Abstract PD3-09: Sulindac reduces breast density and alters collagen alignment in patients on aromatase inhibitors

Background. Preclinical and observational evidence supports cancer prevention activity of non-steroidal anti-inflammatory drugs (NSAIDs) in the breast via suppression of prostaglandin E2 (PGE2) synthesis by cyclooxygenase-2 (COX2). Evidence includes linking of PGE2 to aromatase activity and estrogen synthesis in breast adipose tissue, as well as effects on collagen and breast density (BD). Methods. In an open-label trial, we evaluated the effect of the non-selective NSAID sulindac at 150 mg bid for 12 months on BD in 52 postmenopausal women taking adjuvant aromatase inhibitors (AIs) for breast cancer. BD was measured using a fat-water decomposition MRI based BD measure (MRD) previously shown to be more quantitative than mammographic density. A non-randomized observation cohort of 46 postmenopausal women on AI without NSAID use was conducted in parallel to assess the effect of AI on MRD over 12 months. Eligible participants were recruited at two study sites and included women with an intact, unaffected contralateral breast and BI-RADS ≥ 2. Each subject’s MRI_BD measures at baseline and at 6 and 12 months were included in linear mixed models for longitudinal data. Log-transformation was applied to the outcome of BD. Covariates included log-transformed baseline BD, time on AI, and baseline body mass index (BMI) and change in BMI. Breast tissue collagen fiber alignment for 30 women with paired breast biopsies, before and after 6 months on sulindac, was examined using Second-Harmonic Generation (SHG) microscopy and analysis of the distribution (histogram) of ‘straight’ fibers in three randomly selected areas of breast tissue. Straightness of individual fibers was calculated as the linear length of a fiber divided by the distance along the fiber. Results. Participants on sulindac intervention had a significant change in BD relative to baseline BD at 6 (p=0.05) and 12 months (p<0.001). After adjusting for time on AI, baseline BMI and BMI change, the relative change in BD at 12 months from baseline BD was 10% lower (95% CI; -14.4, -5.4%) for women on sulindac. For the AI only group, no significant change from baseline BD was observed at 6 (p=0.50) or 12 months (p=0.17). The relative change in BD for the AI only group at 12 months was -3.5% (95% CI; -8.3, +1.6%). For women with baseline MRD_BD of ≥ 25%, the relative decrease in BD from baseline in the sulindac group was greater, at -16.3% (95% CI, -25.4, -6.2%). In contrast, there was no evidence for baseline BD effect on change in BD at 12 months in the AI only group whose baseline BD was ≥25% [-3.3% change at 12 mo (95% CI; -12.7, +7.1%)]. Exploratory analyses of collagen fiber alignment in the sulindac group at 6 months showed a significant decrease in straight collagen fibers (p=0.01). The decrease in collagen straightness correlated with a decrease in BD (rho=0.66, p=0.01). Conclusions. Twice daily 150 mg sulindac for 12 months in postmenopausal women on AIs was associated with a significant decrease in BD using MRD that was slightly higher for women with higher baseline BD. At the tissue level, the decrease in BD was associated with change in collagen straightness. No decrease in BD was observed in a non-randomized population of postmenopausal women on AI only therapy. These results suggest that sulindac decreases BD and may do so through effects on collagen alignment. Further investigation of sulindac for effects on BD, including synergy with AIs, for breast cancer prevention is indicated.

Citation Format: Patricia Thompson, Chuan Huang, Betsy Wertheim, Christina Preece, Jie Yang, Jessica Martinez, Denise Roe, Pavani Chalasani, Alison Stopeck. Sulindac reduces breast density and alters collagen alignment in patients on aromatase inhibitors [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 PD3-09.

BAY 94-9027 prophylaxis is efficacious and well tolerated for up to >5 years with extended dosing intervals: PROTECT VIII extension interim results

Introduction

BAY 94‐9027 is an extended‒half‐life, site‐specifically PEGylated, B‐domain‒deleted recombinant factor VIII (FVIII). The PROTECT VIII main study demonstrated efficacy of bleed control using extended‐interval prophylaxis with BAY 94‐9027 for 36 weeks.

Aim

To report long‐term efficacy and safety of prophylaxis with BAY 94‐9027 in a descriptive analysis of the ongoing PROTECT VIII extension with a total treatment time of up to >5 years.

Methods

Previously treated males aged 12‐65 years with severe haemophilia A who completed the PROTECT VIII main study were eligible for the open‐label extension. Patients received on‐demand treatment or prophylaxis (30‒40 IU/kg twice weekly, 45‒60 IU/kg every 5 days, or 60 IU/kg every 7 days) and could switch regimens as needed.

Results

Patients (N = 121; on demand, n = 14; prophylaxis, n = 107) accumulated a median (range) of 3.9 years (297‒1965 days) and 223 (23‒563) total exposure days by 31 January 2018. During the extension, median (quartile [Q]1; Q3) annualized bleeding rates (ABRs) for total bleeds were 1.6 (0.3; 4.6) for patients receiving prophylaxis and 34.1 (20.3; 36.6) for patients receiving on‐demand treatment. ABRs for twice‐weekly (n = 23), every‐5‐days (n = 33), every‐7‐days (n = 23) and variable frequency (n = 28) treatments were 1.7, 1.2, 0.7 and 3.1, respectively. Of prophylaxis patients, 20.6% were bleed‐free throughout the extension (median time, 3.2 years), and 51.0% were bleed‐free during the last 6 months. No patients developed FVIII inhibitors.

Conclusions

BAY 94‐9027 prophylaxis was efficacious and well tolerated with dosing intervals up to every 7 days for a median (range) of 3.9 years (0.8‐5.4 years).

A Phase II Study of Irinotecan and Etoposide as Treatment for Refractory Metastatic Breast Cancer

Lessons Learned.

The combination of irinotecan and etoposide showed modest efficacy in terms of response rate in the refractory setting for patients with metastatic breast cancer.

The studied dose and schedule of irinotecan and etoposide is very toxic, with >70% grade 3 or 4 treatment‐related adverse events.

Background.

As single agents, both irinotecan and etoposide have documented activity against breast cancer among patients who have received multiple lines of prior chemotherapy. Irinotecan interacts with topoisomerase I (Topo I) to stabilize its cleavable complex, and etoposide has an analogous interaction with topoisomerase II (Topo II). This stabilization without rapid resealing of the cleavage point results in apoptotic cell death and accounts for the antitumor activity of these agents. Topo II levels may increase after administration of a Topo I inhibitor, thus providing a rationale for combining these agents in practice. Based on preclinical data, we conducted a phase II trial of the Topo I inhibitor irinotecan combined with the Topo II inhibitor etoposide in patients with metastatic breast cancer (MBC).

Methods.

This was a single‐arm phase II clinical trial in patients with MBC refractory to prior anthracycline, taxane, and capecitabine therapy. All patients were treated with oral etoposide at 50 mg/day on days 1–14 and intravenous irinotecan at 100mg/m² on days 1 and 15. Treatment cycles were repeated every 28 days. The primary endpoint was median time to progression. Secondary end points included overall clinical response rate using RECIST criteria and assessing the toxicity and safety profile associated with this combination regimen.

Results.

We enrolled 31 women with refractory MBC to our trial. Median age was 54 (range, 36‐84), with the majority (64%) having hormone receptor positive (HR+) human epidermal growth factor receptor 2 negative (HER2 neg) MBC. Median number of prior therapies was five (range, 3–14). Efficacy was evaluated in 24 patients. Seventeen percent had a partial response, and 38% had stable disease as best response. Median progression‐free survival was 9 weeks (range, 3–59). All 31 patients were evaluable for toxicity assessment, and 22 patients (71 %) experienced treatment‐related grade 3 or 4 adverse events (AEs; Table 1). The most common grade 3–4 AE was neutropenia. The study was terminated early based on interim analysis assessment that suggested toxicities outweighed the efficacy.

Conclusion.

Irinotecan and etoposide demonstrated only modest clinical activity and poor tolerability in patients with MBC refractory to anthracycline, taxane, and capecitabine therapy. Further studies testing a lower dose and/or different schedule could be considered given ease of administration and responses seen.

Rare tumor with matched germline whole exome sequencing to identify somatic and inherited variants of clinical significance

1523

Background: Rare cancer incidence is defined as <6/100,000 cases. These cases are challenging due to delays in diagnosis, late stage at diagnosis, lack of standard of care and poor outcomes. We present molecular profiling of 28 rare tumor cases analyzed by whole exome sequencing (WES) seen in the Early Phase Therapeutics Program. Methods: We performed WES on 15 rare tumors with matched germline DNA, as well as tumor only on 2 additional cases. We sequenced a panel of 500 candidate cancer genes in 6 tumor/normal and 6 tumor only cases. Copy number alterations (CNAs) were assessed for the tumor-normal WES cases with SNVs and small indels for all cases. Caris (AZ) (tumor only) and liquid biopsy (Gaurdant360, CA) were also conducted in these patients for comparison. Results: Rare tumors affected 18 different tissues of the body with 1 case affecting tissue typical of common cancers. The rare tumor group contained 25% pathogenic or likely pathogenic germline variants compared to 7.1% for common tumors. This increased rate of inherited pathogenic variants met statistical significance: Fisher exact test (p = 0.0118). A total of 69 sequence variants and 8 CNAs were identified, 37 were actionable. For all but 3 patients, there was at least one variant associated with an actionable outcome given off-label use or clinical trial participation. There was excellent concordance with results from commercial sequencing; however, our tumor/germline sequencing identified additional germline variants of clinical significance, all were loss-of-function variants in tumor suppressors. Tumor vs. normal analysis showed that the majority of the commercially reported VUS were in fact germline VUS. In one case, a reported pathogenic variant we found to be an inherited pathogenic germline variant. 15 patients received at least 1 line of therapy indicated by genomic sequencing. For these patients the PFS ratio when compared to the most recent line of therapy prior to targeted therapy was 2.02, with 10/15 (67%) patients having a PFS ratio of >1.0, and 6/15 (40%) of patients having PFS ratio >1.3. Conclusions: We demonstrate the importance of tumor-normal analysis, especially in the context of rare tumors. Rare tumor patients may disproportionately benefit from tumor vs. normal WES at diagnosis to improve PFS within targeted therapy trials, guided by genomics.

Tucatinib, palbociclib, and letrozole in HR+/HER2+ metastatic breast cancer: Report of phase IB safety cohort

1029

Background: Based on preclinical synergy, we are conducting a phase IB/II clinical trial of tucatinib (HER2 small molecule inhibitor, T), palbociclib (CDK4/6 inhibitor, P) and letrozole (aromatase inhibitor, L) in HR+/HER2+ metastatic breast cancer (MBC). Methods: Post-menopausal, or pre-menopausal women on ovarian suppression, with prior ≥2 HER2 inhibitors at any time of disease; ≥1 HER2 inhibitor for MBC or front line bone/soft tissue only disease are eligible provided ≤2 endocrine agents for MBC. Prior CDK4/6 or HER2 small molecule inhibitors are not allowed. Treatment entails T 300 mg BID, P 125 mg/day 21 days on, 7 days off, and L 2.5 mg/day. Safety was assessed using CTCAE v.4.03 with standard definitions for dose limiting toxicity (DLT). Dose reductions of T and / or P for DLTs, and discontinuation of either P or L for toxicity were allowed at any time during the study. Safety thresholds were set as DLTs in ≤7/20 pts for T, ≤15/20 pts for P, or ≤14/20 pts attributable to both T and P. Results: Phase Ib enrolled 20 pts from 11/16/17 to 12/5/18. The median age is 53y (22-70y), median number of prior lines of MBC therapy is 2 (0-5). 70% of pts have visceral disease and 45% CNS disease. Prior treatment includes 100% of pts with trastuzumab and pertuzumab, and 45% of pts with prior TDM-1. One pt required dose reduction of T; 9 (45%) had dose reduction and 2 (10%) discontinued P for DLTs. One pt discontinued L. Safety boundaries were not crossed. The most common grade (G) ≥3 toxicities were neutropenia (G3 55%, G4 15%), diarrhea (G3 20%), infections (G3 20%), thrombocytopenia (G3 10%) and mucositis (G3 10%). The frequency and type of toxicities were consistent with those previously reported for each single agent. PK analysis showed no interaction between P and T. As of 1/4/19, 14 pts (70%) remain on study (5 pts for ≥6 months) and 6 pts removed for progression. No withdrawals for toxicity and no deaths on study. The longest time on study (ongoing) is 10 months for pts without CNS disease, and 6 months for pts with CNS disease. Conclusions: T, P, L combination showed an acceptable safety profile and encouraging antitumor activity. RP2D of T is 300mg PO BID in combination with full doses of P and L. Enrollment in phase II cohort is ongoing. Clinical trial information: NCT03054363.

Abstract P5-13-19: Addressing non-adherence for breast cancer screening across ethnicity in southern Arizona

Background In Arizona, female breast cancer has the highest incidence rate and the second highest death rate compared to all other cancers. This ongoing single arm intervention study investigates non-adherence with recommended annual mammography or follow-up breast imaging. Data collected for this study is both retrospective, using the university Electronic Health Record (EHR) system (January 1, 2014 to September 30, 2017), and prospective, implementing a questionnaire during the intervention phase. Potential study participants were identified using EHR and categorized by BI-RADS (Breast Imaging-Reporting and Data System) 0 to 5. With IRB approval from University of Arizona, we designed a questionnaire to measure barriers to adherence and we navigate participants to schedule and attend follow-up appointments. This study's overall specific aims are to increase first time mammography screening by 25% among women in Southern Arizona; increase adherence or repeat screening rate by 20% among women lost to follow-up; establish the framework for a community- academic partnership in ethnically diverse areas. Women, age 40 and older who are not compliant with recommended annual mammograms or recommended follow-up screenings after a suspicious finding are eligible to participate in this study. Men and children, as well as women for whom breast imaging is not recommended are excluded from participating in this study. Results Patient's age was summarized by mean ± standard deviation for continuous variables and frequency and the associated percentage for categorical variables. BI-RADS scores were classified into Negative, Benign, Possible Malignancy and Proven Malignancy and compared between ethnic and racial groups using Fisher's exact test. Of 8823 non-compliant woman over nearly 4 years of data, 0.2% are BI-RADS 4 and 5, 2.2% are BI-RADS 3, 96% are BI-RADS 1 and 2, and 0.3% are BI-RADS 0. The mean age is 61.59 years, with 25% reporting as Hispanic, 66% reporting as non-Hispanic women (NHW), and 10% preferring to receive care in Spanish. Initial data shows only .24% with proven malignancies. Further, the data reveals that Hispanics have a slightly higher rate of possible malignancy (.36%) than NHW (.18%); however, NHW show a slightly higher rate of proven malignancy (.27% compared to .18%, respectively). Discussion These data provide valuable information for the direction of this study; in particular, understanding the disparity between Hispanic and NHW malignancies and developing culturally competent interventions and education materials to increase compliance with breast cancer screening recommendations. Further, these data indicate our focus should be on screening compliance for BI-RADS 1 and 2. These data also point to a possible high non-compliance issue. Comparing non-compliance data from other regional clinics will continue to shape this study's direction. The target sample size for this study is 300 participants. We accept a 95% confidence level and a 5% margin of error. Out of 420 recruitment letters mailed, the navigators have reached 152 potential participants by phone and have a 26% study recruitment rate (n=40).

Citation Format: Huff AJ, Gomez J, Calhoun E, Hsu C-H, Chalasani P, Fitzpatrick K, Borders M, Lang L, Prado Y. Addressing non-adherence for breast cancer screening across ethnicity in southern Arizona [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 P5-13-19.

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.

Clinical Translation of Tumor Acidosis Measurements with AcidoCEST MRI

PURPOSE

We optimized acido-chemical exchange saturation transfer (acidoCEST) magnetic resonance imaging (MRI), a method that measures extracellular pH (pHe), and translated this method to the radiology clinic to evaluate tumor acidosis.

PROCEDURES

A CEST-FISP MRI protocol was used to image a flank SKOV3 tumor model. Bloch fitting modified to include the direct estimation of pH was developed to generate parametric maps of tumor pHe in the SKOV3 tumor model, a patient with high-grade invasive ductal carcinoma, and a patient with metastatic ovarian cancer. The acidoCEST MRI results of the patient with metastatic ovarian cancer were compared with DCE MRI and histopathology.

RESULTS

The pHe maps of a flank model showed pHe measurements between 6.4 and 7.4, which matched with the expected tumor pHe range from past acidoCEST MRI studies in flank tumors. In the patient with metastatic ovarian cancer, the average pHe value of three adjacent tumors was 6.58, and the most reliable pHe measurements were obtained from the right posterior tumor, which favorably compared with DCE MRI and histopathological results. The average pHe of the kidney showed an average pHe of 6.73 units. The patient with high-grade invasive ductal carcinoma failed to accumulate sufficient agent to generate pHe measurements.

CONCLUSIONS

Optimized acidoCEST MRI generated pHe measurements in a flank tumor model and could be translated to the clinic to assess a patient with metastatic ovarian cancer.

Abstract OT1-03-06: Phase IB/II clinical trial to evaluate safety and efficacy of tucatinib in combination with palbociclib and letrozole in patients with hormone receptor positive and HER2-positive metastatic breast cancer

Breast cancers overexpressing HER2-oncogene and hormone receptors (HR) represent therapeutic challenge because of a bi-directional cross-talk between HR and HER2 pathways leading to tumor progression and drug resistance. There is a strong rationale for evaluation of novel targeted drug combinations in this breast cancer subtype.

We designed a phase IB /II clinical trial to test the combination of novel oral HER2 small molecule inhibitor tucatinib with CDK4/6 inhibitor palbociclib and aromatase inhibitor letrozole in patients with HR+/HER2+ metastatic breast cancer (NCT03054363). In addition to the rationale for the synergy of targeting HR, HER2 and CDK4/6 pathways simultaneously in this disease setting and its potential for anti-tumor efficacy, we propose this novel combination of three oral agents, if well tolerated, will be highly patient-centered as an effective non-chemotherapy based regimen for treatment of HR+/HER2+ breast cancer.

This multicenter clinical trial is conducted through the Academic Breast Cancer Consortium (ABRCC), with the University of Colorado Cancer Center as the lead site.

Target enrollment: 40 patients (20 patients in phase IB and 20 patients in phase II part).

Main inclusion criteria:

1. HR+/HER2+ locally advanced unresectable / metastatic breast cancer

2. Measurable or evaluable disease. Bone only disease is allowed.

3. Subjects without brain metastases are eligible; subjects with untreated asymptomatic CNS metastases not needing immediate local therapy, and subjects with stable brain metastases previously treated with radiation therapy or surgery are eligible

4. ECOG 0-1

5. Postmenopausal women, or premenopausal women on ovarian suppression

6. Prior treatments:

- At least two approved HER2-targeted agents (trastuzumab, pertuzumab, or TDM-1) at any time in the course of the disease

- At least 1 line of HER2-targeted therapy in the metastatic setting (with the exception of asymptomatic subjects with oligometastatic or bone / soft tissue only disease who, on investigator opinion, are appropriate for a front line single agent anti-endocrine therapy per NCCN guidelines)

- Up to 2 lines of prior endocrine therapy in the metastatic setting are allowed

7. Adequate organ and marrow function

Main exclusion criteria:

1. Previously treated progressing brain metastases

2. Brain metastases and contraindications to undergo contrast brain MRI

3. Toxicities of prior cancer therapies that have not resolved to grade 1 or less, except peripheral neuropathy, which must have resolved to grade 2 or less, and alopecia

4. Previous treatment with EGFR or HER2 tyrosine kinase inhibitors or CDK4/6 inhibitors

5. Systemic anti-cancer therapy or radiation within 2 weeks of the first dose of study drugs

6. Active bacterial, fungal or viral infections, hepatitis B, C, or HIV

7. Clinically significant cardio-vascular disease

Primary objectives:

- Phase IB: safety and tolerability of combination therapy

- Phase II: efficacy by PFS

Exploratory assessment of biomarkers of resistance and response will be performed in the blood and biopsy samples

Study contact: Elena Shagisultanova, MD, PhD, elena.shagisultanova@ucdenver.edu

Citation Format: Shagisultanova E, Diamond J, Stopeck A, Pusztai L, O'Regan R, Gradishar W, Brown-Glaberman U, Chalasani P, McSpadden T, Borakove M, Shedin T, Kabos P, Borges V. Phase IB/II clinical trial to evaluate safety and efficacy of tucatinib in combination with palbociclib and letrozole in patients with hormone receptor positive and HER2-positive metastatic breast cancer [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 OT1-03-06.

Abstract 1729: Detection of gene expression biomarkers from enriched CTC preparations

Circulating tumor cells (CTCs) offer an opportunity for non-invasive characterization of metastatic cancer, including the ability to follow subtype evolution, development of resistance, tissue homing biomarkers, and changes in cell signaling mechanisms required for metastasis and continued growth and survival of the tumor. Analysis of CTCs and translation of a CTC assay into a clinical test has been difficult due to issues of obtaining high purity, high yield preparations and/or isolating individual CTCs. This is further compounded by the heterogeneity of CTCs, hurdles in profiling their molecular signatures, and difficulty correlating CTC number/subtype to actionable therapy. We pursued a detailed analysis of CTC gene expression using whole transcriptome TempO-Seq targeted sequencing, a highly sensitive, direct lysis, addition only assay. As this assay does not require purified CTC isolation or RNA extraction, there is no risk of CTC nor RNA loss. We exploited the single cell sensitivity of TempO-Seq to profile enriched CTC preparations prepared by RosetteSep gradient centrifugation, allowing us to characterize the phenotypes of CTCs within a high background of normal blood cells. To handle this large and potentially overwhelming background we developed and exploited a proprietary method of sample normalization that increased the sensitivity and consistency of CTC gene signature measurements. We demonstrated that the TempO-Seq assay could detect a single MCF7 (EpCAM+) Luminal-like cell in a background of 1,000 MDA MB 231 (EpCAM-) Basal-like cells (positive for an Endothelial Mesenchymal Transition, EMT), and vice versa. Next, we prepared mixtures of different proportions of these cultured cells spiked into normal blood, enriched the model “CTCs” using RosetteSep, and profiled the bulk preparation. Proportional discrimination of cell-specific signatures were obtained with as few as 40 spike-in cells. Finally, we profiled enriched CTC preparations from the blood of patients with metastatic breast cancer. The results demonstrated that the expression of HER2, ER, and EpCAM could be measured as well as biomarkers of drug resistance, bone/brain homing, EMT, and all 50 Hallmark cell signaling pathways. TempO-Seq EpCAM gene level correlated with the percent EpCAM+ cells measured by flow analysis while EMT signature levels correlated inversely. Patients with HER2- primary tumor and HER2+ CTCs could be identified, as could patients with elevated chemotherapy resistance pathways. These data demonstrate that it is possible to profile CTC phenotypes that are important in metastases and useful for selecting therapy using a bulk CTC preparation combined with the sensitivity of the TempO-Seq whole transcriptome assay. This suggests the opportunity for the development of a predictive test using currently available purification platforms without need for expensive specialized equipment or separation into single cells.

Citation Format: Bruce Seligmann, Marilyn Marron, Milos Babic, Elliot Imler, Peter Shepard, Pavani Chalasani, Alison Stopeck, Joanne Yeakley. Detection of gene expression biomarkers from enriched CTC preparations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1729. doi:10.1158/1538-7445.AM2017-1729

Abstract 3728: Imaging biomarkers of aromatase-inhibitor induced joint pain

Estrogen receptor positive (ER+) breast cancer patients undergoing treatment with aromatase inhibitors (AI) tend to discontinue the supplement when to painful side effects appear. It is believed that women with AI-induced musculoskeletal syndrome (AIMSS) have specific physiological conditions that differentiate them from women with normal aging-related inflammatory processes (e.g., rheumatoid arthritis or RA). Ultrasound shear wave elastography (USWE) provides a real-time, quantitative assessment of the elastic modulus of soft tissue, which is a potential biomarker that is altered in women with AIMSS.

Because USWE is a completely noninvasive technique available on state-of-the-art clinical ultrasound scanners, it can be readily applied to study patients who undergo AI treatment and help predict adverse effects during therapy.

A Siemens s3000 clinical scanner and 9 MHz linear probe were used for USWE of the hands and wrists in postmenopausal women on AI, postmenopausal women with RA and healthy postmenopausal women. The scans included an evaluation of major wrist tendons, nerve, and joints with shear wave velocities ranging from 0.5 to 15 m/s, which are directly related to the local shear modulus – an absolute measure of tissue stiffness. The ultrasound images and raw shear wave data were then analyzed in MATLAB-TM using a custom graphical user interface (GUI) to calculate the distribution of velocities (or shear moduli) in a user-defined region of interest (ROI). The results were exported to a spreadsheet in Excel for further analysis and comparison among the different groups.

Initial results suggest the shear wave velocity and estimated Young’s modulus (λ) were significantly higher in AI patients (14.6 ± 0.2 m/s, λ=642 ± 17 kPa) compared to RA (6.84 ± 1.1 m/s, λ=143 ± 43 kPa) and healthy (7.58 ± 0.9 m/s, λ=174 ± 42 kPa) patients. These values suggest that the mechanical properties of tendons in the wrist may change during treatment with AI and contribute to joint pain in these subjects. It is critical that ER+ patients on AI complete their full treatment. As a potential biomarker of AIMSS and associated pain, USWE may help predict which patients are most susceptible to these side effects, promote early intervention to reduce or eliminate symptoms, and help increase adherence to AI therapy.

Citation Format: Brian A. Goldstein, Mihra Taljanovic, Pavani Chalasani, C. Kent Kwoh, Amanda Hadden, Russell Witte, Jessica Martinez. Imaging biomarkers of aromatase-inhibitor induced joint pain [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3728. doi:10.1158/1538-7445.AM2017-3728

Optimizing Quality of Life in Patients with Hormone Receptor-Positive Metastatic Breast Cancer: Treatment Options and Considerations

The treatment landscape for hormone receptor-positive metastatic breast cancer continues to evolve as the molecular mechanisms of this heterogeneous disease are better understood and targeted treatment strategies are developed. Patients are now living for extended periods of time with this disease as they progress through sequential lines of treatment. With a rapidly expanding therapeutic armamentarium, the prevalence of metastatic breast cancer patients with prolonged survival is expected to increase, as is the duration of survival. Practice guidelines recommend endocrine therapy alone as first-line therapy for the majority of patients with metastatic hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer. The approval of new agents and expanded combination options has extended their use beyond first line, but endocrine therapy is not used as widely in clinical practice as recommended. As all treatments are palliative, even as survival is prolonged, optimizing and maintaining patient quality of life is crucial. This article surveys data relevant to the use of endocrine therapy in the setting of hormone receptor-positive metastatic breast cancer, including key clinical evidence regarding approved therapies and the impact of these therapies on patient quality of life.

A randomized, placebo-controlled trial of diindolylmethane for breast cancer biomarker modulation in patients taking tamoxifen

PURPOSE

Diindolylmethane (DIM), a bioactive metabolite of indole-3-carbinol found in cruciferous vegetables, has proposed cancer chemoprevention activity in the breast. There is limited evidence of clinically relevant activity of DIM or long-term safety data of its regular use. A randomized, double-blind, placebo-controlled trial was conducted to determine the activity and safety of combined use of BioResponse DIM® (BR-DIM) with tamoxifen.

METHODS

Women prescribed tamoxifen (n = 130) were randomly assigned oral BR-DIM at 150 mg twice daily or placebo, for 12 months. The primary study endpoint was change in urinary 2/16α-hydroxyestrone (2/16α-OHE1) ratio. Changes in 4-hydroxyestrone (4-OHE1), serum estrogens, sex hormone-binding globulin (SHBG), breast density, and tamoxifen metabolites were assessed.

RESULTS

Ninety-eight women (51 placebo, 47 DIM) completed intervention; compliance with treatment was >91%. BR-DIM increased the 2/16α-OHE1 ratio (+3.2 [0.8, 8.4]) compared to placebo (-0.7 [-1.7, 0.8], P < 0.001). Serum SHBG increased with BR-DIM compared to placebo (+25 ± 22 and +1.1 ± 19 nmol/L, respectively). No change in breast density measured by mammography or by MRI was observed. Plasma tamoxifen metabolites (endoxifen, 4-OH tamoxifen, and N-desmethyl-tamoxifen) were reduced in women receiving BR-DIM versus placebo (P < 0.001). Minimal adverse events were reported and did not differ by treatment arm.

CONCLUSION

In patients taking tamoxifen for breast cancer, daily BR-DIM promoted favorable changes in estrogen metabolism and circulating levels of SHBG. Further research is warranted to determine whether BR-DIM associated decreases in tamoxifen metabolites, including effects on endoxifen levels, attenuates the clinical benefit of tamoxifen.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01391689.

Effect of Diindolylmethane on Estrogen-related Hormones, Metabolites and Tamoxifen Metabolism: Results of a Randomized, Placebo-controlled Trial

Dietary supplement use is high among breast cancer survivors. One compound natural to cruciferous vegetables, diindolylmethane (DIM), is among the supplements commonly used. This bioactive compound has significant experimental evidence for bioactivity in breast chemoprevention. Sparse evidence in the form of well-designed human clinical trials exist to test its efficacy or safety. Methods: In this double-blind placebo-controlled study women taking tamoxifen for breast cancer primary or tertiary prevention were randomly assigned to receive 150 mg DIM (BioResponse(BR)-DIM) twice daily or a placebo for a minimum period of 12 months. Primary outcome was change in urinary estrogen metabolites 2-hydroxyestrone and 16α-hydroxyestrone (baseline to 6 weeks, 6 and 12 months). Secondary endpoints included breast density by mammogram and fat:water ratio MRI (baseline to 12 months) and serum estrogens (baseline to 6, 12 months). Safety data were also evaluated, including tamoxifen metabolites. Results: Adherence to study pills was &gt;91% by pill count and urinary DIM metabolite assessment. In participants assigned DIM there was a significant and sustained shift in urinary estrogen metabolism favoring a higher 2-OH:16α-OH ratio; sex hormone binding globulin (SHBG) was also increased. No change in breast density was demonstrated. Safety analysis showed no appreciable differences in adverse events by treatment arm; however, tamoxifen metabolism for the parent compound as well as endoxifen and 4-OH endoxifen were appreciably reduced in women assigned to the DIM arm. Conclusions In this first large study of DIM in the setting of breast cancer chemoprevention, a favorable shift in estrogen metabolism and SHBG was demonstrated. However, the reduction in tamoxifen metabolites raises concern regarding the potential interaction between DIM and tamoxifen, an area in need of continued research. Impact Given the widespread and generally unsupported use of dietary supplementation by breast cancer survivors, these data will help to inform the use of DIM as a dietary supplement for breast cancer patients receiving tamoxifen.

Phase II study of metformin for reduction of obesity-associated breast cancer risk: a randomized controlled trial protocol

Background

Two-thirds of U.S. adult women are overweight or obese. High body mass index (BMI) and adult weight gain are risk factors for a number of chronic diseases, including postmenopausal breast cancer. The higher postmenopausal breast cancer risk in women with elevated BMI is likely to be attributable to related metabolic disturbances including altered circulating sex steroid hormones and adipokines, elevated pro-inflammatory cytokines, and insulin resistance. Metformin is a widely used antidiabetic drug that has demonstrated favorable effects on metabolic disturbances and as such may lead to lower breast cancer risk in obese women. Further, the anti-proliferative effects of metformin suggest it may decrease breast density, an accepted biomarker of breast cancer risk.

Methods/design

This is a Phase II randomized, double-blind, placebo-controlled trial of metformin in overweight/obese premenopausal women who have elements of metabolic syndrome. Eligible participants will be randomized to receive metformin 850 mg BID (n = 75) or placebo (n = 75) for 12 months. The primary endpoint is change in breast density, based on magnetic resonance imaging (MRI) acquired fat-water features. Secondary outcomes include changes in serum insulin levels, serum insulin-like growth factor (IGF)-1 to insulin-like growth factor binding protein (IGFBP)-3 ratio, serum IGF-2 levels, serum testosterone levels, serum leptin to adiponectin ratio, body weight, and waist circumference. Exploratory outcomes include changes in metabolomic profiles in plasma and nipple aspirate fluid. Changes in tissue architecture as well as cellular and molecular targets in breast tissue collected in a subgroup of participants will also be explored.

Discussion

The study will evaluate whether metformin can result in favorable changes in breast density, select proteins and hormones, products of body metabolism, and body weight and composition. The study should help determine the potential breast cancer preventive activity of metformin in a growing population at risk for multiple diseases.

Trial registration

ClinicalTrials.gov Identifier: NCT02028221. Registered on January 2, 2014. Grant #: 1R01CA172444-01A1 awarded on Sept 11, 2013.

Abstract P6-04-10: Clinicopathological and molecular characteristics of pleomorphic invasive lobular carcinoma of breast

Background: Pleomorphic invasive lobular carcinoma (PILC) is described as a distinct morphological variant of invasive lobular carcinoma (ILC) but its clinical behavior is not well characterized. PILCs have loss of E-cadherin similar to ILCs but have distinct morphological features like nuclear contour irregularity, a single prominent nucleolus, increased hyperchromasia and more frequent mitoses. In addition, some studies have reported that PILCs have acquired further molecular alterations such as gain of HER2/neu, amplification of c-myc and loss of p53. To the best of our knowledge there have been no studies evaluating Phosphoinositide 3 kinase/Akt/mammalian (or mechanistic) target of rapamycin (PI3K/Akt/mTOR) pathway in PILC. We hypothesize that there is increased activation of PI3K/Akt/mTOR pathway in PILC compared to ILC. Activation of the PI3k/Akt/mTOR pathway was evaluated by quantifying protein expression of phosphatase and tensin homolog (PTEN) and phosphorylated-S6 kinase1 (p-S6K1). PTEN is a negative regulator of the PI3K pathway and its loss/decreased expression (by mutation or allelic imbalance) activates downstream signaling. Loss (or decrease) of PTEN expression has been reported to be associated with PI3K pathway activation in more than 50% of ER+ breast tumors. Since PI3K pathway can be activated by other mechanisms in addition to PTEN loss, we hypothesized that evaluation of pS6K1 may predict activation of this pathway more than PTEN protein expression alone.

Methods: We conducted a retrospective translational study at the University of Arizona Cancer Center. Our Pathology database was searched to identify PILCs from 2012-2014. Two investigators reviewed the pathology reports independently and abstracted clinocopathological data. Formalin-fixed paraffin embedded (FFPE) primary PILCs were stained for PTEN and pS6K1 expression. Expression of PTEN and pS6K1 was quantified by long score methodology as low (≤ 10), moderate (11-50) or high (≥ 50) expression.

Results: We identified 19 patients with PILC. All tumors were either moderately (n=10) or poorly differentiated (n=9). Estrogen receptor (ER) was positive in all, progesterone receptor (PR) was positive in 11(52%) and HER2 was negative in all tumors. Proliferation index (Ki67) was elevated in all tumors (median 32%, range 20-70%). Lymph nodes were involved with metastatic carcinoma in 7 patients (negative in 9 and unknown in 3). The 21-gene recurrence score assay (Oncotype Dx) was performed in 10 patients and demonstrated higher scores (median 23, range 6-36) with the majority being in the intermediate or high range (8/10). Expression of PTEN and p-S6K1 was quantified on 10 FFPE tumor tissues. PTEN expression was high in all while pS6K1 was high in 8 and low in 2 tumors.

Conclusion: PILCs are a biologically distinct group of ILC. Clinicopathological characteristics suggest they would have a more clinically aggressive behavior (higher grade, high proliferative index and 21 gene recurrence score). In addition, our results indicate that PI3k/Akt/mTOR pathway in activated in majority of these tumors and that PTEN is not the key regulator of this pathway. Genomic profiling is currently underway to further analyze other causes of pathway activation.

Citation Format: Segar J, Baker AF, MacKerricher W, Nagle R, Livingston R, Clarke K, Ley M, Viscusi R, Gonzalez V, LeBeau L, Chalasani P. Clinicopathological and molecular characteristics of pleomorphic invasive lobular carcinoma of breast. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-04-10.

Abstract P4-07-07: Evaluating Rad51/geminin protein expression as an indicator of homologous recombination deficiency in breast cancer models

Background: Homologous recombination deficiency (HRD) in cancer cells can occur due to mutations (germline or sporadic), methylation or other epigenetic causes. HRD leads to a defect in the conservative, error-free DNA repair mechanism and is associated with enhanced susceptibility to DNA targeting chemotherapy. Currently functional HRD assays are not broadly available for clinical use. Many of the HRD assays used in the experimental setting require fresh frozen tissue for optimal results, or require specialized expertise to interpret the results. We evaluated an immunohistochemical (IHC) assay using formalin fixed paraffin embedded (FFPE) tissue to measure protein expression of Rad51 and geminin, a cell proliferation marker, to assess HRD in breast cancer cell line models and clinical breast cancer samples. We hypothesize that Rad51, which is involved in the later stages of HR, can serve as a functional marker of HRD.

Methods: The MCF-7 human breast cancer cell line was used as a model with intact HR. Western blotting of total cell lysates from cells grown in culture was performed to confirm HR response following treatment with DNA damaging chemotherapeutic agents, cisplatin and doxorubicin. Paclitaxel, a microtubule targeting agent, was used as a negative control. Mice with MCF-7 xenograft tumors were also treated with cisplatin, or doxorubicin at two dose levels (low and high) and various time points post treatment to assess the dose and time response to HR markers. Tumors from mice treated with paclitaxel were used as a negative control. Xenograft tumors were fixed and analyzed by IHC using an antibody specific for total Rad51 and geminin expression. DNA damage was also assessed in a portion of the tumor using a pulse gel electrophoresis assay. We also analyzed FFPE breast cancer clinical samples from patients with BRCA1 mutations for Rad51 and geminin expression.

Results: In MCF-7 grown in vitro, total Rad51 was elevated as soon as 4 hours following exposure to doxorubicin and cisplatin, but not in response to paclitaxel treatment. In xenograft tumors, baseline Rad51 and geminin expression were relatively high illustrating proficient HR in an actively proliferating tumor model. Rad51 expression increased post treatment with cisplatin and doxorubicin as early as 6hrs and peaked at 16-24hrs. Geminin expression correlated well with expression of Rad51 at baseline and in time response to treatment. Pulse gel electrophoresis in paired tumor samples confirmed DNA damage was occurring compared to vehicle control treated tumors. However, this technique did not show a strong dose or time response. Five breast tumors from patients with known BRCA1 mutations were stained for Rad51 and geminin expression. High geminin expression and low Rad51 expression was noted in the majority of these tumors.

Conclusions: An IHC assay using FFPE tissue to measure Rad51/geminin is a promising method to assess HRD in breast cancer. Further analytical and clinical validation of this approach is ongoing.

Citation Format: Chalasani P, Nagy D, Livingston RB, Weterings E, Nagle R, Singh S, Barnes M, Grogan T, Ridder R, Baker AF, Kandavel S. Evaluating Rad51/geminin protein expression as an indicator of homologous recombination deficiency in breast cancer models. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-07-07.

Circulating Carbonic Anhydrase IX and Antiangiogenic Therapy in Breast Cancer

INTRODUCTION

Carbonic anhydrase IX (CAIX) is a hypoxia regulated metalloenzyme integral to maintaining cellular pH. Increased CAIX expression is associated with poor prognosis in breast cancer. To explore CAIX as a biomarker for breast cancer therapies, we measured plasma CAIX levels in healthy control subjects and in breast cancer patients.

METHODS

In control subjects we evaluated plasma CAIX stability via commercially available ELISA. We then similarly quantified plasma CAIX levels in (1) locally advanced breast cancer (LABC) patients treated with neoadjuvant paclitaxel + sunitinib (T + S) followed by doxorubicin and cyclophosphamide (AC); (2) metastatic breast cancer (MBC) patients treated with systemic chemotherapy.

RESULTS

Plasma CAIX levels were stable at room temperature for at least 48 hours in control subjects. Mean baseline plasma CAIX levels were lower in controls compared to patients with LABC or MBC. In LABC, CAIX levels rose significantly in response to administration of antiangiogenic therapy (T + S) (p = 0.02) but not AC (p = 0.37). In patients with MBC treated without an antiangiogenic agent CAIX levels did not change with therapy.

CONCLUSIONS

Our results suggest that CAIX may be an easily obtained, stable measure of tumor associated hypoxia as well as a useful pharmacodynamic biomarker for antiangiogenic therapy.

Pathophysiology of tumour-induced microangiopathic haemolytic anaemia

Cancer-associated microangiopathic haemolytic anaemia (CA-MAHA) is a syndrome characterised by Coombs-negative haemolytic anaemia and thrombocytopenia. It is primarily seen in advanced solid tumours and is distinct from thrombotic thrombocytopenic purpura/haemolytic uraemic syndrome. Diagnosis is often delayed and patients have a high mortality. We present the case of CA-MAHA in a patient with metastatic breast cancer treated successfully with early initiation of chemotherapy. In addition, we report longitudinal laboratory evaluation of circulating tumour cells and microparticles and suggest a hypothesis for the mechanism behind CA-MAHA.