Pan-Cancer Interrogation of B7-H3 (CD276) as an Actionable Therapeutic Target across Human Malignancies

B7-H3 (CD276) is a transmembrane glycoprotein of the B7 immune checkpoint superfamily that has emerged as a promising therapeutic target. To better understand the applicability of B7-H3-directed therapies, we analyzed 156,791 samples comprising 50 cancer types to interrogate the clinical, genomic, transcriptomic, and immunological correlates of B7-H3 mRNA expression. DNA (592-gene/whole-exome) and RNA (whole-transcriptome) sequencing was performed from samples submitted to Caris Life Sciences (Phoenix, AZ). B7-H3 high versus low expression was based on top and bottom quartiles for each cancer type. Patients' overall survival was determined from insurance claims data. Pathway analysis was performed using Gene Set Enrichment Analyses (GSEA). Immune cell fractions were inferred using quanTIseq. B7-H3 is expressed across several human malignancies including prostate, pancreatic, ovarian, and lung cancers. High B7-H3 expression is associated with differences in overall survival, possibly indicating a prognostic role of B7-H3 for some cancers. When examining molecular features across all cancer types, we did not identify recurrent associations between B7-H3 expression and genetic alterations in TP53, RB1, and KRAS. However, we find consistent enrichment of EMT, Wnt, TGF-beta, and Notch signaling pathways. Additionally, tumors with high B7-H3 expression are associated with greater proportions of M1 macrophages, but lower fractions of CD8+ T cells. We have begun to define the genomic, transcriptomic, clinical, and immunological features associated with B7-H3 expression in 50 cancer types. We report novel clinical and molecular features of B7-H3-high tumors which may inform how current B7-H3 therapeutics should be deployed and prioritized.

Germline predictors for bevacizumab induced hypertensive crisis in ECOG-ACRIN 5103 and BEATRICE

BACKGROUND

Bevacizumab is a beneficial therapy in several advanced cancer types. Predictive biomarkers to better understand which patients are destined to benefit or experience toxicity are needed. Associations between bevacizumab induced hypertension and survival have been reported but with conflicting conclusions.

METHODS

We performed post-hoc analyses to evaluate the association in 3124 patients from two phase III adjuvant breast cancer trials, E5103 and BEATRICE. Differences in invasive disease-free survival (IDFS) and overall survival (OS) between patients with hypertension and those without were compared. Hypertension was defined as systolic blood pressure (SBP) ≥ 160 mmHg (n = 346) and SBP ≥ 180 mmHg (hypertensive crisis) (n = 69). Genomic analyses were performed to evaluate germline genetic predictors for the hypertensive crisis.

RESULTS

Hypertensive crisis was significantly associated with superior IDFS (p = 0.015) and OS (p = 0.042), but only IDFS (p = 0.029; HR = 0.28) remained significant after correction for prognostic factors. SBP ≥ 160 mmHg was not associated with either IDFS or OS. A common single-nucleotide polymorphism, rs6486785, was significantly associated with hypertensive crisis (p = 8.4 × 10-9; OR = 5.2).

CONCLUSION

Bevacizumab-induced hypertensive crisis is associated with superior outcomes and rs6486785 predicted an increased risk of this key toxicity.

Tissue-specific thresholds of mutation burden associated with anti-PD-1/L1 therapy benefit and prognosis in microsatellite-stable cancers

Immune checkpoint inhibitors (ICIs) targeting programmed cell death protein 1 or its ligand (PD-1/L1) have expanded the treatment landscape against cancers but are effective in only a subset of patients. Tumor mutation burden (TMB) is postulated to be a generic determinant of ICI-dependent tumor rejection. Here we describe the association between TMB and survival outcomes among microsatellite-stable cancers in a real-world clinicogenomic cohort consisting of 70,698 patients distributed across 27 histologies. TMB was associated with survival benefit or detriment depending on tissue and treatment context, with eight cancer types demonstrating a specific association between TMB and improved outcomes upon treatment with anti-PD-1/L1 therapies. Survival benefits were noted over a broad range of TMB cutoffs across cancer types, and a dose-dependent relationship between TMB and outcomes was observed in a subset of cancers. These results have implications for the use of cancer-agnostic and universal TMB cutoffs to guide the use of anti-PD-1/L1 therapies, and they underline the importance of tissue context in the development of ICI biomarkers.

Concurrent predictors of an immune responsive tumor microenvironment within tumor mutational burden-high breast cancer

Background

Data supporting high tumor mutational burden (TMB-H) as a lone biomarker for an immune-responsive tumor microenvironment (TME) in metastatic breast cancer (MBC) are weak, yet tumor agnostic approval in TMB-H advanced tumors provides immune checkpoint inhibition (ICI) as a clinical option. We evaluated concurrent predictors of immune-responsive and non-responsive TME within MBC.

Methods

Tumor samples from patients with MBC (N=5621) were analyzed by next-generation sequencing of DNA (592-gene panel or whole exome) and RNA (whole transcriptome) at Caris Life Sciences (Phoenix, AZ). TMB-H threshold was set to ≥ 10 muts/Mb. PDL-1 was evaluated using SP142 antibody. Gene expression profiling and RNA deconvolution were used to estimate immune and stromal cell population abundance in the TME, and transcriptomic signature of immunotherapy response (T cell-inflamed score).

Results

461 (8.2%) TMB-H MBC samples were identified. Consistent with prior studies, TMB-H tumors exhibited significant dMMR/MSI-H enrichment (7 vs. 0%, p<0.0001) and PD-L1+ expression (36 vs. 28%, p<0.05) compared to TMB-L. Across all samples, T cell-inflamed scores were weakly correlated with TMB. TMB-H was not associated with significantly increased immune responsive cell types (CD8+ T-cells, NK cells, or B cells) or immune response gene signatures (e.g. antigen presentation), yet positive trends were observed, while immunosuppressive fibroblasts were significantly decreased in TMB-H tumors (0.84-fold change compared to TMB-L, P<0.05). HR+/HER2- breast cancer was the only subtype in which TMB-H tumors exhibited increased T cell-inflamed scores vs. TMB-L. Concurrent PD-L1+ or dMMR/MSI-H with TMB-H was associated with high T cell-inflamed scores in both HR+/HER2- and TNBC. Among several associated biomarkers, B2M mutations and CD274 amplifications were positively associated with T-cell inflamed scores in TMB-H tumors; CDH1 and ERBB2 mutations were negatively associated.

Conclusion

High TMB alone does not strongly correlate with immune infiltrate or immune-related gene signatures in MBC. TMB-H predicts T-cell inflamed signature compared to TMB-L in HR+/HER2- tumors only. Along with MSI-H and PD-L1+, several biomarkers, including B2M mutation and CD274 amplification, may help predict ICI benefit amongst TMB-H tumors. Co-occurring biomarkers within TMB-H breast cancer warrant evaluation in larger cohorts for response or resistance to ICI to develop composite predictive biomarkers in MBC.

Cytochrome P450 Oxidoreductase (POR) Associated with Severe Paclitaxel-Induced Peripheral Neuropathy in Patients of European Ancestry from ECOG-ACRIN E5103

PURPOSE

Paclitaxel is a widely used anticancer therapeutic. Peripheral neuropathy is the dose-limiting toxicity and negatively impacts quality of life. Rare germline gene markers were evaluated for predicting severe taxane-induced peripheral neuropathy (TIPN) in the patients of European ancestry. In addition, the impact of Cytochrome P450 (CYP) 2C8, CYP3A4, and CYP3A5 metabolizer status on likelihood of severe TIPN was also assessed.

EXPERIMENTAL DESIGN

Whole-exome sequencing analyses were performed in 340 patients of European ancestry who received a standard dose and schedule of paclitaxel in the adjuvant, randomized phase III breast cancer trial, E5103. Patients who experienced grade 3-4 (n = 168) TIPN were compared to controls (n = 172) who did not experience TIPN. For the analyses, rare variants with a minor allele frequency ≤ 3% and predicted to be deleterious by protein prediction programs were retained. A gene-based, case-control analysis using SKAT was performed to identify genes that harbored an imbalance of deleterious variants associated with increased risk of severe TIPN. CYP star alleles for CYP2C8, CYP3A4, and CYP3A5 were called. An additive logistic regression model was performed to test the association of CYP2C8, CYP3A4, and CYP3A5 metabolizer status with severe TIPN.

RESULTS

Cytochrome P450 oxidoreductase (POR) was significantly associated with severe TIPN (P value = 1.8 ×10-6). Six variants were predicted to be deleterious in POR. There were no associations between CYP2C8, CYP3A4, or CYP3A5 metabolizer status with severe TIPN.

CONCLUSIONS

Rare variants in POR predict an increased risk of severe TIPN in patients of European ancestry who receive paclitaxel.

Antimicrobial exposure is associated with decreased survival in triple-negative breast cancer

Antimicrobial exposure during curative-intent treatment of triple-negative breast cancer (TNBC) may lead to gut microbiome dysbiosis, decreased circulating and tumor-infiltrating lymphocytes, and inferior outcomes. Here, we investigate the association of antimicrobial exposure and peripheral lymphocyte count during TNBC treatment with survival, using integrated electronic medical record and California Cancer Registry data in the Oncoshare database. Of 772 women with stage I-III TNBC treated with and without standard cytotoxic chemotherapy - prior to the immune checkpoint inhibitor era - most (654, 85%) used antimicrobials. Applying multivariate analyses, we show that each additional total or unique monthly antimicrobial prescription is associated with inferior overall and breast cancer-specific survival. This antimicrobial-mortality association is independent of changes in neutrophil count, is unrelated to disease severity, and is sustained through year three following diagnosis, suggesting antimicrobial exposure negatively impacts TNBC survival. These results may inform mechanistic studies and antimicrobial prescribing decisions in TNBC and other hormone receptor-independent cancers.

Abemaciclib plus fulvestrant in East Asian women with HR+, HER2- advanced breast cancer: Overall survival from MONARCH 2

MONARCH 2 is a global, randomized, double-blind, phase 3 study of abemaciclib/placebo + fulvestrant in patients with hormone receptor positive, human epidermal growth factor receptor 2-negative advanced breast cancer. The East Asian population comprised 212 (31.7%) of the 669 intent-to-treat population in the MONARCH 2 trial. Consistent with the primary analysis, this subpopulation analysis of East Asian patients indicated progression-free survival benefit in the abemaciclib arm. The median overall survival was not reached in the abemaciclib arm and was 48.9 months in the placebo arm (hazard ratio 0.80; 95% confidence interval 0.52-1.24; p = 0.377). In addition, other efficacy endpoints, including time to chemotherapy, chemotherapy free survival, and time to second disease progression, indicated benefit in the abemaciclib arm. This analysis found no new safety concerns with longer follow-up. These findings support the positive benefit-risk balance of the MONARCH 2 regimen in East Asian patients with hormone receptor positive, human epidermal growth factor receptor 2-negative advanced breast cancer.

Patient perspectives on window of opportunity clinical trials in early-stage breast cancer

PURPOSE

Window of opportunity trials (WOT) are increasingly common in oncology research. In WOT participants receive a drug between diagnosis and anti-cancer treatment, usually for the purpose of investigating that drugs effect on cancer biology. This qualitative study aimed to understand patient perspectives on WOT.

METHODS

We recruited adults diagnosed with early-stage breast cancer awaiting definitive therapy at a single-academic medical center to participate in semi-structured interviews. Thematic and content analyses were performed to identify attitudes and factors that would influence decisions about WOT participation.

RESULTS

We interviewed 25 women diagnosed with early-stage breast cancer. The most common positive attitudes toward trial participation were a desire to contribute to research and a hope for personal benefit, while the most common concerns were the potential for side effects and how they might impact fitness for planned treatment. Participants indicated family would be an important normative factor in decision-making and, during the COVID-19 pandemic, deemed the absence of family members during clinic visits a barrier to enrollment. Factors that could hinder participation included delay in standard treatment and the requirement for additional visits or procedures. Ultimately, most interviewees stated they would participate in a WOT if offered (N = 17/25).

CONCLUSION

In this qualitative study, interviewees weighed altruism and hypothetical personal benefit against the possibility of side effect from a WOT. In-person family presence during trial discussion, challenging during COVID-19, was important for many. Our results may inform trial design and communication approaches in future window of opportunity efforts.

Harnessing artificial intelligence to automate delineation of volumetric breast cancers from magnetic resonance imaging to improve tumor characterization

597

Background: Automated breast tumor identification and segmentation in magnetic resonance imaging (MRI) is a difficult and crucial area of study in breast cancer research. Artificial intelligence (AI) models are increasingly being developed for automated localization of lesions in imaging studies to facilitate quantitative assessment of features for improved diagnostic, prognostic and predictive performance. Such models have had success in detecting breast cancers in mammography, ultrasound and CT, but few have achieved three-dimensional (3D) volumetric tumor segmentation from breast MRI. The purpose of this study was to apply two state-of-the-art AI – specifically, deep learning (DL) - algorithms to 3D MRI breast cancer data and identify the higher performing algorithm for precise segmentation of breast tumors. Methods: We evaluated pre-treatment, T1 post-gadolinium contrast enhanced breast MRI from 222 patients with known breast cancers (n = 262). Images were split into training (n = 142), validation (n = 36), and hold-out test (n = 44) datasets. Two DL algorithms, U-Net and VAE-UNet, were trained to classify tumors on the training dataset across 1000 epochs. The output for each is a precise localization and segmentation of each tumor at the pixel level from every MRI image. We evaluated the performance of each algorithm using 5-fold cross-validation and testing on the validation and test sets. We calculated a dice accuracy score for each model as the performance comparison metric. Results: The highest dice accuracy score achieved on the validation dataset by generic U-Net was 83.38%, with an average across 1000 epochs of 62.41%. The highest dice accuracy achieved on the validation dataset by VAE-UNet was 82.62%, with an average across epochs of 61.28%. On our test dataset, the highest dice accuracy score achieved by U-Net was 93.09%, with an average across epochs of 66.31%, and the highest accuracy score for VAE-UNet was 90.98%, with average across epochs of 50.47%. Although U-Net appeared to perform slightly better than VAE-Unet for most cases, there were distinct cases where VAE-UNet outperformed U-Net (dice score up to 59% better than U-Net). Subsequent analysis indicated that VAE-UNet preferentially outperforms U-Net for tumors with low sphericity (p = 0.001). Conclusions: Our results suggest that U-Net is well suited for segmenting breast tumors from breast MRI in most cases, but that VAE-UNet outperforms U-Net when the tumor shapes are less spherical. Our findings could inform the choice of DL algorithms in research and clinical endeavors that rely on accurate breast cancer tumor segmentation. In particular, these two tools could be configured to facilitate tumor assessment from breast MRI in the clinical setting for: breast cancer screening in high-risk patient populations, pre-surgical planning, and monitoring of treatment response.

Optimal timing and interval of imaging for metastatic breast cancer

1106

Background: Breast cancer is a family of diseases with varying disease trajectories based on intrinsic biology of the tumor. The time of progression varies across & within subtypes, and with increasing rates of drug resistance depending on prior therapeutic exposure. There is no strong consensus about optimal surveillance and routine imaging in patients with metastatic breast cancer (mBC), but many oncologists report that monitoring strategies are based on strategies used in clinical trials. Methods: We reviewed 17 prior Phase III studies that led to FDA approval in mBC. We reviewed 8 studies for ER+ mBC, 5 studies for HER2+ mBC, 2 studies for triple negative (TNBC) mBC, and 2 studies for BRCA+ mBC. We calculated rates of progression or death (POD) per month for the first year on therapy using data from survival analysis tables and compared them across the different types and lines of therapy. Results: Risk of progression in mBC varies based on receptor status and line of therapy (Table). There was a significant difference in POD rates between ER+ therapies compared with all other disease types (HER2+, TNBC, BRCA) (p = 0.012). Patients with TNBC or receiving PARP inhibitors or later line HER2 therapies had higher POD rates than those with ER+ breast cancer or receiving first line HER2 therapy (6.9% vs 4.1% per month; p = 0.0004). No significant difference was seen in the monitoring frequency between ER+ and HER2+ disease (p = 0.39). Conclusions: These data suggest that shorter interval imaging should be performed for patients with TNBC or receiving PARP inhibitors or later line HER2 therapies. Surveillance imaging for patients with mBC should be based on disease biology, number of prior regimens, time since initiation of therapy, and regimen efficacy. Current imaging recommendations are not data-based and do not adjust for new agents that have been approved. Oncologists should integrate these into individualized estimates to determine optimum frequency of imaging in clinical practice and research. [Table: see text]

A case-control study of healthcare disparities in sex and gender minority patients with breast cancer

6517

Background: Disparities in the quality of diagnosis and treatment of breast cancer in sex and gender minority (SGM) populations are largely undefined. Only 24% of studies funded by the National Cancer Institute capture data on sexual orientation, while only 10% capture data on gender identity. To address this gap, the National Academies 2020 Report calls for adding sexual orientation and gender identity (SOGI) to ongoing data collection efforts. This case-control study matching SGM patients with breast cancer to cisgender heterosexual controls is the result of linking SOGI data to the Stanford University Healthcare (SHC) Oncoshare breast cancer database, which integrates data from the electronic medical record (EMR) and California Cancer Registry. Methods: An initial database query across the SHC EMR was performed for charts containing SOGI terms in patients with breast cancer seen in SHC Oncology. 686 charts were identified for manual review and after eliminating false positives, the sample was reduced to 92 SGM patients, who were then matched by year of diagnosis, age, stage, ER-status, and HER-2 status to cisgender heterosexual controls within Oncoshare. Additional data on demographics, diagnosis, treatment, and relapse were then manually abstracted from the EMR. Results: The SGM cohort was comprised of 80% lesbians, 13% bisexuals and 6% transgender men. The median age at diagnosis across both groups was 49. SGM patients were 72% white, 4% Asian, 12% Black or Latinx 6% other compared to 63% white, 24% Asian, 6% Black or Latinx, 6% other in the controls (p = 0.0006). Thirteen percent and 32% of SGM patients engaged in risky alcohol and illicit drug use respectively, compared to 3% and 6% of controls (p = 0.028; p < 0.0001). Estrogen exposure risk factors including median age of menarche, first delivery, menopause, and use of exogenous estrogens were balanced between the two groups, but SGM patients had fewer children (median 0 vs 2, p < 0.0001). There was a delay in time to diagnosis from symptom onset in SGM patients versus controls (median 64 days vs 37 days, p = 0.043). There was no difference in surgical approach, use of post-lumpectomy radiation, or use of neoadjuvant chemotherapy for stage III disease. However, SGM patients were less likely to undergo chest reconstruction (55% vs 82%, p = 0.0098) and if ER+, to complete ≥5 years of ER-directed therapy (53% vs 72%, p = 0.048). SGM patients used more alternative medicine (46% vs 29%, p = 0.033) and had a higher rate of documented refusal of recommended oncologic treatments (38% vs 21%, p = 0.0088). Correspondingly, SGM patients experienced a higher recurrence rate (31% vs 14%, p = 0.0124). Conclusions: To our knowledge, this is the first study to examine quality of diagnosis and treatment of breast cancer in SGM patients. Several novel potential healthcare disparities are identified, which should be further evaluated in population-based studies to inform interventions.

Impact of African ancestry on the relationship between body mass index and survival in an early-stage breast cancer trial (ECOG-ACRIN E5103)

BACKGROUND

African ancestry (AA) and obesity are associated with worse survival in early-stage breast cancer. Obesity disproportionately affects women of AA; however, the intersection between ancestry and obesity on breast cancer outcomes remains unclear.

METHODS

A total of 2854 patients in the adjuvant trial E5103 were analyzed. Genetic ancestry was determined using principal components from a genome-wide array. The impact of continuous or binary body mass index (BMI) on disease-free survival (DFS) and overall survival (OS) was evaluated by multivariable Cox proportional hazards models in AA patients and European ancestry (EA) patients.

RESULTS

There were 2471 EA patients and 383 AA patients. Higher BMI was significantly associated with worse DFS and OS only in AA patients (DFS hazard ratio [HR], 1.25; 95% CI, 1.07-1.46; OS HR, 1.38; 95% CI, 1.10-1.73), not in EA patients (DFS HR, 0.97; 95% CI, 0.90-1.05; OS HR, 1.03; 95% CI, 0.93-1.14). Severe obesity (BMI ≥40) was significantly associated with worse survival in AA patients (DFS HR, 2.04; 95% CI, 1.21-3.43; OS HR, 2.21; 95% CI, 1.03-4.75) but had no impact on that of EA patients. In the estrogen receptor-positive (ER+) and triple-negative breast cancer subgroups, BMI was significantly associated with worse outcomes only in those AA patients with ER+ disease. Within the AA group, BMI remained associated with worse survival regardless of the AA proportion.

CONCLUSIONS

Higher BMI was statistically significantly associated with worse breast cancer outcomes in AA but not EA patients. This association was most significant for severe obesity and those with ER+ disease. These observations help define optimal populations for weight change interventions designed to affect disparities and survival in early-stage breast cancer.

LAY SUMMARY

African ancestry and obesity are both risk factors for worse survival after early-stage breast cancer. Women of African descent are also disproportionately affected by obesity; however, it is unclear what impact body weight has on racial disparities in breast cancer. Data from a large phase 3 clinical trial in high-risk, early-stage breast cancer were used to determine how body weight affects survival outcomes in European versus African Americans. Study results demonstrate that a higher body mass index is associated with increased risk of breast cancer recurrence and worse survival in women of African ancestry but not in women of European ancestry.

Targeting HER2-positive metastatic breast cancer with ARX788, a novel anti-HER2 antibody-drug conjugate in patients whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens

TPS1112

Background: The overexpression and/or amplification of human epidermal growth factor receptor 2 (HER2) occurs in approximately 20% of breast cancers (BC) and is a major driver of tumor development and progression. This HER2 subtype confers aggressive tumor behavior and the HER2 receptor remains a valuable target for antibodies, bi-specifics, and antibody drug conjugates (ADC). With advances in targeted therapy, patients with HER2-positive breast cancer (HER2+ BC) may experience an improved prognosis, including survival. Novel HER2-targeted therapies are being investigated to overcome drug resistance and to help mitigate adverse events (e.g., cardiotoxicity). ARX788 is a next-generation ADC using a technology platform whereby a HER2 specific monoclonal antibody is conjugated with Amberstatin269 (AS269), a potent cytotoxic tubulin inhibitor. Site-specificity, high homogeneity, and stable covalent conjugation of ARX788 leads to its slow release and prolonged peak of serum pAF-AS269, which may contribute to the lower systemic toxicity and increased targeted delivery of payload to tumor cells at a lower effective dose compared to other HER2 ADCs. Clinical activity has been seen in Phase I HER2 breast and pan-tumor studies. Methods: Trial Design: ACE-Breast-03 (NCT04829604) is a global, phase 2 study designed to assess anticancer activity and safety of ARX788 in patients with metastatic HER2 positive breast cancer. Patients whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens are eligible. Patients must have adequate organ function. Any brain metastases must be radiographically stable without steroid dependence. Efficacy will be assessed using Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 by imaging every 6 weeks on study. Endpoints include objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), best overall response (BOR), duration of response (DOR), and time to response (TTR). The safety and tolerability profile will be evaluated. Blood samples will be collected at specified time points to determine serum concentrations of ARX788, total antibody, and metabolite pAF-AS269. Potential predictive and/or prognostic biomarkers at baseline and on-treatment will be analyzed for exploratory purposes. Descriptive statistics will be used to evaluate anticancer activity, safety, and tolerability. The study is currently recruiting patients. Please contact breast03trialinquiry@ambrx.com for additional information. Clinical trial information: NCT04829604.

Radiomic features quantifying pixel-level characteristics of breast tumors from magnetic resonance imaging predict risk factors in triple-negative breast cancer

e12612

Background: Computationally derived quantitative imaging (radiomic) features that describe tumor phenotypes at the pixel level have demonstrated associations with clinical characteristics in early investigations of other cancers. This implies that molecular differences among tumors may be reflected in their structure on the scales probed by 3D magnetic resonance imaging (MRI). We investigated whether radiomic features computed over tumor volumes from pre-treatment breast MRI could predict risk factors in triple-negative breast cancer (TNBC). Methods: We evaluated breast tumors on pre-treatment, post-contrast T1-weighted MRI from 156 patients with non-metastatic TNBC who underwent neoadjuvant chemotherapy. Tumor regions of interest were segmented by a convolutional neural network algorithm, with validation by breast radiologists. Features quantifying tumor shape and texture were extracted for the largest tumor present in each patient. We identified 23 principal components (PCs) describing these data within the original 364-dimensional feature space for further analysis. Tumor volume was also extracted for comparison with the shape and texture PCs, clinical variables and outcomes, but was kept separate from other radiomic features, since it directly correlates with clinical stage. We compiled for the cohort clinical variables including demographics, stage, grade, and, where available, absolute lymphocyte count (ALC) and Ki-67, a cellular proliferation index routinely used in clinical practice. We then performed a series of univariate and multivariate regression analyses to identify radiomic PCs and clinical variables that significantly predict patient outcomes, and radiomic PCs that predict established risk factors. Our multivariate analyses utilized 5-fold cross-validation and Monte-Carlo determination of p-values (based on 3000 random samplings from the null hypothesis), to ensure statistical rigor in identifying predictive relationships while correcting for multiple hypothesis testing. Results: Our univariate analyses confirmed expected correlations between: overall survival and pre-treatment tumor volume (p = 0.010); survival and ALC (p = 0.002); and clinical stage and tumor volume (p = 1.2⨉10-7). From our multivariate analysis, shape and texture radiomic features were predictive of: tumor volume (p < 0.001); clinical stage (p < 0.001); and Ki-67 (p = 0.02). We confirmed that Ki-67 was predictive of post-treatment residual cancer (p = 0.014), as has been previously reported. Conclusions: Radiomic features predict breast cancer risk factors that are significant for determining outcomes for TNBC patients. Combinations of radiomic shape and texture features track closely with tumor volumes, stage, and proliferative activity, potentially reflecting underlying molecular evolution.

Assessment of Racial Disparity in Survival Outcomes for Early Hormone Receptor-Positive Breast Cancer After Adjusting for Insurance Status and Neighborhood Deprivation: A Post Hoc Analysis of a Randomized Clinical Trial

IMPORTANCE

Racial disparities in survival outcomes among Black women with hormone receptor-positive breast cancer have been reported. However, the association between individual-level and neighborhood-level social determinants of health on such disparities has not been well studied.

OBJECTIVE

To evaluate the association between race and clinical outcomes (ie, relapse-free interval and overall survival) adjusting for individual insurance coverage and neighborhood deprivation index (NDI), measured using zip code of residence, in women with breast cancer.

DESIGN, SETTING, AND PARTICIPANTS

This was a post hoc analysis of 9719 women with breast cancer in the Trial Assigning Individualized Options for Treatment, a randomized clinical trial conducted from April 7, 2006, to October 6, 2010. All participants received a diagnosis of hormone receptor-positive, ERBB2-negative, axillary node-negative breast cancer. The present data analysis was conducted from April 1 to October 22, 2021.

MAIN OUTCOMES AND MEASURES

A multivariate model was developed to evaluate the association between race and relapse-free interval and overall survival adjusting for insurance and NDI level at study entry, early discontinuation of endocrine therapy 4 years after initiation, and clinicopathologic characteristics of cancer. Median follow-up for clinical outcomes was 96 months.

RESULTS

A total of 9719 women (4.2% [n = 405] Asian; 7.1% [n = 693] Black; 84.3% [n = 8189] White; 4.4% [n = 403] others/not specified) were included; 9.1% of included women [n = 889] were Hispanic or Latino. Median (SD) age was 56 (9.2) years. In multivariate models, Black race compared with White race was associated with statistically significant shorter relapse-free interval (hazard ratio [HR], 1.39; 95% CI, 1.05-1.84; P = .02) and overall survival (HR, 1.49; 95% CI, 1.10-2.99; P = .009), adjusting for insurance and NDI level at study entry and other factors. Although uninsured status was not associated with clinical outcomes, patients with Medicare (HR, 1.30; 95% CI, 1.01-1.68; P = .04) and Medicaid (HR, 1.44; 95% CI, 1.01-2.05; P = .05) had shorter overall survival compared with those with private insurance. Participants living in neighborhoods in the highest NDI quartile experienced shorter overall survival compared with those in the lowest quartile (HR, 1.34; 95% CI, 1.01-1.77; P = .04), regardless of self-identified race.

CONCLUSIONS AND RELEVANCE

The findings of this post hoc analysis of a randomized clinical trial suggest that Black women with breast cancer have significantly shorter relapse-free interval and overall survival compared with White women. Early discontinuation of endocrine therapy, clinicopathologic characteristics, insurance coverage, and NDI do not fully explain the observed disparity.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00310180.

Early Local Therapy for the Primary Site in De Novo Stage IV Breast Cancer: Results of a Randomized Clinical Trial (EA2108)

PURPOSE

Distant metastases are present in 6% or more of patients with newly diagnosed breast cancer. In this context, locoregional therapy for the intact primary tumor has been hypothesized to improve overall survival (OS), but clinical trials have reported conflicting results.

METHODS

Women presenting with metastatic breast cancer and an intact primary tumor received systemic therapy for 4-8 months; if no disease progression occurred, they were randomly assigned to locoregional therapy for the primary site (surgery and radiotherapy per standards for nonmetastatic disease) or continuing sysmetic therapy. The primary end point was OS; locoregional control and quality of life were secondary end points. The trial design provided 85% power to detect a 19.3% absolute difference in the 3-year OS rate in randomly assigned patients. The stratified log-rank test and Cox proportional hazards model were used to compare OS between arms. Cumulative incidence of locoregional progression was compared using Gray's test. Quality-of-life assessment used standard instruments.

RESULTS

Of 390 participants enrolled, 256 were randomly assigned: 131 to continued systemic therapy and 125 to early locoregional therapy. The 3-year OS was 67.9% without and 68.4% with early locoregional therapy (hazard ratio = 1.11; 90% CI, 0.82 to 1.52; P = .57). The median OS was 53.1 months (95% CI, 47.9 to not estimable) in the systemic therapy arm and 54.9 months (95% CI, 46.7 to not estimable) in the locoregional therapy arm. Locoregional progression was less frequent in those randomly assigned to locoregional therapy (3-year rate: 16.3% v 39.8%; P < .001). Quality-of-life measures were largely similar between arms.

CONCLUSION

Early locoregional therapy for the primary site did not improve survival in patients presenting with metastatic breast cancer. Although it was associated with improved locoregional control, this had no overall impact on quality of life.

Abstract P2-01-15: Developing highly sensitive high NGS data efficient ctDNA detection assays for breast cancer surveillance

Introduction: Growing data established the importance of monitoring dynamic changes in circulating tumor DNA (ctDNA) to identify early signs of therapeutic responses, allowing for timely management of treatment to achieve more effective personalized therapy. Higher assay accuracy and consistency, and lower assay cost will support more clinical validation trials and benefit more cancer patients with non-invasive ctDNA NGS tests that can simultaneously map multiple genomic alterations at an affordable price. Method: The NVIGEN X - Precision Cancer Profiling test is a next generation sequencing (NGS) based circulating tumor DNA detection assay using the hybridization capture approach with customized gene panels. Our ctDNA NGS assay was developed with the use of high performance magnetic nanobeads, which enhances assay workflow at key steps including cfDNA extraction, NGS library preparation, and target enrichment. Experiments with individual plasma samples and DNA mutant fragments spiked in plasma samples were carried out to establish the assay performance such as sensitivity, specificity, consistency and data efficiency. NGS data QC metrics of the NVIGEN assay were compared with other assays in peer reviewed publications. Results: We developed a focus 32 gene panel that covers 144 kb of gene regions of clinical significance for breast cancer treatment monitoring and guidance, such as AKT1, ERBB2, PIK3CA, EGFR, ESR1, BRCA1/2, and CD274. Our results demonstrated the capability of NVIGEN X ctDNA NGS assay to detect rare copies (8 cp) of gene mutation at 0.07% MAF from DNA mutant fragments spiked into plasma samples. The NVIGEN X ctDNA NGS assays consistently presented 2-5% duplication rate, &gt;80% on-target rate, &lt;10% CV for key NGS data metrics, and on average required 1.36X paired reads per 1X unique coverage. Compared with the Roche Avenio assays (targeted, expanded and surveillance panels) as published in 2020 which on average required 9.36X paired reads per 1X unique coverage, the NVIGEN X -precision cancer profiling assays demonstrated 85% reduction in NGS data need to generate each unique coverage. Compared with the original Capp-seq data as published in the 2014 Nature Medicine paper which required in average 13.78 or 27.56 paired reads per unique coverage, the NVIGEN X assay demonstrated &gt;90% reduction in NGS data need per unique coverage. Conclusion: The NVIGEN X - Precision Cancer Profiling assay provided high NGS assay performance with high sensitivity, specificity, and consistency, and significantly improved NGS data efficiency. This allows for dramatically reduced assay cost and will help support routine applications of ctDNA NGS tests to improve cancer patient treatment. Experiments of applying NVIGEN X assays for clinical research with patient samples are ongoing and will be presented.

Citation Format: Aihua Fu, Wenwu Cui, Minh V. Ton, Kevan Wang, Weiwei Gu, Tianhong Li, Heather A. Parsons, Minetta C. Liu, George W. Sledge. Developing highly sensitive high NGS data efficient ctDNA detection assays for breast cancer surveillance [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 P2-01-15.

Abstract P1-08-35: Stromal tumor infiltrating lymphocytes analysis by race and ethnicity in triple negative breast cancers from 2 phase III randomized adjuvant breast cancer trials: ECOG-ACRIN E2197 and E1199

Background: Black patients with triple negative breast cancer (TNBC) have worse survival outcomes, even after adjusting for stage at diagnosis, income, insurance status and other socioeconomic factors. Little is known regarding anti-tumor immune responses in Black patients and how these differences affect responses to treatment in TNBC. Limited data exists regarding the stromal tumor infiltrating lymphocytes (sTILs, which are strongly prognostic in TNBC) distribution based on race and ethnicity. Here we evaluate the prevalence, distribution, and prognostic impact of sTILs in TNBC by race/ethnicity from 2 prospective clinical trials of adjuvant anthracycline/taxane-based chemotherapy (E2197 and E1199). Methods: Full-face hematoxylin and eosin-stained sections of 481 tumors from ECOG-ACRIN trials E2197 and E1199 were previously evaluated for density of sTILs and shown to be associated with disease-free survival (DFS), distant recurrence-free interval (DRFI), and overall survival (OS) (Adams, et al JCO 2014). Further analyses were undertaken to evaluate the impact of race/ethnicity. Results: The majority of the 481 TNBC were from White patients (82.3%, n=403); with 12.3% (n=59) Black patients, 1.6% (n=14) other (9 Hispanic, 3 Asian, 2 Other), and 0.5% (n=5) unknown race. Age distribution (mean 49.2 for White and 49.2 for Black) and node negative disease (White 68/403 (42%), Black 24/59 (41%)) were similar. However, tumor size ≤2cm was seen more commonly in White patients (34%, 137/403) compared with Black patients (20%, 12/59). Black patients had a higher proportion of high sTILs (≥30%) with 23.7% (14/59) compared to White patients (11.4%, 46/403). The association of continuous stromal TILs with DFS (hazard ratio for a 10-point difference) was 0.84 (95% CI 0.72, 0.98) for White patients and 0.94 (95% CI 0.73, 1.20) for Black patients [159 DFS events for Whites, 26 DFS events for Blacks]. Conclusions: This is the first dataset from prospective clinical trials evaluating sTILs in TNBC in Black patients. Prevalence of high sTILs was greater in Black patients compared to White patients. The association between increasing sTILs and improved invasive disease-free survival across racial/ethnic groups must be investigated in larger datasets.

Table 1.Race/EthnicityTotal (n=481)White (n=403)Black (n=59)Other (n=19)Mean age49.049.249.245.6T1 (tumor &lt;=2cm)157(32.6%)137 (34.0%)12 (20.3%)8 (42.1%)T2 (tumor &gt;2 and &lt;=5cm)283(58.8%)232 (57.6%)41 (69.5%)10 (52.6%)T3 and T441 (8.5%)34 (8.4%)6 (10.2%)1 (5.3%)Node negative197 (41.0%)168 (41.7%)24 (40.7%)5 (26.3%)Median sTILs (Quartiles)10 (10, 20)10 (10, 20)10 (10,20)20 (10, 30)sTILs = 095 (19.8%)83 (20.6%)10 (16.9%)2 (10.5%)sTILs 10-29%319 (66.3%)274 (68.0%)35 (59.3%)10 (52.6%)sTILs ≥30%67 (13.9%)46 (11.4%)14 (23.7%)7 (36.8%)—sTIL 30-49%,46 (9.6%)32 (7.9%)11 (18.6%)3 (15.8%)—sTIL 50-74%,17 (3.5%)11 (2.7%)3 (5.1%)3 (15.8%)—sTIL 75-100%4 (0.8%)3 (0.7%)01 (5.2%)iDFS (HR for 10% sTIL increase)0.86 (95% CI 0.76, 0.98)0.84 (95% CI 0.72, 0.98)0.94 (95% CI 0.73, 1.20)0.97 (95% CI 0.68, 1.40)DRFI (HR for 10% sTIL increase)0.82 (95% CI 0.68, 0.99)0.79 (95% CI 0.63, 1.00)1.08 (95% CI 0.82, 1.44)0.54 (95% CI 0.32, 0.90)OS (HR for 10% sTIL increase)0.81 (95% CI 0.69, 0.95)0.76 (95% CI 0.62, 0.94)1.01 (95% CI 0.76, 1.35)0.83 (95% CI 0.54, 1.29)

Citation Format: Natalie Klar, Robert J Gray, Sylvia Adams, Joseph A Sparano, Lori J Goldstein, Angela M DeMichele, Antonio C Wolff, Nancy E Davidson, George W Sledge, Sunil S Badve. Stromal tumor infiltrating lymphocytes analysis by race and ethnicity in triple negative breast cancers from 2 phase III randomized adjuvant breast cancer trials: ECOG-ACRIN E2197 and E1199 [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 P1-08-35.

Abstract P1-18-21: Abemaciclib plus fulvestrant or nonsteroidal aromatase inhibitor in participants with HR+, HER2- breast cancer - A pooled analysis of the endocrine therapy-naïve participants with measurable disease in MONARCH 2 and MONARCH 3

Background: Abemaciclib is an oral selective cyclin dependent kinases 4 & 6 inhibitor (CDK4 & 6i), administered on a continuous schedule. Abemaciclib demonstrated significant overall survival (OS) and progression-free survival (PFS) benefit in women with hormone receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) in combination with fulvestrant in MONARCH 2 (M2). Similarly, abemaciclib demonstrated a PFS benefit in women with HR+, HER2- ABC in combination with nonsteroidal aromatase inhibitors (NSAI) in MONARCH 3 (M3). Here, we present the objective response rate (ORR) from the pooled cohort of endocrine-naïve (EN) participants with measurable disease enrolled in M2 and M3 that received abemaciclib. Methods: M2 (NCT02107703) and M3 (NCT02246621) were double-blind, Phase 3 studies in women with HR+, HER2- ABC. In M2, all patients received fulvestrant (500 mg, per label) and were randomized to receive either abemaciclib (150 mg or 200 mg BID) or placebo. 20 EN participants with measurable disease at baseline were enrolled to the abemaciclib arm. A M2 single arm addendum enrolled 90 additional EN participants with measurable disease to abemaciclib. EN M2 participants had received no previous endocrine therapy (ET) in any setting nor prior chemotherapy in the metastatic setting. In M3, all participants received NSAI (anastrozole 1 mg or letrozole 2.5 mg daily) and were randomized to receive abemaciclib (150 mg BID) or placebo based on stratification factors including prior neoadjuvant or adjuvant ET (NSAI, no ET or other) with 142 M3 EN participants with measurable disease randomized to abemaciclib. The population for analysis consisted of a pooled EN cohort from M2 and M3 with measurable disease that received abemaciclib (N=252). The primary endpoint was investigator-assessed ORR (percentage of participants with best response of complete [CR] or partial response [PR]). The secondary endpoints included PFS, clinical benefit rate (CBR = CR + PR + stable disease persistent for ≥6 months), disease control rate (DCR = CR + PR + SD), duration of response (DoR), and safety. Results: 252 EN participants with measurable disease (43.7% M2, 56.3% M3) from 21 countries were included in the analysis population. Median participant age was 59.0 years. Most patients (n=167 [66.3%]) had ≥3 metastatic organ sites involved. In the pooled EN cohort, confirmed ORR was 57.5% (95% CI 51.4-63.6). CBR was 78.6% (95% CI 73.5-83.6) and DCR was 92.9% (95% CI 89.7-96.0). PFS and DoR data for the M2 EN addendum are not yet mature. No new safety signals were observed. The safety profile was consistent with the previously reported M2 and M3 populations. Conclusion: Primary analysis of confirmed ORR in M2 and M3 EN participants with measurable disease compares favorably with previously reported ORR for fulvestrant monotherapy (FALCON study: 46% unconfirmed; FIRST study: 36% unconfirmed) or NSAI (PALOMA-2 study: 44.8% confirmed; MONALEESA-2: 34% unconfirmed) in participants with a similar disease state. The safety profile is similar to that reported in the primary M2 and M3 main studies.

Citation Format: Matthew P. Goetz, Jose Luis Gonzalez Trujillo, Masakazu Toi, Jens Huober, Antonio Llombart-Cussac, Wei Zhang, Holly Knoderer, Nadine Haddad, Gertjan Van Hal, George W. Sledge, Jr. Abemaciclib plus fulvestrant or nonsteroidal aromatase inhibitor in participants with HR+, HER2- breast cancer - A pooled analysis of the endocrine therapy-naïve participants with measurable disease in MONARCH 2 and MONARCH 3 [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 P1-18-21.

Abstract OT1-02-02: A global, phase 2 study of ARX788 in patients with HER2-positive metastatic breast cancer whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens

Background: The HER2 receptor is a cancer driver which is overexpressed on 15-20% of breast cancers. Though historically survival is poor with this disease subtype, HER2+ targeted therapy has improved survival in both early and advanced disease. In spite of this, most patients in the metastatic setting will eventually experience disease progression and death. Therefore, new therapeutic options and innovative treatments are needed for patients with recurrent or refractory disease. ARX788 is a next-generation antibody–drug conjugates (ADC) using a technology platform whereby a HER2 specific monoclonal antibody is conjugated with Amberstatin269, a potent cytotoxic tubulin inhibitor. Site-specific, high homogenous, and stable covalent conjugation in ARX788 leads to slow release and prolonged peak of serum pAF-AS269, which may contribute to the lower systemic toxicity, increased targeted delivery of payload to tumor cells, and lower effective dose compared to other HER2 ADCs.Methods: ACE-Breast-03 (NCT04829604) is a global, single arm, phase 2 study designed to assess anticancer activity and safety of ARX788 in patients with metastatic HER2 positive breast cancer. Patients whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens are eligible. Patients must have adequate organ function and any brain metastasis must demonstrate radiographic stability and lack of steroid dependence. Approximately 200 subjects with advanced HER2-positive breast cancer will be enrolled. ARX788 will be administered as an intravenous (IV) infusion at 1.5 mg/kg as the initial dose on Day 1 of the first 4-week cycle and followed by 1.3 mg/kg at every subsequent 4-week cycle. Efficacy will be assessed using Response Evaluation Criteria in Solid Tumors (RECIST) v 1.1 via imaging every 8 weeks (±7 days) on study and endpoints include objective response rate (ORR), duration of response (DOR), time to response (TTR), best overall response (BOR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). The safety and tolerability profile will be assessed. Blood samples will be collected at specified time points to determine serum concentrations of ARX788 (intact ADC), total antibody, and metabolite pAF-AS269. Biomarkers (e.g., cell-free DNA, serum HER2 extracellular domain, and circulating tumor cells) at baseline and on-treatment will be analyzed for exploratory research. Descriptive statistics will be used to evaluate anticancer activity, safety, and tolerability. The study is currently recruiting patients. Please contact breast03trialinquiry@ambrx.com for additional information.

Citation Format: Janice Lu, Kevin M Kalinsky, Debu Tripathy, George W Sledge, William Gradishar, Ruth O’Regan, Joyce O’Shaughnessy, Shanu Modi, Joshua Drago, Haeseong Park, Amelia McCartney, Sophia Frentzas, Catherine Shannon, Katharine Cuff, Richard Eek, Miguel Idzwan Martin, Giuseppe Curigliano, Guy Jerusalem, Chiun-Sheng Huang, Michael Press, Matt Li, Dong Xu, Cynthia Song, Richard Huhn, Jinchun Yan, Sara Hurvitz. A global, phase 2 study of ARX788 in patients with HER2-positive metastatic breast cancer whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens [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 OT1-02-02.

Inflammatory cytokines and distant recurrence in HER2-negative early breast cancer

Systemic inflammation is believed to contribute to the distant recurrence of breast cancer. We evaluated serum samples obtained at diagnosis from 249 case:control pairs with stage II-III Her2-negative breast cancer with or without subsequent distant recurrence. Conditional logistic regression analysis, with models fit via maximum likelihood, were used to estimate hazard ratios (HRs) and test for associations of cytokines with distant recurrence risk. The only biomarker associated with a significantly increased distant recurrence risk when adjusted for multiple testing was the proinflammatory cytokine IL-6 (HR 1.37, 95% confidence intervals [CI] 1.15, 1.65, p = 0.0006). This prospective-retrospective study provides evidence indicating that higher levels of the cytokine IL-6 at diagnosis are associated with a significantly higher distant recurrence risk.

Clinical Significance of PIK3CA and ESR1 Mutations in circulating tumor DNA: Analysis from the MONARCH 2 Study of Abemaciclib Plus Fulvestrant

BACKGROUND

PIK3CA and ESR1 mutations have been implicated in resistance to endocrine therapy (ET) in HR+, HER2- advanced breast cancer (ABC). Inhibition of CDK4&6 has been hypothesized as a therapeutic strategy to overcome endocrine resistance in patients with PIK3CA- or ESR1-mutant breast cancers. The objective of this exploratory analysis was to assess efficacy of abemaciclib plus fulvestrant in patients with or without PIK3CA or ESR1 mutations in MONARCH 2.

PATIENTS AND METHODS

MONARCH 2 was a global, randomized, double-blind Phase 3 trial of abemaciclib plus fulvestrant in women with HR+, HER2- ABC that had progressed on ET. Patients were randomized 2:1 to receive abemaciclib plus fulvestrant or placebo plus fulvestrant. Exploratory analyses assessed progression-free survival (PFS) and overall survival (OS), and other endpoints, in patients with or without PIK3CA or ESR1 mutations detectable in baseline ctDNA.

RESULTS

Abemaciclib plus fulvestrant improved PFS compared to placebo plus fulvestrant in both PIK3CA-wild-type and PIK3CA-mutant subgroups, as well as both ESR1-wild-type and ESR1-mutant subgroups. Additional endpoints, including OS, were also improved following treatment with abemaciclib plus fulvestrant regardless of PIK3CA or ESR1 mutation status.

CONCLUSION

Abemaciclib plus fulvestrant was effective regardless of PIK3CA or ESR1 mutation status, with benefit in both PFS and OS, with a numerically greater improvement in median PFS relative to placebo plus fulvestrant for PIK3CA or ESR1-mutant tumors compared to the respective wild-type subgroups, in women with HR+, HER2- ABC that had progressed on ET.

Fatigue and endocrine symptoms among women with early breast cancer randomized to endocrine versus chemoendocrine therapy: Results from the TAILORx patient-reported outcomes substudy

BACKGROUND

TAILORx (Trial Assigning Individualized Options for Treatment) prospectively assessed fatigue and endocrine symptoms among women with early-stage hormone receptor-positive breast cancer and a midrange risk of recurrence who were randomized to endocrine therapy (E) or chemotherapy followed by endocrine therapy (CT+E).

METHODS

Participants completed the Functional Assessment of Chronic Illness Therapy-Fatigue, the Patient-Reported Outcomes Measurement Information System-Fatigue Short Form, and the Functional Assessment of Cancer Therapy-Endocrine Symptoms at the baseline and at 3, 6, 12, 24, and 36 months. Linear regression was used to model outcomes on baseline symptoms, treatment, and other factors.

RESULTS

Participants (n = 458) in both treatment arms reported greater fatigue and endocrine symptoms at early follow-up in comparison with the baseline. The magnitude of change in fatigue was significantly greater for the CT+E arm than the E arm at 3 and 6 months but not at 12, 24, or 36 months. The CT+E arm reported significantly greater changes in endocrine symptoms from the baseline to 3 months in comparison with the E arm; change scores were not significantly different at later time points. Endocrine symptom trajectories by treatment differed by menopausal status, with the effect larger and increasing for postmenopausal patients.

CONCLUSIONS

Adjuvant CT+E was associated with greater increases in fatigue and endocrine symptoms at early time points in comparison with E. These differences lessened over time, and this demonstrated early chemotherapy effects more than long-term ones. Treatment arm differences in endocrine symptoms were more evident in postmenopausal patients.

LAY SUMMARY

Participants in TAILORx (Trial Assigning Individualized Options for Treatment) with early-stage hormone receptor-positive breast cancer and an intermediate risk of recurrence were randomly assigned to endocrine or chemoendocrine therapy. Four hundred fifty-eight women reported fatigue and endocrine symptoms at the baseline and at 3, 6, 12, 24, and 36 months. Both groups reported greater symptoms at early follow-up versus the baseline. Increases in fatigue were greater for the chemoendocrine group than the endocrine group at 3 and 6 months but not later. The chemoendocrine group reported greater changes in endocrine symptoms in comparison with the endocrine group at 3 months but not later.

Quality of Life Following Receipt of Adjuvant Chemotherapy With and Without Bevacizumab in Patients With Lymph Node-Positive and High-Risk Lymph Node-Negative Breast Cancer

IMPORTANCE

Breast cancer treatment can impact not only short-term health but may also affect longer-term quality of life (QOL).

OBJECTIVE

To describe and evaluate factors associated with diminished QOL following completion of active treatment.

DESIGN, SETTING, AND PARTICIPANTS

This was a secondary analysis of a randomized clinical trial included patients with lymph node-positive or high-risk lymph node-negative breast cancer who had undergone definitive surgery and were enrolled in ECOG-ACRIN E5103, a multisite phase 3 trial. A survey was administered 18 months after enrollment to patients enrolled between January and June 2010. Final analysis of the data took place from March to December 2021.

INTERVENTIONS

Patients received adjuvant doxorubicin, cyclophosphamide, and paclitaxel with either bevacizumab or placebo.

MAIN OUTCOMES AND MEASURES

QOL and health status assessed with the EuroQol 5-Dimension 3-Levels (EQ-5D-3L), EQ-visual analog scale (EQ-VAS), and the Functional Assessment of Cancer Therapy-Breast Cancer, with arm subscale (FACT-B+4). Groups were compared by Fisher exact test, Wilcoxon rank sum, or Kruskal-Wallis test. Multivariable linear regression was used to assess factors independently associated with FACT-B scores.

RESULTS

Data at 18 months were available from 455 of 519 patients (87.7%) enrolled in the trial. Median (range) age at enrollment was 52 (25-76) years. No differences in QOL (median [range] FACT-B scores: group A, 123 [67-146]; group B, 114 [54-148]; group C, 117 [42-148]; P = .23) or health status (median [range] EQ-5D-3L index scores: group A, 0.83 [0.28-1.00]; group B, 0.83 [0.20-1.00]; group C, 0.83 [0.17-1.00], P = .80; median EQ-VAS: group A, 85 [20-100]; group B, 85 [0-100]; group C, 85 [0-100]; P = .79) were observed across treatment groups; results for subsequent analyses were therefore reported irrespective of primary treatment. Overall, half of patients (258 of 444 [58%]) reported at least some pain or discomfort; 170 (38%) reported symptoms of anxiety or depression. In multivariable analyses, mastectomy with radiation (vs breast conserving surgery) and Asian, Black, or American Indian or Alaska Native race (vs White race) were associated with lower QOL (mastectomy with radiation: coefficient: -5.5; 95% CI, -10.1 to -0.9; Asian, Black, or American Indian or Alaska Native race: coefficient: -7.3; 95% CI, -13.2, -1.4).

CONCLUSIONS AND RELEVANCE

In this study, the addition of bevacizumab to chemotherapy was not negatively associated with QOL at 18 months. A substantial proportion of participants reported problems related to pain or discomfort and anxiety or depression, demonstrating persistent consequences for physical and psychosocial well-being in this heavily treated population. Many problems reported are amenable to intervention, underscoring the need for timely referral to supportive resources, especially for women of color and those who have more extensive local therapy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00433511.

Abstract PO-219: The implications of genetic ancestry and allostatic load on clinical outcomes in the ECOG-ACRIN adjuvant breast cancer trial E5103

Introduction: Elevated allostatic load (AL) has been associated with poor tumor prognostic features in Black breast cancer patients and worse disease specific and overall survival among cancer patients. To date, there are no studies evaluating the relationship between genetic ancestry, allostatic load and clinical trial endpoints such as completion of chemotherapy per protocol or overall survival. Prior evaluations of the ECOG-ACRIN adjuvant breast cancer trial E5103 suggests African ancestry is associated with a worse invasive disease-free survival and lower odds of chemotherapy completion. The objective of this study is to evaluate the association of genetic ancestry and AL with trial completion per protocol and with overall survival among patients in E5103. Methods: ECOG-ACRIN E5103 was a clinical trial that compared doxorubicin and cyclophosphamide (AC) for four cycles, followed by 12 weeks of weekly paclitaxel with placebo (Arm A) to the same chemotherapy with either concurrent bevacizumab (Arm B) or with concurrent plus sequential bevacizumab (Arm C) among women with node positive or high-risk node negative HER2 negative disease. Genetic ancestry groups of African ancestry (AA), European ancestry (EA) and other ancestry (OA) were determined using genome-wide single nucleotide polymorphisms. AL, at trial entry, was comprised of the biomarkers body mass index, systolic blood pressure, diastolic blood pressure, creatinine, IL6, IL10, and TNF alpha. To calculate AL, patients were awarded a point if their biomarker value was above the 75 percentile of the study sample. Logistic regression and Cox-Proportional Hazard models (odds ratio(OR) and hazard ratio (HR) estimates with corresponding 95% confidence intervals (CI)) were used to assess association with chemotherapy completion and with overall mortality. Estimates for AL were adjusted for genetic ancestry. Results: There were 348 patients in the study. The majority of the sample was of EA (EA 80%, AA 10%, OA 10%). Median (range) of AL was 2(0-6). Patients of AA (2.1(1.3)) and EA (1.88(1.4)) had a higher mean (SD) AL score compared to OA patients (0.91(1.1). On adjusted analysis, a 1 unit increased in AL was associated with a 15% reduction in the odds of completing chemotherapy per protocol (OR 0.85, 95% CI 0.72-0.99). Additionally, a 1 unit increase in AL was associated with a 14% increase in the hazard of death (HR 1.14, 95%CI 1.02-1.29). There was no association between ancestry and chemotherapy completion (AA OR 0.95, 95%CI 0.47-1.93; OA 1.82, 95%CI 0.78-4.23; ref EA) or survival (AA HR 1.40, 95% CI 0.85-2.31), OA 0.89 (0.46-1.73; ref EA). Moreover, there was no interaction between AL and ancestry. Conclusion: Among patients enrolled in E5103, AL appeared to be a better predictor of chemotherapy completion and overall survival than genetic ancestry. These results suggest life course exposure to chronic stress has implication in clinical outcomes even within the context of equivalent access to and quality of care.

Citation Format: Samilia Obeng-Gyasi, Anne ONeill, Kathy D. Miller, Bryan P. Schneider, Ann H. Patridge, Lava R. Timsina, George W. Sledge, Lynne Wagner, Ruth C. Carlos. The implications of genetic ancestry and allostatic load on clinical outcomes in the ECOG-ACRIN adjuvant breast cancer trial E5103 [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-219.

Phase I Open-Label Study Evaluating the Safety, Pharmacokinetics, and Preliminary Efficacy of Dilpacimab in Patients with Advanced Solid Tumors

Dilpacimab (formerly ABT-165), a novel dual-variable domain immunoglobulin, targets both delta-like ligand 4 (DLL4) and VEGF pathways. Here, we present safety, pharmacokinetic (PK), pharmacodynamic (PD), and preliminary efficacy data from a phase I study (trial registration ID: NCT01946074) of dilpacimab in patients with advanced solid tumors. Eligible patients (≥18 years) received dilpacimab intravenously on days 1 and 15 in 28-day cycles at escalating dose levels (range, 1.25-7.5 mg/kg) until progressive disease or unacceptable toxicity. As of August 2018, 55 patients with solid tumors were enrolled in the dilpacimab monotherapy dose-escalation and dose-expansion cohorts. The most common treatment-related adverse events (TRAE) included hypertension (60.0%), headache (30.9%), and fatigue (21.8%). A TRAE of special interest was gastrointestinal perforation, occurring in 2 patients (3.6%; 1 with ovarian and 1 with prostate cancer) and resulting in 1 death. The PK of dilpacimab showed a half-life ranging from 4.9 to 9.5 days, and biomarker analysis demonstrated that the drug bound to both VEGF and DLL4 targets. The recommended phase II dose for dilpacimab monotherapy was established as 3.75 mg/kg, primarily on the basis of tolerability through multiple cycles. A partial response was achieved in 10.9% of patients (including 4 of 16 patients with ovarian cancer). The remaining patients had either stable disease (52.7%), progressive disease (23.6%), or were deemed unevaluable (12.7%). These results demonstrate that dilpacimab monotherapy has an acceptable safety profile, with clinical activity observed in patients with advanced solid tumors.

Treatment and Monitoring Variability in US Metastatic Breast Cancer Care

PURPOSE

Treatment and monitoring options for patients with metastatic breast cancer (MBC) are increasing, but little is known about variability in care. We sought to improve understanding of MBC care and its correlates by analyzing real-world claims data using a search engine with a novel query language to enable temporal electronic phenotyping.

METHODS

Using the Advanced Cohort Engine, we identified 6,180 women who met criteria for having estrogen receptor-positive, human epidermal growth factor receptor 2-negative MBC from IBM MarketScan US insurance claims (2007-2014). We characterized treatment, monitoring, and hospice usage, along with clinical and nonclinical factors affecting care.

RESULTS

We observed wide variability in treatment modality and monitoring across patients and geography. Most women received first-recorded therapy with endocrine (67%) versus chemotherapy, underwent more computed tomography (CT) (76%) than positron emission tomography-CT, and were monitored using tumor markers (58%). Nearly half (46%) met criteria for aggressive disease, which were associated with receiving chemotherapy first, monitoring primarily with CT, and more frequent imaging. Older age was associated with endocrine therapy first, less frequent imaging, and less use of tumor markers. After controlling for clinical factors, care strategies varied significantly by nonclinical factors (median regional income with first-recorded therapy and imaging type, geographic region with these and with imaging frequency and use of tumor markers; P < .0001).

CONCLUSION

Variability in US MBC care is explained by patient and disease factors and by nonclinical factors such as geographic region, suggesting that treatment decisions are influenced by local practice patterns and/or resources. A search engine designed to express complex electronic phenotypes from longitudinal patient records enables the identification of variability in patient care, helping to define disparities and areas for improvement.

MONARCH 2: subgroup analysis of patients receiving abemaciclib plus fulvestrant as first-line and second-line therapy for HR+, HER2- advanced breast cancer

PURPOSE

In MONARCH 2, abemaciclib plus fulvestrant significantly prolonged progression-free survival (PFS) and overall survival (OS) versus placebo plus fulvestrant in patients with hormone receptor positive (HR+), HER2- advanced breast cancer. This exploratory analysis assessed the efficacy of abemaciclib plus fulvestrant across subgroups of patients receiving study therapy as first- or second-line treatment for metastatic disease.

EXPERIMENTAL DESIGN

Improvements were estimated using Cox models, and a test of interactions of subgroups with treatment was performed.

RESULTS

The benefit in PFS (first-line, HR=0.57 [95% CI: 0.45-0.73]; second-line, HR=0.48 [95% CI: 0.36-0.64]) and OS (first-line, HR=0.85 [95% CI: 0.64-1.14]; second-line, HR=0.66 [95% CI: 0.46-0.94]) was observed across both subgroups, consistent with the intent-to-treat (ITT) population. In first-line patients (abemaciclib arm, n=265; placebo arm, n=133), the numerically largest effect on PFS and OS was observed in patients with primary resistance to endocrine therapy (ET) (PFS, HR=0.40 [95% CI: 0.26-0.63]; OS, HR=0.58 [95% CI: 0.35-0.97]) and visceral disease (PFS, HR=0.54 [95% CI: 0.39-0.73]; OS, HR=0.82 [95% CI: 0.58-1.20]). In second-line patients (abemaciclib arm, n=170; placebo arm, n=86), a numerical benefit in PFS and OS was observed across primary and secondary ET resistance, with numerically more pronounced effects observed in patients with visceral disease (PFS, HR=0.39 [CI: 0.27-0.57]; OS, HR=0.51 [95% CI: 0.33-0.81]). Prolongation of time to second disease progression, time to chemotherapy, and chemotherapy‑free survival was observed in both subgroups.

CONCLUSIONS

Consistent with the ITT population, a benefit in PFS and OS was observed across the first- and second-line subgroups in MONARCH 2.

Abstract 2105: Cell-free DNA fragments inform epigenomic mechanisms for early detection of breast cancer

Introduction: Chromatin accessibility and cell-free DNA fragmentation patterns can be used to identify epigenomic mechanisms (Sharma et al. 2010) and infer cell-types contributing to cfDNA in pathological states such as cancer (Snyder et al. 2016; Ulz et al. 2017). We describe results from a novel blood-based cell-free DNA (cfDNA) assay using epigenomic signatures that have high sensitivity for detecting early stages of breast cancer, a cancer type that is characterized by low tumor burden (Phallen et al. 2017). We present the results from a prospective, case-control study demonstrating improved sensitivity to the screening mammogram and other published blood-based assays.

Methods: Assay performance was evaluated using a case-control study design enrolling 123 total subjects (58% Healthy, 18% Stage I, 13% Stage II, 11% Stage III). Cases were defined as subjects with a confirmatory diagnosis of invasive breast cancer, at any stage, by tissue biopsy. Controls were composed of subjects with either a negative finding by mammography (BI-RADS 1 or 2) or self-declared cancer-free. Whole blood samples were collected in Streck BCT tubes and shipped to a central laboratory for processing. Total cell-free DNA was extracted from plasma and prepped for next-generation sequencing. Sequencing libraries were enriched using a custom panel targeting genomic regions with distinct epigenomic activity in breast cancer. We trained a neural net to predict regulatory events in each of these regions, and then identified those events that were predictive of the presence of breast cancer. Final classification was performed by logistic regression over the predicted regulatory events.

Results: Performance was tested using a held-out test set and achieved an overall sensitivity of 92.5% (95% CI: 88.1%, 97%) at specificity of 88.9% with an overall AUC of 95.8%. Performance of screening mammography is reported to be 86.9% (95% CI: 86.3%, 87.6%) sensitive at 88.9% specificity on data obtained from six Breast Cancer Surveillance Consortium (BCSC) registries on 792808 women (Lehman et al. 2017).

Conclusion: These results support the utility for detecting epigenomic signals from cell-free DNA to enhance early detection of breast cancer. A prospective breast cancer screening study in a larger cohort is needed to further validate performance.

Citation Format: Erik Gafni, Adam Harvey, Artur Jaroszewicz, Omid Shams Solari, Jane Landolin, Mouadh Barbirou, Amanda Miller, Peter J. Tonellato, Anshul Kundaje, Stefanie S. Jeffrey, Christina Curtis, George W. Sledge, Paul Giresi, Nathan Boley. Cell-free DNA fragments inform epigenomic mechanisms for early detection of breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2105.

Association of Modifiable Risk Factors With Early Discontinuation of Adjuvant Endocrine Therapy: A Post Hoc Analysis of a Randomized Clinical Trial

IMPORTANCE

Early discontinuation of adjuvant endocrine therapy (ET) is problematic among breast cancer survivors, with previous studies suggesting that up to 50% of women do not adhere to the recommended full 5 years of ET treatment.

OBJECTIVE

To identify the association between early discontinuation of ET in the Trial Assigning Individualized Options for Treatment (TAILORx) and modifiable risk factors, polypharmacy, and types of additional medications such as antidepressants and opioids.

DESIGN, SETTING, AND PARTICIPANTS

This post hoc analysis includes a subgroup of 954 patients with breast cancer in TAILORx, a randomized clinical trial conducted from April 7, 2006, to October 6, 2010. All participants received a diagnosis of hormone receptor-positive, ERBB2-negative, axillary node-negative breast cancer and started ET within a year of study entry. Analyses were conducted in the intent-to-treat population. Statistical analysis took place from January 15, 2020, to April 6, 2021.

MAIN OUTCOMES AND MEASURES

Participants completed measures on cancer-related health-related quality of life including physical well-being and social well-being prior to initiating ET. Early discontinuation of ET was defined as discontinuation less than 4 years from initiation for reasons other than death or recurrence. Kaplan-Meier estimates were used to calculate discontinuation, and Cox proportional hazards regression joint prediction models were used to analyze the association between rates of adherence to ET with patient-level factors.

RESULTS

A total of 954 women (mean [SD] age, 56.6 [8.9] years) were included in this analysis. In a joint model, receipt of chemoendocrine therapy (vs receipt of ET only; hazard ratio [HR], 0.57; 95% CI, 0.35-0.92; P = .02) and age older than 40 years (vs ≤40 years; HR for 41-50 years, 0.39; 95% CI, 0.18-0.85; P = .02; HR for 51-60 years, 0.28; 95% CI, 0.13-0.60; P = .001; HR for 61-70 years, 0.40; 95% CI, 0.18-0.86; P = .02; and HR for >70 years, 0.23; 95% CI, 0.07-0.77; P = .02) were associated with a lower probability of early discontinuation of ET. Adjusted for these factors, a history of depression compared with no history of depression (HR, 1.82; 95% CI, 1.19-2.77; P = .005), worse physical well-being compared with better physical well-being (HR, 2.12; 95% CI, 1.30-3.45; P = .002), and worse social well-being compared with better social well-being (HR, 1.94; 95% CI, 1.20-3.13; P = .006) were individually and significantly associated with a higher probability of early discontinuation of ET. Only antidepressant use at study baseline was associated with early discontinuation (HR, 1.87; 95% CI, 1.23-2.84; P = .003).

CONCLUSIONS AND RELEVANCE

In this post hoc analysis of a randomized clinical trial, baseline patient-reported health-related quality of life components, such as poor social well-being, poor physical well-being, and comorbid depression, were significant risk factors for early discontinuation of endocrine therapies. These results support systematic screening for patient-reported outcomes and depressive symptoms to identify women at risk for discontinuation of ET.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00310180.

Social determinants of health, genetic ancestry, and mortality in ECOG-ACRIN E5103

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Background: Social determinants of health (SDH) and genetic ancestry have been independently implicated in breast cancer presentation, treatment and mortality. However, little is known about the relationship between SDH and genetic ancestry on clinical trial outcomes. The objective of this study is to assess the association between SDH, genetic ancestry and clinical outcomes in patients enrolled in an adjuvant breast cancer clinical trial. Methods: ECOG-ACRIN (EA) 5103 randomized patients to receive AC + taxane + bevacizumab or placebo. SDH were operationalized as insurance status at trial registration (individual SES) and neighborhood socioeconomic status (nSES). Insurance categories included: (1) Private, 2) Medicare including private/Medicare, military, 3) Medicaid including Medicaid/Medicare, uninsured, 4) self-pay). The nSES index was calculated using zip codes linked to county level data on occupation, income, poverty, wealth, education and crowding. Genome-wide single-nucleotide polymorphism arrays were used to define African ancestry (AA), European ancestry (EA) and other (OA). Multivariable regression and Cox-Proportional Hazard models (odds ratios (OR) and hazard ratios (HR) with corresponding 95% confidence intervals (CI)) were used to assess associations with chemotherapy completion and overall mortality. Estimates were adjusted for the following clinical covariates: age, tumor size, nodal status, hormone receptor status, and primary surgery at randomization. Results: The study cohort included 2453 EA (79.2%), 381 AA (12.2%) and 265 OA (8.6%). Medicaid patients (OR 0.76(0.59-0.99); ref private) and those with AA (OR 0.62(0.49-0.78); ref EA) were less likely to complete chemotherapy. Regarding overall mortality, Medicaid insurance (HR 1.42(1.05-1.92) was associated with a higher mortality than private insurance. Conversely, there was no significant difference in mortality by ancestry (AA HR 1.27 (0.97-1.66); OA HR 0.90 (0.63-1.29): ref EA). Neighborhood socioeconomic status did not appear to be associated with chemotherapy completion or mortality. Conclusions: SDH reflective of individual SES, such as insurance, appear to be stronger drivers of trial completion and mortality compared to nSES among patients enrolled in E5103. Moreover, study results suggest an interplay between ancestry and individual proxies for SDH in trial completion. Nevertheless, the relationship between ancestry and lower rates of chemotherapy completion do not appear to translate into higher mortality rates among patients of AA.

Inflammatory cytokines and distant recurrence in HER2-negative early breast cancer in the ECOG-ACRIN 5103 trial

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Background: Systemic inflammation may contribute to cancer progression (PMC2803035), including recurrence of early breast cancer (PMC4828958). We hypothesized that inflammatory cytokines and/or chemokines may be associated with distant recurrence (DR). Methods: We performed a case:control study in women with stage II-III Her2-negative breast cancer, all of whom had surgery and adjuvant chemotherapy (doxorubicin/cyclophosphamide, then weekly paclitaxel) with/without bevacizumab, plus endocrine therapy if ER-positive (PMC6118403). Propensity score matching was used to identify approximately 250 case:control pairs (with/without DR). Serum samples obtained before adjuvant chemotherapy were analyzed using the MSD V-Plex Human Cytokine 36-Plex Kit for detection of human cytokines and chemokines involved in the Th1/Th2 pathway, chemotaxis, the Th17 pathway, angiogenesis, and immune system regulation. Conditional logistic regression analysis, with models fit via maximum likelihood, were used to estimate hazard ratios (HRs) and test for associations. Due to skewed nature of cytokines, HRs are reported on log base 2 scale. If adjusted for multiple testing including 36 markers, a p value of < 0.0014 would be required for statistical significance. Results: A total 249 matched pairs (498 patients) were identified. Covariates used for propensity score matching included age, menopausal status (post 54% vs. pre/peri 46%), ER/PR status (one/both pos 64% vs. both neg 36%) tumor size ( < = 2cm 17%, > 2-5cm 67%, > 5cm 16%) nodal status (neg 15%,1-3+ 32%, 4+ 53%), and grade (low 3%, int. 31%, high 66%). The only biomarker associated with a significantly increased DR risk when adjusted for multiple testing was the proinflammatory cytokine IL-6 (HR 1.37, 95% confidence intervals [CI] 1.15, 1.65, p = 0.0006). Others associated with a 2-sided p value < 0.05 included the chemokine MDC(macrophage-derived chemokine/CCL22) (1.90, 95% CI 1.17, 3.1, p = 0.0098), the T helper cell inflammatory cytokine IL-17A (HR 1.36, 95% CI 1.10, 1.67, p = 0.0052), and the cytokine VEGF-A (HR 1.13 for, 95% CI 1.01, 1.27, p = 0.037). There was no statistical interaction between VEGF-A and bevacizumab benefit. The median and mean value for IL-6 was 0.95 and 7.5 pg/ml (range 0.04-2761.24 pg/ml). Conclusions: This analysis provides level 1B evidence indicating that higher levels of the cytokine IL-6 at diagnosis are associated with a significantly higher DR risk in high-risk stage II-III breast cancer despite optimal adjuvant systemic therapy. This provides a foundation for confirmatory validation of IL-6 as a prognostic biomarker, and potentially as a predictive biomarker for testing therapeutic interventions targeting the IL-6/JAK/STAT3 pathway. Supported by NCI U10CA180820,180794,180821; UG1CA189859,232760,233290, 233196; Komen Foundation; Breast Cancer Research Foundation. Clinical trial information: NCT00433511.

Abemaciclib in combination with endocrine therapy for East Asian patients with HR+, HER2- advanced breast cancer: MONARCH 2 & 3 trials

This post hoc analysis of MONARCH 2 and MONARCH 3 assesses the efficacy, safety, and pharmacokinetics (PK) of abemaciclib in combination with endocrine therapy (ET) in East Asian patients with hormone receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer. MONARCH 2 and MONARCH 3 are global, randomized, double-blind, phase 3 studies of abemaciclib/placebo + fulvestrant and abemaciclib/placebo + nonsteroidal aromatase inhibitor (NSAI, anastrozole or letrozole), respectively. The East Asian population comprised 212 (31.7%) of the 669 intent-to-treat (ITT) population in the MONARCH 2 trial and 144 (29.2%) of the 493 ITT patients in the MONARCH 3 trial. In the East Asian population, median progression-free survival (PFS) was significantly prolonged in the abemaciclib arm compared with placebo in both MONARCH 2 (hazard ratio [HR], 0.520; 95% confidence interval [CI], 0.362 to 0.747; P < .001; median: 21.2 vs 11.6 months) and MONARCH 3 (HR, 0.326; 95% CI, 0.200 to 0.531, P < .001; median: not reached vs 12.82 months). Diarrhea (MONARCH 2: 90%; MONARCH 3: 88%) and neutropenia (MONARCH 2: 68%; MONARCH 3: 58%) were the most frequent adverse events observed in the East Asian populations. Abemaciclib exposures and PK were similar in East Asians and the non-East Asian populations of both trials. Abemaciclib in combination with ET in the East Asian populations of MONARCH 2 and MONARCH 3 provided consistent results with the ITT populations, demonstrating improvements in efficacy with generally tolerable safety profiles for patients with HR+, HER2- advanced breast cancer.

Race, Ethnicity, and Clinical Outcomes in Hormone Receptor-Positive, HER2-Negative, Node-Negative Breast Cancer in the Randomized TAILORx Trial

BACKGROUND

Black race is associated with worse outcomes in early breast cancer. We evaluated clinicopathologic characteristics, the 21-gene recurrence score (RS), treatment delivered, and clinical outcomes by race and ethnicity among women who participated in the Trial Assigning Individualized Options for Treatment.

METHODS

The association between clinical outcomes and race (White, Black, Asian, other or unknown) and ethnicity (Hispanic vs non-Hispanic) was examined using proportional hazards models. All P values are 2-sided.

RESULTS

Of 9719 eligible women with hormone receptor-positive, HER2-negative, node-negative breast cancer, there were 8189 (84.3%) Whites, 693 (7.1%) Blacks, 405 (4.2%) Asians, and 432 (4.4%) with other or unknown race. Regarding ethnicity, 889 (9.1%) were Hispanic. There were no substantial differences in RS or ESR1, PGR, or HER2 RNA expression by race or ethnicity. After adjustment for other covariates, compared with White race, Black race was associated with higher distant recurrence rates (hazard ratio [HR] = 1.60, 95% confidence intervals [CI] = 1.07 to 2.41) and worse overall survival in the RS 11-25 cohort (HR = 1.51, 95% CI = 1.06 to 2.15) and entire population (HR = 1.41, 95% CI = 1.05 to 1.90). Hispanic ethnicity and Asian race were associated with better outcomes. There was no evidence of chemotherapy benefit for any racial or ethnic group in those with a RS of 11-25.

CONCLUSIONS

Black women had worse clinical outcomes despite similar 21-gene assay RS results and comparable systemic therapy in the Trial Assigning Individualized Options for Treatment. Similar to Whites, Black women did not benefit from adjuvant chemotherapy if the 21-gene RS was 11-25. Further research is required to elucidate the basis for this racial disparity in prognosis.

Breast cancer patients' insurance status and residence zip code correlate with early discontinuation of endocrine therapy: An analysis of the ECOG-ACRIN TAILORx trial

BACKGROUND

Early discontinuation is a substantial barrier to the delivery of endocrine therapies (ETs) and may influence recurrence and survival. The authors investigated the association between early discontinuation of ET and social determinants of health, including insurance coverage and the neighborhood deprivation index (NDI), which was measured on the basis of patients' zip codes, in breast cancer.

METHODS

In this retrospective analysis of a prospective randomized clinical trial (Trial Assigning Individualized Options for Treatment), women with hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer who started ET within a year of study entry were included. Early discontinuation was calculated as stopping ET within 4 years of its start for reasons other than distant recurrence or death via Kaplan-Meier estimates. A Cox proportional hazards joint model was used to analyze the association between early discontinuation of ET and factors such as the study-entry insurance and NDI, with adjustments made for other variables.

RESULTS

Of the included 9475 women (mean age, 55.6 years; White race, 84%), 58.0% had private insurance, whereas 11.7% had Medicare, 5.8% had Medicaid, 3.8% were self-pay, and 19.1% were treated at international sites. The early discontinuation rate was 12.3%. Compared with those with private insurance, patients with Medicaid (hazard ratio [HR], 1.53; 95% confidence interval [CI], 1.23-1.92) and self-pay patients (HR, 1.65; 95% CI, 1.25-2.17) had higher early discontinuation. Participants with a first-quartile NDI (highest deprivation) had a higher probability of discontinuation than those with a fourth-quartile NDI (lowest deprivation; HR, 1.34; 95% CI, 1.11-1.62).

CONCLUSIONS

Patients' insurance and zip code at study entry play roles in adherence to ET, with uninsured and underinsured patients having a high rate of treatment nonadherence. Early identification of patients at risk may improve adherence to therapy.

LAY SUMMARY

In this retrospective analysis of 9475 women with breast cancer participating in a clinical trial (Trial Assigning Individualized Options for Treatment), Medicaid and self-pay patients (compared with those with private insurance) and those in the highest quartile of neighborhood deprivation scores (compared with those in the lowest quartile) had a higher probability of early discontinuation of endocrine therapy. These social determinants of health assume larger importance with the expected increase in unemployment rates and loss of insurance coverage in the aftermath of the coronavirus disease 2019 pandemic. Early identification of patients at risk and enrollment in insurance optimization programs may improve the persistence of therapy.

Safety and efficacy of abemaciclib plus endocrine therapy in older patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer: an age-specific subgroup analysis of MONARCH 2 and 3 trials

PURPOSE

Abemaciclib in combination with endocrine therapy (ET) has demonstrated significant efficacy benefits in HR+ , HER2- advanced breast cancer patients in the Phase 3 studies MONARCH 2 (fulvestrant as ET) and MONARCH 3 (letrozole or anastrozole as ET). Here, we report age-specific safety and efficacy outcomes.

METHODS

Exploratory analyses of MONARCH 2 and 3 were performed for 3 age groups (<65, 65-74, and ≥75 years). For safety, data were pooled from both studies; for efficacy, a subgroup analysis of PFS was performed for each trial independently.

RESULTS

Pooled safety data were available for 1152 patients. Clinically relevant diarrhea (Grade 2/3) was higher in older patients receiving abemaciclib + ET (<65, 39.5%; 65-74, 45.2%; ≥75, 55.4%) versus placebo + ET (<65, 6.8%; 65-74, 4.5%; ≥75, 16.0%). Nausea, decreased appetite, and venous thromboembolic events were all moderately higher in older patients. Neutropenia (Grade ≥ 3) did not differ as a function of age in the abemaciclib + ET arm (<65, 25.8%; 65-74, 27.4%; ≥75, 18.1%). Dose adjustments and discontinuation rates were slightly higher in older patients. Abemaciclib + ET improved PFS compared with placebo + ET independent of patient age, with no significant difference in abemaciclib treatment effect between the 3 age groups (MONARCH 2: interaction p-value, 0.695; MONARCH 3: interaction p-value, 0.634). Estimated hazard ratios ranged from 0.523-0.633 (MONARCH 2) and 0.480-0.635 (MONARCH 3).

CONCLUSIONS

While higher rates of adverse events were reported in older patients, they were manageable with dose adjustments and concomitant medication. Importantly, a consistent efficacy benefit was observed across all age groups.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02107703 (first posted April 8, 2014) and NCT02246621 (first posted September 23, 2014).

Y box binding protein 1 inhibition as a targeted therapy for ovarian cancer

Y box binding protein 1 (YB-1) is a multifunctional protein associated with tumor progression and the emergence of treatment resistance (TR). Here, we report an azopodophyllotoxin small molecule, SU056, that potently inhibits tumor growth and progression via YB-1 inhibition. This YB-1 inhibitor inhibits cell proliferation, resistance to apoptosis in ovarian cancer (OC) cells, and arrests in the G1 phase. Inhibitor treatment leads to enrichment of proteins associated with apoptosis and RNA degradation pathways while downregulating spliceosome pathway. In vivo, SU056 independently restrains OC progression and exerts a synergistic effect with paclitaxel to further reduce disease progression with no observable liver toxicity. Moreover, in vitro mechanistic studies showed delayed disease progression via inhibition of drug efflux and multidrug resistance 1, and significantly lower neurotoxicity as compared with etoposide. These data suggest that YB-1 inhibition may be an effective strategy to reduce OC progression, antagonize TR, and decrease patient mortality.

Novel Aza-podophyllotoxin derivative induces oxidative phosphorylation and cell death via AMPK activation in triple-negative breast cancer

BACKGROUND

To circumvent Warburg effect, several clinical trials for different cancers are utilising a combinatorial approach using metabolic reprogramming and chemotherapeutic agents including metformin. The majority of these metabolic interventions work via indirectly activating AMP-activated protein kinase (AMPK) to alter cellular metabolism in favour of oxidative phosphorylation over aerobic glycolysis. The effect of these drugs is dependent on glycaemic and insulin conditions.  Therefore, development of small molecules, which can activate AMPK, irrespective of the energy state, may be a better approach for triple-negative breast cancer (TNBC) treatment.

METHODS

Therapeutic effect of SU212 on TNBC cells was examined using in vitro and in vivo models.

RESULTS

We developed and characterised the efficacy of novel AMPK activator (SU212) that selectively induces oxidative phosphorylation and decreases glycolysis in TNBC cells, while not affecting these pathways in normal cells.   SU212 accomplished this metabolic reprogramming by activating AMPK independent of energy stress and irrespective of the glycaemic/insulin state. This leads to mitotic phase arrest and apoptosis in TNBC cells. In vivo, SU212 inhibits tumour growth, cancer progression and metastasis.

CONCLUSIONS

SU212 directly activates AMPK in TNBC cells, but does not hamper glucose metabolism in normal cells. Our study provides compelling preclinical data for further development of SU212 for the treatment of TNBC.

Impact of insurance and neighborhood socioeconomic status on clinical outcomes in therapeutic clinical trials for breast cancer

The objective of this study was to evaluate the impact of insurance and neighborhood SES (nSES) on chemotherapy completion and overall mortality among participants in breast cancer clinical trials. The data sources for this study were two adjuvant breast cancer trials (ECOG E1199 and E5103) collectively including 9790 women. Insurance status at trial registration was categorized into private, government (Medicaid, Medicare, and other government type insurance), and self‐pay. An Agency for Healthcare Research Quality (AHRQ) nSES index was calculated using residential zip codes linked to county level data on occupation, income, poverty, wealth, education, and crowding. Logistic regression and Cox Proportional Hazard models estimated odds ratios (OR) for chemotherapy treatment completion and hazard ratios (HR) for mortality, respectively, for insurance status and nSES. The models adjusted for: race, age, tumor size, nodal status, hormone receptor status, and primary surgery. The majority of patients had private insurance at trial registration: E1199: 85.6% (4154/4854) and E5103: 82.4% (3987/4836); median SES index was 53.8 (range: 41.8‐66.8) and 54.1 (range: 44.5‐66.1), respectively. Patients with government insurance were less likely to complete chemotherapy treatment (E1199 OR (95%CI): 0.73 (0.57‐0.94); E5103 0.76 (0.64‐0.91)) and had an increased risk of death (E1199 HR (95%CI): 1.44 (1.22‐1.70); E5103 1.29 (1.06‐1.58)) compared to the privately insured patients. There was no association between nSES and chemotherapy completion or overall mortality. Patients with government insurance at trial registration appeared to face barriers in chemotherapy completion and had a higher overall mortality compared to their privately insured counterparts.

Understanding patient perspectives on window of opportunity clinical trials

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Background: In “window of opportunity” (WOO) clinical trials, people with newly diagnosed early-stage cancer are exposed to an experimental drug during the period of time between diagnosis and definitive anti-cancer treatment. These trials allow investigators to study drug efficacy in untreated disease, which can expedite drug development. However, for trial participants, the WOO approach requires them to decide about an altruistic clinical trial during an intense time immediately after cancer diagnosis. This qualitative study aimed to understand patient perspectives on WOO clinical trials. Methods: We recruited adults newly diagnosed with early-stage breast cancer who were awaiting definitive therapy at a single academic medical center. We developed an interview guide grounded in the theoretical framework, the Theory of Planned Behavior (TPB). TBP is a well-validated decision-making model with three domains that guide behavior: (1) attitudes (2) normative factors and (3) perceived difficulty of a behavior. We conducted one-on-one semi-structured interviews that were audio-recorded and transcribed. Transcripts were analyzed to ensure interrater reliability and content analysis was performed to assess themes that emerged. Results: We interviewed 15 women (age 32-72) with early-stage breast cancer, and the majority were White (n = 12, 80%) and at least college educated (n = 12, 80%). Key themes that emerged included favorable attitudes towards participating in a WOO trial that were altruistic, including the desire to contribute to science (n = 10, 67%) and to help future breast cancer patients (n = 5, 33%). Several individuals also identified a potential benefit to themselves (n = 10, 67%), including access to a targeted drug (n = 4, 27%) and adding meaning to their diagnosis (n = 3, 20%). However, most interviewees reported concerns about drug side effects (n = 12, 80%) and whether side effects would impact other planned treatments (n = 10, 67%). Interviewees also expressed family would be an important normative factor in decision-making (n = 8, 53%). A key theme that emerged as a difficulty was the potential delay in standard treatment (n = 14, 93%). Despite this concern, at the end of the interviews, most interviewees stated they would participate in a WOO trial if offered (n = 10, 67%). Conclusions: WOO trials are becoming increasingly common in oncology research. In this qualitative study, interviewees weighed altruism against the possibility delaying or impacting other treatments. Our results may inform trial design and communication approaches in future WOO efforts.

Abstract 766: Clinical outcomes of patients with PIK3CA mutations in circulating tumor DNA: Update from the MONARCH 2 study of abemaciclib plus fulvestrant

BACKGROUND: Mutations (mt) in PIK3CA have been implicated in resistance to endocrine therapy (ET) in HR+ advanced breast cancer (ABC). In the MONARCH 2 study the addition of abemaciclib to fulvestrant (fulv) demonstrated a clinically meaningful and statistically significant median overall survival (OS) benefit of 9.4 months (mos) (HR 0.757, p=0.01), in addition to prolonging time to chemotherapy (TTC) (Sledge et al. JAMA Oncology 2019). We previously showed that abemaciclib plus fulv demonstrated improvement in progression-free survival (PFS) regardless of PIK3CA mt status, with a numerically larger magnitude of benefit for patients (pts) with PIK3CA mt in baseline circulating tumor DNA (ctDNA; Tolaney et al. AACR 2019). Here, we assessed the OS, TTC, and chemotherapy-free survival (CFS) in patients with and without PIK3CA mt in MONARCH 2.

METHODS: MONARCH 2 (NCT02107703) was a global, randomized, double-blind phase III trial of abemaciclib plus fulv or placebo plus fulv in pre-/perimenopausal (with ovarian suppression) and postmenopausal women with ET resistant HR+, HER2- ABC. Results of PIK3CA mt status (E542K; E545K; H1047L; H1047R) from baseline ctDNA were available for 238 patients. Exploratory analyses of OS, TTC, and CFS were assessed in pts with and without PIK3CA mt using the Cox Interaction Model including treatment, PIK3CA mt status and treatment by PIK3CA interaction term.

RESULTS: Abemaciclib plus fulv demonstrated a similar OS benefit for pts with PIK3CA mt (HR: 0.57; 95% CI: 0.34, 0.96) and for pts with PIK3CA wild-type (HR: 0.56; 95% CI: 0.34, 0.91) compared with placebo plus fulv. Median TTC and CFS were longer in the abemaciclib plus fulv arm compared with the placebo plus fulv arm both in pts with detectable PIK3CA mt and in pts without PIK3CA mt, as shown in Table 1.

Table 1.PIK3CA mutantPIK3CA wild-typeAbemaciclib +Fulvestrant (n=58)Placebo + Fulvestrant (n=38)Hazard Ratio (95% CI)Abemaciclib + Fulvestrant (n=91)Placebo + Fulvestrant (n=51)Hazard Ratio (95% CI)Interaction p-valueOverall Survival Median (95% CI)44.5 mos (31.0, NR)33.8 mos (24.2, 41.7)0.57 (0.34, 0.96)55.5 mos (47.7, 55.5)41.7 mos (29.4, 49.7)0.56 (0.34, 0.91)0.949Time to Chemotherapy Median (95% CI)39.2 mos (24.6, NR)19.2 mos (6.7, NR)0.65 (0.37, 1.18)NR (34.3, NR)19.2 mos (12.0, 31.1)0.50 (0.31, 0.78)0.463Chemotherapy-Free Survival Median (95% CI)25.8 mos (16.0, 42.1)12.8 mos (5.2, 33.2)0.63 (0.39, 1.03)36.9 mos (20.7, NR)19.2 mos (12.0, 29.4)0.53 (0.35, 0.80)0.588CI = confidence interval; NR = not reached; mos = months

CONCLUSIONS: In this exploratory analysis of MONARCH 2, abemaciclib plus fulv demonstrated benefit in OS, TTC, and CFS in patients with and without PIK3CA mutations.

Citation Format: Sara M. Tolaney, Masakazu Toi, Patrick Neven, Joohyuk Sohn, Eva-Maria Grischke, Hatem Soliman, Lacey M. Litchfield, Hong Wang, Sameera R. Wijayawardana, Valerie M. Jansen, George W. Sledge. Clinical outcomes of patients with PIK3CA mutations in circulating tumor DNA: Update from the MONARCH 2 study of abemaciclib plus fulvestrant [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 766.

A randomized phase III trial of systemic therapy plus early local therapy versus systemic therapy alone in women with de novo stage IV breast cancer: A trial of the ECOG-ACRIN Research Group (E2108)

LBA2

Background: About 6% of newly diagnosed breast cancer patients present with Stage IV disease and an intact primary tumor (IPT). Locoregional treatment (LRT) for the IPT is hypothesized to improve survival based on retrospective analyses, but randomized trials have provided conflicting data. We now report the results of E2108, a Phase 3 trial that examined the worth of LRT for the IPT following initial systemic therapy. Methods: Stage IV patients with IPT were registered, treated with optimal systemic therapy (OST) based on patient and tumor characteristics; those who did not progress during 4-8 months of OST were randomized to LRT for the IPT, or no LRT. The primary endpoint was overall survival (OS), with locoregional disease control as a secondary endpoint. Stratified log rank test and Cox proportional hazard model were used to compare OS between treatment groups. Cumulative incidence of locoregional recurrence/progression was estimated and Gray test was used for treatment group comparisons. The trial was designed to detect an improvement in 3 year OS rate from 30% with OST alone to 49.3% for OST+LRT (power 95%, 1-sided alpha 0.05) with full information expected after 152 deaths; the data monitoring committee recommended data release after 80% of full information. Results: 390 patients were enrolled between 2/8/11 and 7/23/15, and received OST. Of these, 256 eligible patients were randomized to either continued OST alone (N = 131) or OST+LRT (N = 125).There were 121 deaths and 43 locoregional progression events after a median follow up 59 months (range: 0-91). There was no significant difference in OS (3-year OS rate 68.4% in OST+LRT vs. 67.9% OST alone arm, stratified log-rank p = 0.63, HR = 1.09, 90% CI: 0.80, 1.49) or in progression-free survival (p = 0.40). The locoregional recurrence/progression was significantly higher in the OST alone arm (3-year rate 25.6% vs 10.2%, Gray test p = 0.003). Health-related quality of life (HRQOL) measured by FACT-B Trial Outcome Index was significantly worse in the OST+LRT arm than OST alone arm at 18 months post randomization (60% completion, Wilcoxon rank sum test p = 0.01), but no difference was observed at time points 6 months (74% completion) or 30 months (56% completion). Conclusions: Early local therapy does not improve survival in patients with de novo metastatic breast cancer and an IPT. Although there was a 2.5-fold higher risk of local disease progression without LRT, LRT of the IPT did not lead to improved HRQOL. Clinical trial information: NCT01242800 .

Early discontinuation to adjuvant endocrine therapy in the ECOG-ACRIN TAILORx Trial

7004

Background: The TAILORx study demonstrated women with an intermediate Oncotype DX score receive the same benefit with endocrine therapy (ET) compared to chemoendocrine therapy (CET). However, early discontinuation of adjuvant ET is problematic among breast cancer survivors, with previous studies suggesting that up to 50% of women do not adhere to the full 5 years of recommended ET treatment. The aim of this study was to identify patient-level risk factors associated with early discontinuation of ET in the TAILORx study. Methods: TAILORx was coordinated by the ECOG-ACRIN Cancer Research Group. Participants were a subgroup of 954 women who completed additional measures on health-related quality of life (HRQoL) including endocrine symptoms (ES) physical well-being (PWB) and social well-being (SWB) prior to initiating ET, which categorized into three groups by tertile for analysis. All participants were diagnosed with hormone-receptor–positive, human epidermal growth factor receptor 2–negative, axillary node–negative breast cancer who started ET within a year of study entry. Early discontinuation of ET, defined as discontinuation less than 4 years from initiation for reasons other than death or recurrence, was assessed by clinician report. Rate of discontinuation was calculated using Kaplan-Meier estimates, and Cox-proportional hazards joint models were used to analyze the association between rates of adherence to ET with patient-level factors. Results: In a joint model, receipt of CET therapy (vs receipt of ET only; HR = .59, 95% CI .38-.94, p = .02) and age above 40 (versus age < = 40; HR = .30, 95% CI .14-.66, p = .003) were associated with a lower probability of early discontinuation of ET. Adjusted for these factors, a history of depression compared to no history of depression (HR 1.82, 95% CI 1.19-2.77, p = 0.005), worse ES compared to better ES (HR 1.70, 95% CI 1.06-2.74, p = 0.03), worse PWB compared to better PWB (HR 2.12, 95% CI 1.30-3.45,p = 0.003), and worse SWB compared to better SWB (HR 1.94, 95% CI 1.20-3.13, p = 0.007) were individually and significantly associated with a higher probability of early discontinuation of ET, although none reached statistical significance when all were included in a joint model. Conclusions: Younger women are at risk for early discontinuation and modifiable characteristics such as HRQoL and history of depression are potential risk factors for early discontinuation of ET. These results support systematic screening for HRQoL and depressive symptoms to identify women at risk for discontinuation of ET. Clinical trial information: NCT00310180 .

Real-world outcomes of patients with metastatic breast cancer (BC) treated with osteoclast inhibitors (OIs)

e19314

Background: Patients with metastatic BC have a high incidence of bone metastasis with associated morbidity and mortality. OIs including denosumab and zoledronic acid reduce the rate of skeletal-related events (SREs). Since denosumab was approved in 2011, there have been no analyses about the comparative effectiveness and safety of denosumab versus zoledronic acid. Methods: Patients with BC treated with three or more doses of either denosumab or zoledronic acid after 2011 were identified in Stanford’s BC research database, Oncoshare. SREs were defined as a composite measure of spinal cord compression, pathologic fracture, surgery or radiation to bone. Unadjusted Cox proportional hazard models were fit to time to: first SRE, subsequent SRE, overall survival (OS) and BC-specific survival. Results: 515 patients were identified: 388 and 127 treated with denosumab and zoledronic acid per oncologist’s discretion, respectively. Groups were well balanced for age at diagnosis, race/ethnicity, tumor grade, prior chemotherapy use and median time from first OI therapy to last follow-up. More patients with triple-negative BC (TNBC) received zoledronic acid. Median follow-up time from first OI dose was 28 months. 42% of patients experienced at least one SRE and there were no differences in incidence of first or subsequent SREs between groups (Table). Median OS was 91 months with no statistically significant difference between groups. Median BC-specific survival was not reached (78% of patients survived), however, patients in the zoledronic acid group had over twice the risk of BC-specific mortality, a difference that remained significant after adjustment for TNBC status. There was no difference in adverse events including osteonecrosis of the jaw, vertebral fracture or hypocalcemia. Conclusions: In a contemporary, real-world care setting, we observed no difference in the incidence of SREs or OS between metastatic BC patients treated with denosumab or zoledronic acid. [Table: see text]

MONARCH 2: Subgroup analysis of patients receiving abemaciclib + fulvestrant as first- and second-line therapy for HR+, HER2- advanced breast cancer

1061

Background: In MONARCH 2 (M2), abemaciclib (A), an oral selective cyclin dependent kinase 4 & 6 inhibitor, + fulvestrant (F) demonstrated statistically significant improvements in progression-free survival (PFS) and overall survival (OS) compared to placebo (P) + F in hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer (ABC). Numerically more pronounced PFS & OS improvement was noted in subgroups (Sub) with visceral (V) disease and primary endocrine resistance. Here we report efficacy data for M2 with respect to 1L and 2L Sub (last line of endocrine therapy [ET] in (neo)adjuvant and metastatic setting, respectively). Methods: M2 (NCT02107703) was a global, randomized, double-blind Phase 3 trial of A+ F (N = 446) or P + F (N = 223) in women with ET resistant (ETR) HR+, HER2- ABC regardless of menopausal status. Patients (pts) were stratified by site of metastasis (V, bone-only, or other) and resistance to prior ET (primary vs secondary). Exploratory Sub analyses of PFS and OS were conducted among pts in the ITT population with 1L vs 2L. Hazard ratios (HR) were estimated using Cox models with a test of interactions of Sub with treatment performed. Results: At data cut-off (June 20th, 2019), the effect of A + F vs P + F was consistent across 1L (N = 265/133) and 2L (N = 170/86) Sub, with no statistically significant interaction for PFS (p = 0.341) or OS (p = 0.265). For 1L pts, improvements in PFS (HR: 0.57; 95% CI:0.45, 0.73) and OS (HR: 0.85; 95% CI:0.64, 1.14) were observed. Similar efficacy results were observed for 2L pts (PFS: HR: 0.48; [95% CI: 0.36, 0.64]; OS HR: 0.66 [95% CI: 0.46, 0.94]). The numerically largest effects in the 1L population were noted in pts with less favorable prognostic factors such as primary ETR (PFS: HR 0.40 [95% CI: 0.26, 0.63]; OS: HR 0.58 [95% CI:0.35, 0.97]) and V disease (PFS: HR 0.54 [95% CI: 0.39, 0.73]; OS: HR 0.82 [95% CI: 0.57, 1.17]). Conclusions: The statistically significant benefit observed in the M2 study was observed across 1L and 2L patients. In 1L patients (A+F Arm), improvements were observed for PFS and OS with the most pronounced effects noted in patients with less favorable prognostic factors. Clinical trial information: NCT02107703 .

Linking insurance claims across time to characterize treatment, monitoring, and end-of-life care in metastatic breast cancer

7063

Background: Treatment and monitoring options for metastatic breast cancer (MBC) are increasing, but little is known about patterns or predictors of their use. Insurance claims are potentially informative, but tracking patient care timelines using episodic claims data has been cumbersome. Methods: We used an advanced cohort engine, implementing a temporal query language, to link IBM Marketscan claims over time for > 125 million US individuals from 2007-2014. To select the most common MBC subtype (ER+, HER2-), our criteria were: ≥2 MBC ICD codes, ≥1 year of follow-up, and ≥1 CPT or medication code for endocrine therapy and 0 for HER2-targeted therapy. We defined aggressive MBC as ≥1 ICD code for visceral or central nervous system metastasis < 1 year after the first MBC code. Geographic area was defined by 9 Census-Bureau designated regions. End-of-record was used as a surrogate for death in a Cox regression. We used multivariate logistic regression to determine correlation of factors, including disease aggressiveness and geography, with treatment, monitoring, and end-of-life events. Results: 7,335 women met criteria for ER+, HER2- MBC, with median age 59. Nearly half (46%) had aggressive disease, which correlated with shorter survival (hazard ratio (HR) 1.5 [1.4-1.6], P < 0.001). Treatment: first-line was endocrine therapy for 64% versus chemotherapy for 36%. Monitoring: 79% were imaged mostly by CT versus 21% by PET-CT, with median between-scan interval of 81 days; 63% received CA 15-3 serum tumor markers. End-of-life: 10% had a hospice code, of whom 19% had an ICU stay and 34% chemotherapy in the prior 3 months. Correlates of care: Disease aggressiveness correlated with first-line chemotherapy (odds ratio (OR) 2.0 [1.8-2.2], P < 0.001), PET/CT (OR 1.6 [1.4-1.8], P < 0.001), more frequent scans (OR 2.3 [2.1-2.6], P < 0.001), and chemotherapy < 3 months pre-hospice (OR 1.2 [1.1-1.4], P < 0.001), but not with CA 15-3 monitoring or ICU stay. Disease aggressiveness did not vary by region (χ2 P = 0.8), but region was significantly associated with treatment, monitoring, and end-of-life care (P < 0.001). Conclusions: Approximately two-thirds of ER+, HER2- MBC patients receive first-line endocrine therapy and are monitored with CA 15-3 serum tumor markers; 10% had evidence of hospice use, a likely underestimate due to differential follow-up. MBC care patterns vary by geography while disease aggressiveness does not, suggesting that care is not optimally tailored to individuals. These insights from claims data can inform quality improvement for MBC care.