Repeatability of 18F-FDG uptake in metastatic bone lesions of breast cancer patients and implications for accrual to clinical trials

BACKGROUND

Standard measures of response such as Response Evaluation Criteria in Solid Tumors are ineffective for bone lesions, often making breast cancer patients that have bone-dominant metastases ineligible for clinical trials with potentially helpful therapies. In this study we prospectively evaluated the test-retest uptake variability of 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) in a cohort of breast cancer patients with bone-dominant metastases to determine response criteria. The thresholds for 95% specificity of change versus no-change were then applied to a second cohort of breast cancer patients with bone-dominant metastases.

METHODS

For this study, nine patients with 38 bone lesions were imaged with 18F-FDG in the same calibrated scanner twice within 14 days. Tumor uptake was quantified by the most commonly used PET parameter, the maximum tumor voxel normalized by dose and body weight (SUVmax) and also by the mean of a 1-cc maximal uptake volume normalized by dose and lean-body-mass (SULpeak). The asymmetric repeatability coefficients with confidence intervals for SUVmax and SULpeak were used to determine the limits of 18F-FDG uptake variability. A second cohort of 28 breast cancer patients with bone-dominant metastases that had 146 metastatic bone lesions was imaged with 18F-FDG before and after standard-of-care therapy for response assessment.

RESULTS

The mean relative difference of SUVmax and SULpeak in 38 bone tumors of the first cohort were 4.3% and 6.7%. The upper and lower asymmetric limits of the repeatability coefficient were 19.4% and - 16.3% for SUVmax, and 21.2% and - 17.5% for SULpeak. 18F-FDG repeatability coefficient confidence intervals resulted in the following patient stratification using SULpeak for the second patient cohort: 11-progressive disease, 5-stable disease, 7-partial response, and 1-complete response with three inevaluable patients. The asymmetric repeatability coefficients response criteria for SULpeak changed the status of 3 patients compared to the standard Positron Emission Tomography Response Criteria in Solid Tumors of ± 30% SULpeak.

CONCLUSION

In evaluating bone tumor response for breast cancer patients with bone-dominant metastases using 18F-FDG SUVmax, the repeatability coefficients from test-retest studies show that reductions of more than 17% and increases of more than 20% are unlikely to be due to measurement variability. Serial 18F-FDG imaging in clinical trials investigating bone lesions in these patients, such as the ECOG-ACRIN EA1183 trial, benefit from confidence limits that allow interpretation of response.

Alcohol, Smoking, and Risks of Breast Cancer Recurrence and Mortality among Women with Luminal, Triple-Negative, and HER2-Overexpressing Breast Cancer

BACKGROUND

This study evaluates the relationship between smoking, alcohol, and breast cancer outcomes according to molecular subtype.

METHODS

This population-based prospective cohort consisted of 3,876 women ages 20 to 69 diagnosed with a first primary invasive breast cancer from 2004 to 2015 in the Seattle-Puget Sound region. Breast cancer was categorized into three subtypes based on estrogen receptor (ER), progesterone receptor (PR), and HER2 expressions: luminal (ER+), triple-negative (TN; ER-/PR-/HER2-), and HER2-overexpressing (H2E; ER-/HER2+). We fit Cox proportional hazards models to assess the association between alcohol consumption and smoking status at diagnosis and risks of recurrence, breast cancer-specific mortality, and all-cause mortality.

RESULTS

Histories of ever smoking [HR, 1.33; 95% confidence interval (CI), 1.01-1.74] and current smoking (HR, 1.59; 95% CI, 1.07-2.35) were associated with greater risk of breast cancer recurrence among TN cases. Smoking was also associated with greater risk of recurrence to bone among all cases and among luminal cases. Elevated risks of breast cancer-specific and all-cause mortality were observed among current smokers across all subtypes. Alcohol use was not positively associated with risk of recurrence or mortality overall; however, TN patients who drank four or more drinks per week had a decreased risk of recurrence (HR, 0.71; 95% CI, 0.51-0.98) and breast cancer-specific mortality (HR, 0.73; 95% CI, 0.55-0.97) compared with non-current drinkers.

CONCLUSIONS

Patients with breast cancer with a history of smoking at diagnosis have elevated risks of recurrence and mortality.

IMPACT

These findings underscore the need to prioritize smoking cessation among women diagnosed with breast cancer.

Repeatability of 18F-FDG uptake in metastatic bone lesions of breast cancer patients and implications for accrual to clinical trials

BACKGROUND

Standard measures of response such as Response Evaluation Criteria in Solid Tumors are ineffective for bone lesions, often making breast cancer patients with bone-dominant metastases ineligible for clinical trials with potentially helpful therapies. In this study we prospectively evaluated the test-retest uptake variability of 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) in a cohort of breast cancer patients with bone-dominant metastases to determine response criteria. The thresholds for 95% specificity of change versus no-change were then applied to a second cohort of breast cancer patients with bone-dominant metastases.In this study, nine patients with 38 bone lesions were imaged with 18F-FDG in the same calibrated scanner twice within 14 days. Tumor uptake was quantified as the maximum tumor voxel normalized by dose and body weight (SUVmax) and the mean of a 1-cc maximal uptake volume normalized by dose and lean-body-mass (SULpeak). The asymmetric repeatability coefficients with confidence intervals of SUVmax and SULpeak were used to determine limits of 18F-FDG uptake variability. A second cohort of 28 breast cancer patients with bone-dominant metastases that had 146 metastatic bone lesions was imaged with 18F-FDG before and after standard-of-care therapy for response assessment.

RESULTS

The mean relative difference of SUVmax in 38 bone tumors of the first cohort was 4.3%. The upper and lower asymmetric limits of the repeatability coefficient were 19.4% and -16.3%, respectively. The 18F-FDG repeatability coefficient confidence intervals resulted in the following patient stratification for the second patient cohort: 11-progressive disease, 5-stable disease, 7-partial response, and 1-complete response with three inevaluable patients. The asymmetric repeatability coefficients response criteria changed the status of 3 patients compared to standard the standard Positron Emission Tomography Response Criteria in Solid Tumors of ±30% SULpeak.

CONCLUSIONS

In evaluating bone tumor response for breast cancer patients with bone-dominant metastases using 18F-FDG uptake, the repeatability coefficients from test-retest studies show that reductions of more than 17% and increases of more than 20% are unlikely to be due to measurement variability. Serial 18F-FDG imaging in clinical trials investigating bone lesions from these patients, such as the ECOG-ACRIN EA1183 trial, benefit from confidence limits that allow interpretation of response.

Fluorine-18-Labeled Fluoroestradiol PET/CT: Current Status, Gaps in Knowledge, and Controversies-AJR Expert Panel Narrative Review

PET/CT using 16α-[18F]-fluoro-17β-estradiol (FES) noninvasively images tissues expressing estrogen receptors (ERs). FES has undergone extensive clinicopathologic validation for ER+ breast cancer and received FDA approval in 2020 for clinical use as an adjunct to biopsy in patients with recurrent or metastatic ER+ breast cancer. Clinical use of FES PET/CT is increasing, but is not widespread in the United States. This AJR Expert Panel Narrative Review explores the present status and future directions of FES PET/CT, including image interpretation, existing and emerging uses, knowledge gaps, and current controversies. Specific controversies discussed include whether both FES PET/CT and FDG PET/CT are warranted in certain scenarios, whether further workup is required after negative FES PET/CT results, whether FES PET/CT findings should inform endocrine therapy selection, and whether immunohistochemistry should remain the standalone reference standard for determining ER status for all breast cancers. Consensus opinions from the panel include agreement with the appropriate clinical uses of FES PET/CT published by a multidisciplinary expert workgroup in 2023; anticipated expanded clinical use of FES PET/CT for staging ER-positive invasive lobular carcinomas and low-grade invasive ductal carcinomas pending ongoing clinical trial results; and the need for further research regarding use of FES PET/CT for ER-expressing nonbreast malignancies.

Secondary Breast Angiosarcoma After a Primary Diagnosis of Breast Cancer: A Retrospective Analysis of the Surveillance, Epidemiology, and End Results (SEER) Database

OBJECTIVES

Angiosarcoma is a rare complication of breast-conserving therapy. This study evaluated the change in incidence between 1992 and 2016 of secondary breast angiosarcoma (SBA) in patients with a history of breast cancer and the impact of management strategies for the original breast carcinoma on angiosarcoma treatment.

METHODS

Breast cancer and angiosarcoma cases were abstracted from the Surveillance, Epidemiology, and End Result (SEER) database. SBAs were defined as angiosarcomas located in the breast occurring after a prior breast cancer diagnosis. Primary breast angiosarcomas (PBAs) were defined as an angiosarcoma diagnosis listed as "one primary only." Incidence rates were estimated using a proportion of the US total population. Survival was analyzed by the Kaplan-Meier method, and Cox proportional hazard models were used to assess the association of clinicopathologic characteristics on overall survival.

RESULTS

Between 1992 and 2016, 193 cases of SBA were reported in the SEER dataset in patients with a prior history of breast cancer. The incidence of breast angiosarcoma in patients with a prior diagnosis of breast cancer increased 3-fold from about 10 cases per 100,000 person-years to about 30 cases per 100,000 person-years over this same period ( P =0.0037). For treatment of SBA (n=193), almost all (95%) had surgery. Nine percent received radiation (compared with 35% of patients with PBA, P <0.001) and 23% received chemotherapy (vs. 45% for PBA, P =0.11).

CONCLUSIONS

We demonstrate an increasing incidence of SBA over the study period. These data can help inform shared decision-making for optimal management of locoregional breast cancer and raise awareness of secondary angiosarcoma.

Multimodal prediction of neoadjuvant treatment outcome by serial FDG PET and MRI in women with locally advanced breast cancer

PURPOSE

To investigate combined MRI and 18F-FDG PET for assessing breast tumor metabolism/perfusion mismatch and predicting pathological response and recurrence-free survival (RFS) in women treated for breast cancer.

METHODS

Patients undergoing neoadjuvant chemotherapy (NAC) for locally-advanced breast cancer were imaged at three timepoints (pre, mid, and post-NAC), prior to surgery. Imaging included diffusion-weighted and dynamic contrast-enhanced (DCE-) MRI and quantitative 18F-FDG PET. Tumor imaging measures included apparent diffusion coefficient, peak percent enhancement (PE), peak signal enhancement ratio (SER), functional tumor volume, and washout volume on MRI and standardized uptake value (SUVmax), glucose delivery (K1) and FDG metabolic rate (MRFDG) on PET, with percentage changes from baseline calculated at mid- and post-NAC. Associations of imaging measures with pathological response (residual cancer burden [RCB] 0/I vs. II/III) and RFS were evaluated.

RESULTS

Thirty-five patients with stage II/III invasive breast cancer were enrolled in the prospective study (median age: 43, range: 31-66 years, RCB 0/I: N = 11/35, 31%). Baseline imaging metrics were not significantly associated with pathologic response or RFS (p > 0.05). Greater mid-treatment decreases in peak PE, along with greater post-treatment decreases in several DCE-MRI and 18F-FDG PET measures were associated with RCB 0/I after NAC (p < 0.05). Additionally, greater mid- and post-treatment decreases in DCE-MRI (peak SER, washout volume) and 18F-FDG PET (K1) were predictive of prolonged RFS. Mid-treatment decreases in metabolism/perfusion ratios (MRFDG/peak PE, MRFDG/peak SER) were associated with improved RFS.

CONCLUSION

Mid-treatment changes in both PET and MRI measures were predictive of RCB status and RFS following NAC. Specifically, our results indicate a complementary relationship between DCE-MRI and 18F-FDG PET metrics and potential value of metabolism/perfusion mismatch as a marker of patient outcome.

Can Molecular Imaging Find a Path to Navigate Evolving Breast Cancer Treatments?

FES PET is an FDA-approved imaging biomarker. Like IHC, FES positivity predicts clinical benefit of endocrine therapy. In addition, FES measures the target activity in endocrine agent drug development. A recent study found that whole body tumor heterogeneity of expression predicts clinical benefit, and serial FES monitors ER blockade and post treatment release.

Summary: Appropriate Use Criteria for Estrogen Receptor-Targeted PET Imaging with 16α-18F-Fluoro-17β-Fluoroestradiol

PET imaging with 16α-¹⁸F-fluoro-17β-fluoroestradiol (¹⁸F-FES), a radiolabeled form of estradiol, allows whole-body, noninvasive evaluation of estrogen receptor (ER). ¹⁸F-FES is approved by the U.S. Food and Drug Administration as a diagnostic agent "for the detection of ER-positive lesions as an adjunct to biopsy in patients with recurrent or metastatic breast cancer." The Society of Nuclear Medicine and Molecular Imaging (SNMMI) convened an expert work group to comprehensively review the published literature for ¹⁸F-FES PET in patients with ER-positive breast cancer and to establish appropriate use criteria (AUC). The findings and discussions of the SNMMI ¹⁸F-FES work group, including example clinical scenarios, were published in full in 2022 and are available at https://www.snmmi.org/auc Of the clinical scenarios evaluated, the work group concluded that the most appropriate uses of ¹⁸F-FES PET are to assess ER functionality when endocrine therapy is considered either at initial diagnosis of metastatic breast cancer or after progression of disease on endocrine therapy, the ER status of lesions that are difficult or dangerous to biopsy, and the ER status of lesions when other tests are inconclusive. These AUC are intended to enable appropriate clinical use of ¹⁸F-FES PET, more efficient approval of FES use by payers, and promotion of investigation into areas requiring further research. This summary includes the rationale, methodology, and main findings of the work group and refers the reader to the complete AUC document.

The oral selective estrogen receptor degrader GDC-0810 (ARN-810) in postmenopausal women with hormone receptor-positive HER2-negative (HR + /HER2 -) advanced/metastatic breast cancer

PURPOSE

GDC-0810 (ARN-810) is a novel, non-steroidal, orally bioavailable, selective estrogen receptor degrader (SERD) that potentially inhibits ligand-dependent and ligand-independent estrogen receptor (ER)-mediated signaling.

METHODS

A phase Ia/Ib/IIa dose escalation, combination treatment with palbociclib or a luteinizing hormone-releasing hormone, and expansion study determined the safety, pharmacokinetics, and recommended phase 2 dose (RP2D) of GDC-0810 in postmenopausal women with ER + (HER2 -) locally advanced or metastatic breast cancer (MBC). Baseline plasma ctDNA samples were analyzed to determine the ESR1 mutation status.

RESULTS

Patients (N = 152) received GDC-0810 100-800 mg once daily (QD) or 300-400 mg twice daily, in dose escalation, expansion, as single agent or combination treatment. Common adverse events regardless of attribution to study drug were diarrhea, nausea, fatigue, vomiting, and constipation. There was one dose-limiting toxicity during dose escalation. The maximum tolerated dose was not reached. GDC-0810 600 mg QD taken with food was the RP2D. Pharmacokinetics were predictable. FES reduction (> 90%) highlighting pharmacodynamic engagement of ER was observed. Outcomes for the overall population and for patients with tumors harboring ESR1 mutations included partial responses (4% overall; 4% ESR1), stable disease (39% overall; 42% ESR1), non-complete response/non-progressive disease (13% overall; 12% ESR1), progressive disease (40% overall; 38% ESR1), and missing/unevaluable (5% overall; 5% ESR1). Clinical benefit (responses or SD, lasting ≥ 24 weeks) was observed in patients in dose escalation (n = 16, 39%) and expansion (n = 24, 22%).

CONCLUSION

GDC-0810 was safe and tolerable with preliminary anti-tumor activity in heavily pretreated patients with ER + advanced/MBC, with/without ESR1 mutations, highlighting the potential for oral SERDs. Clinical Trial and registration date April 4, 2013. NCT01823835 .

Abstract CT517: Amcenestrant, an oral selective estrogen receptor (ER) degrader (SERD), in ER+/HER2- advanced breast cancer (aBC): combined biomarker analyses from a Phase 1/2 study in postmenopausal women and a Phase 1 study in postmenopausal Japanese women

Background: Amcenestrant is an optimized oral SERD that has shown safety and clinical benefit in patients (pts) with wild-type (WT) and mutated ESR1 aBC. Here we provide a pooled analysis of biomarkers from two studies in heavily-pretreated, postmenopausal women with ER+/HER2- aBC.

Methods: Pooled analysis included study data from AMEERA-1 (NCT03284957), in which pts received single-agent amcenestrant in dose escalation (20-600 mg QD or 300 mg BID) and dose expansion (400 mg QD), and from AMEERA-2 (NCT03816839), in which Japanese pts received single-agent amcenestrant at 400 mg QD or 300 mg BID. Mutational profiling of plasma circulating cell-free DNA was conducted by droplet digital polymerase chain reaction (ddPCR) for 12 pathogenic ESR1 mutations at baseline (BL) and on treatment (OT; Cycle 2, Day 28), and by next-generation sequencing (NGS; 77-gene panel) at BL and end of treatment (EOT). Clinical benefit (CB; complete response + partial response [PR] + stable disease ≥ 24 weeks) was assessed in pooled pts who received amcenestrant≥ 150 mg QD or BID. In tumor tissue, ER, progesterone receptor (PgR), Ki67 and Bcl-2 expression levels over time were assessed by immunohistochemistry; functional ER pathway activity was assessed by gene set variation analysis with RNA-seq data (ER activity score).

Results: Among pts with data for ESR1 mutation status at BL (N = 80; ddPCR), 41 pts were WT and 39 pts had at least one ESR1 mutation, with D538G and Y537S the most prevalent. CB was observed in pts with both WT (13 pts) and mutated ESR1 (12 pts) at BL. The most frequent pathogenic mutations detected in pts (N = 79; NGS) at BL were ESR1 (49%), followed by PI3KCA (46%)and TP53 (33%). In response-evaluable pts with ESR1 mutational profiling at BL and OT (N = 40; ddPCR), 17 of 19 pts with ESR1 mutation at BL showed a decrease in ESR1 mutation allele frequency, independently of clinical benefit. Eight pts showed an increase (7/25 no CB and 1/15 CB). Among 17 pts with biopsies, pts with ER or PgR -/low (H-score: 0-3) at BL did not derive benefit from treatment. In the remaining patients with ER high (H-score ≥ 140), no difference between pts with and without CB was observed in ER, Bcl-2 or ER activity score, while pts with CB had a tendency for lower Ki67. ER and PgR decreased upon treatment independently of CB, while ER activity score and Ki67 mostly decreased in pts with CB and mostly increased in pts without CB.

Conclusions: In postmenopausal women with ER+/HER2- aBC treated with single-agent amcenestrant, low Ki67 at BL and the pharmacodynamic decrease of Ki67 and ER activation score by amcenestrant trended toward an association with CB, whereas increase in ESR1 mutation allele frequency on treatment trended toward an association with lack of CB. Clinical benefit was observed in both pts with WT and mutated ESR1 at BL.

Citation Format: Hiroji Iwata, Aditya Bardia, Simon Lord, Hannah M. Linden, Mario Campone, Kenji Tamura, Kan Yonemori, Toru Mukohara, Cécile Combeau, Nils Ternes, Dimitri Carene, Jeff Ming, Joon Sang Lee, Marina Celanovic, Anne-Laure Bauchet, Monsif Bouaboula, Tomoyuki Tanaka, Yumiko Kawabata, Sarat Chandarlapaty. Amcenestrant, an oral selective estrogen receptor (ER) degrader (SERD), in ER+/HER2- advanced breast cancer (aBC): combined biomarker analyses from a Phase 1/2 study in postmenopausal women and a Phase 1 study in postmenopausal Japanese women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT517.

Matched FES and FDG PET imaging in patients with hormone receptor-positive, HER2+ advanced breast cancer

1042

Background: The recently FDA approved 18F-Fluoroestradiol (FES) is a PET imaging tracer for characterizing disease in patients with ER+ breast cancer. As FES PET enters clinical practice it will be important to establish its utility in the full population of hormone-receptor positive patients, including those with HER2+ tumors. Historically the consensus around ER+/HER+ disease has been that these tumors are primarily driven by HER2, with therapies focused on targeting this pathway. Emerging research suggests that ER+ and HER2+ tumors represent a distinct phenotype, with bidirectional crosstalk between ER and HER2 pathways contributing to resistance to therapies targeting these critical pathways. Methods: Our cross-sectional database of patients with one or more FES scans stretches back to 1996. We selected all patients with HER2+ advanced breast cancer to determine whether ER is functional in the ER+/HER2+ subset. We examined paired FDG and FES scans and recorded SUVmax in matched lesions between the FDG and FES scans. We also looked at a subset of patients who underwent scans at more than one time-points and examined the clinical characteristics of these cases over time. Results: 36 patients with metastatic ER+, HER2+ breast cancer underwent concurrent FDG and FES PET scans between 1996 and 2013. 34 subjects (94%) were female; 32 (89%) were Caucasian, and 4 (11%) were Asian. Eight patients underwent serial scans. A total of 200 metastatic sites were recorded with the majority (67%) being bony lesions. No difference in quantitative FES avidity was observed between soft tissue and osseous sites. Six patients (16%) had negative FES scans despite displaying FDG avid lesions; three patients had at least one negative FES scan on serial scans, and two demonstrated FES-avid lesions with no FDG activity. Average FES SUVmax for positive scans was 3.5, with a range of 0.8 to 10.7. Among eight patients with multiple scans, half had 2 scans, three had 3 scans, and one had 4 scans. In 7/8 patients (88%) FES avidity increased over time even as FDG decreased or stayed stable with treatment; in one, both FES and FDG decreased on follow up scan. Conclusions: In a cohort of ER+, HER2+ patients undergoing FDG and FES PET scans, robust concordance between FDG and FES uptake was observed. FES avidity increased in patients with multiple scans, suggesting that the ER pathway remained active during treatment. The strong FES positivity in many HER2+ patients in this cohort suggests that FES PET could be used to guide patient selection for trials examining deescalated regimens employing a non-chemotherapy partner for HER2-directed therapy or emphasizing more ER-directed therapies such as CDK4/6 inhibitors, which are not currently approved in this population. With the ongoing development of HER2- PET imaging, combination scans could carry the potential for discrimination between sites, possibly serving as a tool to guide biopsy.

Real-world practice patterns in the diagnosis of recurrent metastatic breast cancer in Washington state

e13640

Background: Evidence-based, national guidelines for the diagnosis of recurrent metastatic breast cancer (MBC) recommend confirmation of recurrence with biopsy and reassessment of biomarker status. Real world practice patterns may demonstrate disparities in adherence to guidelines with implications for patients and health systems. Methods: We utilized the Hutchinson Institute for Cancer Outcomes Research (HICOR) data repository that links Washington State cancer registry data to enrollment and claims from the major insurance payers in the state. We identified women > 18 years old diagnosed with recurrent MBC between 2008 and 2017 with evidence of enrollment in a commercial plan (Premera or Regence), Medicare, or Medicaid. Recurrence in Stage I-III patients was detected through identification of ICD 9/10 codes for metastatic disease or resumption of breast cancer systemic therapy (after minimum of 4 months from completion of early breast cancer therapy). Using claims, we identified receipt of and factors associated with biopsy, biomarker re-assessment, and treatment administered at recurrence. Results: We identified 715 patients with recurrent MBC (any ER or HER2 status) with median age of 62 (range 52-73). The majority of the cohort were Caucasian (89%) with the rest comprising of Asian, Black, American Indian, and Hispanic patients. Based on the Rural Urban Commuting Area (RUCA) classification, patients predominantly lived in metropolitan neighborhoods (97%). Approximately 13% of patients lived in areas of high deprivation (area of deprivation index, ADI, 8-10). Patients had either Commercial (53.1%), Medicaid (4.2%), Medicare (29.7%) or multiple (13.0%) insurance. Patients were primarily treated at high volume centers (70.9%), though 23% of patients were seen at low volume centers (<25 breast cancer patients/year). Of the patients with recurrent MBC, 49.5% received a biopsy to confirm metastatic diagnosis. Similarly, 48.7% of recurrent MBC patients underwent biomarker reassessment. Patients with highest co-morbidity index (>2) were more likely to undergo biopsy confirmation (20.3% vs 13.0%, p = 0.02). Biopsy was more often performed in patients receiving care at a high-volume center compared to low-volume center (74.3% vs 18.6%, p = 0.03). First line treatment selection was directly associated with receipt of biopsy and biomarker testing. Hormone therapy only was more common in patients who did not undergo biopsy (62.3% vs 37.7%, p <0.001) or biomarker reassessment (62.7% vs 37.3%, p <0.001). Conclusions: Our study shows there is variation across Washington state in biopsy and biomarker assessment in the diagnosis of recurrent metastatic breast cancer. Nearly half of cases had metastatic biopsy omitted. Our findings demonstrate downstream implications for treatment selection and support the need for quality initiatives to improve adherence to guidelines.

Phase 3 ENABLAR-2 study to evaluate enobosarm and abemaciclib combination compared to estrogen-blocking agent for the second-line treatment of AR+, ER+, HER2- metastatic breast cancer in patients who previously received palbociclib and estrogen-blocking agent combination therapy

TPS1121

Background: Targeting the androgen receptor (AR) may be the next important endocrine therapy for advanced breast cancer. The AR has been demonstrated to be a tumor suppressor when activated. Enobosarm is an oral selective AR targeting agonist that activates the AR in breast cancer. Preclinical studies in CDK4/6 inhibitor resistant PDX models demonstrated combinatorial synergistic activity of enobosarm plus CDK 4/6 inhibitors. An open-label, Phase 2 study, was conducted in 136 women with heavily pretreated ER+ HER2- metastatic breast cancer that were randomized to oral daily enobosarm at a dose of 9 or 18 mg. The efficacy evaluable (EE) group were patients that were AR positive (> 10% AR nuclear staining). In the EE population with measurable disease at baseline, 10 patients had received prior endocrine therapy + a CDK 4/6 inhibitor. Subsequent treatment with enobosarm resulted in a clinical benefit rate of 50% and the best overall response rate (ORR) was 30% (2CRs and 1 PR). Of the 10 patients, 7 had AR nuclear staining ≥40%. None of the patients with AR nuclear staining < 40% responded to enobosarm. Although a small subset of the study, it appears that enobosarm has activity in patients who had ≥40% AR staining and who had progressed on standard endocrine therapy with a CDK 4/6 inhibitor. Overall, treatment with enobosarm was well tolerated with significant positive effects on quality-of-life measurements. Methods: The ENABLAR-2 trial is an ongoing Phase 3, randomized, open-label, efficacy and safety study in patients with AR+ ER+ HER2- MBC with AR nuclear staining of ≥40%, who have progressed after one line of systemic therapy comprising estrogen blocking agent and palbociclib. The planned sample size is 186 patients randomized 1:1 to enobosarm + abemaciclib OR fulvestrant if the first line of therapy for MBC was a non-steroidal AI plus palbociclib, until disease progression, toxicity, or loss of clinical benefit. If first line therapy for metastatic breast cancer was fulvestrant plus palbociclib, then the patient will be randomized 1:1 to either enobosarm + abemaciclib OR an AI. Randomization will be stratified by AR% nuclear staining, ≥60% versus < 60%, as well as by estrogen blocking agent such that each cohort will have the same number of subjects previously receiving fulvestrant + palbociclib in first line therapy. The key objectives are to determine the safety and efficacy of enobosarm and abemaciclib combination versus an alternative estrogen blocking agent with the primary endpoint of PFS. Secondary endpoints include ORR, duration of response, overall survival, change from baseline in Short Physical Performance Battery (SPPB), change in EORTC Quality of Life Questionnaire (EORTC-QLQ) and change in body composition as measured by DEXA. Clinical trial information: NCT05065411.

Abstract P1-17-11: Updated data from AMEERA-1: Phase 1/2 study of amcenestrant (SAR439859), an oral selective estrogen receptor (ER) degrader (SERD), combined with palbociclib in postmenopausal women with ER+/HER2- advanced breast cancer

Background: In Arm 2 of the ongoing AMEERA-1 trial (NCT03284957), amcenestrant, an optimized oral SERD combined with the CDK4/6 inhibitor (CDK4/6i) palbociclib demonstrated favorable safety and encouraging antitumor activity among patients with endocrine-resistant ER+/HER2− advanced breast cancer in dose escalation (Part C) and dose expansion (Part D) (Chandarlapaty et al., ASCO 2021; abstract 1058). Here we report an update of safety, antitumor activity data, and progression-free survival (PFS), of amcenestrant 200 mg in combination with palbociclib. Analysis of genomic data, including modulation over time and correlation with clinical outcome, will also be presented. Methods: The trial enrolled postmenopausal women with ER+/HER2- locally-advanced or metastatic breast cancer with disease progression while on ≥ 6 months of prior endocrine therapy (ET) in the advanced setting, or who relapsed on adjuvant ET after the first 2 years of treatment or within 12 months of completing adjuvant ET. Prior chemotherapy (≤ 1) was allowed as well as prior CDK4/6i-based therapy (≤ 1, in Part C only). In this pooled analysis (N = 39), patients in Parts C + D received amcenestrant 200 mg once daily + palbociclib 125 mg (21 days on/7 days off), administered in 28-day cycles. Safety in the pooled analysis was reported using methods previously described (Chandarlapaty et al., ASCO 2021; abstract 1058). Data from investigator-assessed, response-evaluable patients in the pooled analysis without prior exposure to targeted therapies (N = 34) were used to evaluate antitumor activity per RECIST v1.1, including the objective response rate (ORR), clinical benefit rate (CBR), and PFS. Results: At a data cutoff of May 30, 2021, in the pooled analysis (N = 39), the median (range) duration of treatment exposure was 44.3 weeks (1-80). Of 39 patients, 24 (61.5%) had initiated at least 10 cycles (40 weeks) of treatment, with 20/39 (51.3%) still receiving ongoing treatment. Among the 34/39 (87.2%) patients in the response-evaluable population, median follow-up was 48.3 weeks with a PFS probability of being event free at 24 weeks of 78.2% (95% CI: 59.6%; 89.0%). Median PFS is not yet mature, with 14/34 (41.2%) patients having had a PFS event (all were progression events and no deaths occurred). The ORR was 11/34 (32.4%; all partial responses). Clinical benefit at 24 weeks was seen in 25/34 (CBR = 73.5%) patients. Median (range) time to first response was 16.3 weeks (8-32). Amcenestrant treatment-related adverse events (TRAEs) and palbociclib TRAEs, respectively, occurred in 27/39 (69.2%) and 35/39 (89.7%) patients for all grade events and in 5/39 (12.8%) and 18/39 (46.2%) patients for Grade ≥ 3 events. Non-hematological amcenestrant and palbociclib TRAEs are reported in Table 1. Neutrophil count decrease based on hematological laboratory abnormalities was observed in the majority of patients (94.9%; with Grade ≥ 3 in 56.4%).

Conclusions: Among postmenopausal women with endocrine-resistant ER+/HER2- advanced breast cancer, amcenestrant 200 mg in combination with the approved dose of palbociclib continues to demonstrate encouraging long-term antitumor activity, sustained clinical benefit, and a favorable safety profile consistent with previous results. Funding: Sanofi.

Table 1.Non-hematological amcenestrant and palbociclib TRAEs occurring in &gt; 10% of patientsPooled Analysis. Amcenestrant 200 mg + Palbociclib. (Parts C + D; N = 39)Amcenestrant Non-hematological TRAEs, n (%)All GradesGrade ≥ 3–Fatigue7 (17.9)0–Nausea7 (17.9)0–Arthralgia4 (10.3)0–Asthenia4 (10.3)0–Hot flush4 (10.3)0Palbociclib Non-hematological TRAEs, n (%)All GradesGrade ≥ 3–Fatigue12 (30.8)0–Nausea10 (25.6)0–Asthenia4 (10.3)0–Dysgeusia4 (10.3)0–Stomatitis4 (10.3)0

Citation Format: Sarat Chandarlapaty, Hannah M Linden, Patrick Neven, Katarina Petrakova, Aditya Bardia, Peter Kabos, Sofia Braga, Valentina Boni, Alice Gosselin, Marina Celanovic, Patrick Cohen, Gautier Paux, Vasiliki Pelekanou, Nils Ternès, Joon Sang Lee, Mario Campone. Updated data from AMEERA-1: Phase 1/2 study of amcenestrant (SAR439859), an oral selective estrogen receptor (ER) degrader (SERD), combined with palbociclib in postmenopausal women with ER+/HER2- advanced breast cancer [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 P1-17-11.

Abstract P1-17-02: ZN-c5, an oral selective estrogen receptor degrader (SERD), in women with advanced estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer

Background: Hormone receptor+/HER2- breast cancer is the most common subtype of breast cancer. Resistance to endocrine therapy is a major clinical challenge. Although fulvestrant binds and degrades the ER and shows anti-tumor activity in patients with advanced breast cancer, intramuscular injection is inconvenient and precludes achievement of higher and potentially more efficacious exposure. ZN-c5 is a novel, orally bioavailable SERD with high potency and has demonstrated activity in estrogen-dependent tumor models. Methods: This Phase 1/2, open-label, multicenter study is evaluating the safety, pharmacokinetics and preliminary anti-tumor activity of ZN-c5 as monotherapy or in combination with palbociclib. In the Phase 1 portion evaluating ZN-c5 as monotherapy, participants were adult, post-menopausal (or receiving a gonadotropin-releasing hormone agonist) women with advanced adenocarcinoma of the breast, ER+/HER2- disease, and sensitive to endocrine therapy for metastatic disease (partial response [PR], complete response or stable disease [SD] lasting &gt; 6 months or disease recurrence after at least 24 months of adjuvant endocrine treatment). ZN-c5 was administered orally and continuously in 28-day cycles until disease progression or unacceptable toxicity. Dose escalation cohorts of subjects were enrolled at several dose levels of ZN-c5, based on a modified 3+3 design. Enrollment in the Phase 1 ZN-c5 monotherapy dose escalation and expansion has been completed and results are presented. Phase 1 testing of ZN-c5 in combination with palbociclib and Phase 2 testing in monotherapy are ongoing and will be presented at a future meeting. Results: In Phase 1 monotherapy, a total of 56 female subjects were enrolled to receive ZN-c5 at dose levels of 50 mg once daily (QD, n=16), 75 mg QD (n=3), 100 mg QD (n=3), 75 mg twice daily (BID, n=6), 150 mg QD (n=15), 150 mg BID (n=3), or 300 mg QD (n=10). Median age was 58.5 years (range, 38 - 89) and ECOG performance status was 0 (55%) or 1 (45%). Subjects had a median of 2 prior therapies for advanced/metastatic disease (range, 0 - 9), with a median of 2 prior hormonal-based therapies (range, 0 - 6) and a median of 0 prior chemotherapies (range, 0 - 3). Twenty-six subjects (46%) received prior fulvestrant and 38 (68%) received a prior CDK4/6 inhibitor. Twenty subjects (38%) had a baseline ESR1 mutation. The cut-off date for this analysis was 11 May 2021. There was no increase in severity of treatment-emergent adverse events (TEAEs) with increase in dose level. No dose-limiting toxicities were reported. The most common TEAEs were nausea (30%), fatigue (25%), and arthralgia (20%). Grade 3 TEAEs reported in &gt; 1 subject were gamma-glutamyltransferase (GGT) increased and hyponatremia (2 subjects each); no Grade 4 TEAEs were reported. Among treatment-related events, the most common were hot flushes and nausea (14% each); the only Grade 3 events were GGT increased and hypersensitivity in 1 subject each. ZN-c5 was rapidly absorbed, with a median Tmax of 2 to 4 hours. AUC and Cmax on Days 1 and 15 were less than dose proportional. No ZN-c5 accumulation after 15 days of dosing was observed. Confirmed PRs have been observed in 2 subjects (at 150 and 300 mg QD, respectively), and 14/45 (31%) evaluable subjects have experienced clinical benefit (PR or SD ≥ 24 weeks). Five of the 14 subjects with long SD received prior fulvestrant. Median progression-free survival (PFS) was 3.8 months (95% CI: 3.2, 5.3). Conclusions: In this first-in-human study, ZN-c5 monotherapy was well tolerated and showed clinical benefit, including confirmed PRs, in subjects with advanced ER+/HER2- breast cancer. These data warrant further evaluation of ZN-c5 as monotherapy and in combination with palbociclib.

Citation Format: Kevin Kalinksy, Vandana Abramson, Pavani Chalasani, Hannah M. Linden, Jasmina Alidzanovic, Rachel M. Layman, Živko Vranješ, Julie R. Nangia, Katherine D. Crew, Zoran Andric, Marijana Milovic-Kovacevic, Jasna Trifunovic, Jose Suarez, Matt Suster, Mieke Ptaszynski, Joanne Mortimer. ZN-c5, an oral selective estrogen receptor degrader (SERD), in women with advanced estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer [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 P1-17-02.

Abstract OT2-11-03: AMEERA-1 : Phase 1/2 study of amcenestrant (SAR439859), an oral selective estrogen receptor (ER) degrader (SERD), with alpelisib in postmenopausal women with ER+/human epidermal growth factor receptor 2-negative (HER2-)PIK3CA-mutated advanced breast cancer

Background Amcenestrant is an optimized oral SERD with potent dual activity of ER antagonism and degradation resulting in inhibition of ER signaling. Amcenestrant monotherapy or combination with palbociclib showed antitumor activity and a favorable safety profile in postmenopausal women with heavily pretreated ER+/HER2- mBC. PIK3CA mutations are associated with endocrine resistance in ER+/HER2- patients (pts). Published data support the addition of the PI3Kα inhibitor alpelisib to SERD therapy for these pts. Methods AMEERA-1 (NCT03284957) is an open-label, non-comparative, dose escalation and dose expansion Phase 1/2 study of amcenestrant as monotherapy, then in combination with other anti-cancer targeted therapies. Parts F and G investigate safety run-in and dose expansion, respectively, of amcenestrant in combination with alpelisib. Postmenopausal women with ER+/HER2- advanced breast cancer, PIK3CA mutated in tumor tissue or cfDNA, ECOG performance status 0-1, and ≥ 6 months prior endocrine therapy are eligible. Pts must have progressed on an aromatase inhibitor plus CDK4/6 inhibitor as first-line therapy for advanced disease. Part F allows ≤ 1 prior chemotherapy for advanced disease; no prior chemotherapy is allowed in Part G. Exclusion criteria in Parts F and G include prior drugs targeting the PI3K axis, type 1 diabetes, uncontrolled type 2 diabetes, history of severe cutaneous reactions, and ongoing osteonecrosis of the jaw. Part F assesses dose-limiting toxicities and pharmacokinetics (PK) of a standard dose of amcenestrant plus the approved dose of alpelisib (300 mg once daily). Additional amcenestrant doses or a lower dose of alpelisib may be explored based on safety and PK. The primary objective in Part F is to confirm the recommended phase 2 dose (RP2D) of amcenestrant in combination with alpelisib, based on safety. In Part G, approximately 34 pts will be treated at the RP2D, the primary endpoint being safety and tolerability. Secondary endpoints include PK and antitumor activity. This study is currently recruiting participants. This abstract was previously submitted to the 2021 European Society for Medical Oncology Annual Congress. Funding: Sanofi.

Citation Format: Mario Campone, Aditya Bardia, Peter Kabos, Sarat Chandarlapaty, Patrick Neven, Valentina Boni, Simon Lord, Sylvaine Cartot-Cotton, Marina Celanovic, Alice Gosselin, Vasiliki Pelekanou, Hannah M Linden. AMEERA-1 : Phase 1/2 study of amcenestrant (SAR439859), an oral selective estrogen receptor (ER) degrader (SERD), with alpelisib in postmenopausal women with ER+/human epidermal growth factor receptor 2-negative (HER2-)PIK3CA-mutated advanced breast cancer [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 OT2-11-03.

A Phase II Study Evaluating the Safety and Efficacy of Sunitinib Malate in Combination With Weekly Paclitaxel Followed by Doxorubicin and Daily Oral Cyclophosphamide Plus G-CSF as Neoadjuvant Chemotherapy for Locally Advanced or Inflammatory Breast Cancer

INTRODUCTION

Neoadjuvant chemotherapy is standard treatment for locally advanced breast cancer (LABC) or inflammatory breast cancer (IBC). We hypothesized that adding sunitinib, a tyrosine kinase inhibitor with antitumor and antiangiogenic activity, to an anthracycline and taxane regimen would improve pathologic complete response (pCR) rates to a prespecified endpoint of 45% in patients with HER2-negative LABC or IBC.

METHODS

We conducted a multicenter, phase II trial of neoadjuvant sunitinib with paclitaxel (S+T) followed by doxorubicin and cyclophosphamide plus G-CSF for patients with HER2-negative LABC or IBC. Patients received sunitinib 25 mg PO daily with paclitaxel 80 mg/m² IV weekly ×12 followed by doxorubicin 24 mg/m² IV weekly + cyclophosphamide 60 mg/m² PO daily with G-CSF support. Response was evaluated using pCR in the breast and the CPS + EG score (clinical-pathologic scoring + estrogen receptor [ER] and grade).

RESULTS

Seventy patients enrolled, and 66 were evaluable for efficacy. Eighteen patients (27%) had pCR in the breast (10 had ER⁺ disease and 8 had triple-negative disease). When defining response as pCR and/or CPS + EG score ≤2, 31 (47%) were responders. In pateints with ER positive disease, 23 (64%) were responders. The most common toxicities were cytopenias and fatigue.

CONCLUSIONS

Neoadjuvant S+T followed by AC+G-CSF was safe and tolerable in LABC and IBC. The study did not meet the prespecified endpoint for pCR; however, 47% were responders using pCR and/or CPS + EG score ≤2. ER positive patients had the highest response rate (64%). The addition of sunitinib to neoadjuvant chemotherapy may provide promising incremental benefit for patients with ER positive LABC.

Real-world practice patterns in treatment of metastatic breast cancer in Washington State

e13038

Background: Evidence-based, national guidelines for the management of metastatic breast cancer (MBC) recommend numerous treatment options that do not capture the nuances of real-world practice. Disparities may exist across Washington State with financial implications for patients and health systems. The objective of this study was to assess practice patterns around treatment of ER+/HER2- MBC in actual clinical practice. Methods: We collaborated with Hutchinson Institute for Cancer Outcomes Research (HICOR) to link enrollment and insurance claims records with Washington State cancer registries from 2008-2017. Our cohort comprised of women >18 years old with de novo ER+/HER2- MBC who met enrollment criteria in one of four payors (Premera, Regence, Medicare, or Medicaid). We identified receipt of first line treatment, categorized as CDK4/6 inhibitors plus endocrine therapy (CDKi+ET), chemotherapy (CT), or endocrine therapy alone (ET). We examined factors influencing treatment selection using Fisher's and Kruskal-Wallis tests. Total costs (defined as costs from inpatient and outpatient claims one year after diagnosis) was estimated for patients and payors. Results: We identified 140 patients with de novo ER+/HER2- MBC with median age of 64 (range 28-95). The majority of the cohort were Caucasian (90%) with the rest comprising of Asian, Black, American Indian, and Hispanic patients. Based on the Rural Urban Commuting Area (RUCA) classification, patients predominantly lived in metropolitan neighborhoods (96%). Over 20% of patients lived in areas of high deprivation (area of deprivation index, ADI, 8-10). Patients had either Commercial (40.7%), Medicaid/Medicare (43.6%) or multiple (15.7%) insurance. Our data show that 17 patients (12%) received first line therapy with CDKi + ET, 64 patients (46%) with CT, and 59 patients (42%) with ET alone. Factors influencing treatment selection include age, co-morbidity score, and payor type. Older patients (>65 years old) were more likely to receive ET alone compared to younger patients (56% vs 44%, p value <0.001). Patients with high co-morbidity score were more likely to receive ET (30%) compared to CT (5%) or CDKi + ET (23%), p value <0.001. Patients with commercial insurance made up over 50% of patients in our cohort who received CDKi +ET, while Medicare-insured patients were most likely to receive ET alone (p value <0.001). We estimated the mean cost of receiving first line therapy with CDKi +ET ($20,368 and $175,932), CT ($10,624 and $117,847) and ET alone ($13,292 and $60,338) for patients and payors, respectively (costs inflated to December 2019). Conclusions: Our study shows substantial variation across Washington state in treatment selection and costs for patients with metastatic breast cancer in the first-line setting. Our findings demonstrate the need for initiatives to standardize quality of care relative to clinical guidelines in metastatic breast cancer care.

Efficacy of enobosarm, a selective androgen receptor (AR) targeting agent, correlates with the degree of AR positivity in advanced AR+/estrogen receptor (ER)+ breast cancer in an international phase 2 clinical study

1020

Background: The AR is expressed in up to 90% of ER+ breast cancer where it acts as a tumor suppressor. Historically, therapy with synthetic androgens had efficacy, but virilizing side effects and toxicity limited their use. Enobosarm is a selective AR activating agent that does not cause masculinization and has positive attributes such as promotion of bone and improvement of physical function. In a phase 2 study, correlation between the degree of AR staining and antitumor activity in AR+/ER+ patients with metastatic breast cancer (MBC) was examined. Methods: A phase 2, open label, parallel design randomized study was conducted in 136 patients to evaluate the efficacy and safety of enobosarm in heavily pretreated women with AR+/ER+ MBC. Patients were randomized to 9 mg (n=72) or 18 mg (n=64) of oral daily enobosarm. AR expression (%AR nuclei staining) in breast cancer samples was determined centrally by immunohistochemistry. The correlation between %AR staining and clinical outcomes was examined with a focus on the 9mg dose, selected for the phase 3 study and the optimal %AR staining established. Results: Tumor objective outcomes correlated with percent AR staining (Table). Further, using a 40% AR staining cutoff in patients with measurable disease, the clinical benefit rate (CBR) for ≥40% AR is 80% and <40% is 18% (p<0.0001). Best objective tumor response (BOR) in patients with ≥40% AR is 48% and <40% is 0% (p<0.0001). At ≥40% AR, median radiographic progression free survival (rPFS) is 5.47 and mean is 7.15 months vs <40% AR where the median rPFS is 2.72 and mean is 2.7 months. Similar %AR staining correlation was observed in the 18mg cohort. Enobosarm treatment was well tolerated with significant positive effects on quality of life measurements. Conclusions: Enobosarm is a novel oral selective AR activating agent in which a higher % AR staining correlates with a greater antitumor activity. By targeting and activating AR, enobosarm may represent a new hormone treatment approach for AR+/ER+ MBC. The phase 3, ARTEST trial will commence in early 2021 and randomize patients with AR+/ER+/HER2- heavily treated MBC that have progressed on a non-steroidal aromatase inhibitor, fulvestrant and CDK 4/6 inhibitor to receive enobosarm or standard endocrine therapy. Clinical trial information: NCT02463032 .[Table: see text]

AMEERA-1: Phase 1/2 study of amcenestrant (SAR439859), an oral selective estrogen receptor (ER) degrader (SERD), with palbociclib (palbo) in postmenopausal women with ER+/ human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC)

1058

Background: AMEERA-1 (NCT03284957) investigates amcenestrant, an oral SERD, as monotherapy and combined with targeted therapies in ER+/HER2– mBC. Here we report data from dose escalation (Part C) and dose expansion (Part D) of amcenestrant + palbo. Methods: Patients (pts) were postmenopausal women with ER+/HER2– mBC and ≥ 6 mos prior advanced endocrine therapy (ET) or adjuvant (adj) ET resistance (relapse on adj ET started ≥ 24 mos ago or < 12 mos after completing adj ET). Prior chemotherapy (≤ 1) for advanced disease was allowed; targeted therapies were not except ≤ 1 CDK4/6i in Part C. Part C assessed dose-limiting toxicities (DLTs) and aimed to establish the recommended phase 2 dose (RP2D) for amcenestrant (200 or 400 mg once daily [QD], in 28-day cycles) in combination with palbo (125 mg QD for 21 days on/ 7 days off). Safety (treatment-emergent adverse events [TEAEs] and lab abnormalities per CTCAE v4.03) and pharmacokinetics (PK) were evaluated. Antitumor activity at the RP2D for amcenestrant + palbo was evaluated in a subset of Part C pts and Part D, according to RECIST v1.1, determined locally by investigators. Results: Feb 8, 2021 data cutoff. In Part C (n = 15; 200 mg: 9; 400 mg: 6), no DLTs occurred and amcenestrant 200 mg QD was selected as the RP2D with palbo, based on PK and safety data. In the pooled safety population at the RP2D (n = 39; Part C: 9; Part D: 30), median (range) age was 59 y (33–86) with ECOG PS 0 (74.4%) or 1 (25.6%) and 2 (1–6) organs involved. Immediate prior therapy was neo/adj (41.0%, all ET resistant) or advanced (59.0%, range 1–4 lines). Median (range) exposure was 32 wks (1–66) with 59.0% pts on ongoing therapy. No amcenestrant dose reductions occurred; 25.6% had ≥ 1 palbo dose reduction. Most common non-hematological TEAEs related to amcenestrant were Grade 1–2 nausea and fatigue (17.9% each), asthenia and hot flush (10.3% each); to palbo were fatigue (30.8%), nausea (25.6%), asthenia and dysgeusia (10.3% each). Two pts discontinued due to AEs. The majority (94.9%) had neutrophil count decrease (53.8% Grade ≥ 3). Preliminary antitumor activity after at least 6 cycles of therapy (unless early treatment discontinuation) is reported in the table below. Conclusions: In pts with ER+/HER2– mBC, safety at the RP2D of amcenestrant + palbo was favorable, with no safety signals of bradycardia or eye disorders. Preliminary antitumor activity was observed (ORR: 31.4% and CBR: 74.3%). Clinical trial information: NCT03284957 .[Table: see text]

Abstract PS3-06: Fluoroestradiol F18 positron emission tomography diagnostic performance to characterize estrogen receptor status in breast cancer

Background

Estrogen receptor (ER) status by immunohistochemistry (IHC) of breast cancer tissue is currently used to direct endocrine therapy. Fluoroestradiol F18 (18F-FES) is a noninvasive method to determine the presence and ligand-binding function of the ER in metastatic breast cancer lesions throughout the body. Concordance of imaging and tissue assays should be established for 18F-FES PET to be an alternative or complement to tissue biopsy for metastatic lesions.

Objective

We conducted a meta-analysis of published results comparing 18F-FES PET and tissue assays of ER status in patients with breast cancer.

Method

PubMed and EMBASE were searched for English-language manuscripts with at least 10 patients and low overall risk of bias. We used hierarchical summary receiver-operating characteristic (HSROC) curve models for four analyses.

-For the first three analyses, IHC was used as the standard for tissue reference assay: i)18F-FES PET performance for nonbreast lesions in patients with metastatic breast cancer; ii)18F-FES PET performance for breast tumors; iii)18F-FES PET performance for all lesions (combined analysis);

-The last analysis assesses 18F-FES PET performance with all evaluable studies, which used a variety of standards for the tissue reference.

Results

PubMed and EMBASE searches identified 103 breast cancer studies involving 18F-FES PET, and 12 studies met the criteria for inclusion in our meta-analysis. Results are presented in Table 1.

Tests of homogeneity did not find differences in sensitivity or specificity among the studies in the primary analysis or other analyses with IHC as the tissue reference standard.

Examining all tumor sites and all breast cancer stages, our results are consistent with other published meta-analyses (Table 2).

Conclusion

A strong correlation has been demonstrated between ER status determined by IHC of tissue from a single lesion and 18F-FES PET in this meta-analysis, which validates the accuracy of 18F-FES PET assessment of metastatic ER status. These results suggest that 18F-FES PET is useful for characterization of ER status of metastatic breast cancer lesions. Moreover, 18F-FES has been approved by the FDA in May 2020 as an adjunct to biopsy in recurrent and metastatic breast cancer.

Table 1: 18F-FES PET test accuracy resultsNumber of studiesPooled number of ER-positive lesionsSensitivity (95% confidence region)Pooled number of ER-negative lesionsSpecificity (95% confidence region)Nonbreast lesions, IHC4690.78 (0.65-0.88)440.98 (0.65-1)Breast lesions, IHC3600.86 (0.73-0.94)180.76 (0.52-0.90)Combined, IHC71430.83 (0.72-.90)640.83 (0.64-0.93)Combined, all reference standards112110.81 (0.73-0.87)1160.86 (0.68-0.94)

Table 2: Comparison with other published meta-analysesStudyVan Kruchten 2013 1Evangelista 2016 2Chae 2019 3Combined, IHCSensitivity (95% Confidence Region)0.84 (0.73-0.91)0.82 (0.74-0.88)0.83 (0.72-0.91)0.83 (0.72, 0.90)Specificity (95% Confidence Region)0.98 (0.90-1.00)0.95 (0.86-0.99)0.93 (0.74-0.99)0.83 (0.64-0.93)1Van Kruchten et al., “PET Imaging of Oestrogen Receptors in Patients with Breast Cancer.”2 Evangelista et al., “18F-Fluoroestradiol Positron Emission Tomography in Breast Cancer Patients.”3 Chae et al., « Diagnostic Accuracy and Safety of 16α-[18F]Fluoro-17β-Oestradiol PET-CT for the Assessment of Oestrogen Receptor Status in Recurrent or Metastatic Lesions in Patients with Breast Cancer ».

Citation Format: Peter Webner, Brenda F. Kurland, Jay R. Wiggins, Amandine Coche, Charlotte Fontan, Yann Bouvet, Chaitanya Divgi, Hannah M. Linden. Fluoroestradiol F18 positron emission tomography diagnostic performance to characterize estrogen receptor status in breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS3-06.

Abstract PS13-38: Cardiotoxicity among patients with breast cancer treated with doxorubicin: A real-world database study

Background While novel targeted agents are increasingly used to care for patients with breast cancer, doxorubicin (DOX) continues to play a role in management of patients, particularly those with aggressive disease. Dose-dependent cardiomyopathy is a challenge in its use. Strategies have been proposed to mitigate this, including administration by continuous intravenous (CIV) infusion as an alternative to bolus (BOL) administration. This study used real world data to explore the impact of DOX administration mode on cardiotoxicity, duration of DOX and time to treatment failure (TTF). Methods IBM MarketScan claims were used to identify patients age ≥ 18 who received at least 2 DOX administrations (excluding liposomal DOX) after cancer diagnosis. Patients with history of cardiac events were excluded. Cardiac events based on a range of International Classification of Disease (ICD) codes were compared for BOL versus CIV overall, by tumor site and by regimen during three follow-up periods, early (within 1 year), middle (&gt;1 to 5 years) and late (&gt;5 years), from DOX initiation using Fisher’s exact test. Duration of DOX and TTF, defined as time from initiation of DOX to subsequent systemic therapy, hospice or death, were evaluated using Kaplan-Meier method and unadjusted Cox proportional hazards models. Results: A total of 38,924 patients with breast cancer met eligibility criteria (13,186 with confirmed metastatic disease). The most common regimen used was DOX plus cyclophosphamide (n=31,815, 81.7%). Most patients had codes for both modes on the same claim date and could not be definitely assigned to BOL or CIV infusion groups; however, 917 and 5,433 patients had exclusive BOL and CIV codes, respectively. Among patients receiving DOX monotherapy (n=687), 361 and 100 had exclusive BOL and CIV codes, respectively. For patients with exclusive infusion type codes, the mean duration of DOX treatment was not significantly different for BOL vs CIV (58.9 vs 56.2 days, p=0.33 overall; 74.4 vs 74.8 days for monotherapy, p=0.97). Overall, cardiac events for BOL vs CIV were 5.1% vs 4.7% (p=0.55) during the early period, 3.1% vs 5.0%, (p=0.01) during the middle period, and 0.4% vs 1.0% (p=0.10) in the late period. There were no differences in cardiac events for BOL vs CIV among those treated with DOX monotherapy (p=0.90, 0.56 and 0.52 for the early, middle, and late period, respectively). TTF was shorter for BOL vs CIV (262.3 vs 366.0 days, p&lt;0.001). However, when evaluating TTF, there was a significant relationship between cardiotoxicities and longer TTF (hazard ratio, HR=0.85, 95% confidence interval, CI: 0.81-0.88, p&lt;0.001). This relationship was statistically significant for the early, middle and late periods, respectively (all p&lt;0.001). Conclusions: These data suggest that cardiac events may occur at a similar rate for BOL and CIV. This study is limited by the retrospective nature of this study and the ability to determine causality; the use of strict coding rules to correctly assign patients to BOL vs CIV groups maintained scientific integrity and a large sample size but did result in the loss of eligible patients. Future research, including adjusted analyses, are needed to further investigate the relationship between mode of infusion and clinical outcomes.

Citation Format: Poorni Manohar, Hannah M Linden, Lisa M Hess, Tomoko Sugihara, Yajun E Zhu, Howard G Muntz, Lee D Cranmer. Cardiotoxicity among patients with breast cancer treated with doxorubicin: A real-world database study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS13-38.

Abstract PD8-08: A phase 1/2 study of SAR439859, an oral selective estrogen receptor (ER) degrader (SERD), as monotherapy and in combination with other anti-cancer therapies in postmenopausal women with ER-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC): AMEERA-1

Background SERDs belong to a class of ER-targeted therapies that antagonize and degrade ERs, including in ER-dependent tumors resistant to other endocrine therapies (ET). This study (AMEERA-1; NCT03284957) investigates SAR439859, an oral SERD, as monotherapy and (in ongoing cohorts) in combination with targeted therapies in patients (pts) with ER+/HER2- mBC. Here we report updated safety and antitumor activity with SAR439859 monotherapy, including exploratory analyses by prior therapy and ESR1 status. Methods This open-label, phase 1/2, first-in-human study assessed SAR439859 as monotherapy in Parts A (dose escalation 20-600 mg once daily [QD]) and B (dose expansion with recommended dose at 400 mg QD). Eligible pts were heavily pre-treated, postmenopausal women with ER+/HER2- mBC and measurable disease who received ≥6 months of prior ET in the advanced setting. Prior chemotherapy, mammalian target of rapamycin inhibitors (mTORi) and cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) for advanced disease were allowed. This analysis pooled data from pts receiving SAR439859 ≥150 mg (Part A) and 400 mg (Part B), administered in 28-day cycles. Antitumor activity was assessed by the objective response rate and clinical benefit rate (CBR: complete response [CR], partial response [PR] and stable disease [SD] ≥24 weeks) per RECIST v1.1, determined by investigators. Analyses by prior therapy and baseline ESR1 mutation status were performed. Safety was also evaluated. Results Pts (n = 62; Part A: 13; Part B: 49) had a median age of 63 (range 37-88) years and ECOG PS 0 (59.7%) or 1 (40.3%); 93.5% had visceral metastases. Pts had a median of 2 (range 1-8) prior lines of therapy in the advanced setting (48.4% had ≥3 prior lines): all had prior ET and 72.6% had prior targeted therapy. SAR439859 monotherapy showed antitumor activity in the response-evaluable population (n = 59) and in subset populations with ≤3 prior lines (n = 33) or without prior mTORi, CDK4/6i, or SERD (n = 14) (Table 1). For pts with ESR1 status (n = 58), CBR with SAR439859 was comparable in ESR1 wild-type (36.7%) and mutant mBC (32.1%), with similar results in subpopulations. Treatment-related adverse events (TRAEs) occurred in 62.9% of pts (all grade 1-2); none resulted in SAR439859 discontinuation. Most frequent TRAEs were hot flush (16.1%); constipation and arthralgia (each 9.7%); decreased appetite, vomiting, diarrhea and nausea (each 8.1%); and fatigue (6.5%). Conclusions Among heavily pre-treated pts, SAR439859 demonstrated antitumor activity, similar to historical single-agent fulvestrant activity in less heavily pre-treated pts with advanced/mBC (2L+ setting; no prior targeted agents) (indirect comparison). In both subsets of pts with fewer prior advanced lines of therapy, SAR439859 showed trends of greater clinical activity versus historical fulvestrant activity. SAR439859 had a favorable safety profile with limited TRAEs. No safety signals of cardiac or ocular toxicities were observed. Ongoing parts of the study are investigating SAR439859 in combination with targeted therapies. Based on the monotherapy results, a randomized phase 2 study is investigating SAR439859 compared with physician’s choice in a 2L+ setting (AMEERA-3; NCT04059484). Funding: Sanofi.

Antitumor activity overall and in subpopulations by prior lines of therapy (Parts A+B)Overall population (A+B)≤3 Prior advanced linesWithout prior targeted therapy(n = 59)a(n = 33)b(n = 14)cBOR, n (%)–CR000–PR5 (8.5)5 (15.2)3 (21.4)–SD24 (40.7)15 (45.5)8 (57.1)–PD30 (50.8)13 (39.4)3 (21.4)ORR, n (%)5 (8.5)5 (15.2)3 (21.4)CBR, n (%)20 (33.9)14 (42.4)9 (64.3)aPooled cohort (A ≥150 mg QD + B);bSubset of pooled cohort with ≤3 prior lines in the metastatic setting, including ≤1 of either prior chemotherapy or CDK4/6i and no prior mTORi; cSubset of pooled cohort with no prior mTORi, CDK4/6i, or fulvestrant.BOR, best overall response; CBR, clinical benefit rate; CR, complete response; ORR, objective response rate; PD, progressive disease; PR, partial response; SD, stable disease.

Citation Format: Hannah M Linden, Mario Campone, Aditya Bardia, Gary A Ulaner, Alice Gosselin, Séverine Doroumian, Vasiliki Pelekanou, Marina Celanovic, Sarat Chandarlapaty. A phase 1/2 study of SAR439859, an oral selective estrogen receptor (ER) degrader (SERD), as monotherapy and in combination with other anti-cancer therapies in postmenopausal women with ER-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC): AMEERA-1 [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD8-08.

18F-fluorodeoxyglucose (FDG) PET or 18F-fluorothymidine (FLT) PET to assess early response to aromatase inhibitors (AI) in women with ER+ operable breast cancer in a window-of-opportunity study

PURPOSE

This study evaluated the ability of ¹⁸F-Fluorodeoxyglucose (FDG) and ¹⁸F-Fluorothymidine (FLT) imaging with positron emission tomography (PET) to measure early response to endocrine therapy from baseline to just prior to surgical resection in estrogen receptor positive (ER+) breast tumors.

METHODS

In two separate studies, women with early stage ER+ breast cancer underwent either paired FDG-PET (n = 22) or FLT-PET (n = 27) scans prior to endocrine therapy and again in the pre-operative setting. Tissue samples for Ki-67 were taken for all patients both prior to treatment and at the time of surgery.

RESULTS

FDG maximum standardized uptake value (SUVmax) declined in 19 of 22 lesions (mean 17% (range -45 to 28%)). FLT SUVmax declined in 24 of 27 lesions (mean 26% (range -77 to 7%)). The Ki-67 index declined in both studies, from pre-therapy (mean 23% (range 1 to 73%)) to surgery [mean 8% (range < 1 to 41%)]. Pre- and post-therapy PET measures showed strong rank-order agreement with Ki-67 percentages for both tracers; however, the percent change in FDG or FLT SUVmax did not demonstrate a strong correlation with Ki-67 index change or Ki-67 at time of surgery.

CONCLUSIONS

A window-of-opportunity approach using PET imaging to assess early response of breast cancer therapy is feasible. FDG and FLT-PET imaging following a short course of neoadjuvant endocrine therapy demonstrated measurable changes in SUVmax in early stage ER+ positive breast cancers. The percentage change in FDG and FLT-PET uptake did not correlate with changes in Ki-67; post-therapy SUVmax for both tracers was significantly associated with post-therapy Ki-67, an established predictor of endocrine therapy response.

Determinants of Guideline-Discordant Breast Cancer Care

BACKGROUND

Evidence-based breast cancer treatment guidelines recommend the most appropriate course of therapy based on tumor characteristics and extent of disease. Evaluating the multilevel factors associated with guideline discordance is critical to identifying strategies to eliminate breast cancer survival disparities.

METHODS

We identified females diagnosed with a first primary, stage I-III breast cancer between the ages of 20-69 years of age from the population-based Seattle-Puget Sound Surveillance, Epidemiology, and End Results registry. Participants completed a survey about social support, utilization of patient support services, hypothesized barriers to care, and initiation of breast cancer treatment. We used logistic regression to estimate odds ratios and 95% confidence intervals (CI).

RESULTS

Among 1,390 participants, 10% reported guideline-discordant care. In analyses adjusted for patient-level sociodemographic factors, individuals who did not have someone to go with them to appointments or drive them home (OR 1.96; 95% CI, 1.09-3.59) and those who had problems talking to their doctors or their staff (OR 2.03; 95% CI, 1.13-3.64) were more likely to be guideline discordant than those with social support or without such problems, respectively. Use of patient support services was associated with a 43% lower odds of guideline discordance (OR 0.57; 95% CI, 0.36-0.88).

CONCLUSIONS

Although guideline discordance in this cohort of early-stage breast cancer survivors diagnosed <70 years of age was low, instrumental social support, patient support services, and communication with doctors and their staff emerged as potential multilevel intervention targets for improving breast cancer care delivery.

IMPACT

This study supports extending the reach of interventions designed to improve guideline concordance.

18F-Fluoroestradiol PET Imaging in a Phase II Trial of Vorinostat to Restore Endocrine Sensitivity in ER+/HER2- Metastatic Breast Cancer

Histone deacetylase inhibitors (HDACIs) may overcome endocrine resistance in estrogen receptor-positive (ER+) metastatic breast cancer. We tested whether ¹⁸F-fluoroestradiol PET imaging would elucidate the pharmacodynamics of combination HDACIs and endocrine therapy. Methods: Patients with ER+/human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer with prior clinical benefit from endocrine therapy but later progression on aromatase inhibitor (AI) therapy were given vorinostat (400 mg daily) sequentially or simultaneously with AI. ¹⁸F-fluoroestradiol PET and ¹⁸F-FDG PET scans were performed at baseline, week 2, and week 8. Results: Eight patients were treated sequentially, and then 15 simultaneously. Eight patients had stable disease at week 8, and 6 of these 8 patients had more than 6 mo of stable disease. Higher baseline ¹⁸F-fluoroestradiol uptake was associated with longer progression-free survival. ¹⁸F-fluoroestradiol uptake did not systematically increase with vorinostat exposure, indicating no change in regional ER estradiol binding, and ¹⁸F-FDG uptake did not show a significant decrease, as would have been expected with tumor regression. Conclusion: Simultaneous HDACIs and AI dosing in patients with cancer resistant to AI alone showed clinical benefit (6 or more months without progression) in 4 of 10 evaluable patients. Higher ¹⁸F-fluoroestradiol PET uptake identified patients likely to benefit from combination therapy, but vorinostat did not change ER expression at the level of detection of ¹⁸F-fluoroestradiol PET.

Outcomes Among Homeless Patients With Non-Small-Cell Lung Cancer: A County Hospital Experience

PURPOSE

Lung cancer remains the leading cause of cancer death in the United States, with outcomes likely worsened by the presence of poorer outcomes among vulnerable populations such as the homeless. We hypothesized that homeless patients experience delays in biopsy, decreased appointment adherence, and increased overall mortality rates.

METHODS

We conducted a retrospective electronic medical record-based review of all patients with non-small-cell lung cancer (NSCLC; N = 133) between September 2012 and September 2018 at an academic county hospital in Seattle, Washington.

RESULTS

Of the 133 patients treated for NSCLC, 22 (17%) were homeless at the time of their treatment. Among homeless patients with localized lung cancer, the mean time from radiographic finding to biopsy was 248 days, compared with 116 days among housed patients (P = .37). Homeless patients with advanced disease missed a mean of 26% of appointments in the year after diagnosis, compared with 16% among housed patients (P = .03). Homeless patients with advanced NSCLC had a median survival of 0.58 years, versus 1.30 years in housed patients (P = .48).

CONCLUSION

To our knowledge, this is the first US study comparing outcomes among homeless and housed patients with NSCLC within the same institution; we found homeless patients had longer delays to biopsy, increased rates of missed appointments, and a trend toward decreased survival. This study shows potential areas where interventions could be implemented to improve lung cancer outcomes in this patient population.

Clinical Trial Design and Development Work Group Within the Quantitative Imaging Network

The Clinical Trial Design and Development Working Group within the Quantitative Imaging Network focuses on providing support for the development, validation, and harmonization of quantitative imaging (QI) methods and tools for use in cancer clinical trials. In the past 10 years, the Group has been working in several areas to identify challenges and opportunities in clinical trials involving QI and radiation oncology. The Group has been working with Quantitative Imaging Network members and the Quantitative Imaging Biomarkers Alliance leadership to develop guidelines for standardizing the reporting of quantitative imaging. As a validation platform, the Group led a multireader study to test a semi-automated positron emission tomography quantification software. Clinical translation of QI tools cannot be possible without a continuing dialogue with clinical users. This article also highlights the outreach activities extended to cooperative groups and other organizations that promote the use of QI tools to support clinical decisions.

Phase I/II study of SAR439859, an oral selective estrogen receptor degrader (SERD), in estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC)

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Background: SERDs competitively antagonize and degrade the ER and can block signaling in ER-dependent tumors resistant to standard endocrine therapy (ET). This study (NCT03284957) investigates SAR439859, a potent oral SERD, in ER+/HER2- mBC. We present pooled dose escalation/expansion (Part A/B) data for SAR439859. Methods: Postmenopausal patients (pts) with ER+/HER2- mBC treated for ≥ 6 mos with prior ET received SAR439859 ≥ 150 mg QD (Part A) or 400 mg QD (Part B). Chemotherapy and targeted therapy in the advanced setting were allowed. Objective response rate (ORR; RECIST v1.1), clinical benefit rate (CBR; complete or partial response [PR] or stable disease [SD] ≥ 24 weeks), safety, and pharmacokinetics (PK) were assessed. Results: Pts (n = 62; Part A, 13; Part B, 49) had a median age of 63 yrs (range 37–88) and ECOG PS 0 (59.7%) or 1 (40.3%); 93.5% had visceral disease. All had prior ET, 74.2% had prior targeted therapy and 48.4% had ≥ 3 prior lines in the advanced setting. 61.3% of pts had treatment-related adverse events (TRAEs), all grade 1–2. Most frequent: hot flush (16.1%), constipation, arthralgia (both 9.7%), decreased appetite, vomiting, diarrhea, nausea (all 8.1%), fatigue (6.5%). No pts discontinued due to AEs. CBR was 35.6% overall, with antitumor activity irrespective of ESR1 mutation status (Table). In pts with no prior SERD, CDK4/6 or mTOR inhibitors (n = 14), ORR was 21.4% and CBR 64.3%. PK data for Part B and ESR1 mutation data will be provided. Conclusions: SAR439859 had a favorable safety profile with limited TRAEs. In these heavily pre-treated pts (prior targeted therapy in 74.2%), ORR and CBR were similar to historical fulvestrant performance in pts with no prior targeted therapy. Encouraging ORR and CBR in pts with no prior SERD, CDK4/6 or mTOR inhibitors (n = 14; ORR 21.4%; CBR 64.3%) supports SAR439859 development in earlier lines of therapy. Clinical trial information: NCT03284957 . [Table: see text]

Whole-Body Characterization of Estrogen Receptor Status in Metastatic Breast Cancer with 16α-18F-Fluoro-17β-Estradiol Positron Emission Tomography: Meta-Analysis and Recommendations for Integration into Clinical Applications

Estrogen receptor (ER) status by immunohistochemistry (IHC) of cancer tissue is currently used to direct endocrine therapy in breast cancer. Positron emission tomography (PET) with 16α-18F-fluoro-17β-estradiol (¹⁸ F-FES) noninvasively characterizes ER ligand-binding function of breast cancer lesions. Concordance of imaging and tissue assays should be established for ¹⁸ F-FES PET to be an alternative or complement to tissue biopsy for metastatic lesions. We conducted a meta-analysis of published results comparing ¹⁸ F-FES PET and tissue assays of ER status in patients with breast cancer. PubMed and EMBASE were searched for English-language manuscripts with at least 10 patients and low overall risk of bias. Thresholds for imaging and tissue classification could differ between studies but had to be clearly stated. We used hierarchical summary receiver-operating characteristic curve models for the meta-analysis. The primary analysis included 113 nonbreast lesions from 4 studies; an expanded analysis included 327 total lesions from 11 studies. Treating IHC results as the reference standard, sensitivity was 0.78 (95% confidence region 0.65-0.88) and specificity 0.98 (0.65-1.00) for the primary analysis of nonbreast lesions. In the expanded analysis including non-IHC tissue assays and all lesion sites, sensitivity was 0.81 (0.73-0.87) and specificity 0.86 (0.68-0.94). These results suggest that ¹⁸ F-FES PET is useful for characterization of ER status of metastatic breast cancer lesions. We also review current best practices for conducting ¹⁸ F-FES PET scans. This imaging assay has potential to improve clinically relevant outcomes for patients with (historically) ER-positive metastatic breast cancer, including those with brain metastases and/or lobular histology. IMPLICATIONS FOR PRACTICE: 16α-18F-fluoro-17β-estradiol positron emission tomography (¹⁸ F-FES PET) imaging assesses estrogen receptor status in breast cancer in vivo. This work reviews the sensitivity and specificity of ¹⁸ F-FES PET in a meta-analysis with reference tissue assays and discusses best practices for use of the tracer as an imaging biomarker. ¹⁸ F-FES PET could enhance breast cancer diagnosis and staging as well as aid in therapy selection for patients with metastatic disease. Tissue sampling limitations, intrapatient heterogeneity, and temporal changes in molecular markers make it likely that ¹⁸ F-FES PET will complement existing assays when clinically available in the near future.

Abstract OT1-04-05: Phase 1/2 dose-escalation and expansion study investigating SAR439859, a potent, oral, selective estrogen receptor degrader, +/- palbociclib in metastatic breast cancer

Background: Anti-estrogen therapy remains the gold standard for prevention and treatment of estrogen receptor-positive (ER+)/human epidermal growth factor receptor-negative (HER2-) breast cancer. However, resistance to anti-estrogen therapy is often observed in the clinic and frequently occurs through reactivation of ER transcriptional function. Unlike other classes of anti-estrogen therapy that have one mode of action, selective ER degraders (SERDs) block ER function through both competitive antagonism of the ligand binding pocket and induced degradation of the receptor. These have the potential to overcome multiple resistance mechanisms including ligand-independent mutations in ER 1. SAR439859 is a potent, oral SERD with improved preclinical efficacy and pharmaceutical properties compared with other SERDs. This study investigates SAR439859 +/- the cyclin-dependent kinase 4/6 inhibitor, palbociclib, in postmenopausal women with ER+/HER2- metastatic breast cancer.

Methods: This prospective, open-label, non-randomized Phase 1/2 study (NCT03284957; TED14856) assesses SAR439859 single agent at dose levels increasing from 20 mg/day up to the maximum administered dose (Part A) followed by cohort expansion at the recommended dose (RD; Part B). The study will also assess two dose levels of SAR439859, in combination with palbociclib 125 mg/day (Days 1-21 in 28-day cycles; Part C) followed by cohort expansion (Part D). The protocol has been amended to investigate the safety, pharmacokinetics and pharmacodynamics of alternative SAR439859 doses in an exploratory patient population. These patients will receive SAR439859 as two daily doses of up to 300 mg taken 12 hours apart with a maximum dose intensity of 600 mg/day (Table). Postmenopausal women with ER+/HER2- metastatic breast cancer, who have received ≥ 6 months of prior endocrine therapy, are eligible. Patients are permitted to have received ≤ 3 (Part A) or ≤ 1 (Parts B-D) prior chemotherapies (including antibody drug conjugates) for metastatic disease. Patients in Parts C and D with early progression on adjuvant therapy or progression on adjuvant endocrine therapy &lt; 12 months after ending therapy are eligible. Exclusion criteria include Eastern Cooperative Oncology Group performance status ≥ 2, concomitant illness (including those related to HIV or hepatitis and other cancers ≤ 3 years) and factors potentially affecting absorption of SAR439859 or palbociclib. Study endpoints include assessment of dose-limiting toxicities, determination of maximum tolerated dose and RD in dose escalation (Parts A and C), and objective response rate according to the Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 in dose expansion (Parts B and D). 18F-fluoroestradiol positron emission tomography scan between Days 11-15 in Part A will assess ER availability. Safety, pharmacokinetics and response will be evaluated for Parts A-D. As of May 9, 2019, 69 patients have been enrolled (Part A: n = 16; B: n = 47; C: n = 6; D: n = 0). Funding: Sanofi.

Table. DLs for determining the RD for SAR439859 alone (Part A) and in combination with palbociclib (Part C)Part ADLaDose (mg)ScheduleDL(-1)10QDDL120QDDL1bis50QDDL2100QDDL2bis150QDDL3200QDDL4400QDDL4bis200BIDDL5600QDDL5bis300BIDPart Cb,cDL1One DL below Part A QD RDQDDL2Part A QD RDQDDL3dPart A BID RDBIDaAdditional intermediate or higher DLs can be tested after agreement between Sponsor and Investigators (study committee). A twice-daily schedule of administration may be added during the study, the starting dose will be a DL of the same dose intensity as the highest cleared DL with the daily schedule. Other schedules of administration may be added during the study.bLower dose, intermediate DLs and a BID dose regimen can be tested after agreement between Sponsor and Investigators (study committee).cAll patients will also receive palbociclib at 125 mg QD with food for 21 days of each 28-day cycle. Lower doses (e.g. 100 mg or 75 mg) can be proposed depending on tolerance.dA BID dose could be tested assuming that BID monotherapy in Part A indicates a benefit compared with the RD given QD.BID, twice daily; DL, dose level; QD, once daily; RD, recommended dose.

Citation Format: Mario Campone, Aditya Bardia, Gary A Ulaner, Sarat Chandarlapaty, Alice Gosselin, Séverine Doroumian, Marina Celanovic, Hannah M Linden. Phase 1/2 dose-escalation and expansion study investigating SAR439859, a potent, oral, selective estrogen receptor degrader, +/- palbociclib in metastatic breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-04-05.

Validation of the DNA Damage Immune Response Signature in Patients With Triple-Negative Breast Cancer From the SWOG 9313c Trial

PURPOSE

To independently validate two biomarkers, a 44-gene DNA damage immune response (DDIR) signature and stromal tumor-infiltrating lymphocytes (sTILs), as prognostic markers in patients with triple-negative breast cancer (TNBC) treated with adjuvant doxorubicin (A) and cyclophosphamide (C) in SWOG 9313.

METHODS

Four hundred twenty-five centrally determined patient cases with TNBC from S9313 were identified. DDIR signature was performed on RNA isolated from formalin-fixed paraffin-embedded tumor tissue, and samples were classified as DDIR negative or positive using predefined cutoffs. Evaluation of sTILs was performed as described previously. Markers were tested for prognostic value for disease-free survival (DFS) and overall survival (OS) using Cox regression models adjusted for treatment assignment, nodal status, and tumor size.

RESULTS

Among 425 patients with TNBC, 33% were node positive. DDIR was tested successfully in 90% of patients (381 of 425), 62% of which were DDIR signature positive. DDIR signature positivity was associated with improved DFS (hazard ratio [HR], 0.67; 95% CI, 0.48 to 0.92; P = .015) and OS (HR, 0.61; 95% CI, 0.43 to 0.89; P = .010). sTILs density assessment was available in 99% of patients and was associated with improved DFS (HR, 0.70; 95% CI, 0.51 to 0.96; P = .026 for sTILs density ≥ 20% v < 20%) and OS (HR, 0.59; 95% CI, 0.41 to 0.85; P = .004 for sTILs density ≥ 20% v < 20%). DDIR signature score and sTILs density were moderately correlated (r = 0.60), which precluded statistical significance for DFS in a joint model. Three-year DFS and OS in a subgroup of patients with DDIR positivity and T1c/T2N0 disease were 88% and 94%, respectively.

CONCLUSION

The prognostic role of sTILs and DDIR in early-stage TNBC was confirmed. DDIR signature conferred improved prognosis in two thirds of patients with TNBC treated with adjuvant AC. DDIR signature has the potential to stratify outcome and to identify patients with less projected benefit after AC chemotherapy.

A pilot study of a comprehensive financial navigation program in cancer patients and caregivers

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Background: Few studies have reported on interventions to alleviate financial toxicity (FT) in cancer patients (pts) and informal caregivers (cgs). We developed a financial navigation program in collaboration with Consumer Education and Training Services (CENTS), Patient Advocate Foundation (PAF), and Family Reach Foundation (FRF), to offer financial coaching, insurance navigation, and assistance with unpaid non-medical bills. We conducted a pilot study to assess feasibility of enrolling cgs with pts and to describe the assistance provided. Methods: Pts with any stage solid tumor actively receiving treatment (tx) at the Seattle Cancer Care Alliance were asked to identify a cg who could participate. Pts or pt/cg dyads received an online financial education course and monthly contact for 6 months (mo) with CENTS and PAF. Subjects were referred to FRF for assistance in paying non-medical bills. We describe pt and cg characteristics, and assistance provided by the program. Results: Of 54 pts approached, 30 (median age 59.5, 61% white, 97% stage III/IV disease) were consented. Most pts (53%) had income ≤ $25,000, and all were insured (48% commercial, 28% Medicare, 21% Medicaid). 18 cgs (67% spouse/partner) were consented. At consent, 55% of pts reported debt in the prior 3 mo. Mean score using the COST PRO FT measure (range 0-44, lower score = higher FT) was 17.4 at baseline. After pts’ physical health, out-of-pocket costs were the most stressful aspects of tx for cgs. Cgs with high financial burden from caregiving more often reported taking on new debt, dipping into retirement accounts, or changing their jobs or hours. CENTS coaches assisted with budgeting, updating wills, and employment rights counsel. PAF case managers assisted with financial assistance for drugs, cost of living (e.g. transportation), disability applications, and secured $6,950 in debt relief. FRF dispersed $4,133, primarily for housing expenses. Conclusions: Implementing a financial navigation program that engages both pts and cgs is feasible. This lower income, financially stressed population received $11,000 in financial assistance. Future work will focus on evaluating the impact of this program on financial and psychosocial outcomes in pts and cgs.

Phase 1/2 dose-escalation and expansion study investigating SAR439859 +/- palbociclib in postmenopausal women with estrogen receptor-positive (ER+)/HER2- metastatic breast cancer

TPS1105

Background: Endocrine therapy +/- cyclin-dependent kinase 4/6 inhibitors, such as palbociclib, is the standard of care for ER+/HER2- breast cancer. Tumors often become resistant to this combination but retain ER signaling dependence, allowing for sequential ER-directed therapy. Unlike other classes of endocrine therapy with one mode of action, selective ER degraders (SERDs) block signaling by both ER competitive antagonism and degradation, targeting resistance settings that other treatments cannot. SAR439859 is a potent, oral SERD with improved preclinical efficacy and pharmaceutical properties vs other SERDs. This study investigates SAR439859 +/- palbociclib in postmenopausal women with ER+/HER2- metastatic breast cancer. Methods: This prospective, open-label, non-randomized Phase 1/2 study (NCT03284957; TED14856) assesses SAR439859 single agent at dose levels increasing from 20 mg/day up to the maximum administered dose (Part A) followed by cohort expansion at the recommended dose (RD; Part B). The study will also assess two dose levels of SAR439859, in combination with palbociclib 125 mg/day (Days 1–21 in 28-day cycles; Part C) followed by cohort expansion (Part D). Postmenopausal women with ER+/HER2- metastatic breast cancer, who received ≥ 6 months of prior endocrine therapy, are eligible. Patients were permitted to have received ≤ 3 (Part A) or ≤ 1 (Parts B–D) prior chemotherapies for metastatic disease. Exclusion criteria include Eastern Cooperative Oncology Group performance status ≥ 2, concomitant illness (including those related to HIV or hepatitis and other cancers ≤ 3 years) and factors potentially affecting absorption of SAR439859 or palbociclib. Study endpoints include assessment of dose-limiting toxicities, determination of maximum tolerated dose and RD in dose escalation (Parts A and C), and objective response rate according to RECIST v1.1 in dose expansion (Parts B and D). 18FES-PET scan between Days 11–15 in Part A will assess ER availability. Safety, pharmacokinetics and response were evaluated for Parts A–D. Recruitment and screening are ongoing (Part A n = 16; B n = 18; C n = 2; D n = 0). Funding: Sanofi. Clinical trial information: NCT03284957.

Homeless outcomes in non-small cell lung cancer: A county hospital experience

e20582

Background: Vulnerable populations such as homeless with non-small cell lung cancer (NSCLC) likely have higher mortality rates compared to the general population due to inadequate care, but their outcomes have not been described. We hypothesize that homeless patients with NSCLC experience greater mortality, shorter time from diagnosis to last known contact, delays in biopsy after imaging and treatment after biopsy, and greater rates of missed appointments following diagnosis. Methods: We conducted a retrospective review of all non-small cell lung cancer patients (N = 133) with appointments made between 9/2012 and 9/2018 at an academic county hospital with a dedication to the underserved in a major US city. Data were collected from electronic medical records manually and analyzed using ANOVA for continuous variables or Pearson's Chi-squared for categorical data. Results: Of the 133 patients diagnosed with non-small cell lung cancer, 21 (15.8%) were homeless at the time of their diagnosis. The mean time from diagnosis to last known contact was 1.4 vs 4.2 years (p = 0.0002) in localized disease and 1.41 vs 1.43 years (p = 0.95) in advanced disease for homeless vs housed patients. Kaplan Meier curve in advanced disease shows median survival time is 6.9 months (95% CI: 4.6 to N/A) for homeless (n = 13) vs 14.4 months (95% CI: 11.0 to 35.8) for housed (n = 67) patients (p = 0.51).The time from radiographic finding to biopsy, biopsy to intervention, and percentage of missed appointments in the year following diagnosis for homeless vs housed NSCLC with localized disease was 248 vs 116 days (p = 0.37), 20.1 vs 49.7 days (p = 0.19), and 21% vs 11% (p = 0.17) respectively; 35 vs 46 days (P = 0.64), 50 vs 58 days (p = 0.75), and 26% vs 16% (p = 0.034) among those with advanced disease. Conclusions: In this retrospective analysis, homeless with localized NSCLC experienced a significantly shorter time from diagnosis to last known contact. Homeless patients with advanced NSCLC had shorter median survival time compared to housed patients, although this was not statistically significant. Homeless patients with both localized and advanced disease had increased rates of missed appointments without significant delays in treatment. Further research is needed to improve outcomes.

Outcomes among patients with a history of substance abuse in non-small cell lung cancer: A county hospital experience

e20031

Background: Insufficient outpatient care among vulnerable patients, such as those with a history of alcohol or illicit substance use disorder (SUD), may contribute to poor outcomes in non-small cell lung cancer (NSCLC). We hypothesize that patients with newly diagnosed localized NSCLC and a history of SUD have a shorter time from diagnosis to last known contact, greater rates of depression, less family support, poorer follow-up, and increased emergency room and inpatient usage compared to those without a history of SUD. Methods: To investigate this, we conducted a retrospective review of all lung cancer patients with localized non-small cell carcinoma (N = 52) with visits between 9/2012 and 9/2018 at an academic county hospital with a dedication to the underserved in a major US city. Data were collected from electronic medical records manually and analyzed using ANOVA for continuous variables or Pearson's Chi-squared for categorical data. Results: Among patients with localized NSCLC (n = 52), 44% had a history of SUD. The mean time from diagnosis to last known contact and rate of loss-to-follow-up among those with a history of SUD vs no history of SUD was: 2.9 vs 4.4 years (p = 0.14) and 26.1% vs 20.7% (p = 0.64) respectively. Patients with history of SUD were more likely to live without family members and have a history of depression, anxiety or PTSD than those without a SUD history; 78.3% vs 44.8% (p = 0.023) and 60.9% vs 20.7% (p = 0.004). In the year following diagnosis the mean percentage of missed appointments, number of ER visits, number of inpatient stays, and total length of inpatient stay for patients with history of SUD vs no history of SUD were: 19% vs 8% (p = 0.01), 3.7 vs 1.4 (p = 0.08), 2.6 vs 0.9 (p = 0.10), and 17.7 vs 5.9 days (p = 0.06) respectively. Conclusions: In this retrospective analysis of patients with localized NSCLC, those with a history of SUD had shorter time from diagnosis to last known contact without increased rates of loss-to-follow-up. They also had greater rates of depression, less family support, increased rates of missed appointments, more emergency room visits, increased hospitalizations, and increased total duration of inpatient stay in the year following their diagnosis.

Dose-escalation study of SAR439859, an oral selective estrogen receptor (ER) degrader (SERD), in postmenopausal women with ER+/HER2- metastatic breast cancer (mBC)

1054

Background: SERDs result in ER competitive antagonism and degradation and can block signaling in ER-dependent tumors resistant to other endocrine therapies. This study investigates SAR439859, a potent oral SERD, +/- palbociclib in ER+/HER2- mBC. Here are preliminary results, as of 28 Nov 2018, for single-agent SAR439859 dose escalation. Methods: Part A of this Phase 1/2 study (NCT03284957; TED14856) assessed SAR439859 dose escalation (dose range: 20–600 mg once daily [QD]; 3 + 3 design) in postmenopausal women with ER+/HER2- mBC treated for ≥ 6 months with prior endocrine therapy and ≤ 3 chemotherapies in the advanced setting. Endpoints: dose-limiting toxicities (DLTs); maximum tolerated dose (MTD); safety; pharmacokinetics (PK); tumor response (RECIST 1.1); pharmacodynamic (PD) inhibition of ER occupancy (18FES-PET scan). Results: Patients (pts; n = 16) had a median age of 59.5 years (range 40–79), ECOG performance status of 0 (62.5%) or 1 (37.5%) and a median of three prior anticancer therapies (range 1–8) in the advanced setting (endocrine therapy n = 16; chemo/targeted therapy n = 13). All pts had ≥ 1 treatment emergent adverse event (mostly grade 1–2); most frequent were asthenia/fatigue (43.8%), hot flushes (37.5%), nausea (37.5%), diarrhea (31.3%), constipation (31.3%), and decreased appetite (31.3%). There were no DLTs at any of the five dose levels (maximum administered dose: 600 mg QD); MTD was not reached. In 18FES-PET scans, signal inhibition > 87% occurred with plasma concentrations > 100 ng/mL. There was a dose proportional increase of exposure up to 400 mg after repeated QD doses. Average Ctrough was reached after repeated 400 mg QD allowing 90% of 18FES-PET signal inhibition. One pt (6.3%) had confirmed partial response (150 mg QD); eight (50%) had stable disease (SD) including three (18.8%) long-term SD (≥ 24 weeks); seven (43.8%) had progressive disease. Conclusions: SAR439859 had a favorable safety profile, high ER occupancy and encouraging antitumor activity (to be confirmed in dose expansion) in pretreated pts with ER+/HER2- mBC. With no DLTs and MTD, 400 mg QD was selected for expansion cohorts based on safety, PD and PK data. Funding: Sanofi. Clinical trial information: NCT03284957.

Impact of homologous recombination deficiency biomarkers on outcomes in patients with triple-negative breast cancer treated with adjuvant doxorubicin and cyclophosphamide (SWOG S9313)

Background

Homologous recombination deficiency (HRD)-causing alterations have been reported in triple-negative breast cancer (TNBC). We hypothesized that TNBCs with HRD alterations might be more sensitive to anthracycline plus cyclophosphamide-based chemotherapy and report on HRD status and BRCA1 promoter methylation (PM) as prognostic markers in TNBC patients treated with adjuvant doxorubicin (A) and cyclophosphamide (C) in SWOG9313.

Patients and methods

In total, 425 TNBC patients were identified from S9313. HRD score, tumor BRCA1/2 sequencing, and BRCA1 PM were carried out on DNA isolated from formalin-fixed paraffin-embedded tissue. Positive HRD status was defined as either a deleterious tumor BRCA1/2 (tBRCA) mutation or a pre-defined HRD score ≥42. Markers were tested for prognostic value on disease-free survival (DFS) and overall survival (OS) using Cox regression models adjusted for treatment assignment and nodal status.

Results

HRD status was determined in 89% (379/425) of cases. Of these, 67% were HRD positive (27% with tBRCA mutation, 40% tBRCA-negative but HRD score ≥42). HRD-positive status was associated with a better DFS [hazard ratio (HR) 0.72; 95% confidence interval (CI) 0.51-1.00; P = 0.049] and non-significant trend toward better OS (HR = 0.71; 95% CI 0.48-1.03; P = 0.073). High HRD score (≥42) in tBRCA-negative patients (n = 274) was also associated with better DFS (HR = 0.64; 95% CI 0.43-0.94; P = 0.023) and OS (HR = 0.65; 95% CI 0.42-1.00; P = 0.049). BRCA1 PM was evaluated successfully in 82% (348/425) and detected in 32% of cases. The DFS HR for BRCA1 PM was similar to that for HRD but did not reach statistical significance (HR = 0.79; 95% CI 0.54-1.17; P = 0.25).

Conclusions

HRD positivity was observed in two-thirds of TNBC patients receiving adjuvant AC and was associated with better DFS. HRD status may identify TNBC patients who receive greater benefit from AC-based chemotherapy and should be evaluated further in prospective studies.

Clinical Trials Number

Int0137 (The trial pre-dates Clinicaltrial.Gov website establishment).

Abstract P1-14-02: A phase 2 study of low dose metronomic eribulin in metastatic breast cancer

Background: Eribulin mesylate is a non-taxane microtubule dynamics inhibitor approved by FDA in treatment of metastatic breast cancer (MBC) based on improvements in overall survival in the pivotal EMBRACE trial. Eribulin is approved at 1.4mg/m2 administered D1,8 of q21d cycle. However, this dose and schedule may have significant myelosuppression and peripheral neuropathy requiring dose reductions and treatment delays for some patients. We hypothesized that a low dose metronomic schedule will allow responding patients to remain on treatment, resulting in longer TTP (time to progression) and decreased incidence of toxicities and treatment-related discontinuations.

Methods: A multi-site prospective open-label phase II trial of metronomic dosing of eribulin in patients with MBC has completed accrual of 60 patients, outcomes will be updated at presentation. Patients whose disease had progressed following 1-6 prior regimens with prior exposure to a taxane, ECOG performance status of 0 – 2, measurable disease per RECIST 1.1, with normal marrow and organ function were eligible. Eribulin was administered at 0.9mg/m2 weekly for 3 out of 4 weeks. For patients with HER2 positive disease, concurrent trastuzumab administration was allowed. Concurrent denosumab or bisphosphonates were allowed for patients with bone disease.

Results: 60 patients were enrolled, average age 58 (range 34-83). Majority were postmenopausal Caucasian females, but the study included African American, Hispanic, native American, male patients. The majority of tumors were ER+, infiltrating ductal, but the study included 13 HER2+, and 12 TN tumors, with 5 ILC, and 5 mixed ILC/IDC. Nearly half of the enrolled patients had clinical benefit from the regimen, remaining on therapy for 6 months or longer, with stable disease or response; 50% had progression PD at 3 months 32% had stable disease and 18% had a partial or complete response (1, long term). Overall Survival, OS, for the entire group of heavily pre-treated patients was 1.2 years, with TN and HER2 positive patients faring better than ER+ in this small study. One HER2+ patient remains in long-term remission, off chemotherapy.

The regimen was extremely well tolerated. The majority of the patients experienced grade 0 or 1 toxicity for alopecia (48/60) and peripheral neuropathy (7 with grade 2 neuropathy, 5 pre-existing, 2 with grade 3 neuropathy). There were few dose reductions (n=15), thrombocytopenia (11 grade 1 only), or use of G-CSF (14).

Conclusions: Metronomic weekly low dose eribulin appears to be an active and tolerable regimen with less myelosuppression, alopecia and peripheral neuropathy than is seen with approved dose, allowing longer duration of use and disease control, with similar outcomes compared to the standard dose regimen. Outcomes will be updated at presentation.

Citation Format: Chalasani P, Liu AJ, Khanjian JA, Peha M, Buening BJ, Gadi VK, Specht JM, Salazar L, Linden HM. A phase 2 study of low dose metronomic eribulin in metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-14-02.

Abstract PD4-10: 18F-fluoroestradiol (FES) and 18F-fluorodeoxyglucose (FDG) PET imaging in staging extent of disease in metastatic lobular breast cancer

Background: The histology and pattern of spread in lobular breast cancer has presented challenges in estimating extent of disease and identifying treatment options. 18F-FES is an estrogen analogue PET imaging tracer which measures tumor ER expression at multiple tumor sites simultaneously and predicts response to endocrine therapy. We analyzed FES-PET and FDG-PET SUV uptake in patients with metastatic lobular and ductal carcinoma to identify sites of tumor and responsiveness to therapy.

Methods: We retrospectively reviewed FES and FDG SUV uptake between ER+ lobular (n = 36) and ductal (n= 173, including 6 men) metastatic breast cancer patients enrolled in various institutional studies. Up to 3 lesions in each patient were evaluated by FES SUVmax and/or FDG SUVmax for a total of 475 lesions in FES images and 462 lesions in FDG images. Classification into three categories (low FDG, high FDG/high FES, and high FDG/low FES) was generated using recursive portioning with 5-fold internal cross validation. Using a Pearson Chi-squared test, we compared degree of uptake in FES and FDG between lobular and ductal carcinomas. We used linear mixed effects model to assess association of FES SULmean3 (Lean body mass adjusted SUV) and FDG SULmean3 with histology. Overall survival (OS), from time of FES-PET scan to death, and progression free survival (PFS) was evaluated between classification groups in both histologies using Kaplan-Meier curves and Cox model.

Results: In patients with metastatic breast cancer, 72 patients had low FDG, 96 had high FES/high FDG, and 41 with high FES/low FDG. Lobular lesions tended to have a higher proportion of patients in the risk group with lower FDG (42% vs 33%) and a lower proportion in the risk group with high FDG/low FES (11% vs 21%) but the difference was not statistically significant (p = 0.32). Mean (range) FES SULmean3 and FDG SULmax3 respectively for ductal was 1.38 (0.10, 6.7) and 3.17 (0.88, 12.26) and for lobular was 1.42 (0.34, 3.43) and 3.13 (1.04, 13.87). There was no significant difference between in FES SULmean3 and FDG SULmax3 between histologies. Following FES-PET imaging, patients with lobular carcinomas and low FDG demonstrated a higher median survival time (7.7 years) compared to high FDG/low FES (4.3 years) and high FDG/high FES (2.6 years). Similarly, patients with ductal carcinomas and low FDG had an improved median survival time (5.6 years) compared to both high FDG/high FES (2.9 years) and high FDG/low FES (2.5 years). However, the interaction between histology and the FDG/FES classifications was not significant (p = 0.86). Across a variety of tumor sites, lobular histology can be detected by both FES and FDG with no difference between the imaging modalities.

Conclusions: In the metastatic setting, quantitative FES and FDG can be used to discriminate indolent and aggressive phenotypes in both lobular and ductal breast cancer. A greater proportion of lobular carcinoma lesions had higher FES/lower FDG and would be anticipated to be more sensitive to endocrine therapy. Further prospective trials are needed to confirm the utility of FES to stage extent of disease in metastatic breast cancer.

Citation Format: Manohar PM, Peterson LM, Wu V, Jenkins IC, Novakova-Jiresova A, Specht JM, Link JM, Krohn KA, Kinahan PE, Mankoff DA, Linden HM. 18F-fluoroestradiol (FES) and 18F-fluorodeoxyglucose (FDG) PET imaging in staging extent of disease in metastatic lobular breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD4-10.

Abstract P4-08-06: Impact of molecular subtypes on long-term outcomes in triple-negative breast cancer (TNBC) patients treated with adjuvant AC chemotherapy on SWOG S9313

Introduction: TNBC is heterogeneous disease with several molecularly defined subtypes (Lehman et al), each of which may be predictive of response to chemotherapy. TNBC molecular subtypes are associated with varied pathological responses to neoadjuvant chemotherapy. However, subtype specific long-term outcomes for TNBC patients treated with uniform adjuvant chemotherapy are not known.

Aims: To characterize long-term outcomes of TNBC molecular subtypes (TNBCtypes) in patients treated with adjuvant doxorubicin (A) and cyclophosphamide (C) on S9313

Methods: SWOG 9313 accrued 3,125 women with early stage breast cancer to two alternative dose schedules of AC with no difference in outcomes between the two arms (J Clin Oncol 2007). From this trial we identified 425 (14%) patients with centrally determined TNBC for whom tissue was available. Microarray profiling was performed on genomic RNA extracted from pre-treatment FFPE tissue. A 101-gene expression model which has shown to reproduce the classification provided by the original 2188-gene algorithm (Ring et al) was applied to the microarray profiling to generate the following TNBCtypes–Basal-Like 1 (BL1), Basal-Like 2 (BL2), Mesenchymal (M), mesenchymal stem–like (MSL), and luminal androgen receptor (LAR). Immunomodulatory +/- (IM) status was assigned independent of the subtypes. Sequencing of BRCA1/2 from tumor DNA was also performed. The subtypes were tested for prognostic effect on DFS and OS using Cox regression model with adjustment for nodal status.

Results: For 425 TNBC patients, the median age was 45 years, 33% were node-positive and 10-year DFS and OS = 66.3% and 74.1%, respectively. A total of 381/424 (89.7%) cases could be classified into TNBCtypes with distribution as follows: BL1=24%, BL2=8%, M=24%, MSL=11%, LAR=9%, unclassified (UNL) =24%. No association between TNBCtypes and race or nodal status was noted. Compared to other subtypes LAR subtype was associated with older age at diagnosis (median age 53 vs 45, p&lt;0.001). Overall 24% of samples were IM+ and 25% demonstrated deleterious tBRCA1/2 mutation. DFS, tBRCA1/2 mutation and IM+ status distribution across different subtypes are provided in the table. All subtypes except for LAR demonstrated a drop in hazard function for recurrence after 5 years.

 5 year DFS (%)10 year DFS (%)DFS HR (95% CI), p valueDeleterious tBRCA1/2 mutationIM+ statusBL184.5%77.5%141%60%BL281.3%70.5%1.59 (0.81-3.13) p = 0.1816%12%M69.2%61.2%2.06 (1.25-3.40) p = 0.00528%0%MSL54.8%50.0%2.38 (1.33-4.28) p = 0.00418%7%LAR74.3%53.8%2.24 (1.22-4.14) p = 0.0112%8%UNL76.4%71.8%1.36 (0.80-2.33) p = 0.2620%30%

Conclusions: In the presence of adjuvant AC, TNBC molecular subtypes have varied prognosis, with BL1 subtype demonstrating the best prognosis and MSL and LAR subtypes demonstrating the worst prognosis. LAR subtype is associated with older age at diagnosis and continued elevated hazard function for recurrence after year 5. tBRCA1/2 mutations are distributed across all subtypes with the highest prevalence in BL1 and M subtypes. IM+ status was infrequently noted in non-BL1 subtypes. These findings underscore TNBC heterogeneity and the need to account for this heterogeneity in prospective clinical trials.

Citation Format: Sharma P, Barlow WB, Hout DR, Seitz RS, Bailey DB, Godwin AK, Pathak H, Timms KM, Solimeno C, Linden HM, Porter P, Tripathy D, Hortobagyi GN, Thompson A, Pusztai L, Hayes DF. Impact of molecular subtypes on long-term outcomes in triple-negative breast cancer (TNBC) patients treated with adjuvant AC chemotherapy on SWOG S9313 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-08-06.

Clinical Potential of Estrogen and Progesterone Receptor Imaging

Molecular imaging using 16α-[¹⁸F]fluoro-17β-estradiol (FES) and ¹⁸F-fluoro-furanyl-norprogesterone PET can assess in vivo function of steroid hormone receptors in breast cancer. These experimental agents have been tested in many single-center clinical trials and show promise to elucidate prognosis and predict endocrine therapy response. The current multicenter trial of FES-PET imaging will help bring this radiotracer closer to clinical use. There is tremendous potential for these tracers to advance drug development, enhance understanding of estrogen receptor-positive tumor biology, and personalize treatment.

The Use of Quantitative Imaging in Radiation Oncology: A Quantitative Imaging Network (QIN) Perspective

Modern radiation therapy is delivered with great precision, in part by relying on high-resolution multidimensional anatomic imaging to define targets in space and time. The development of quantitative imaging (QI) modalities capable of monitoring biologic parameters could provide deeper insight into tumor biology and facilitate more personalized clinical decision-making. The Quantitative Imaging Network (QIN) was established by the National Cancer Institute to advance and validate these QI modalities in the context of oncology clinical trials. In particular, the QIN has significant interest in the application of QI to widen the therapeutic window of radiation therapy. QI modalities have great promise in radiation oncology and will help address significant clinical needs, including finer prognostication, more specific target delineation, reduction of normal tissue toxicity, identification of radioresistant disease, and clearer interpretation of treatment response. Patient-specific QI is being incorporated into radiation treatment design in ways such as dose escalation and adaptive replanning, with the intent of improving outcomes while lessening treatment morbidities. This review discusses the current vision of the QIN, current areas of investigation, and how the QIN hopes to enhance the integration of QI into the practice of radiation oncology.

Test-Retest Reproducibility of 18F-FDG PET/CT Uptake in Cancer Patients Within a Qualified and Calibrated Local Network

Calibration and reproducibility of quantitative ¹⁸F-FDG PET measures are essential for adopting integral ¹⁸F-FDG PET/CT biomarkers and response measures in multicenter clinical trials. We implemented a multicenter qualification process using National Institute of Standards and Technology-traceable reference sources for scanners and dose calibrators, and similar patient and imaging protocols. We then assessed SUV in patient test-retest studies. Methods: Five ¹⁸F-FDG PET/CT scanners from 4 institutions (2 in a National Cancer Institute-designated Comprehensive Cancer Center, 3 in a community-based network) were qualified for study use. Patients were scanned twice within 15 d, on the same scanner (n = 10); different but same model scanners within an institution (n = 2); or different model scanners at different institutions (n = 11). SUV_max was recorded for lesions, and SUV_mean for normal liver uptake. Linear mixed models with random intercept were fitted to evaluate test-retest differences in multiple lesions per patient and to estimate the concordance correlation coefficient. Bland-Altman plots and repeatability coefficients were also produced. Results: In total, 162 lesions (82 bone, 80 soft tissue) were assessed in patients with breast cancer (n = 17) or other cancers (n = 6). Repeat scans within the same institution, using the same scanner or 2 scanners of the same model, had an average difference in SUV_max of 8% (95% confidence interval, 6%-10%). For test-retest on different scanners at different sites, the average difference in lesion SUV_max was 18% (95% confidence interval, 13%-24%). Normal liver uptake (SUV_mean) showed an average difference of 5% (95% confidence interval, 3%-10%) for the same scanner model or institution and 6% (95% confidence interval, 3%-11%) for different scanners from different institutions. Protocol adherence was good; the median difference in injection-to-acquisition time was 2 min (range, 0-11 min). Test-retest SUV_max variability was not explained by available information on protocol deviations or patient or lesion characteristics. Conclusion: ¹⁸F-FDG PET/CT scanner qualification and calibration can yield highly reproducible test-retest tumor SUV measurements. Our data support use of different qualified scanners of the same model for serial studies. Test-retest differences from different scanner models were greater; more resolution-dependent harmonization of scanner protocols and reconstruction algorithms may be capable of reducing these differences to values closer to same-scanner results.

Correction to: a Phase 2 Study of 16α-[18F]-Fluoro-17β-Estradiol Positron Emission Tomography (FES-PET) as a Marker of Hormone Sensitivity in Metastatic Breast Cancer (MBC)

Two data points from Table 1. (continued) were published in error. The corrected data in Table 1. (continued) are shown, in italic, below.

Prospective Study of Serial 18F-FDG PET and 18F-Fluoride PET to Predict Time to Skeletal-Related Events, Time to Progression, and Survival in Patients with Bone-Dominant Metastatic Breast Cancer

Assessing therapy response of breast cancer bone metastases is challenging. In retrospective studies, serial ¹⁸F-FDG PET was predictive of time to skeletal-related events (tSRE) and time to progression (TTP). ¹⁸F-NaF PET improves bone metastasis detection compared with bone scanning. We prospectively tested ¹⁸F-FDG PET and ¹⁸F-NaF PET to predict tSRE, TTP, and overall survival (OS) in patients with bone-dominant metastatic breast cancer (MBC). Methods: Patients with bone-dominant MBC were imaged with ¹⁸F-FDG PET and ¹⁸F-NaF PET before starting new therapy (scan1) and again at a range of times centered around approximately 4 mo later (scan2). Maximum standardized uptake value (SUV_max) and lean body mass adjusted standardized uptake (SUL_peak) were recorded for a single index lesion and up to 5 most dominant lesions for each scan. tSRE, TTP, and OS were assessed exclusive of the PET images. Univariate Cox regression was performed to test the association between clinical endpoints and ¹⁸F-FDG PET and ¹⁸F-NaF PET measures. mPERCIST (Modified PET Response Criteria in Solid Tumors) were also applied. Survival curves for mPERCIST compared response categories of complete response+partial response+stable disease versus progressive disease for tSRE, TTP, and OS. Results: Twenty-eight patients were evaluated. Higher ¹⁸F-FDG SUL_peak at scan2 predicted shorter time to tSRE (P = <0.001) and TTP (P = 0.044). Higher ¹⁸F-FDG SUV_max at scan2 predicted a shorter time to tSRE (P = <0.001). A multivariable model using ¹⁸F-FDG SUV_max of the index lesion at scan1 plus the difference in SUV_max of up to 5 lesions between scans was predictive for tSRE and TTP. Among 24 patients evaluable by ¹⁸F-FDG PET mPERCIST, tSRE and TTP were longer in responders (complete response, partial response, or stable disease) than in nonresponders (progressive disease) (P = 0.007, 0.028, respectively), with a trend toward improved survival (P = 0.1). An increase in the uptake between scans of up to 5 lesions by ¹⁸F-NaF PET was associated with longer OS (P = 0.027). Conclusion: Changes in ¹⁸F-FDG PET parameters during therapy are predictive of tSRE and TTP, but not OS. mPERCIST evaluation in bone lesions may be useful in assessing response to therapy and is worthy of evaluation in multicenter, prospective trials. Serial ¹⁸F-NaF PET was associated with OS but was not useful for predicting TTP or tSRE in bone-dominant MBC.

Abstract PD5-07: A phase III randomized trial of anastrozole and fulvestrant versus anastrozole or sequential anastrozole and fulvestrant as first-line therapy for postmenopausal women with metastatic breast cancer: Final survival outcomes of SWOG S0226

Background: Anastrozole depletes estrogen via aromatase inhibition and fulvestrant binds and degrades estrogen receptor. In a Phase III trial we compared the concurrent use of these agents to anastrozole alone or sequential anastrozole and fulvestrant in first-line therapy of hormone receptor-positive metastatic breast cancer in postmenopausal women, and demonstrated improved progression-free (PFS) and overall survival (OS)-NEJM 2012. Now we report PFS and OS five years after the initial positive findings. Methods: A total of 707 patients were randomized to either 1 mg anastrozole P.O. daily (Arm 1) or to the combination of anastrozole and fulvestrant (Arm 2). Fulvestrant was administered as a loading dose of 500 mg on day 1, 250 mg on days 14, 28 and monthly thereafter. Randomization was stratified by adjuvant tamoxifen use. The primary endpoint was PFS with OS a secondary outcome. 40% patients not in visceral crisis crossed over to fulvestrant after progression on arm 1. Analysis of survival was by 2-sided stratified log-rank tests and Cox regression using intent-to-treat. Subset analyses include treatment effect by adjuvant tamoxifen exposure, initial sites of metastases and time from diagnosis. Results: There were 646 PFS events (328 and 318 for arms 1 and 2, respectively) among 694 eligible patients (345 and 349, respectively). Overall, median PFS was 13.5 months for arm 1 and 15.0 months for the arm 2 (log-rank p=0.007; HR=0.81 (95% CI 0.69-0.94)). This benefit extended similarly in visceral and non-visceral subgroups. In subset analysis for Arms 1 and 2, respectively, in tamoxifen-naive women (60%, n=414), median PFS was 12.7 vs. 16.7 months (log-rank p=0.002; HR=0.73 (95% CI 0.60-0.89) while in women exposed to tamoxifen, median PFS was 13.9 vs. 13.6 months (log-rank p=0.57; HR=0.93 (95% CI 0.73-1.19)). An improved OS in the combination arm was seen, median OS 42 and 50 months in arms 1 and 2, based on 261 and 247 deaths, respectively (log-rank p=0.028; HR=0.82 (95% CI 0.69-0.98)). In subset analysis in tamoxifen-naive women, median OS was 40.3 vs. 52.2 months for Arms 1 and 2, respectively (log-rank p=0.007; HR=0.73 (95% CI 0.58-0.92)) while in women exposed to tamoxifen, median OS was 43.5 vs. 48.2 months (log-rank p=0.85; HR=0.97 (95% CI 0.74-1.27). Patients with initial diagnosis &gt;10 years benefitted most from the combination (HR=0.66 (95% CI 0.49-0.89)) regardless of tamoxifen exposure. Patients in Arm 1 who crossed over had post-progression survival similar to post-progression survival of Arm 2 patients. Conclusion: The addition of fulvestrant to anastrozole was associated with improved long-term PFS and OS compared to anastrozole alone, despite the use of fulvestrant at a dose lower than the approved, and despite the substantial cross over to fulvestrant after progression on anastrozole alone. The benefit was especially notable in those without recent exposure to adjuvant endocrine therapy. Ongoing translational medicine studies will further refine the need for up front fulvestrant. ClinicalTrials.gov:NCT00075764. Funding: NIH/NCI U10CA180888, U10CA180819 and AstraZeneca.

Citation Format: Mehta RS, Barlow WE, Albain KS, Vandenberg TA, Dakhil SR, Tirumali NL, Lew DL, Hayes DF, Gralow JR, Linden HM, Livingston RB, Hortobagyi GN. A phase III randomized trial of anastrozole and fulvestrant versus anastrozole or sequential anastrozole and fulvestrant as first-line therapy for postmenopausal women with metastatic breast cancer: Final survival outcomes of SWOG S0226 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD5-07.