Abstract P3-12-05: Fractionation patterns in adjuvant breast radiotherapy in Ontario, Canada from 2009 to 2015

Purpose: To report the patterns of use of hypofractionated radiotherapy (HFRT) (≤16 fractions)in breast cancer and ductal carcinoma in situ (DCIS) patients in Ontario, Canada from 2009 to 2015 and identify factors related to HFRT use.

Methods: A retrospective cohort study of Ontario women diagnosed with breast cancer or DCIS followed by adjuvant breast or chest wall radiation (RT) from 2009 to 2015 was conducted using data from the Institute for Clinical Evaluative Sciences (ICES). Logistic regression models were used to identify factors associated with HFRT use. Physician was included as a random effect. To calculate the potential amount of time that could be saved if all patients were to receive 16 fractions of HFRT, the number of extra RT treatments after the 16th visit was multiplied by the median amount of time spent to treat one patient at our cancer centre (8.76 minutes). This time was found with Sunnybrook Health Sciences Centre data collected from October 2017 to March 2018 (n=523) and represents the amount of time from when a patient enters the RT unit for treatment setup, until the RT beam is turned off.

Results: A total of 42,072 patients were included. Most patients were aged between 50 and 69 years old (56.7%) with stage I or II breast cancer (74.6%) and had breast conserving surgery (BCS) (76.9%). Half previously received chemotherapy and 7.9% were DCIS patients. Use of sequential boost, simultaneous boost, and regional nodal RT was 17.2%, 3.1%, and 31.7% respectively. Institutional variation in HFRT use ranged from 27.5% to 71.6%. HFRT use has increased in all patient populations over the study period. HFRT use was more common in breast cancer and DCIS patients with BCS than in chest wall and nodal RT. Simultaneous boost (OR=0.09), nodal RT (OR=0.08), previous chemotherapy (OR=0.7), stage 0, II, and III breast cancer (OR=0.06 relative to stage I), were correlated with less HFRT use. Older age, later year of diagnosis, sequential boost (OR=0.09), BCS and no surgery (OR=1.2, 1.5 relative to mastectomy) were correlated with higher HFRT use. Institution was significantly correlated to HFRT use. The variance estimate for the physician random effect was 0.33 (p<0.0001). For breast cancer patients with BCS and breast RT specifically, 62,396 extra visits occurred from 2009 to 2015, corresponding to ˜9100 hours of treatment if all patients received HFRT. For the entire patient population, a total of 190,726 extra visits occurred or ˜27,900 hours.

Trends in the use of HFRT (%) from 2009 to 2015 for DCIS and breast cancer patients in Ontario.YearStage I-IV + BCS + Breast RTStage I-IV + BCS + Breast + Nodal RTStage I-IV + Mastectomy + Breast RTStage I-IV + Mastectomy + Breast + Nodal RTDCIS + BCS200962.610.329.09.545.2201062.06.323.76.951.2201162.24.121.34.752.7201263.79.621.711.452.0201365.112.629.315.057.3201469.37.835.415.164.5201573.711.839.217.573.4BCS: breast conserving surgery, RT: radiation treatment

Conclusions: HFRT use in Ontario has increased over time for all patient populations, and reflects the current evidence supporting HFRT in different patient populations, with lower HFRT use seen in chest wall and nodal RT and higher HFRT use in early-stage breast cancer patients with BCS.

Citation Format: Chow E, Chan S, Yao Z, Sutradhar R, Lee J, Wan BA, Paszat L. Fractionation patterns in adjuvant breast radiotherapy in Ontario, Canada from 2009 to 2015 [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 P3-12-05.

The mTOR downstream regulator (p-4EBP1) is a novel independent prognostic marker in ovarian cancer

Ovarian cancer is associated with the highest mortality rate among gynaecologic malignancies. There is a need to refine the classification of ovarian cancer and identify novel targets. The mammalian target of rapamycin (mTOR) pathway has a crucial role in the pathogenesis and progression of ovarian cancer. This study aims to investigate the prognostic role of p-mTOR and its major downstream effectors p-4EBP1 (eukaryotic initiation factor 4E-binding protein 1) and p-P70S6K (ribosomal protein S6 kinase) in ovarian cancer. p-mTOR, p-4EBP1 and p-P70S6K protein expression was assessed on 195 consecutive ovarian epithelial cancers and correlated to clinicopathological features and survival. We found that high cytoplasmic expression of p-4EBP1 and p-P70S6K was associated with a serous type carcinoma (p = .005) and an advanced FIGO stage (p = .012), respectively. Univariate outcome analysis showed an inverse association between a high expression of p-4EBP1 expression and overall ovarian cancer survival (OS; p = .005) and progression-free survival (PFS; p = .005). p-P70S6K showed an inverse association with PFS (p = .001). Multivariate analyses indicated that p-4EBP1 was an independent predictor of both OS and PFS (p = .016 and p = .041, respectively). Therefore, we concluded that p-4EBP1 high protein expression is an independent predictor of outcome in ovarian cancer patients. Therefore, it could be used as a potential biomarker for prognostic stratification and treatment decisions. Impact statement What is already known on this subject? The mammalian target of rapamycin (mTOR) pathway has a crucial role in the pathogenesis and progression of ovarian cancer. To-date, very limited knowledge is known about the importance of mTOR major downstream effectors p-4EBP1 (eukaryotic initiation factor 4E-binding protein 1) and p-P70S6K (ribosomal protein S6 kinase) in ovarian cancer. What do the results of this study add? In this study, we have provided further evidence of the adverse prognostic behaviour associated with the positive expression of p-mTOR and its major downstream effectors. Moreover and by performing multivariate analysis, we for the first time have proved that p-4EBP1 is an independent predictor of clinical outcome in ovarian cancer. What are the implications of these findings for clinical practice and/or further research? p-4EBP1 could be used as a potential biomarker for prognostic stratification and treatment decisions in ovarian cancer management.

Aspirin treatment does not increase microhemorrhage size in young or aged mice

Microhemorrhages are common in the aging brain and are thought to contribute to cognitive decline and the development of neurodegenerative diseases, such as Alzheimer’s disease. Chronic aspirin therapy is widespread in older individuals and decreases the risk of coronary artery occlusions and stroke. There remains a concern that such aspirin usage may prolong bleeding after a vessel rupture in the brain, leading to larger bleeds that cause more damage to the surrounding tissue. Here, we aimed to understand the influence of aspirin usage on the size of cortical microhemorrhages and explored the impact of age. We used femtosecond laser ablation to rupture arterioles in the cortex of both young (2–5 months old) and aged (18–29 months old) mice dosed on aspirin in their drinking water and measured the extent of penetration of both red blood cells and blood plasma into the surrounding tissue. We found no difference in microhemorrhage size for both young and aged mice dosed on aspirin, as compared to controls (hematoma diameter = 104 +/- 39 (97 +/- 38) μm in controls and 109 +/- 25 (101 +/- 28) μm in aspirin-treated young (aged) mice; mean +/- SD). In contrast, young mice treated with intravenous heparin had an increased hematoma diameter of 136 +/- 44 μm. These data suggest that aspirin does not increase the size of microhemorrhages, supporting the safety of aspirin usage.

Palliative care clinicians and online education in India: a survey

BACKGROUND

Whether online resources can facilitate spread of palliative care knowledge and skills in India is an urgent question given few providers and a large, ageing population.

OBJECTIVES

We surveyed needs and feasibility regarding e-learning.

METHODS

Indian, Australian and North American palliative care experts developed an electronic survey using Qualtrics, emailed to all registrants of the 2017 Indian Association of Palliative Care (IAPC) conference and distributed during the conference.

RESULTS

Of 60 respondents (66% men, 60% doctors), most worked in hospitals and had oncology backgrounds, and 35% were from Kerala and Tamil Nadu. Most (90.9%) received palliative care training in India or overseas with 41% trained in a Trivandrum Institute of Palliative Sciences residential course (4-6 weeks). 17% completed the IAPC essential certificate and 22% had undertaken various distance learning courses. Interest in online training was substantial for most aspects of palliative care.

CONCLUSION

There was a high level of interest and reported feasibility in taking a case-based online course. This pilot survey provides support for online case-based education in India, particularly among physicians.

What Do Cancer Patients Value? A Unique Experience at Maggie's Cancer Caring Centre in Hong Kong

Background: Maggie's Cancer Caring Centre in Hong Kong (“Maggie's HK”) adopted a person-centered approach advocated by Maggie Keswick Jencks, who was the founder and a cancer patient. Witnessing first-hand that many psychosocial needs of a cancer patient could not be met through the existing medical system, Maggie created a blueprint for a purposefully-designed architecture and the services complementary to the existing system. The centre aims to empower people affected by cancer, be they cancer patients or caregivers, to live with, live through and live beyond cancer via informational and psychological consultations, psychosocial support programs and a therapeutic environment. People in need are welcome to drop-in anytime to use the centre while all services/programs are free and no referral/appointment is needed. As this patient-oriented drop-in service, integrated multidisciplinary approach and the therapeutic architecture, as one of a kind would conceptually make people feel at home, feel respected, see themselves as a person rather than a patient, and gain confidence in facing and walking through the cancer journey, how does this translate into practice in Maggie's HK? Aim: To examine the uniqueness of Maggie's HK cancer care service, especially the patient-oriented drop-in service and the purposefully-designed environment, this study investigated cancer patients' related experience at Maggie's HK and its influences on their cancer adjustment and adaptive coping in the community. Methods: A qualitative study design was adopted. Thirteen semistructured focus group interviews, each with 5-6 cancer patients/care-givers at Maggie's HK, were held from August 2016 to January 2017. Each interview lasted from 1.5 to 2.5 hours and were audio recorded then transcribed verbatim. Different themes were generated through repeated readings and content analysis with constant comparison. Results: Three main themes regarding the unique experiences of the drop-in service model under a purposefully-designed environment at Maggie's HK were emerged from the focus groups: Creating a sense of home for the centre users. Users reported the centre is like their second home giving them a sense of autonomy, security, trust and comfort. Empowering users to deal with uncertainties. Users reported the (drop-in) service helps to reduce their fear, worries and doubts. Providing a nurturing context for users' needs. Users reported the design of the physical environment has catered to their specific needs at different moments in time. Conclusion: The study reveals that the innovative model of patient-oriented drop-in service under a therapeutic physical environment at Maggie's HK contributes significantly a positive experience and impact on cancer patients in the reduction of their fear and worries, while enhancing their role as active participants in their care. There is also a developed sense of autonomy, security and confidence in the cancer journey.

First Results from the DEAP-3600 Dark Matter Search with Argon at SNOLAB

This Letter reports the first results of a direct dark matter search with the DEAP-3600 single-phase liquid argon (LAr) detector. The experiment was performed 2 km underground at SNOLAB (Sudbury, Canada) utilizing a large target mass, with the LAr target contained in a spherical acrylic vessel of 3600 kg capacity. The LAr is viewed by an array of PMTs, which would register scintillation light produced by rare nuclear recoil signals induced by dark matter particle scattering. An analysis of 4.44 live days (fiducial exposure of 9.87 ton day) of data taken during the initial filling phase demonstrates the best electronic recoil rejection using pulse-shape discrimination in argon, with leakage <1.2×10^{-7} (90% C.L.) between 15 and 31  keV_{ee}. No candidate signal events are observed, which results in the leading limit on weakly interacting massive particle (WIMP)-nucleon spin-independent cross section on argon, <1.2×10^{-44}  cm^{2} for a 100  GeV/c^{2} WIMP mass (90% C.L.).

Monitoring biofilm function in new and matured full-scale slow sand filters using flow cytometric histogram image comparison (CHIC)

While slow sand filters (SSFs) have produced drinking water for more than a hundred years, understanding of their associated microbial communities is limited. In this study, bacteria in influent and effluent water from full-scale SSFs were explored using flow cytometry (FCM) with cytometric histogram image comparison (CHIC) analysis; and routine microbial counts for heterotrophs, total coliforms and Escherichia coli. To assess if FCM can monitor biofilm function, SSFs differing in age and sand composition were compared. FCM profiles from two established filters were indistinguishable. To examine biofilm in the deep sand bed, SSFs were monitored during a scraping event, when the top layer of sand and the schmutzdecke are removed to restore flow through the filter. The performance of an established SSF was stable: total organic carbon (TOC), pH, numbers of heterotrophs, coliforms, E. coli, and FCM bacterial profile were unaffected by scraping. However, the performance of two newly-built SSFs containing new and mixed sand was compromised: breakthrough of both microbial indicators and TOC occurred following scraping. The compromised performance of the new SSFs was reflected in distinct effluent bacterial communities; and, the presence of microbial indicators correlated to influent bacterial communities. This demonstrated that FCM can monitor SSF performance. Removal of the top layer of sand did not alter the effluent water from the established SSF, but did affect that of the SSFs containing new sand. This suggests that the impact of the surface biofilm on effluent water is greater when the deep sand bed biofilm is not established.

Paediatric pain management: knowledge, attitudes, barriers and facilitators among nurses - integrative review

AIMS

To identify and synthesize evidence regarding the knowledge and attitudes of nurses, and barriers and facilitators to effective pain assessment and management in infants and children.

BACKGROUND

Pain among children is a common experience. Relief from pain is a fundamental human right, yet hospitalized children continue to experience unrelieved pain. Provision of effective pain management is an integral part of the nurse's role.

METHODS

Guided by Whittemore & Knafl's five-stage framework, primary peer-reviewed studies published in English between 2000 and 2018 were searched using CINAHL, PubMed, ProQuest, PsycINFO and Scopus. The initial search yielded 292 papers. Twenty-seven papers were included in this review: quantitative (n = 18), qualitative (n = 5) and mixed-methods (n = 4).

RESULTS

Findings showed that nurses internationally have poor knowledge and attitudes of basic pain assessment and management principles. Barriers to effective pain management include the absence of pain education and assessment tools, parents' reluctance to report pain and insufficient prescription of analgesia by physicians. Facilitators for the effective management of pain include parental participation in care, trusting and respectful relationships between nurses and children, and adequate nurse-patient ratios.

CONCLUSION

The review findings suggest a need to improve education for nurses, doctors and the patients' family in relation to paediatric pain management, communication and interprofessional collaborations. There is a need to maximize facilitators and overcome barriers, such as those identified in this review, to ensure the quality of paediatric pain management.

IMPLICATIONS FOR NURSING AND HEALTH POLICY

Nursing and health policy should mandate the prioritization of paediatric pain management and the clinical roles and responsibilities of the interdisciplinary team members. Undergraduate, postgraduate and in-service education for nurses and other health professionals should also address paediatric pain management. In-service education on paediatric pain management should be compulsory for all health professionals caring for children.

Disease-free and overall survival at 3.5 years for neoadjuvant bevacizumab added to docetaxel followed by fluorouracil, epirubicin and cyclophosphamide, for women with HER2 negative early breast cancer: ARTemis Trial

Background

The ARTemis trial previously reported that addition of neoadjuvant bevacizumab (Bev) to docetaxel (D) followed by fluorouracil, epirubicin and cyclophosphamide (D-FEC) in HER2 negative breast cancer improved the pathological complete response (pCR) rate. We present disease-free survival (DFS) and overall survival (OS) with central pathology review.

Patients and methods

Patients were randomized to 3 cycles of D followed by 3 cycles of FEC (D-FEC), ±4 cycles of Bev (Bev + D-FEC). DFS and OS were analyzed by treatment and by central pathology reviewed pCR and Residual Cancer Burden (RCB) class.

Results

A total of 800 patients were randomized [median follow-up 3.5 years (IQR 3.2–4.4)]. DFS and OS were similar across treatment arms [DFS hazard ratio (HR)=1.18 (95% CI 0.89–1.57), P = 0.25; OS HR = 1.26 (95% CI 0.90–1.76), P = 0.19). Both local pathology report review and central histopathology review confirmed a significant improvement in DFS and OS for patients who achieved a pCR [DFS HR = 0.38 (95% CI 0.23–0.63), P < 0.001; OS HR = 0.43 (95% CI 0.24–0.75), P = 0.003]. However, significant heterogeneity was observed (P = 0.02); larger improvements in DFS were obtained with a pCR achieved with D-FEC than a pCR achieved with Bev + D-FEC. As RCB class increased, significantly worse DFS and OS was observed (P for trend <0.0001), which effect was most marked in the ER negative group.

Conclusions

The addition of short course neoadjuvant Bev to standard chemotherapy did not demonstrate a DFS or OS benefit. Achieving a pCR with D-FEC is associated with improved DFS and OS but not when pCR is achieved with Bev + D-FEC. At the present time therefore, Bev is not recommended in early breast cancer.

ClinicalTrials.gov number

NCT01093235.

Abstract P2-08-02: Novel tumor suppressor regulating the PI3K/AKT pathway in breast cancer

Breast cancer affects approximately 1 in 8 women over the course of their lifetime. Of the many genes and pathways deregulated by this heterogeneous disease, alterations of members in the PI3K/AKT pathway are present in approximately 20% of all cases, making it one of the more frequently mutated pathways in breast cancer. The PI3K/AKT pathway is well known to be involved in essential cellular processes necessary for cancer development and progression, including altered proliferation, metabolism, and cell survival. Previous studies have made it well known that the activation of AKT is regulated through its phosphorylation, but recent studies have also shown that AKT can also be regulated via ubiquitination, leading to AKT hyperactivation. However, the mechanism and players involved in this process are not well understood. Better understanding of these pathways could inform on better potential therapeutics to target this disease.

Recent work in our lab has identified GPS2, a member of the NCoR/SMRT complex, as a regulator of the insulin-signaling pathway through the inhibition of AKT ubiquitination by Ubc13. As many human cancers frequently have an increase in activated AKT, here we explore the potential of GPS2 as a tumor suppressor in the context of breast cancer and hope to elucidate the mechanism by which AKT ubiquitination regulates its activation.

Citation Format: Chan S, Cardamone MD, Perissi V. Novel tumor suppressor regulating the PI3K/AKT pathway in 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 P2-08-02.

Phase II study of buparlisib (BKM120) and trastuzumab in patients with HER2+ locally advanced or metastatic breast cancer resistant to trastuzumab-based therapy

PURPOSE

A Phase Ib study in patients with trastuzumab-resistant, human epidermal growth factor receptor-2- (HER2)-positive advanced breast cancer defined the recommended Phase II dose of buparlisib as 100 mg/day in combination with 2 mg/kg weekly trastuzumab, and reported preliminary signs of clinical activity. Here we present results from the Phase II portion.

METHODS

Patients with trastuzumab-resistant, HER2-positive advanced breast cancer received buparlisib plus trastuzumab. Study endpoints included safety/tolerability and antitumour activity. The study was extended to include a Phase Ib dose-escalation phase, in which patients with progressive brain metastases also received capecitabine.

RESULTS

In the Phase II portion, of 50 patients treated with buparlisib and trastuzumab, the most common (≥ 30%) all-grade adverse events (AEs) were diarrhoea (54%), nausea (48%), decreased appetite, increased alanine aminotransferase (36% each), increased aspartate aminotransferase (34%), fatigue, rash (32% each), cough and hyperglycemia (30% each). One (2%) patient achieved complete response and four (8%) patients had confirmed partial responses [PR; including two patients with phosphatidylinositol 3-kinase (PI3 K) pathway-activated tumours]. Overall response rate (ORR) was 10%: the primary endpoint (ORR ≥ 25%) was therefore not met. In the Phase Ib portion, all patients with measurable brain lesions at baseline showed tumour shrinkage to some degree; due to low enrollment, maximum tolerated dose of buparlisib in combination with trastuzumab and capecitabine was not determined.

CONCLUSION

Buparlisib plus trastuzumab, as a chemotherapy-free regimen, demonstrated an acceptable safety profile but limited efficacy in patients with heavily pretreated, trastuzumab-resistant HER2-positive breast cancer, and in patients with progressive brain metastases also receiving capecitabine.

Abstract P2-08-01: Results from a randomized placebo-controlled phase 2 trial evaluating exemestane ± enzalutamide in patients with hormone receptor–positive breast cancer

This abstract was withdrawn by the authors.

Abstract P3-07-18: Exercise and triple negative breast cancer: Unravelling the anti-neoplastic molecular factors through novel culture method

Background

Despite advances to ameliorate breast cancer survival, triple negative breast cancers (TNBCs) attribute to highly disproportionate mortalities due to its aggressiveness and poor therapeutic response (Bao et al., Cancer Medicine 2014). Despite the lack of target-specific drugs, chemotherapy is the mainstay treatment, warranting more efficacious measures against TNBCs. Studies have shown that physical activity intervention reduced breast cancer risk between 20-80% (Monnikohf et. al., Epidemiology 2007) as well as breast cancer related mortality by 34% (Ibrahim et al., Med Onc 2010). However, it is clear that such intervention uptake in the population may not be feasible given the longstanding public health drive to increase physical activity. Therefore it is imperative to identify the molecular factors that might be involved in cancer prevention and therapy with the long term goal of developing a supplement. Due to the recent epidemiological findings on exercise and breast cancer, we wanted to develop a system to comprehensively identify beneficial myokines using a cell culture system.

Methods

For this study we differentiated C2C12 myoblasts into myotubules. Myotubules were contracted in Krebs Ringer Buffer solution with the C-Pace EP Pacer for 8 hours. Buffer was collected and concentrated using Amicon Ultra-0.5 centrifugal filter tubes to produced an exercise/conditioned medium. To explore the effects of exercise on breast cancer cell lines MCF-7 (ER+) and MDA-MB468 (TNBC line) were treated with conditioned medium for 48 hrs. To explore the effects of exercise and chemotherapeutic efficacy MDA-MB468 cells were treated with doxorubicin, conditioned medium or both for 48 hrs. Protein was isolated and processed for immunoblot analysis. Cell cycle markers p21, pRb, cyclin D1, PCNA as well as apoptotic marker cPARP were assessed to reveal the effects treatment.

Results

Treatment of conditioned medium in MCF-7 revealed marked changes in both p21 (92% increase, p=0.05) and pRb protein expression (62% decrease, p&lt;0.05) as well as a modest reduction in PCNA (24% decrease , p&lt;0.02). Conditioned medium treatment in MDA-MB468 cells showed a reduction in cyclin D1 and PCNA expression (40%, p&lt;0.01 and 30%, p&lt;0.02) as well as an induction of cPARP expression (32%, p=0.09). Doxorubicin treatment increased p21 and cPARP protein expression (2.2-fold increase, p&lt;0.01 and 80% increase, p&lt;0.05 respectively). Treatment of conditioned medium and doxorubicin displayed a synergistic effect with a 3.65-fold increase in p21 (p&lt;0.01) and 130% increase in cPARP (p=0.01).

Conclusions

We have developed a novel system that may enable, for the first time, mechanistic studies to elucidate the role of skeletal muscle/exercise in breast cancer prevention and chemotherapy. Our data indicates a secreted factor(s) from skeletal muscles that plays a role in anti-proliferative and pro-apoptotic effects, which are the hallmark of exercise's anti-neoplastic properties. Studies are ongoing to further understand, characterize and isolate this factor(s) for therapeutic purposes. Given the limited chemotherapeutic options and heterogeneity in TNBC, our exercise culture system sheds a promising light on novel drug development and chemo-sensitization.

Citation Format: Dela Cruz MA, Roy P, Chowdhury S, Chan S, Roy HK. Exercise and triple negative breast cancer: Unravelling the anti-neoplastic molecular factors through novel culture method [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-07-18.

Abstract P4-22-08: A single-arm phase 2 study to assess clinical activity, efficacy and safety of enzalutamide with trastuzumab in HER2+ AR+ metastatic or locally advanced breast cancer

Background:Androgen receptor (AR) expression has been observed in up to 77% of human epidermal growth factor receptor 2–positive (HER2+) breast cancer (BC).References:1 Enzalutamide (ENZA) is a potent AR inhibitor approved for patients (pts) with metastatic castration-resistant prostate cancer. In vitro, ENZA enhances antitumor activity of trastuzumab in HER2+ AR+ cell lines and inhibits proliferation in trastuzumab-resistant HER2+ cell lines.2

Methods:Pts with metastatic or locally advanced BC that was HER2+ AR+ by local or central laboratory assessment were enrolled in a single-arm, Simon 2-stage phase 2 study (NCT02091960). Key eligibility criteria included availability of a tissue sample, presence of measurable or evaluable disease per RECIST v1.1, progression on prior trastuzumab and ≥1 prior line of anti-HER2 therapy as the most recent regimen. Brain metastases and history of seizure were exclusionary. Evaluable pts were those with centrally confirmed nuclear AR expression≥10% by immunohistochemistry who received ≥1 dose of ENZA and had ≥1 postbaseline tumor assessment. Pts received ENZA 160 mg daily and trastuzumab 6 mg/kg every 21 days until disease progression. The primary objective was clinical benefit rate at 24 weeks (CBR24), defined as complete or partial response (CR or PR) or stable disease (SD) for ≥24 weeks in evaluable pts. Additional endpoints included safety and progression-free survival (PFS). CBR24 in ≥3 of 21 evaluable pts was required to continue to stage 2 and enrollment of up to 66 evaluable pts total. This design yields a 1-sided type 1 error of 5% and 90% power when the true response is 25%.

Results:Here we present results from stage 1 (data cutoff: Mar 23, 2016), with 22 evaluable pts enrolled (pts 21 and 22 enrolled simultaneously); 18 had received ≥4 prior lines of therapy. Median duration of ENZA exposure was 144 days (range, 22-495), mean number of complete trastuzumab infusions was 6.5. CBR24 was 27.3% (95% confidence interval [CI], 10.7-50.2); 2 confirmed PR and 4 SD ≥24 weeks. Median PFS was 108 days (95% CI, 56-144). All pts experienced ≥1 adverse event (AE) any grade; 5 pts experienced AEs grade ≥3. ENZA-related AEs were reported in 16 pts (72.7%), the most common (in ≥10% of pts) were fatigue (22.7%), nausea (18.2%), diarrhea (13.6%) and arthralgia (13.6%). Serious AEs were reported in 6 pts (27.3%; 2 each of infection and back pain, 1 each of abdominal pain, nausea, vomiting, pyrexia, urinary retention and pulmonary edema). Two pts discontinued due to drug-related AEs: 1 related to both drugs, 1 related to trastuzumab. One on-study death from pulmonary edema was reported, which was not considered related to either drug.

Conclusion:Stage 1 met its primary objective. No new safety signals were identified, and the safety profile in this study was similar to that in men with prostate cancer and women with other BC subtypes treated with ENZA. These results are encouraging for a heavily pretreated population with advanced HER2+ AR+ BC. Enrollment in stage 2 continues with the combination of ENZA and trastuzumab.

1. Micello D et al. Virchows Arch. 2010;457:467-476.

2. Richer J. Presented at AACR Advances in Breast Cancer, San Diego, CA, 2013.

Citation Format: Krop I, Cortes J, Miller K, Huizing MT, Provencher L, Gianni L, Chan S, Trudeau M, Steinberg J, Sugg J, Liosatos M, Paton VE, Peterson A, Wardley A. A single-arm phase 2 study to assess clinical activity, efficacy and safety of enzalutamide with trastuzumab in HER2+ AR+ metastatic or locally advanced breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-08.