWEL trial will compare the efficacy of a telephone-based weight-loss intervention plus health education materials versus health education materials alone on invasive disease-free survival in 3,181 women with stage II or III breast cancer and BMI > 27 kg/m² . This report provides a detailed description of the goals and methods of the lifestyle intervention and the evidence supporting the intervention used in the BWEL trial. The intervention's primary goal for participants is to achieve and maintain a weight loss ≥ 10% of baseline weight through increased physical activity and caloric restriction. The evidence supporting the diet, physical activity, and behavioral components of this telephone-based weight-loss intervention, as well as strategies to promote participant engagement and retention, is described. The intervention is provided through 42 sessions delivered by trained health coaches over a 2-year period. If the BWEL lifestyle intervention is successful in improving cancer outcomes, then weight loss will be incorporated into the care of thousands of breast cancer patients.

Cancer Antigen 15-3/Mucin 1 Levels in CCTG MA.32: A Breast Cancer Randomized Trial of Metformin vs Placebo

Background

Circulating levels of cancer antigen (CA) 15-3, a tumor marker and regulator of cellular metabolism, were reduced by metformin in a nonrandomized neoadjuvant study. We examined the effects of metformin (vs placebo) on CA 15-3 in participants of MA.32, a phase III randomized trial in early-stage breast cancer.

Methods

A total of 3649 patients with T1-3, N0-3, M0 breast cancer were randomly assigned; pretreatment and 6-month on-treatment fasting plasma were centrally assayed for CA 15-3. Genomic DNA was analyzed for the rs11212617 single nucleotide polymorphism. Absolute and relative change of CA 15-3 (metformin vs placebo) were compared using Wilcoxon rank and t tests. Regression models adjusted for baseline differences and assessed key interactions. All statistical tests were 2-sided.

Results

Mean (SD) age was 52.4 (10.0) years. The majority of patients had T2/3, node-positive, hormone receptor-positive, HER2-negative breast cancer treated with (neo)adjuvant chemotherapy and hormone therapy. Mean (SD) baseline CA 15-3 was 17.7 (7.6) and 18.0 (8.1 U/mL). At 6 months, CA 15-3 was statistically significantly reduced in metformin vs placebo arms (absolute geometric mean reduction in CA 15-3 = 7.7% vs 2.0%, P < .001; relative metformin: placebo level of CA 15-3 [adjusted for age, baseline body mass index, and baseline CA 15-3] = 0.94, 95% confidence interval = 0.92 to 0.96). This reduction was independent of tumor characteristics, perioperative systemic therapy, baseline body mass index, insulin, and the single nucleotide polymorphism status (all Ps > .11).

Conclusions

Our observation that metformin reduces CA 15-3 by approximately 6% was corroborated in a large placebo-controlled randomized trial. The clinical implications of this reduction in CA 15-3 will be explored in upcoming efficacy analyses of breast cancer outcomes in MA.32.

Crown-like structures in breast adipose tissue of breast cancer patients: associations with CD68 expression, obesity, metabolic factors and prognosis

Crown-like structures of the breast (CLS-B), defined by the clustering of macrophages (identified using CD68 immunohistochemical staining) to surround a dying adipocyte, are a sign of adipose-tissue inflammation. In human cohorts, CLS-B positively correlates with older age, obesity, dyslipidemia and higher levels of glucose, insulin, C-reactive protein and IL-6. In an existing cohort of early-stage breast cancer patients, CLS-B were identified using H&E stained histologic sections (hCLS-B), and by CD68 immunohistochemistry (CD68 + CLS-B). We examined associations of H&E and CD68-detected CLS-B with clinicopathologic features using χ2 tests, with metabolic factors using Wilcoxon rank sum tests and with disease free and overall survival using Cox regression models. hCLS-B were detected in 59 of 163 patients with slides (36.2%) and CD68 + CLS-B in 37 of 119 patients with paraffin blocks (31.1%). hCLS-B were positively correlated with higher weight (p = 0.003), BMI (p = 0.0008) and C-reactive protein (p = 0.045). CD68 + CLS-B were positively correlated with higher weight (p = 0.006), BMI p = 0.001), leptin (p = 0.034), insulin (p = 0.008) and Homeostasis Model Assessment (p = 0.027). CD68 + CLS-B were associated with poor distant disease-free with a hazard ratio (HR) of 2.81, 95% confidence interval (CI) 1.20-6.57, and overall survival with HR 3.97 (1.66-9.48), while hCLS-B were not associated with either: HR for distant recurrence 0.59 (0.26-1.30); HR for death 1.04 (0.50-2.16). The presence of hCLS-B and of CD68 + CLS-B were associated with obesity; CD68 + CLS-B were associated with insulin resistance and adverse prognosis. Similar patterns were not seen for hCLS-B. Research is needed to understand the biologic basis for these differences.

Circulating tumor cell number and endocrine therapy index in ER positive metastatic breast cancer patients

Circulating tumor cells (CTC) are prognostic in metastatic breast cancer (MBC). The CTC-endocrine therapy index (CTC-ETI), consisting of CTC-ER (estrogen receptor), BCL2, human epidermal growth factor receptor (HER2), and Ki67 expression, might predict resistance to endocrine therapy (ET) in patients with ER-positive MBC. One hundred twenty-one patients with ER-positive/HER2-negative MBC initiating a new ET after ≥1 lines of ET were enrolled in a prospective, multi-institutional clinical trial. CTC-ETI and clinical/imaging follow-up were performed at baseline and serial time points. Progression-free survival (PFS) and rapid progression (RP; determined at the 3-month time point) were primary endpoints. Associations with clinical outcomes used logrank and Fisher’s exact tests. At baseline, 36% (38/107) of patients had ≥5 CTC/7.5 ml whole blood (WB). Patients with ≥5 vs. <5 CTC/7.5 ml WB had significantly worse PFS (median 3.3 vs. 5.9 months, P = 0.03). Elevated CTC at 1 month was associated with even worse PFS (1.9 vs. 5.0 months from the 1-month sample, P < 0.001). Low, intermediate, and high CTC-ETI were observed in 71 (66%), 8 (8%), and 28 (26%) patients, with median PFS of 6.9, 8.5, and 2.8 months, respectively (P = 0.008). Patients with high vs. low CTC and CTC-ETI more frequently experienced RP (CTC: 66% vs. 41%; P = 0.03; CTC-ETI: 79% vs. 40%; P = 0.002). In conclusion, CTC enumeration and the CTC-ETI assay are prognostic at baseline and follow-up in patients with ER-positive/HER2-negative MBC starting new ET. CTC at first follow-up might identify a group of patients with ER-positive MBC that could forego ET, but CTC-ETI did not contribute further.

Effect of metformin versus placebo on metabolic factors in the MA.32 randomized breast cancer trial

Metformin may exert anticancer effects through indirect (mediated by metabolic changes) or direct mechanisms. The goal was to examine metformin impact on metabolic factors in non-diabetic subjects and determine whether this impact varies by baseline BMI, insulin, and rs11212617 SNP in CCTG MA.32, a double-blind placebo-controlled randomized adjuvant breast cancer (BC) trial. 3649 subjects with T1-3, N0-3, M0 BC were randomized; pretreatment and 6-month on-treatment fasting plasma was centrally assayed for insulin, leptin, highly sensitive C-reactive protein (hsCRP). Glucose was measured locally and homeostasis model assessment (HOMA) calculated. Genomic DNA was analyzed for the rs11212617 SNP. Absolute and relative change of metabolic factors (metformin versus placebo) were compared using Wilcoxon rank and t-tests. Regression models were adjusted for baseline differences and assessed interactions with baseline BMI, insulin, and the SNP. Mean age was 52 years. The majority had T2/3, node positive, hormone receptor positive, HER2 negative BC treated with (neo)adjuvant chemotherapy and hormone therapy. Median baseline body mass index (BMI) was 27.4 kg/m2 (metformin) and 27.3 kg/m2 (placebo). Median weight change was -1.4 kg (metformin) vs +0.5 kg (placebo). Significant improvements were seen in all metabolic factors, with 6 month standardized ratios (metformin/placebo) of 0.85 (insulin), 0.83 (HOMA), 0.80 (leptin), and 0.84 (hsCRP), with no qualitative interactions with baseline BMI or insulin. Changes did not differ by rs11212617 allele. Metformin (vs placebo) led to significant improvements in weight and metabolic factors; these changes did not differ by rs11212617 allele status.

Association of Obesity with Breast Cancer Outcome in Relation to Cancer Subtypes: A Meta-Analysis

Background

Obesity at breast cancer (BC) diagnosis has been associated with poor outcome, although the magnitude of effect in different BC subtypes is uncertain. We report on the association of obesity or overweight at diagnosis of nonmetastatic BC with disease-free (DFS) and overall survival (OS) in the following defined subtypes: hormone receptor positive/HER2 negative (HR+HER2−), HER2 positive (HER2+), and triple negative (TNBC).

Methods

We searched MEDLINE, EMBASE, and COCHRANE databases up to January 1, 2019. Study eligibility was performed independently by 2 authors. Studies reporting hazard ratios (HRs) of OS and/or DFS for obesity or overweight in BC subtypes were included. The pooled hazard ratio was computed and weighted using generic inverse variance and random effects models.

Results

Twenty-seven studies were included. Obese compared with nonobese women had worse DFS in all subtypes: the hazard ratios were 1.26 (95% confidence interval [CI] = 1.13 to 1.41, P < .001) for HR+HER2− BC, 1.16 (95% CI = 1.06 to 1.26, P < .001) for HER2+ BC, and 1.17 (95% CI = 1.06 to 1.29, P = .001) for TNBC. OS was also worse in obese vs nonobese women (HR+HER2− BC HR = 1.39, 95% CI = 1.20 to 1.62, P < .001; HER2+ BC HR = 1.18, 95% CI = 1.05 to 1.33, P = .006; and TNBC HR = 1.32, 95% CI = 1.13 to 1.53, P < .001). As opposed to obesity, overweight was not associated with either DFS or OS in HER2+ BC (HR = 1.02, 95% CI = 0.81 to 1.28, P = .85; and HR = 0.96, 95% CI = 0.76 to 1.21, P = .99, respectively) or TNBC (HR = 1.04, 95% CI = 0.93 to 1.18, P = .49; and HR = 1.08, 95% CI = 0.81 to 1.44, P = .17), respectively. In HR+HER2− BC, being overweight was associated with worse OS (HR = 1.14, 95% CI = 1.07 to 1.22, P < .001).

Conclusions

Obesity was associated with modestly worse DFS and OS in all BC subtypes.

Abstract PS18-25: Concordance of immunohistochemical assays between peri-operative and post-operative breast tumor specimens: A prospective observational study of 18 cases

Background and Rationale: Biomarker evaluation on breast tumor tissue is an important component of clinical research. There is a concern that tissues collected at different times (pre- vs intra-op) and with different techniques (core biopsy vs. surgical excision) produce different results that may confound comparisons of patient samples. Our objective is to address the difference between tumor tissue from the same patient collected pre- vs intra-op and by core biopsy (Core Bx) vs surgical excision, with an emphasis on ER/PgR/HER2/Ki-67 and biomarkers related to insulin metabolism.

Design: Following a protocol approved by the IRB, patients with Core Bx proven invasive breast cancer (BC) &gt;1.5 cm in size by imaging underwent a peri-operative Core Bx followed by surgical excision. No neoadjuvant therapy was administered. Formalin-fixed paraffin-embedded tumor sections of the diagnostic and peri-operative Core Bx and surgical excision were immunohistochemically (IHC) stained for ER, PgR, HER2, Ki-67, insulin receptor (IR), phospho-AKT (pAKT), and phospho-AMPK (pAMPK) using standardized protocols on the same platforms. A pathologist (MCC) scored all sections in blinded order to yield H-Scores (which combine percentage of stain-positive cells and staining intensity). The level of agreement for each assay between specimens was assessed by using pairwise models based on normal theory.

Results: 18 women (mean age = 66.8 years, 16/18 postmenopausal) provided all specimens. Mean (± SD) invasive tumor size was 2.7 (± 1.2) cm. 1 BC was Nottingham Grade 1 (6%), 9 Grade 2 (50%), and 8 Grade 3 (44%). An in situ component was present in 4/18 (22%) cases (all non-extensive). Lymphovascular invasion was present in 6/18 (33%) cases. 10/18 were node-negative (N0, 56%), 2/18 had isolated tumor cells (pN0[i+], 22%), 5/18 had 1 to 3 nodes (pN1, 28%), 1/18 had &gt;9 nodes involved (pN3, 6%).There was high concordance between diagnostic Core Bx, peri-op Core Bx, and excisions for the standard prognostic markers ER, PgR, and HER2. ER was concordant in all samples including 16/18 (89%) ER-positive and 2/19 (11%) ER-negative BCs. PgR was concordant in 16/18 (89%) of cases. In the 2 discordant cases, PgR was negative in 2 of 3 tissue samples with low expression in the 3rd sample (1 diagnostic Core Bx and 1 excision). HER2 was concordant in all samples in 16/18 (89%) HER2-negative cases and in 2/18 (11%) HER2-positive cases including 1/18 cases (6%) positive by IHC, and 1/18 cases (6%) positive by ISH.

Table 1 summarizes the agreement between samples for Ki-67, IR, pAKT, and pAMPK. Ki-67 scores were statistically similar between diagnostic and peri-op Core Bx and excision samples. The IR, pAKT, and pAMPK H-Scores were statistically similar between diagnostic and peri-op Core Bx, but significantly different between Core Bxs versus excisional specimens. There was a systematic tendency towards lower IHC H-Scores in the excisional specimen for IR, pAKT, and pAMPK.

Conclusion: Tissue from surgical excisions are susceptible to reduced IHC staining for metabolic markers such as IR, and phosphorylated kinases, when compared to core biopsies. When evaluating non-standard biomarkers for research, core biopsies should be used when possible.

Funding: This study was funded by the Hold'Em For Life Charity and the Breast Cancer Research Foundation

Table 1: Concordance Between IHC Scores for Ki-67, Insulin Receptor, pAKT, and pAMPKScore: Mean ± Standard DeviationPeri-Operative Core Bx versus Diagnostic Core BxExcision versus Diagnostic Core BxDiagnostic Core BxPeri-Operative Core BxExcisionDifferenceP-valueDifferenceP-valueKi-67 (% Positive)33.5 ± 28.235.9 ± 31.034.2 ± 29.1Mean ± SD: 2.4 ± 5.60.09Mean ± SD: 0.6 ± 6.30.68Range: -7.7 to 12.3Range: -11.5 to 12.2Insulin Receptor (H-Score**)136 ± 102124 ± 9986 ± 78Mean ± SD: -13 ± 530.32Mean ± SD: -51 ± 540.001*Range: -215 to 40Range: -150 to 5Phospho-AKT (H-Score**)102 ± 70100 ± 8641 ± 41Mean ± SD: -1 ± 750.95Mean ± SD: -61 ± 520.0001*Range: -170 to 170Range: -144 to 0Phospho-AMPK (H-Score**)201 ± 79185 ± 78157 ± 86Mean ± SD: -15 ± 760.41Mean ± SD: -44 ± 690.016*Range: -225 to 120Range: -215 to 70* Statistically significant difference in pairwise values based on t-test** H-Score is the percentage of stain-positive cells multiplied by the average intensity score (0 = absent, 1 = faint, 2 = moderate, 3 = strong)

Citation Format: Martin C. Chang, Marguerite Ennis, Jaime Escallon, Karina Bukhanov, Ryan JO Dowling, Vuk Stambolic, Pamela J Goodwin. Concordance of immunohistochemical assays between peri-operative and post-operative breast tumor specimens: A prospective observational study of 18 cases [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS18-25.

The Effect of Metformin vs Placebo on Sex Hormones in Canadian Cancer Trials Group MA.32

BACKGROUND

Metformin has been associated with lower breast cancer (BC) risk and improved outcomes in observational studies. Multiple biologic mechanisms have been proposed, including a recent report of altered sex hormones. We evaluated the effect of metformin on sex hormones in MA.32, a phase III trial of nondiabetic BC subjects who were randomly assigned to metformin or placebo.

METHODS

We studied the subgroup of postmenopausal hormone receptor-negative BC subjects not receiving endocrine treatment who provided fasting blood at baseline and at 6 months after being randomly assigned. Sex hormone-binding globulin, bioavailable testosterone, and estradiol levels were assayed using electrochemiluminescence immunoassay. Change from baseline to 6 months between study arms was compared using Wilcoxon sum rank tests and regression models.

RESULTS

312 women were eligible (141 metformin vs 171 placebo); the majority of subjects in each arm had T1/2, N0, HER2-negative BC and had received (neo)adjuvant chemotherapy. Mean age was 58.1 (SD=6.9) vs 57.5 (SD=7.9) years, mean body mass index (BMI) was 27.3 (SD=5.5) vs 28.9 (SD=6.4) kg/m2 for metformin vs placebo, respectively. Median estradiol decreased between baseline and 6 months on metformin vs placebo (-5.7 vs 0 pmol/L; P < .001) in univariable analysis and after controlling for baseline BMI and BMI change (P < .001). There was no change in sex hormone-binding globulin or bioavailable testosterone.

CONCLUSION

Metformin lowered estradiol levels, independent of BMI. This observation suggests a new metformin effect that has potential relevance to estrogen sensitive cancers.

Prognostic associations of plasma hepcidin in women with early breast cancer

PURPOSE

Iron is essential to energy metabolism, cell proliferation and DNA synthesis, and sufficient iron availability may be required for tumor growth. The hormone hepcidin is a systemic regulator of iron concentration in plasma. Intra-tumor RNA expression of hepcidin has been linked to shorter metastasis-free survival in women with early breast cancer, but the prognostic implications of this inflammatory marker and iron-regulating plasma peptide in the blood are unknown.

METHODS

Using an ELISA assay, hepcidin was measured in the banked blood of 518 women who were recruited from 1989 to 1996 for a prospective cohort study of diet and lifestyle factors in breast cancer. Blood samples were obtained 4-12 weeks post-operatively, prior to treatment with chemotherapy or tamoxifen.

RESULTS

Hepcidin was not associated with time to distant breast cancer recurrence (primary outcome) nor time to death from any cause. However, a pre-planned interaction test of body mass index (BMI) was statistically significant (p < 0.01). Among obese women (BMI > 30 kg/m²), higher hepcidin was associated with a shorter time to distant breast cancer recurrence in both uni- and multivariable analyses (adjusted HR 1.84; 95% CI 1.04-3.25). For overall survival, a similar pattern was seen in the univariable model but the effect was diminished in a multivariable analysis. Plasma hepcidin was not associated with high-sensitivity C-reactive protein, but it was significantly associated (r ≥ 0.32) with iron indices, including total iron (p < 0.01), transferrin (p < 0.01) and soluble transferrin receptor (p < 0.01).

CONCLUSIONS

Hepcidin may be associated with poor breast cancer outcome in obese women, however, replication is required. The biologic basis for this prognostic association requires further research.

Association between BMI, vitamin D, and estrogen levels in postmenopausal women using adjuvant letrozole: a prospective study

Studies have suggested that women with elevated BMI or 25-OH vitamin D levels may derive less benefit from AIs versus tamoxifen. We prospectively investigated whether high BMI or 25-OH vitamin D levels were associated with higher estrogen levels in post-menopausal women receiving standard adjuvant letrozole (2.5 mg/day). Furthermore, we evaluated whether an increased dose of letrozole resulted in lower serum estrogens in women with BMI > 25 kg/m2. Correlation between entry BMI and day 29 serum biomarkers (estrogens, 25-OH vitamin D, insulin, CRP, leptin) was assessed in all patients. On day 29, participants with BMI > 25 kg/m2 switched to letrozole 5 mg/day for 4-weeks and blood was drawn upon completion of the study. The change in serum estrogen levels was assessed in these patients (BMI > 25 kg/m2). 112 patients completed days 1-28. The Pearson correlations of estradiol and estrone with BMI or serum 25-OH vitamin D levels were near zero (-0.04 to 0.07, p = 0.48-0.69). Similar results were obtained for correlation with markers of obesity (insulin, CRP, and leptin) with estradiol and estrone (-0.15 to 0.12; p = 0.11-0.82). Thirty-one patients (BMI > 25 kg/m2) completed the interventional component; Increasing the dose of letrozole did not further reduce estradiol or estrone levels (change 0.1 and 0.4 pmol/L respectively; p = 0.74 and 0.36). There was no observed association between markers of obesity (BMI, insulin, leptin, and CRP), serum 25-OH vitamin D levels and estradiol or estrone levels. Additionally, an increased dose of letrozole did not further reduce estradiol or estrone levels compared to the standard dose.

The LISA randomized trial of a weight loss intervention in postmenopausal breast cancer

Obesity has been associated with poor breast cancer (BC) outcomes. We investigated whether a standardized, telephone-based weight loss lifestyle intervention in the adjuvant setting would impact BC outcomes. We conducted a multicenter trial randomizing women 1:1 to mail-based educational material alone (control) or combined with a standardized, telephone-based lifestyle intervention that focused on diet, physical activity, and behavior and involved 19 calls over 2 years to achieve up to 10% weight loss. In all, 338 (of 2150 planned) T1-3, N0-3, M0 hormone receptor positive BC patients with body mass index (BMI) ≥24 kg/m2 receiving adjuvant letrozole were randomized (enrolment ended due to funding loss). The primary outcome was disease-free survival (DFS); secondary outcome was Overall Survival (OS). At 8 years' median follow-up, in a planned analysis, DFS and OS were compared using the Kaplan-Meier method. Baseline BMI and other characteristics were similar between study arms. In all, 22 of 171 (12.9%) in the lifestyle intervention arm versus 30 of 167 (18.0%) in the education had DFS events; the hazard ratio (HR) was 0.71 (95% confidence interval [CI]: 0.41-1.24, p = 0.23). Although loss of funding reduced sample size, we view these hypothesis generating results as compatible with our hypothesis of a potential beneficial effect of a lifestyle intervention on DFS. They provide support for completion of ongoing randomized controlled trials of the effect of lifestyle interventions in BC outcomes.

Abstract P3-02-02: CD68-positive crown-like structures of the breast are independently associated with adverse survival: A retrospective analysis of cases from a prospective cohort

Introduction: The association of breast cancer (BC) with obesity is complex and multifactorial, depending partly on diet and related metabolic imbalances. Previous reports have shown that local inflammation in adipocytes can be seen in tissue sections as rings of macrophages of macrophages around necrotic adipocytes (“Crown-Like Structures of the Breast”, CLS-B). We and others have shown that CLS-B have higher prevalence and density within the adipose tissue of obese patients. Our goal was to examine the association of CLS-B with survival in participants enrolled at one center (Mount Sinai Hospital, Toronto) of a multicenter prospective cohort study designed to investigate obesity-related prognostic factors in early stage BC.

Design: Archived H&E sections of breast adipose tissue were retrieved from Mount Sinai (Toronto) participants (N=163). All specimens were from breast excisions for invasive carcinoma. A CLS-B was defined as a ring of macrophages surrounding an adipocyte in otherwise normal breast tissue. In a subset (N=119), immunostains for CD68 were performed on a representative block to highlight macrophages. Sections containing tumor, fat necrosis, and mastitis were excluded. Slides were pathologist-reviewed, recording the number of CLS-B, slides containing CLS-B, and slides with normal tissue. Serologic markers of metabolism and inflammation were previously performed in a central laboratory. Correlations with clinical and serologic markers were examined using descriptive statistics and Wilcoxon tests. Survival analysis was performed with Cox proportional hazards models.

Results: CLS-B were identified in routine H&E sections of normal fat in 59 out of 163 cases (36%). In the representative subset stained for CD68 (N=119), 22 cases were identified as positive for CLS-B by both H&E and CD68, 15 cases by CD68 alone and 24 by H&E alone, giving a CLS-B prevalence of 39% as detected by H&E, 31% by CD68 and 51% when combining the two. Both i) CD68-positive and ii) H&E-positive CLS-B showed similar positive relationships with BMI (median BMI 27 versus 24 kg/m2, P&lt;0.01 for CLS-B present versus absent); however the relationship with insulin was stronger for CD68-positive CLS-B (median insulin 49 vs 35 pmol/L, P=0.009) than for H&E-positive CLS-B (insulin 39 vs 35 pmol/L, P=0.39).

Univariable Cox model hazard ratios (HRs) for CD68-positive CLS-B were 2.79 (95% confidence interval (CI) 1.31-5.95) and 3.74 (CI 1.73-8.07) for disease-free and overall survival respectively, and after adjustment for age, nodal status, tumour grade, stage, ER/PR status, adjuvant treatment and BMI, HRs were 2.43 (CI 1.01-5.81) and 3.19 (CI 1.3-7.79). In the same subset, H&E-positive CLS-B had univariable HRs of 0.66 (CI 0.29-1.52) and 1.18 (CI 0.55-2.54) respectively and adjusted HRs of 0.31 (CI 0.11-0.82) and 0.57 (CI 0.23-1.39). Combining H&E and CD68 did not improve prediction over using CD68 alone.

Conclusion: CLS-B visualized by the macrophage immunostain CD68 were associated with poor outcome, independent of patient BMI and tumour characteristics. Detection of CLS-B using H&E alone was not associated with poor outcome. Our results demonstrate that although CLS-B are a phenotype of obesity, they may also reflect a tissue-specific risk of adverse BC outcome. This risk may relate to localized tissue inflammation with higher prevalence in obese individuals. Although we do not advocate the clinical use of the CD68 stain, further work is warranted to clarify the connection between tissue inflammation and poor breast cancer outcome.

Acknowledgement: The authors wish to acknowledge the Hold'Em For Life Charity Challenge for Cancer Research for their generous support.

Citation Format: Martin C. Chang, Marguerite Ennis, Zohreh Eslami, Pamela J. Goodwin. CD68-positive crown-like structures of the breast are independently associated with adverse survival: A retrospective analysis of cases from a prospective cohort [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-02-02.

Toronto Workshop on Late Recurrence in Estrogen Receptor-Positive Breast Cancer: Part 2: Approaches to Predict and Identify Late Recurrence, Research Directions

Late disease recurrence (more than 5 years after initial diagnosis) represents a clinical challenge in the treatment and management of estrogen receptor-positive breast cancer (BC). An international workshop was convened in Toronto, Canada, in February 2018 to review the current understanding of late recurrence and to identify critical issues that require future study. The underlying biological causes of late recurrence are complex, with the processes governing cancer cell dormancy, including immunosurveillance, cell proliferation, angiogenesis, and cellular stemness, being integral to disease progression. These critical processes are described herein as well as their role in influencing risk of recurrence. Moreover, observational and interventional clinical trials are proposed, with a focus on methods to identify patients at risk of recurrence and possible strategies to combat this in patients with estrogen receptor-positive BC. Because the problem of late BC recurrence of great importance, recent advances in disease detection and patient monitoring should be incorporated into novel clinical trials to evaluate approaches to enhance patient management. Indeed, future research on these issues is planned and will offer new options for effective late recurrence treatment and prevention strategies.

Toronto Workshop on Late Recurrence in Estrogen Receptor-Positive Breast Cancer: Part 1: Late Recurrence: Current Understanding, Clinical Considerations

Disease recurrence (locoregional, distant) exerts a significant clinical impact on the survival of estrogen receptor-positive breast cancer patients. Many of these recurrences occur late, more than 5 years after original diagnosis, and represent a major obstacle to the effective treatment of this disease. Indeed, methods to identify patients at risk of late recurrence and therapeutic strategies designed to avert or treat these recurrences are lacking. Therefore, an international workshop was convened in Toronto, Canada, in February 2018 to review the current understanding of late recurrence and to identify critical issues that require future study. In this article, the major issues surrounding late recurrence are defined and current approaches that may be applicable to this challenge are discussed. Specifically, diagnostic tests with potential utility in late-recurrence prediction are described as well as a variety of patient-related factors that may influence recurrence risk. Clinical and therapeutic approaches are also reviewed, with a focus on patient surveillance and the implementation of extended endocrine therapy in the context of late-recurrence prevention. Understanding and treating late recurrence in estrogen receptor-positive breast cancer is a major unmet clinical need. A concerted effort of basic and clinical research is required to confront late recurrence and improve disease management and patient survival.

A phase II randomized clinical trial of the effect of metformin versus placebo on progression-free survival in women with metastatic breast cancer receiving standard chemotherapy

OBJECTIVES

Pre-clinical data suggest metformin might enhance the effect of chemotherapy in breast cancer (BC). We conducted a Phase II randomized trial of chemotherapy plus metformin versus placebo in metastatic breast cancer (MBC).

MATERIAL AND METHODS

In this double blind phase II trial we randomly assigned non-diabetic MBC patients on 1st to 4th line chemotherapy to receive metformin 850 mg po bid or placebo bid. Primary outcome was progression-free survival (PFS); secondary outcomes included overall survival (OS), response rate (RR), toxicity and quality of life (QOL). With 40 subjects and a type-one error of 0.2 (one-sided), a PFS hazard ratio (HR) of 0.58 could be detected with 80% power.

RESULTS

40 patients were randomized (22 metformin, 18 placebo) with a mean age of 55 vs 57 years and ER/PR positive BC in 86.4% vs 83.3% off metformin vs placebo, respectively. Mean BMI was 27kg/m2 in both arms. The majority of patients were on 1st line chemotherapy. Grade 3-4 toxicity occurred in 31.8% (metformin) vs 58.8% (placebo). Best response: Partial response 18.2% metformin vs 25% placebo, stable disease 36.4% metformin vs 18.8% placebo, progressive disease 45.4% metformin vs 56.2% placebo. Mean PFS was 5.4 vs 6.3 months (metformin vs placebo), HR 1.2 (95% CI 0.63-2.31). Mean OS was 20.2 (metformin) vs 24.2 months (placebo), HR 1.68 (95% CI 0.79-3.55).

CONCLUSION

In this population metformin showed no significant effect on RR, PFS or OS. These results do not support the use of metformin with chemotherapy in non-diabetic MBC patients.

Abstract P1-16-03: Phase II randomized clinical trial (RCT) of metformin (MET) vs placebo (PLAC) in combination with chemotherapy (CXT) in refractory locally advanced (LABC) or metastatic breast cancer (MBC)

Background: MET treatment of diabetes is associated with improved BC outcomes. Hirsch et al (Cancer Res 2009;69:7505-7511) suggested MET may act synergistically with CXT in BC rodent models. We conducted a double-blind Phase II RCT of CXT plus MET vs placebo in LABC/MBC.

Methods: Non-diabetic BC patients (pts) about to commence 1st-4th line CXT (prespecified anthracycline, taxane, vinorelbine, platinum or capecitabine; HER2 Rx permitted) for MBC or refractory LABC (any ER, PgR, HER2) were eligible if (i) age 18-75, (ii) ECOG 0-2, (iii) adequate hepatic, renal, bone marrow, cardiac function and (iv) measurable or evaluable disease. Those with CNS metastases, recent MET use or radiotherapy to target lesions, intake of ≥ 3 alcoholic drinks/day, history of lactic acidosis or current/planned pregnancy or lactation were ineligible. Randomization was to MET 850 mg po bid (or identical PLAC bid) with a 2 day ramp up of one tablet/day; dose was reduced/drug discontinued in a pre-specified manner for grade 2-4 toxicity. Disease status and toxicity/HRQOL were assessed at baseline and q9 weeks until progression. Primary outcome was progression-free survival (PFS); secondary outcomes included survival (OS), response and toxicity. With 40 subjects and type one error 0.2 (1-sided), a PFS HR of 0.58 could be detected with 80% power. PFS was analyzed using Cox proportional hazards regression.

Results: 40 pts were randomized (22 MET, 18 PLAC). Mean age 55.4 vs 56.9 years; ER/PgR+ in 86.4 vs 83.3%; time from 1st metastases to randomization 297 vs 405 days, in MET vs PLAC respectively. MET pts were more likely to have visceral metastases (95.5% vs 72.2% PLAC) and less likely to be HER2+ (9.1% vs 23.5% PLAC). CXT was 1st line in 68.2% MET and 66.7% PLAC pts. Toxicity - # events: Gr 4: 0 MET vs 1 PLAC, Gr 3: 14 MET vs 14 PLAC; Gr 1 or 2: 193 MET (mainly GI) vs 53 PLAC. Best response: PR 18.2% MET vs 22.2% PLAC, SD 31.8% MET vs 11.1% PLAC, PD 45.4% MET vs 50.0% PLAC, P = 0.41. Mean PFS 164 days MET vs 192 days PLAC; HR (MET vs PLAC) 1.14 (95% CI 0.59-2.2), 1-sided p=0.65. Mean OS 645 MET vs 831 PLAC days; HR (MET vs PLAC) 1.6, 95% CI 0.72-3.54, 1-sided p=0.88.

Conclusion: In these BC pts receiving 1st-4th line CXT, MET (vs PLAC) did not improve response rates, PFS or OS. Gr 1 and 2 toxicity was higher with MET than PLAC. These results do not support use of MET with CXT in refractory LABC/MET BC. MA32, an adjuvant trial of MET vs PLAC in early BC will provide information on MET in the adjuvant setting.

Funded by the Breast Cancer Research Foundation (New York) and Hold'em for Life Charity (Toronto)

Citation Format: Goodwin PJ, Ennis M, Cescon DW, Elser C, Haq R, Hamm CM, Lohmann AE, Pimentel I, Chang MC, Dowling RJ, Stambolic V. Phase II randomized clinical trial (RCT) of metformin (MET) vs placebo (PLAC) in combination with chemotherapy (CXT) in refractory locally advanced (LABC) or metastatic breast cancer (MBC) [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 P1-16-03.

Abstract OT1-12-01: Exploration of factors associated with imminent risk of late recurrence in hormone receptor positive breast cancer

Research objectives: To conduct a prospective observational study of patient and tumor-related factors in women with high risk hormone receptor (HR)+/HER2- breast cancer (BC) following at least 5 years of adjuvant hormonal therapy, in order to identify risk factors for imminent recurrence.

Rationale: Many of the life-threatening BC recurrences in women with HR+HER2- BC take place more than 5 years post-diagnosis, often after completion of adjuvant hormonal therapy. The identification of a biomarker(s) for late BC recurrence could lead to interventional trials to evaluate preventive therapies. We will evaluate whether the presence of blood-based biomarkers [(i) Circulating Tumor Cells (CTCs), (ii) circulating tumor DNA (ctDNA), (iii) tumor markers (CA 15-3, CEA)] and patient factors may predict BC recurrence.

Trial design: A prospective cohort of eligible women with previously treated HR+HER2- BC who have not experienced a distant recurrence will be enrolled; patient and circulating factors will be measured annually until distant recurrence or study completion. Host factors (including BMI, lifestyle, medical illness, surgery, trauma and stress, as well as circulating PlGF, VEGF-1 and inflammatory markers) that may contribute to exit of BC cells from dormancy will also be assessed.

The primary outcome is distant BC recurrence. Any BC event, including loco-regional recurrence, new breast or other primary cancer will be evaluated as a secondary endpoint. Outcomes will be ascertained by regular self-report (via annual telephone calls) and/or physician report and confirmed by medical record review.

Key eligibility criteria: i) Diagnosis of ER and/or PR positive (either or both 10% positive), HER2 negative invasive BC, ii) predicted &gt;1.5-2% annual risk of recurrence (T2, T3 or T4 with any N+;T1 N2+; T2N0 or T1 N1 cancers with high risk genomic scores), iii) receipt of adjuvant endocrine therapy for at least 4 years, with discontinuation planned in the next 12 months or completion of endocrine therapy within the last 5 years, iv) prior adjuvant chemotherapy, targeted therapy and bone targeted therapies are allowed provided they have been completed.

Specific aims: 1) Determine if the presence of (i) CTCs, (ii) ctDNA, (iii) CA15-3 and CEA are associated with imminent risk (within 1-2 years) of distant recurrence in the study population. 2) Identify host factors associated with these blood-based biomarkers, as well as clinical outcomes.

Statistical methods: A matched case control design (matching for time since completion of adjuvant hormone therapy, baseline T, N and grade) will be used to investigate associations of key study variables with imminent risk of distant recurrence within the next 1-2 years. Measurements of patients who do versus do not recur will be compared over the 1-2 years prior to relapse. Each variable will be allocated one third of a study-wide type one error of 0.05 (2-sided). ROC analyses and multivariable modelling will be used to optimize sensitivity, specificity, PPV and NPV. Available questionnaire data will be summarized at all time-points to generate descriptive survivorship data.

Accrual: Starting in August 2018, we plan to recruit 1,000 patients over 2 years at selected Canadian cancer centres.

Citation Format: Jerzak KJ, Cescon DW, Chia SK, Bratman S, Ennis M, Stambolic V, Chang M, Dowling R, Goodwin PJ. Exploration of factors associated with imminent risk of late recurrence in hormone receptor positive 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 OT1-12-01.

Abstract PD6-04: Lifestyle intervention study (LISA) in early breast cancer (BC): An RCT of the effects of a telephone-based weight loss intervention (with educational materials) vs educational materials alone on disease-free survival (DFS)

Background: Obesity has been associated with poor BC outcomes. We investigated whether a standardized, telephone-based weight loss lifestyle intervention in recently diagnosed BC patients would lower recurrence and death rates.

Methods: We conducted a multicenter RCT comparing mail-based educational material alone (control arm) or combined with a standardized, telephone-based lifestyle intervention (19 calls over 2 years, (intervention arm) that focused on diet (500-100 kcal/day deficit), physical activity (150-200 minutes of moderate-intensity activity per week) and behavior (compliance, relapse prevention) to achieve up to 10% weight loss. 338 (of 2150 planned) T1-3, N0-3, M0 ER/PgR+ BC patients with body mass index (BMI) ≥ 24 kg/m2 receiving adjuvant letrozole were randomized Aug 2007 to Jan 2010 (enrolment ended due to funding loss). Primary outcome was DFS; secondary outcome OS. Weight loss (5.3 vs 0.7% at 6 months and 3.6 vs 0.4% at 24 months in the intervention vs control arms, respectively) has been reported (JCO 2014;32:2331). At 8 years median follow-up (May 2018), DFS and OS were compared using Cox proportional hazards regression.

Results: Mean age was 61.6 vs 60.4 years, mean BMI 31.4 vs 31.0 kg/m2 and adjuvant chemotherapy was received by 56.1 vs 57.5% in intervention vs controls arms respectively. T1/T2/T3 66.7/27.5/5.9% vs 61.7/33.5/3.6% and N0/1/2+ 62.6/28.7/8.8 vs 63.5/32.3/4.2% in intervention vs controls arms respectively. HER2+ in 8.8 vs 15.0% (intervention vs control). 20 of 171 (11.7%) in the lifestyle intervention arm vs 30 of 167 (18.0%) in the mail-based arm had DFS events, HR 0.71, 95%CI 0.41-1.24, p=0.23). DFS curves separated at 2 yrs; beyond 3-3.5 yrs separation approximated 5%. In a landmark DFS analysis of women alive at 24 months, DFS HR=0.68 (0.34-1.37, p=0.28).

Conclusions: We identified fewer DFS events in the lifestyle intervention arm. Although loss of funding reduced sample size and lowered power, these results are consistent with a potential beneficial effect of a lifestyle intervention on DFS in postmenopausal ER/PgR+ BC patients. They provide strong support for completion of ongoing RCTs (e.g. BWEL) that will provide definitive evidence regarding the effect of lifestyle based weight loss on BC outcomes.

Funded by Novartis Pharmaceuticals Inc.; Sponsored by the Ontario Clinical Oncology Group

Citation Format: Goodwin PJ, Segal R, Vallis M, Ligibel JA, Pond GR, Robidoux A, Findlay BP, Gralow JR, Mukherjee SD, Levine MN, Pritchard KI. Lifestyle intervention study (LISA) in early breast cancer (BC): An RCT of the effects of a telephone-based weight loss intervention (with educational materials) vs educational materials alone on disease-free survival (DFS) [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 PD6-04.

Association of Metabolic, Inflammatory, and Tumor Markers With Circulating Tumor Cells in Metastatic Breast Cancer

Background

Circulating tumor cells (CTCs) are associated with worse prognosis in metastatic breast cancer (BC). We evaluated the association of metabolic, inflammatory, and tumor markers with CTCs in women with metastatic BC before commencing a new systemic therapy.

Methods

Ninety-six patients with newly diagnosed or progressing metastatic BC without current diabetes or use of anti-inflammatory agents were recruited from four Ontario hospitals. Women provided fasting blood for measurement of metabolic, inflammatory, and tumor markers and CTCs. CTCs were assayed within 72 hours of collection using CellSearch. Other blood was frozen at –80°C, and assays were performed in a single batch. Associations between CTC counts with study factors were evaluated using Spearman correlation, and the chi-square or Fisher exact test. All statistical tests were two-sided and P value ≤ .05 was considered statistically significant.

Results

The median age was 60.5 years; 90.6% were postmenopausal. The cohort included hormone receptor–positive (87.5%), HER2–positive (15.6%), and triple-negative (10.4%) BCs. Patients were starting firstline (35.5%), second-line (26.0%), or third-or-later-line therapy (38.5%). CTC counts (per 7.5 mL of blood) ranged from 0 to 1238 (median 2); an elevated CTC count, defined as five or more CTCs, was detected in 42 (43.8%) patients. Those with liver metastases (vs not) more frequently had an elevated CTC count (59.0% vs 33.3%, P = .02). CTCs were significantly associated with C-reactive protein (R = .22, P = .02), interleukin (IL)-6 (R = .25, P = .01), IL-8 (R = .38, P = .0001), plasminogen activator inhibitor 1 (R = .31, P = .001), carcinoembryonic antigen (R = .31, P = .002), and cancer antigen 15-3 (R = .40, P = .0001) and inversely associated with body mass index (R = –.23, P = .02) and leptin (R = –.26, P = .01).

Conclusions

CTC counts were positively associated with tumor and inflammatory markers and inversely associated with some metabolic markers, potentially reflecting tumor burden and cachexia.

Abstract P3-08-08: Prognostic associations of plasma hepcidin in early breast cancer (BC)

Background: Intra-tumor RNA expression of hepcidin has been linked to adverse metastasis-free survival in women with early BC, but the prognostic implications of this inflammatory marker and iron-regulating peptide are unknown.

Methods: Using an ELISA assay, we measured plasma hepcidin in the banked blood of 518 women who were recruited from 1989-1996 for a prospective cohort study regarding diet and lifestyle factors in BC. Blood had been obtained 4-12 weeks post-operatively and prior to treatment with radiation, chemotherapy or hormonal therapy. Women ages 18 to 75 with T1-3, N0-1, M0 BC who underwent surgery and axillary dissection were included; those with metabolic disorders were excluded. Tumor size, grade and ER/PR expression were abstracted from pathology reports; HER2 status was unknown. Median follow-up was 12.1 years (range, 0.2 to 17 years).

Univariable Cox regression models were used to determine the association between hepcidin and i) time to distant BC recurrence (primary outcome), and ii) time to death due to any cause. Multivariable Cox proportional hazards models were adjusted for age (continuous), T stage (T2, T3, Tx vs T1), tumor grade (3 vs 2 or 1), N stage (node positive vs negative), ER/PR expression (both ER and PR negative vs either positive) a-priori. Associations between hepcidin and CRP, IL6, insulin, cholesterol, glucose, vitamin D, total iron, transferrin, and soluble transferrin receptor; sTfR were explored (Pearson's coefficients).

Results: Hepcidin ranged from 4.70-190.70 ng/L (median 16.25; IQR 16.40 ng/L). To ensure normal distribution, a transformed [-1/sqrt (x)] hepcidin variable was used for prognostic analyses. Average age was 50.3±9.7 years. 16% were obese [body mass index (BMI) &gt;30kg/m2], 30% (n=156) were node positive, 35% (n=181) had grade 3 tumors and 71% (n=370) had ER and/or PR positive tumors. 77% underwent a lumpectomy, 73% (n=380) received adjuvant radiotherapy and 39% (n=203) received adjuvant chemotherapy.

Plasma hepcidin was not univariably associated with either time to distant BC recurrence (HR for 75th percentile versus 25th 1.20; 95%CI 0.79-1.32) or time to death due to any cause (HR 1.23; 95%CI 0.95-1.59) in the overall cohort; multivariable results were similar. In pre-planned analyses, the prognostic association of hepcidin differed by BMI (≤30 vs &gt;30 kg/m2; interaction p-values &lt;0.05): among obese women, higher hepcidin was significantly associated with a shorter time to distant BC recurrence in both univariable (HR 1.81; 95%CI 1.06–3.10) and multivariable (HR 1.84; 95%CI 1.04–3.25) models. Higher hepcidin was associated with shorter time to death due to any cause in a univariable model (HR 1.91; 95%CI 1.13–3.22) but not in a multivariable analysis. There was a moderate association between hepcidin and total iron (r=0.35), transferrin (r=0.43) and sTfR (r=-0.39); associations with IL6, CRP and metabolic factors were very weak (r&lt;0.2).

Conclusion: Higher plasma hepcidin was independently associated with a shorter time to distant BC recurrence in obese women but not in the overall cohort. Further investigation of hepcidin and mechanisms linking it to adverse BC outcomes is warranted.

Citation Format: Jerzak KJ, Lohmann AE, Ennis M, Nemeth E, Ganz T, Goodwin PJ. Prognostic associations of plasma hepcidin in early breast cancer (BC) [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 P3-08-08.

Abstract P6-12-22: Sexual health in long-term breast cancer survivors

Background Significant sexual dysfunction is reported in women with breast cancer (BC) in the years following diagnosis. It is unclear whether symptoms persist over time in BC survivors (BCS) as long-term data compared to healthy controls is lacking. We compared sexual functioning in long-term BCS to controls and explored the impact of adjuvant therapy on sexual health. Methods A cohort of women with localized BC recruited from 1989 to 1996 was prospectively followed as previously described. BCS without recurrence and controls without BC were contacted between 2005 and 2007 and answered self-reported quality of life questionnaires. Sexual health was measured with the Sexual Activity Questionnaire (SAQ). Vasomotor, gynecological and bladder symptoms were scored using the Menopausal Symptom Scale (scale ranges 0-4) based on the Breast Cancer Prevention Trial Symptom Checklist. Regression analysis was used to compare groups, with and without adjustment for age (quadratic) and menopausal status. P values &lt;0.05 were considered significant. Results 248 of 285 BCS and 159 of 167 controls completed the SAQ. The median time from diagnosis of BCS was 12.5 years. BCS were slightly older (61.9 vs 59.1 years, p=0.0004) and somewhat more likely to be post-menopausal (94.4 vs 85.5%, p=0.0025) than controls. Overall, fewer BCS were sexually active than controls (45.2 vs 59.7%, p=0.0041). This difference was no longer significant when adjusted for age and menopausal status (odds ratio 0.68, p=0.075). In those sexually active, no significant differences were noted on the SAQ Pleasure and Discomfort scales.Differences in adjuvant treatment were not significantly associated with being sexually active or the SAQ subscales. BCS scored higher (worse) on the gynecological and bladder symptom scale than controls (0.66 vs 0.43, p=0.0036, adjusted difference 0.24, p=0.0029; 0.60 vs 0.41, p=0.02, adjusted difference 0.18, p=0.029 respectively), but no difference was seen in vasomotor scores. Gynecological symptom scores were greatest in BCS who received adjuvant chemotherapy. Conclusion Despite more frequent long-term gynecological and bladder symptoms, sexual health is similar in BCS and controls. Adjuvant chemotherapy is associated with persistent gynecological symptoms and interventions aimed at improving these could improve quality of life.

Citation Format: Soldera SV, Ennis M, Lohmann AE, Goodwin PJ. Sexual health in long-term breast cancer survivors [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 P6-12-22.

Weight management and physical activity throughout the cancer care continuum

Mounting evidence suggests that weight management and physical activity (PA) improve overall health and well being, and reduce the risk of morbidity and mortality among cancer survivors. Although many opportunities exist to include weight management and PA in routine cancer care, several barriers remain. This review summarizes key topics addressed in a recent National Academies of Science, Engineering, and Medicine workshop entitled, "Incorporating Weight Management and Physical Activity Throughout the Cancer Care Continuum." Discussions related to body weight and PA among cancer survivors included: 1) current knowledge and gaps related to health outcomes; 2) effective intervention approaches; 3) addressing the needs of diverse populations of cancer survivors; 4) opportunities and challenges of workforce, care coordination, and technologies for program implementation; 5) models of care; and 6) program coverage. While more discoveries are still needed for the provision of optimal weight-management and PA programs for cancer survivors, obesity and inactivity currently jeopardize their overall health and quality of life. Actionable future directions are presented for research; practice and policy changes required to assure the availability of effective, affordable, and feasible weight management; and PA services for all cancer survivors as a part of their routine cancer care. CA Cancer J Clin 2018;68:64-89. © 2017 American Cancer Society.

Abstract P6-02-03: Leptin receptor (OB-R) in breast carcinoma tissue: Ubiquitous expression and correlation with leptin-mediated signaling, but not with systemic markers of obesity

Background/Aims: Obesity is associated with a 30-50% increased risk of breast-cancer (BC) mortality, most consistently in estrogen receptor (ER) positive disease, through unclear mechanisms. Leptin is a multi-functional protein with key actions on adipose tissue. In pre-clinical studies, leptin stimulates the growth, survival, and progression of BC cells through both estrogen dependent and other (e.g. JAK/STAT, PI3K/Akt, MAPK) pathways. Leptin has also been associated with increased BC risk and poor prognosis. Our aim was to correlate tumor leptin-receptor (OB-R) expression with tissue markers of cell signaling and systemic markers of obesity, inflammation, and metabolism in a cohort of ER+/HER2- BC patients.

Methods: From our biorepository, we identified ER+/HER2- BC patients having both blood and tissue samples available. Data included BMI, menopausal status, and family/cancer/medical history, tumor histology, grade, stage, and ER/PgR/HER2 status. We performed blood assays for factors related to inflammation, tumor growth, hormonal regulation, and metabolism (see below). Immunohistochemistry for OB-R, pAkt (S473), pERK (T202/Y204), and insulin-receptor (IR) was performed on archived tissue, and scored for % positive cells and intensity of staining. Allred and H-scores were calculated. Associations with OB-R scores were calculated using Pearson, Spearman, and χ2 methods.

Results: 129 patients were eligible; 69.8% were post-menopausal and mean BMI was 27.8 ± 6.5 kg/m2. Most tumors were no-special-type (79%), PgR+ (90%), and node-neg (78%). The tissue expression of OB-R and other markers was scorable in 118 (91%) cases.

OB-R was expressed in all 118/118 cancers (Allred score range: 3 to 8; median 7, mean 6.61). High blood leptin did not downregulate OB-R (Spearman R=0), even though leptin was strongly correlated with BMI (Pearson r=0.78, p&lt;0.00001). Increasing OB-R correlated with phosphorylation of Akt (R=0.19) but not ERK (R=0.08). By contrast, high BMI was associated with lower Akt (R=-0.18) and ERK (R=-0.11) phosphorylation.

OB-R correlated with ER (Spearman R = 0.27), PgR (R=0.29), and insulin receptor (R = 0.24), weakly correlated with estradiol (Spearman, R=0.11) and fasting glucose (R=0.18), and negatively correlated with systemic IL-2 (R=-0.11) and IL-6 (R=-0.21). OB-R was not correlated with other blood markers (insulin, HOMA, PAI-1, IL-1ẞ, IL-8, VEGF, EGF, TNF-α,hsCRP, SHBG, or estrogens) or tumor grade.

Conclusions: OB-R is highly expressed in breast tumor tissue even in non-obese patients. Although leptin and BMI did not modulate OB-R expression, downstream signaling (e.g. Akt, ERK) did show a BMI-dependent effect, albeit of limited magnitude. This suggests that leptin acts on breast cancer cells through OB-R activation and downstream Akt/ERK signaling, without a coupled change in total OB-R expression. Further work is needed to elucidate the roles of inflammation, estrogens, and regulatory mechanisms within the PI3K-PTEN and Ras-MAPK cell-signaling networks.

The authors wish to acknowledge the generous support of the Breast Cancer Research Foundation and Hold'Em For Life Charity Challenge.

Citation Format: Chang MC, Ennis M, Dowling RJO, Stambolic V, Goodwin PJ. Leptin receptor (OB-R) in breast carcinoma tissue: Ubiquitous expression and correlation with leptin-mediated signaling, but not with systemic markers of obesity [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 P6-02-03.

Abstract P1-02-03: Circulating inflammatory markers, growth factors, and tumor associated antigens in women with early stage breast cancer receiving neoadjuvant metformin

Background: Numerous clinical studies have reported that diabetic patients receiving metformin exhibit decreased cancer incidence and cancer related mortality. Metformin's mechanism of anti-tumor action has been attributed to both direct effects on cancer cells and systemic changes in insulin metabolism. Indeed, metformin reduces circulating insulin levels, which may be integral to its effectiveness in the breast cancer (BC) setting where hyperinsulinemia is associated with both recurrence and death. While the impact of metformin on blood glucose and insulin is well documented, its effects on other systemic physiologic and inflammatory factors are unknown. We completed a neoadjuvant "window of opportunity" study of metformin in non-diabetic women with BC and a series of analyses were performed on plasma samples to assess the impact of metformin on circulating inflammatory markers, growth factors, and tumor associated antigens.

Methods: Non-diabetic women with early stage, untreated BC were given metformin 500 mg tid for ≥2 weeks post diagnostic core biopsy until surgery. Fasting blood was collected at diagnosis and surgery to assess circulating markers pre- and post-metformin administration. Plasma was isolated from blood samples and evaluated for CRP, TNF-alpha, IL-6, IL-8, VEGF, EGF, PlGF (placenta growth factor), CA15-3, and SHBG (sex hormone binding globulin). Change scores (post-metformin minus pre-) were calculated and the degree of change characterized by the median change and the rank-biserial correlation. The Wilcoxon signed-rank test was used to test the null hypothesis that the change scores were symmetrically distributed around zero versus more positive or negative change.

Results: A total of 39 patients (mean age 51 years) completed the study and received metformin for a median of 18 days (range 13-40). Metformin was associated with changes in the levels of growth factors, with increases seen in EGF (median increase 1.1 pg/mL, r=0.42, p=0.027) and VEGF (1.7 pg/mL, r=0.31, p=0.09). A reduction in PlGF levels (-0.18 pg/mL, r=-0.6, p=0.0028) was also observed. The tumor associated antigen CA15-3 was significantly reduced after metformin treatment (-0.4 pg/mL, r=-0.56, p=0.0024) and a marker of sex hormone bioavailability (SHBG) was increased (2 nM, r=0.30, p=0.1). For circulating inflammatory markers, a significant increase in the levels of IL-8 (0.8 pg/mL, r=0.36, p=0.048) was observed, but changes in TNF-alpha and IL-6 were minimal (TNF-alpha 0.2 pg/mL, r=0.20, p=0.29; IL-6 0.1 pg/mL, r=0.14, p=0.46) and no change was seen in CRP (0 mg/L, r=-0.05, p=0.93).

Conclusions: Short-term metformin administration was associated with alterations in systemic physiologic and inflammatory factors. Such increases in circulating cytokines and growth factors indicate possible alterations in the inflammatory state of the host and/or tumor. Of note, the reduction seen in the tumor antigen CA15-3 may reflect a disease-modifying effect of metformin in BC.

The authors wish to acknowledge the generous support of the Hold'Em For Life Charity Challenge and the Breast Cancer Research Foundation.

Citation Format: Dowling RJ, Niraula S, Chang MC, Ennis M, Stambolic V, Goodwin PJ. Circulating inflammatory markers, growth factors, and tumor associated antigens in women with early stage breast cancer receiving neoadjuvant metformin [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 P1-02-03.

Abstract P1-01-01: Circulating tumor cell number and CTC-endocrine therapy index predict clinical outcomes in ER positive metastatic breast cancer patients: Results of the COMETI Phase 2 trial

Introduction: Only half of hormone receptor positive (HR+) metastatic breast cancer (MBC) patients (pts) benefit from endocrine therapy (ET). Circulating tumor cells (CTC) are prognostic in pts with MBC using CellSearch® technology. The CTC-endocrine therapy index (CTC-ETI) provides semi-quantitative analyses of CTC-ER (estrogen receptor), BCL2, HER2, and Ki67 expression. We hypothesized that CTC-ETI high (elevated CTC number and/or low expression of ER and BCL2, and high expression of HER2 and Ki-67) might predict resistance to ET in a prospective, multi-institutional clinical trial: COMETI-P2-2012.0 (NCT01701050).

Methods: 121 pts with ER+, HER2 negative (-), and progressive MBC after one or more lines of ET or within 12 months (mos) of completing adjuvant ET, who were initiating a new ET, were enrolled after informed consent. CTC and CTC-ETI were determined as previously reported (Paoletti C et al, CCR 2015) at baseline (BL), 1, 2, 3, and 12 mos, and/or at the time of progression. Imaging was performed every 3 mos. Association of CTC levels and CTC-ETI with patient outcomes (progression free survival (PFS); rapid progression (RP) defined as progression within 3 mos) was assessed using logrank and Fisher's exact tests. Trial design estimated 85 PFS and 51 RP events, providing &gt;90% power (2-sided a=0.05); pts with unsuccessful BL CTC-ETI or ineligible were unevaluable. Only baseline (BL) data are reported in this abstract.

Results: 32% of enrolled pts had progression within 12 mos of completing adjuvant ET, whereas 40%, 20%, and 8% had 1, 2, ≥3 lines of ET for MBC. CTC-ETI was successfully determined in 93% of pts (90% CI, 88% to 97%). CTC were ≥5 CTC/7.5 ml whole blood in 37/108 (34%) pts evaluable for clinical validity. Elevated CTC was associated with worse PFS (median (m) PFS: 3.3 vs. 5.9 mos; P&lt;0.01). Low, intermediate, and high CTC-ETI were observed in 75 (69%), 6 (6%), and 27 (25%) pts, respectively. CTC-ETI was associated with PFS (logrank P&lt;0.01): pts with low, intermediate, and high CTC-ETI had mPFS of 5.7, 8.5, and 2.8 mos, respectively. In the 96 pts eligible for determination, elevated CTC was associated with RP, (65.6% vs. 42.2%; P=0.05) as was CTC-ETI (P=0.003): 79.2% (95% CI, 57.8% to 92.9%) of pts with high CTC-ETI had RP versus 41.2% (95% CI, 29.4% to 53.8%) with low CTC-ETI; in the small group with intermediate CTC-ETI 1 of 4 pts (25%) had RP.

Conclusions: In this multi-institutional, prospective study, CTC-ETI was accurately determined, confirming the previously established analytical validity of the assay, meeting the primary objective of the trial. Elevated CTC and CTC-ETI high compared to low were associated with poor outcomes to ET. CTC-ETI distribution resulted in a small number of patients assigned to the intermediate group, restricting our ability to associate this group with outcomes. These results suggest that CTC-biomarker phenotype and enumeration have clinical validity. CTC-ETI may identify ER+ HER2– MBC pts who are unlikely to benefit from ET and might be better treated with ET in combination with other therapies or proceed to chemotherapy. Further analyses including CTC-ETI at serial time points during ET are planned.

Citation Format: Paoletti C, Regan MM, Liu MC, Marcom PK, Hart LL, Smith II JW, Tedesco KL, Amir E, Krop IE, DeMichele AM, Goodwin PJ, Block M, Aung K, Cannell EM, Darga EP, Baratta PJ, Brown ME, McCormack RT, Hayes DF. Circulating tumor cell number and CTC-endocrine therapy index predict clinical outcomes in ER positive metastatic breast cancer patients: Results of the COMETI Phase 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 P1-01-01.

Obesity and breast cancer - what's new?

Obesity rates are increasing in the developed and developing world; this has implications for breast cancer risk and outcome. Areas covered: Recent advances relating to the association of obesity with breast cancer are reviewed. Expert commentary: Obesity has been associated with increased risk of postmenopausal hormone receptor positive and premenopausal triple negative breast cancer and with poor prognosis of most types of breast cancer. Obese individuals may present with breast cancer at a more advanced stage and their breast cancer may differ biologically from cancers diagnosed in nonobese women. A picture of a complex, multifactorial biology underlying the obesity-cancer link is emerging, with the identification of obesity-associated tissue and systemic changes that are cancer promoting, enhancing proliferation, invasion and metastasis. Intervention research to ascertain effects of weight loss and of pharmacologic interventions that reverse the metabolic changes of obesity is needed.

Association of Obesity-Related Metabolic Disruptions With Cancer Risk and Outcome

Over the past 40 years, the prevalence of obesity has increased epidemically worldwide, which raises significant concerns regarding public health and the associated economic burden. Obesity is a major risk factor for several conditions including cardiovascular disease and type 2 diabetes, and recent evidence suggests that obesity negatively affects cancer risk and outcome. The relationship between obesity and cancer is complex and involves multiple factors both at the systemic and cellular level. Indeed, disruptions in insulin metabolism, adipokines, inflammation, and sex hormones all contribute to the adverse effects of obesity in cancer development and progression. The focus of this review will be the impact of these systemic obesity-related factors on cancer biology, incidence, and outcome. Potential therapeutic interventions and current clinical trials targeting obesity and its associated factors will also be discussed.

Obesity and Breast Cancer Prognosis: Evidence, Challenges, and Opportunities

Purpose To summarize the evidence of an association between obesity and breast cancer prognosis. Methods We reviewed the literature regarding overweight and obesity and breast cancer survival outcomes, overall and with regard to breast cancer subtypes, breast cancer therapies, biologic mechanisms, and possible interventions. We summarize our findings and provide clinical management recommendations. Results Obesity is associated with a 35% to 40% increased risk of breast cancer recurrence and death and therefore poorer survival outcomes. This is most clearly established for estrogen receptor-positive breast cancer, with the relationship in triple-negative and human epidermal growth factor receptor 2-positive subtypes less well established. A range of biologic mechanisms that may underlie this association has been identified. Weight loss and lifestyle interventions, as well as metformin and other obesity-targeted therapies, are promising avenues that require further study. Conclusion Obesity is associated with inferior survival in breast cancer. Understanding the nature and mechanisms of this effect provides an important opportunity for interventions to improve the diagnosis, treatment, and outcomes of obese patients with breast cancer.

Abstract P5-12-02: Effect of 5 vs 2.5 mg/day letrozole on residual estrogen levels in post-menopausal women with high BMI - A prospective crossover study

Background: Some studies have suggested that women with high BMI have less benefit from aromatase inhibitors (AI) vs. tamoxifen as adjuvant treatment for early breast cancer. One possible mechanism for this observation is that complete suppression of estrogen is not achieved in these women with the standard flat dose of AI. We evaluated whether a doubling of letrozole to 5 mg/day for 4 weeks affected residual estrogen levels in this population.

Methods: Post-menopausal women with early breast cancer and BMI&gt;25 already taking adjuvant letrozole for at least 3 months were recruited from medical oncology clinics at 4 sites in Toronto, Canada. Fasting blood samples were collected 24 hours following the last dose at baseline (routine use of own letrozole), after 28 days of monitored adherence to a provided supply of letrozole (Femara) 2.5 mg/day (Part A), and after an additional 28 days of letrozole (Femara) 5 mg/day (Part B). Symptom/quality of life questionnaires were completed at the same timepoints. Estradiol and estrone were measured using a high sensitivity liquid chromatography-tandem mass spectrometry assay. One interim analysis for futility and efficacy was planned after 31 eligible patients had completed the study, using estradiol and O'Brien-Fleming boundaries with an inner wedge.

Results: 36 patients were enrolled and started on study, and 31 eligible patients completed Parts A and B. The 5 non-completers withdrew because of adverse events (n=4, unlikely related to drug) or withdrawal of consent (n=1). Median age was 62 (range 48 to 77) and BMI 28.3 kg/m2 (Range 25.2 to 42.2 kg/m2). One patient had non-postmenopausal estrogen levels at Day 29 and Day 57 and one patient's blood assay was unsuccessful; both were excluded from further analyses. The predetermined stopping rule for futility was met. Estradiol levels (mean±standard deviation) changed from 2.68±0.40 pg/mL at baseline to 2.67±0.59 pg/mL at Day 29 to 2.70±0.53 pg/mL at Day 57. Mean change from Day 29 to Day 57 was 0.03±0.48 pg/mL (95% confidence interval -0.15 to 0.21 pg/mL). Four patients reported new or increased arthralgias (to NCI CTCAE Grade 2 or 3) while taking letrozole 5 mg/day in Part B. There was no association between changes in estradiol levels and either study non-completion or the development of arthralgias. Estrone results were similar.

Conclusion: Increasing letrozole from 2.5 to 5 mg/day did not further suppress estrogen levels in women with BMI&gt;25. It is unlikely that letrozole dosing tailored to body size would improve clinical outcomes. The letrozole 5 mg/day intervention was terminated based on the results of the interim analysis for futility.

Citation Format: Cescon DW, Ennis M, Pritchard KI, Townsley C, Warr D, Elser C, Rao L, Stambolic V, Sridhar S, Goodwin PJ. Effect of 5 vs 2.5 mg/day letrozole on residual estrogen levels in post-menopausal women with high BMI - A prospective crossover study. [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 P5-12-02.

Abstract P5-05-01: Prevalance of crown-like structures of the breast, a histologic biomarker linked to obesity: A retrospective study of 99 cases

Introduction: Breast cancer risk is multifactorial, and depends partly on obesity and related metabolic imbalances, including inflammation. Obesity is increasing worldwide, and is a known cancer risk albeit with complex mechanisms. Previous reports (Morris et al., 2011; Iyengar et al., 2015) indicate that local inflammation can be seen histologically as a rings of macrophages around necrotic adipocytes ("crown-like structures of the breast", CLS-B). Our goal was to determine the prevalence of CLS-B in routine specimens from a cohort of patients with known BMI.

Methods: We retrieved archival H&E slides from a breast cancer cohort (N=99) previously characterized for BMI and fasting plasma/serum metabolic factors. Two pathologists reviewed all available sections of white adipose tissue not adjacent to tumour (median 7 blocks/case), excluding fat necrosis and mastitis, blinded to correlative data/BMI. We recorded the presence/absence and numbers of CLS-B, defined as a continuous ring of macrophages surrounding an adipocyte. Paraffin blocks were available in a subset (N=72) and a representative block was immunostained for CD68 to highlight CLS-B. For all cases, the average fat vacuole size was determined by digital image analysis (NIH ImageJ Software). We performed correlative statistics between CLS-B status and clinical data (χ2, Wilcoxon rank-sum tests).

Results: CLS-B were present in 37 of 99 cases (37%). When present the total number of CLS-B ranged from 1 to 18 (mean=4.3, median=3). CLS-B were detected in 7/10 (70%) patients with BMI &gt;30 vs. 30/89 (34%) with BMI ≤ 30 (p=0.02). CLS-B also trended to higher prevalence in women over 60 compared to women under 60 (12/20, 60% vs. 25/79, 32%, p = 0.063). There was no significant association of CLS-B status with tumor T- and N-stage or grade (all P&gt;0.4). The median C-reactive protein in the group with CLS-B was 1.5 mg/L vs. 0.8 mg/L in the group without CLS-B (P=0.10) There was no significant association of CLS-B with insulin, glucose, HOMA, leptin, adiponectin, total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, or IGF-1 (all P&gt;0.27). The average fat globule area determined by image analysis correlated significantly with BMI (Spearman correlation 0.54, p&lt;0.0001) but not to the presence of CLS-B (p=0.102).

Within the subset immunostained for CD68, 32/72 (44%) had CLS-B on the original H&E sections, whereas 13/72 (18%) had CLS-B on the representative CD68-stained section. This corresponded to a false negative in 22/59 (37%) CD68-negative cases, and increased detection in 3/13 of the CD68-positive cases.

Conclusion: In our cohort, obesity is correlated with elevated tissue inflammation as seen by the presence of CLS-B, but CLS-B is not correlated with metabolic markers. CLS-B are well appreciated on routine H&E sections; however, more work is needed to find a practical approach to both ancillary testing (e.g. CD68) and quantitation. Our work independently confirms the association of CLS-B with obesity, and supports the concept that CLS-B is a tissue biomarker of obesity-related inflammation.

(Z.E. was co-principal author.)

Citation Format: Chang MC, Eslami Z, Ennis M, Goodwin PJ. Prevalance of crown-like structures of the breast, a histologic biomarker linked to obesity: A retrospective study of 99 cases. [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 P5-05-01.

Abstract P2-02-12: Association of inflammatory and tumor markers with circulating tumor cells in metastatic breast cancer

Background: Circulating tumor cells (CTCs) are associated with prognosis in metastatic breast cancer (BC). We evaluated the association of inflammatory/tumor markers and CTCs in women with progressing metastatic breast cancer prior to commencing a new line of systemic therapy.

Methods: From February 2013 to April 2015, 96 patients with metastatic BC about to start a new treatment (due to progression), without current diabetes or use of anti-inflammatory agents, were recruited from four Ontario cancer hospitals. Women provided fasting blood for inflammatory and tumor markers and CTC measurement; CTCs were assayed within 72 hours of collection using CellSearch. Blood was frozen at -80C until assays were performed in a single batch (C-reactive protein (CRP), IL-6, PAI-1, Ca15-3, Ca125, VEGF, TNFa). Associations of CTCs with blood factors were evaluated using Pearson correlation coefficients after transforming the variables to normality. For CTCs the transformation log(x+0.5) was used. Associations with categorical variables were tested using one-way analysis of variance. P values &lt;0.05 were significant.

Results: Median age of patients was 60.5 years, 87 (90.6%) were post-menopausal, 83 (86.5%) had hormone receptor positive BC, 16 (16.7%) HER2 positive BC, 10 (10.4%) triple negative; 75 (78.1%) grade II/III. At the time of CTC measurement, bone, lung, liver and brain metastases were present in 79%, 44%, 40% and 6% of patients respectively, with 54%, 37%, 35% and 3% having progression at these sites respectively. PAI-1 and CA15-3 exceeded the limit of the assay in 11 and 5 cases respectively (the upper limit of the assay was used in the analysis). 33.4% of patients were starting first line therapy, 25% second line and 16.7% third line. CTC counts (per 7.5cc) ranged from 0 to 1238 (median 2, geometric mean 3.63); none were detected in 29 (30.2%) patients, 1 to 4 in 25 (26%) and 5 or more in 42 (43.8%) patients. CTCs were not associated with age, estrogen receptor, progesterone receptor, HER2, line of treatment, lymph-vascular invasion or tumor grade. Compared to metastatic disease at other sites, CTCs were higher in the presence of bone (p=0.027) and liver metastases (p=0.002) and with progressing bone (p=0.018) and liver (p=0.012) metastases. CTCs were significantly associated with CRP (R =0.25, p=0.014), IL-6 (R=0.31, p=0.002), PAI-1 (R=0.31, p=0.002), Ca15-3 (R=0.44, p=&lt;0.0001) and Ca 125 (R=0.21, p=0.04) but not with VEGF and TNFa (R = 0.11, p= 0.29 and R = 0.16, p=0.11, respectively).

Conclusion: CTCs were associated with bone and liver metastases and with higher levels of inflammatory and tumor markers, potentially reflecting tumor burden. Additional inflammatory marker assays are underway. Future studies are warranted to confirm these findings.

Citation Format: Lohmann AE, Chang M, Dowling RJO, Ennis M, Amir E, Elser C, Brezden-Masley C, Vandenberg T, Lee E, Fazae K, Stambolic V, Goodwin PJ. Association of inflammatory and tumor markers with circulating tumor cells in metastatic 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 P2-02-12.