Abstract SP092: Special topics in metastatic ER+ breast cancer

About 70% of all diagnosed breast cancers express hormone receptors (estrogen [ER+], progesterone [PR+] or both [HR+]). Despite an overall good prognosis, the clinicopathological and molecular heterogeneity of these tumors account for a diverse natural history of disease, with several patients still developing distant metastatic recurrence at virtually any point during the disease trajectory, regardless of endocrine therapy. Improved risk stratification and treatment individualization accounts for longer disease-free and overall survival, but distant metastatic recurrences still occur and about half of these occur beyond 6 years from the original diagnosis. A better understanding of breast cancer biology and mechanisms of endocrine therapy resistance has resulted in the approval of novel therapeutic strategies for patients with HR+ metastatic breast cancer (MBC), which now often include addition of targeted treatment, such as CDK4/6 or PI3K pathway inhibitors, to first, second or third line endocrine therapy. Improvement in progression-free survival and sometimes even overall survival, as well as a delay in chemotherapy use in the metastatic setting and maintenance of a good quality of life have been important achievements with these targeted therapies. However, more refined clinical and molecular biomarkers are lacking to determine which patients truly need (or not) the (early or at all) addition of these targeted treatments to conventional endocrine therapy, the timing and order of targeted therapy addition and even the timing to introduce chemotherapy. Currently, the amount of ER/PR expression in the tumor, presence of tumor actionable genomic alterations (such as PIK3CA, ESR1, BRCA mutations to name a few), the patient’s disease-free interval between original (early) and metastatic breast cancer diagnosis, metastatic burden and sites of metastasis, absence or presence of symptoms or visceral crisis, previous treatments, among others, are some of the main variables that clinicians take into account to customize HR+ MBC treatment. Several research efforts are under way, focusing on important questions addressing the optimal sequence and administration of drugs to circumvent current endocrine therapy with or without CDK4/6 inhibition strategies, such as (a) timing and order of CDK4/6 inhibitor addition to endocrine therapy, (b) if CDK4/6 inhibitors should be continued with a different endocrine therapy partners beyond progression of disease on endocrine therapy and CDK4/6 inhibitors, (c) novel combination of endocrine therapy with or without CDK4/6 inhibitors with targeted treatments or immunotherapy, (d) new endocrine therapy agents such as novel selective ER downregulators (SERDs) and selective ER covalent agonists (SERCAs), (e) serial collection of tumor tissue and blood for profiling at different timepoints during the metastatic setting treatment in an effort to identify new mechanisms of resistance, and (f) novel chemotherapy combinations with targeted treatment or immunotherapy. In conclusion: many therapeutic and diagnostic advances have contributed to better outcomes in HR+ MBC, but recognition of differences between clinicopathological and molecular characteristics of patients and their tumors is key in promoting optimization of treatment choices that would maximize survival, palliation of symptoms and quality of life for patients with HR+ MBC in the years to come.

Citation Format: I Mayer. Special topics in metastatic ER+ 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 SP092.

Time course and management of key adverse events during the randomized phase III SOLAR-1 study of PI3K inhibitor alpelisib plus fulvestrant in patients with HR-positive advanced breast cancer

BACKGROUND

Alpelisib (α-selective phosphatidylinositol 3-kinase inhibitor) plus fulvestrant is approved in multiple countries for men and postmenopausal women with PIK3CA-mutated, hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer following progression on or after endocrine therapy. A detailed understanding of alpelisib's safety profile should inform adverse event (AE) management and enhance patient care.

PATIENTS AND METHODS

AEs in the phase III SOLAR-1 trial were assessed in patients with and without PIK3CA mutations. The impact of protocol-specified AE-management recommendations was evaluated, including an amendment to optimize hyperglycemia and rash management.

RESULTS

Patients were randomly assigned to receive fulvestrant plus alpelisib (n = 284) or placebo (n = 287). The most common grade 3/4 AEs with alpelisib were hyperglycemia (grade 3, 32.7%; grade 4, 3.9%), rash (grade 3, 9.9%), and diarrhea (grade 3, 6.7%). Median time to onset of grade ≥3 toxicity was 15 days (hyperglycemia, based on fasting plasma glucose), 13 days (rash), and 139 days (diarrhea). Metformin alone or in combination with other antidiabetic agents was used by most patients (87.1%) with hyperglycemia. Preventive anti-rash medication resulted in lower incidence (any grade, 26.7% versus 64.1%) and severity of rash (grade 3, 11.6% versus 22.7%) versus no preventative medication. Discontinuations due to grade ≥3 AEs were lower following more-detailed AE management guidelines (7.9% versus 18.1% previously). Patients with PIK3CA mutations had a median alpelisib dose intensity of 248 mg/day. Median progression-free survival with alpelisib was 12.5 and 9.6 months for alpelisib dose intensities of ≥248 mg/day and <248 mg/day, respectively, compared with 5.8 months with placebo.

CONCLUSIONS

Hyperglycemia and rash occurred early during alpelisib treatment, while diarrhea occurred at a later time point. Early identification, prevention, and intervention, including concomitant medications and alpelisib dose modifications, resulted in less severe toxicities. Reductions in treatment discontinuations and improved progression-free survival at higher alpelisib dose intensities support the need for optimal AE management. CLINICALTRIALS.

GOV ID

NCT02437318.

Contrasting associations between breeding coloration and parasitism of male Arctic charr relate to parasite species and life cycle stage

Conspicuous carotenoid ornamentation is considered a signal of individual "quality" and one of the most intensely studied traits found to co-vary with parasitism. Since it has been suggested that only "high quality" individuals have enough resources to express excessive sexual ornaments and resist parasites, current theory struggles to explain cases where the brightest individuals carry the most parasites. Surprisingly little emphasis has been put on the contrasting routes to fitness utilized by different parasite species inhabiting the same host. Using Arctic charr (Salvelinus alpinus) as model species, we hypothesized that skin redness and allocation of carotenoids between skin and muscle (redness ratio) will be positively and negatively associated with parasites using the fish as an intermediate and final host, respectively. Both pigment parameters were indeed positively associated with abundances of parasites awaiting trophic transmission (Diplostomum sp. and Diphyllobothrium spp.) and negatively associated with the abundance of adult Eubothrium salvelini tapeworms. These empirical data demonstrate that contrasting associations between carotenoid coloration and parasite intensities relates to the specific premises of different parasite species and life cycle stages.

Abstract PD2-12: Palbociclib in combination with fulvestrant or tamoxifen as treatment for hormone receptor positive (HR+) metastatic breast cancer (MBC) with prior chemotherapy for advanced disease (TBCRC 035) A phase II study with pharmacodynamics markers

Background

Addition of the cyclin dependent kinase 4/6 inhibitor (CDK4/6i) palbociclib to endocrine therapy in the first and later line settings significantly improves progression free survival (PFS) in patients with HR+ MBC. The primary toxicity is neutropenia without an increase in febrile neutropenia. TBCRC035 explored rates of neutropenia in patients who had received prior chemotherapy for MBC with 2 dose levels of palbociclib, and correlated changes in retinoblastoma protein phosphorylation (pRB) and Ki67 expression in proliferating keratinocytes and tumor with response.

Methods

TBCRC035 is a 1:1 randomized multicenter phase II study evaluating palbociclib at either 125 or 100 mg in combination with physician choice fulvestrant or tamoxifen. Eligible patients (pts) with HR+ MBC had received &gt;1 but &lt;3 lines of chemotherapy for MBC, any number of prior hormone therapies, and were naïve to CDK4/6i. The primary endpoint was grade 3/4 neutropenia; secondary endpoints included response, safety/tolerability, inhibition of pRB and change in Ki67 in skin and tumor at day 14-21 of treatment compared to baseline. FFPE sections of skin punch and tumor biopsies obtained before and on treatment were stained using antibodies to Ki67, total RB, and phospho-RB-S780 using BOND polymer red detection. Stained slides were scanned into the Aperio image analysis platform; the percentage of marker positive cells and H-score was determined.

Results

70 pts were enrolled (fully accrued); 35 randomized to 100 vs 125 mg of palbociclib respectively; data for the last 3 pts on the 125 mg arm is pending. Grade 3/4 neutropenia was more common in the 125 mg vs the 100 mg arm (56 vs 34%); dose adjustments for adverse events (AEs) occurred in 47 vs 43%, 4 vs 0 pts discontinued treatment due to AEs. Grade 3 febrile neutropenia was rare (1 patient each arm). Median duration of treatment was 5.2 vs 7.2 months. Response data and correlation with changes in pRB and Ki67 expression in skin and tumor by treatment arm will be reported.

Conclusion

In pts with prior chemotherapy for HR+ MBC, treatment with 100 mg of palbociclib in patients is associated with a lower rate of &gt; grade 3 neutropenia compared to 125 mg. Correlation of response by dose with pRB and Ki67 has the potential to inform palbociclib dosing and reduce toxicity for pts with HR+ MBC.

Citation Format: Rugo HS, Mayer EL, Storniolo AM, Isaacs C, Mayer I, Stearns V, Nanda R, Nangia J, Wabl C, Deluca A, Kochupurakkal B, Wolff AC, Shapiro GI. Palbociclib in combination with fulvestrant or tamoxifen as treatment for hormone receptor positive (HR+) metastatic breast cancer (MBC) with prior chemotherapy for advanced disease (TBCRC 035) A phase II study with pharmacodynamics markers [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 PD2-12.

Abstract P1-15-01: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Metzger Filho O, Janiszewska M, Guo H, Yardley D, Mayer I, Spring L, Arteaga C, Wrabel E, DeMeo M, Freedman R, Tolaney S, Waks A, Bardia A, Parsons H, Partridge A, Mayer E, King T, Polyak K, Viale G, Winer E, Krop I. Withdrawn [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 P1-15-01.

Abstract PL2: Neoadjuvant Endocrine Therapy: The Times They are A-Changing

Neoadjuvant endocrine therapy (NET) in hormone-receptor positive breast cancers (HR+ BC) has been, in general, under-utilized, mostly because the majority of HR+ BC are diagnosed as stage I or II, and undergo surgical management as their first strategic step. However, NET is a suitable therapeutic choice for HR+ BC in cases where downsizing of the tumor is necessary (i.e. achievement of breast conservation). A seminal clinical trial comparing NET with neoadjuvant chemotherapy (NAC) in post-menopausal patients with HR+ BC revealed that the rates of overall response and breast conservation surgery were almost identical. NET also allows clinicians to infer prognosis based on simple pathologic characteristics: several clinical trials, including the phase III POETIC clinical trial (n=4486) showed that low Ki67 (less than 10%) at baseline and after 2 weeks had excellent long term outcome, whereas Ki67 larger than 10% at baseline and after 2 weeks had significantly worse long term outcome. Additionally, the Preoperative Endocrine Prognostic Index (PEPI), which is based on pathologic tumor size, node status, Ki67 level and ER status (Allred score) at the time of surgery, post NET, can accurately predict long term outcome. Interestingly, the early (about 2 weeks) Ki67 levels post NET has consistently predicted results of several phase III adjuvant or metastatic endocrine therapy trials (IMPACT - ATAC; Z1031 - MA-27) even in combination with targeted agents (LORELEI - SANDPIPER; NET + everolimus - BOLERO-2). Results of the ALTERNATE (A011106), a NET comparing AI with fulvestrant in post-menopausal patients with stage II and III HR+ BC is eagerly awaited, as it is bound to mimic the results of phase II and III trials comparing fulvestrant and AI in HR+ MBC (FIRST, FALCON, FACT, SWOG0226). Ultimately, these tools help clinicians decide if the addition of chemotherapy is necessary or not in patients with HR+ BC. Finally, NEC is an excellent tool in providing insights into the biologic basis of endocrine therapy efficacy (biomarkers of response and mechanisms of resistance studied in the post-treatment residual cancer). NET incorporating targeted therapies such as PI3K pathway inhibitors have yielded somewhat disappointing results compared to endocrine therapy alone (LORELEI, Neo-ORB), considering that PIK3CA mutations are the most common genomic alterations seen in HR+ BC. However, several ongoing trials of NET with CDK4/6 inhibitors were recently completed or are ongoing (NeoPalAna, NeoMONARCH, PALLET, PELOPS), and these trials may be instrumental not only in predicting the success of the large phase III adjuvant endocrine therapy with or without CDK4/6 inhibitors clinical trials. Ultimately, relatively small NET clinical trials could help with the design of more intelligent large clinical trials, providing the opportunity of residual tissue availability as a platform of discovery for biomarkers of sensitivity and resistance, an excellent platform for the development of investigational drugs and triaging of novel combinations.

Citation Format: Mayer I. Neoadjuvant Endocrine Therapy: The Times They are A-Changing [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 PL2.

Abstract PD1-02: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Cortes J, Martin M, Pernas S, Gomez Pardo P, Lopez-Tarruella S, Gil-Martin M, Manso L, Ciruelos E, Perez-Fidalgo JA, Hernando C, Ademuyiwa FO, Weilbaecher K, Mayer I, Pluard TJ, Martinez Garcia M, Vahdat L, Wach A, Barker D, Romagnoli B, Kaufman PA. Withdrawn [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 PD1-02.

Abstract OT2-01-19: A randomized phase II trial of fulvestrant with or without ribociclib after progression on aromatase inhibition plus cyclin-dependent kinase 4/6 inhibition in patients with unresectable or metastatic hormone receptor positive, HER2 negative breast cancer

Background

Cyclin dependent kinase 4 and 6 inhibitors (CDK4/6i), including palbociclib and ribociclib (R), have demonstrated remarkable benefit in progression free survival (PFS) in patients (pts) with hormone receptor positive (HR+), HER2- metastatic breast cancer (MBC) when combined with anti-estrogen therapy. Switching between anti-estrogen therapies at disease progression is standard of care in the treatment of HR+ MBC. We evaluate the strategy of switching anti-estrogen therapy to fulvestrant (F) and maintaining CDK4/6 inhibition with R in pts with HR+, HER2- MBC who have progressed on an aromatase inhibitor (AI) + CDK4/6i.

Trial Design

Phase II, multi-center, randomized, double-blind, placebo-controlled trial to evaluate F +/- R in pts with HR+, HER2- MBC who have previously progressed on any AI + CDK4/6i. Pts can be screened and registered at two different time points:

Scenario 1: Before receiving any CDK4/6i

Scenario 2: At the time of progression of disease (POD) while being treated with an AI + CDK4/6i

In scenario 1, the study will provide pts with letrozole + R, but pts will not be randomized until they demonstrate POD. At randomization, pts will be assigned 1:1 to either a) F + R or b) F + placebo, with treatment given in 4-week cycles. F will be given as a 500 mg dose intramuscularly every 2 weeks for 3 times and then every 4 weeks, as per standard of care. R or placebo will be given orally at 600 mg daily, 3 weeks on/1 week off. CT scans and bone scan are to be performed prior to every third cycle. Serum and whole blood samples and optional tissue biopsies for biomarker assessment will be performed prior to study treatment (scenario 1), prior to randomization to R +/- F, and when the patient goes off study.

Main Eligibility Criteria:

1. Age ≥ 18 years with unresectable or metastatic BC

2. Estrogen and/or progesterone receptor positive, HER2 negative, as per ASCO-CAP

3. Postmenopausal status or receiving ovarian suppression

4. Measurable or unmeasurable disease; stable CNS disease allowed

5. No clinically significant cardiac disease

6. No concomitant CYP3A4/5 inducer or inhibitor

Specific Aims

Primary: Progression free survival (PFS), defined as the time from randomization to POD or death.

Secondary: Objective response rate (ORR), clinical benefit rate (CBR = ORR + stable disease rate), overall survival (OS), and duration of response. Pts in scenario 1 will also be assessed for PFS, OS, CBR, and safety while receiving AI + R (pre-randomization).

Biomarker assessment will include amplification of cyclin D1 and cyclin E, phosphoRb and TK1 expression, Rb1 and p16 loss, and ctDNA for ESR1 and PIK3CA mutations.

Target Accrual

132 pts accrued from 11 academic medical centers in the U.S, with a goal of completing accrual in two years (∼60 to 72 pts in each scenario).

Statistical Methods

Assuming a median PFS of 3.8 months with F alone, we predict that F + R will lead to a median PFS of at least 6.5 months. A one-sided log-rank test with a sample size of N=120 and alpha=0.025, achieves 80% power to detect a difference in PFS of 2.7 months. N=132 pts allows for a 10% drop-out rate.

Citation Format: Mundi PS, Codruta C, Accordino MK, Sparano J, Andreopoulou E, Vadhat LT, Tiersten A, Esteva F, O'Regan R, Jain S, Mayer I, Forero A, Crew KD, Hershman DL, Kalinsky KM. A randomized phase II trial of fulvestrant with or without ribociclib after progression on aromatase inhibition plus cyclin-dependent kinase 4/6 inhibition in patients with unresectable or metastatic hormone receptor positive, HER2 negative 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 OT2-01-19.

Vaccination and triploidy increase relative heart weight in farmed Atlantic salmon, Salmo salar L

Heart morphology is particularly plastic in teleosts and differs between farmed and wild Atlantic salmon. However, little is known about how different culture practices and sex affect heart morphology. This study investigated how vaccination, triploidy and sex affected heart size and heart morphology (ventricle shape, angle of the bulbus arteriosus) in farmed Atlantic salmon for 18 months following vaccination (from c. 50-3000 g body weight). In addition, hearts were examined histologically after 7 months in sea water. All fish sampled were sexually immature. Vaccinated fish had significantly heavier hearts relative to body weight and a more triangular ventricle than unvaccinated fish, suggesting a greater cardiac workload. Irrespective of time, triploids had significantly heavier hearts relative to body weight, a more acute angle of the bulbus arteriosus and less fat deposition in the epicardium than diploids. The ventricle was also more triangular in triploids than diploids at seawater transfer. Sex had transient effects on the angle of the bulbus arteriosus, but no effect on relative heart weight or ventricle shape. From a morphological perspective, the results indicate that vaccination and triploidy increase cardiac workload in farmed Atlantic salmon.

Abstract PD1-3: Ph1b study of the PI3K inhibitor GDC-0032 in combination with fulvestrant in patients with hormone receptor-positive advanced breast cancer

Background: GDC-0032 is a next-generation PI3K inhibitor with increased anti-tumor activity against PIK3CA mutant cancers. GDC-0032 is an orally bioavailable, potent, and selective inhibitor of Class I PI3K alpha, delta, and gamma isoforms, with 30-fold less inhibition of the PI3K beta isoform relative to the PI3K alpha isoform. Preclinical data show that GDC-0032 has enhanced activity against PI3K alpha isoform (PIK3CA) mutant breast cancer cell lines. Preclinical data also show enhanced antitumor activity when GDC-0032 is combined with fulvestrant.

Material and Methods: A Phase 1b dose escalation study was conducted with evaluation of GDC-0032 doses ranging from 6-9 mg QD in combination with fulvestrant 500mg q4wk (with loading dose of 500mg at day 1, 14 and 28) in a modified 3+3 design. A dose expansion cohort was conducted at the recommended Phase 2 dose of 6 mg QD. Safety and tolerability of GDC-0032 was assessed, as well as pharmacokinetics (PK), pharmacodynamic (PD) assessment of PI3K pathway inhibition by paired tumor biopsies and by FDG-PET, and anti-tumor activity by RECIST.

Results: As of 1 Mar 2013, 17 patients were enrolled onto this study with the completion of dose escalation. No dose limiting toxicities (DLTs) were observed at either the 6 mg or 9 mg dose levels. Adverse events (AEs) assessed by the investigator as related to GDC-0032 in ≥10% of patients, were diarrhea, hyperglycemia, stomatitis, fatigue, asthenia, decreased appetite, nausea, mucosal inflammation and rash. No observed apparent PK interactions were observed between GDC-0032 and fulvestrant. The median number of prior systemic therapies was 6. Metabolic partial responses via FDG-PET (≥ 20% decrease in mSUVmax) were observed in 8 out of 11 patients assessed (73%). Confirmed partial responses by RECIST have been observed at both the 6mg and 9mg GDC-0032 dose levels. These include patients who have had prior treatment with fulvestrant. As of 29 May 2013, enrollment onto the dose escalation and expansion cohort has been completed (n = 27). Updated data on safety, pharmacodynamics, efficacy, and biomarker correlates will be presented.

Conclusions: The combination of GDC-0032 and fulvestrant is a well-tolerated regimen with promising preliminary efficacy. GDC-0032 is being further investigated in combination with fulvestrant for patients with hormone receptor-positive advanced breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD1-3.

Abstract PD1-2: PIK3CA mutations and/or low PTEN predict resistance to combined anti-HER2 therapy with lapatinib and trastuzumab and without chemotherapy in TBCRC006, a neoadjuvant trial of HER2-positive breast cancer patients

We have recently reported that in patients with HER2-positive breast cancer, neoadjuvant targeted therapy with lapatinib and trastuzumab to more completely block the HER receptor layer, combined with endocrine therapy (in ER-positive tumors) and without chemotherapy led to a substantial 27% pathologic complete response (pCR) rate in the breast. Activation of downstream signaling pathways may lead to resistance to therapies targeting the HER pathway receptors. Aberrant activation of the PI3K pathway via decreased levels of PTEN and/or the presence of activating PIK3CA mutations has been implicated in resistance to targeted anti-HER2 therapy, but results of clinical trials are all confounded by the co-administration of chemotherapy and are inconsistent. We sought to clarify the role of these variables in predicting pCR, a surrogate for long-term outcome, in patients treated with potent targeted therapy alone in a prospective Phase II neoadjuvant trial in patients with HER2-positive breast cancer.

Patients with large tumors (median 6 cm) were given 12 weeks of lapatinib plus trastuzumab followed by surgery (Rimawi et al. JCO, 2013). Serial tissue biopsies were obtained from study participants. For this study, we focused on baseline pre-treatment characteristics. PTEN protein levels were measured by IHC and scored using the H-score. PIK3CA mutations were identified on extracted DNA using multiplex PCR with targeted next generation sequencing (the Ion Torrent 50-gene cancer mutation panel).

Of 64 evaluable patients, tissue was available on 59 for PTEN IHC, and sufficient DNA was available on 33 for the mutation panel. PTEN median H-score was 100 (range 0-300). PTEN status when dichotomized by the median was correlated with pCR (32% in high PTEN vs. 9% in low PTEN, p = 0.04). Activating PIK3CA mutations were identified in 12 out of 33 tumors (36%; 3 mutations in the helical and 9 in the catalytic domain) and were independent of ER status. None of the patients whose tumors harbored a PIK3CA mutation achieved pCR (p = 0.06). There was no association between PTEN status and PIK3CA mutation suggesting they are independent variables (p = 0.44). When PIK3CA mutations were considered together with PTEN status, there were 31 cases with data on both. The overall pCR rate in this cohort was 16% (lower than pCR rate observed in the overall trial). However, 0/17 cases (0%) with a mutation and/or PTEN low expression (&lt;100 H score) had a pCR compared to 5/14 cases (36%) with PI3KCA wild type and high PTEN levels (p = 0.01).

We conclude that PI3K pathway activation downstream of HER2 as a result of either low PTEN or activating PIK3CA mutation results in resistance to the combination of lapatinib and trastuzumab. This is the first report on patient tissue samples from a neoadjuvant trial using the combination of lapatinib and trastuzumab without chemotherapy. If validated in a larger cohort, our findings suggest that patients with HER2 positive tumors and who also harbor aberrant downstream PI3K pathway activation may benefit from the addition of PI3K/Akt/mTOR inhibitors to potent HER2 blockade.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD1-2.

Abstract OT1-4-04: A phase II randomized, open-label, neoadjuvant study of LCL161, an oral antagonist of inhibitor of apoptosis proteins, in combination with paclitaxel in patients with triple-negative breast cancer

Background: Inhibitor of apoptosis proteins (IAPs) negatively regulate cell death through a variety of mechanisms. LCL161 is an oral small-molecule antagonist of IAPs that has demonstrated single-agent activity and synergy with paclitaxel in breast cancer tumor models. In preclinical studies, a gene expression signature has been shown to enrich for response to LCL161. The recommended dose of LCL161 1800 mg once weekly has demonstrated preliminary antitumor activity with paclitaxel in an ongoing Phase Ib study in patients with breast cancer.

Trial design: This is a Phase II, randomized, open-label study of neoadjuvant paclitaxel with or without LCL161 in women with operable, newly diagnosed triple-negative breast cancer (NCT01617668). Key inclusion criteria include women with histologically confirmed diagnosis of triple-negative breast cancer; clinical stages T2, N0–N2, M0; candidates for mastectomy or breast-conserving surgery; ECOG performance status ≤1; known status of the LCL161-predictive gene expression signature (positive and negative gene signature is a stratification factor); and adequate bone marrow and organ function. Key exclusion criteria are: bilateral or inflammatory breast cancer; locally recurrent breast cancer; patients currently receiving systemic therapy for any other malignancy, or having received systemic therapy for a malignancy in the preceding 3 months; impaired gastrointestinal function that may affect the absorption of LCL161; or uncontrolled cardiac disease.

Patients are randomized 1:1 to receive paclitaxel IV (80 mg/m2 weekly) with or without oral LCL161 (1800 mg once weekly) for 12 weeks (corresponding to 4 treatment cycles). Each treatment arm is stratified 1:1 based on gene expression signature status (positive or negative).

Endpoints: The primary endpoint is pathologic complete response (pCR), defined as the absence of invasive disease in the breast after 12 weeks of therapy, analyzed separately in the gene expression signature positive and negative groups. The key secondary endpoint is the pCR rate following treatment with LCL161 and paclitaxel in gene expression signature-positive or -negative tumors. Other secondary endpoints include: pCR rate in breast after 12 weeks of therapy in the full study population, and in patients with gene expression signature-positive and -negative tumors treated with paclitaxel alone; pCR rate in breast, regional nodes and axilla; biomarker evaluation including caspase 3 activation in tumor; safety; and pharmacokinetics of LCL161.

Statistical methods: pCR analysis will be performed according to treatment group and gene expression signature status. An absolute increase of at least 7.5% in pCR rate of the experimental arm over the control arm will be considered as evidence of clinically relevant efficacy.

Target accrual: Approximately 200 patients will be randomized into this study. Recruitment is ongoing across America, Europe, and Asia.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT1-4-04.

Abstract OT2-6-14: Phase 2, single arm study of a steroid-based mouthwash to prevent stomatitis in women with hormone receptor–positive advanced breast cancer treated with everolimus plus exemestane

BACKGROUND: Stomatitis, the inflammation of mucous membranes lining the mouth and throat, is a frequent adverse event that is associated with the oral mTOR inhibitor everolimus and can significantly impact treatment adherence. Specific strategies to prevent and/or lessen the severity of everolimus-associated stomatitis are not well documented. Steroid mouthwashes and steroid gels or pastes used to treat recurrent aphthous stomatitis may be effective for stomatitis associated with everolimus. This phase 2, single-arm study will evaluate a steroid-based therapeutic intervention to prevent stomatitis (Grade ≥2) in breast cancer patients taking everolimus + exemestane.

METHODS: Eligible participants will be patients with HR-positive, HER2-negative advanced breast cancer with no evidence of oral stomatitis or other oral pathology who have been prescribed everolimus + exemestane but have not yet started treatment. A baseline oral assessment will be conducted, and patients will be provided instructions on how to self-monitor for stomatitis, along with instructions to contact the study site at the first sign of oral pain or changes to the oral mucosa. All patients will be instructed to perform routine good oral care. Eligible patients will receive a steroid-based mouthwash (alcohol-free 0.5mg/5ml dexamethasone solution) prophylactically. Patients will be instructed to perform the mouthwash regimen four times per day and swish the mouthwash in mouth for a minimum of 120 seconds before spitting it out. Patients will be instructed to abstain from eating or drinking for at least an hour after taking the mouthwash. Mouthwash regimen will begin on the first day of everolimus after administration of the dose and patients will continue the regimen for the first 4 months of everolimus therapy.

Primary endpoint is the incidence of stomatitis (Grade ≥2) at 2 months defined as meeting at least one of the following criteria: ≤50 on Normalcy of Diet Scale to assess oral intake and a rating of 7 on two consecutive days or a rating of 8, 9 or 10 on any one day using Visual Analog Scale to assess oral pain. Evidence of stomatitis must be confirmed by investigator on physical exam and/or phone call assessment. Secondary endpoints include average number of times per day the mouthwash regimen was performed and time to resolution of stomatitis (Grade ≥2) that occurs during the trial. Assuming a 13% absolute reduction in the rate of grade ≥ stomatitis from the historical control rate of 33% and one sided Type 1 error = 0.05 and power = 80%,73 evaluable patients will be needed. To account for 25% of the total patient population being non-evaluable, 97 patients will be enrolled for this study.

Supported by funding from Novartis Pharmaceuticals Corporation.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT2-6-14.

Anti-androgens act jointly in suppressing spiggin concentrations in androgen-primed female three-spined sticklebacks - prediction of combined effects by concentration addition

Increasing attention is being directed at the role played by anti-androgenic chemicals in endocrine disruption of wildlife within the aquatic environment. The co-occurrence of multiple contaminants with anti-androgenic activity highlights a need for the predictive assessment of combined effects, but information about anti-androgen mixture effects on wildlife is lacking. This study evaluated the suitability of the androgenised female stickleback screen (AFSS), in which inhibition of androgen-induced spiggin production provides a quantitative assessment of anti-androgenic activity, for predicting the effect of a four component mixture of anti-androgens. The anti-androgenic activity of four known anti-androgens (vinclozolin, fenitrothion, flutamide, linuron) was evaluated from individual concentration-response data and used to design a mixture containing each chemical at equipotent concentrations. Across a 100-fold concentration range, a concentration addition approach was used to predict the response of fish to the mixture. Two studies were conducted independently at each of two laboratories. By using a novel method to adjust for differences between nominal and measured concentrations, good agreement was obtained between the actual outcome of the mixture exposure and the predicted outcome. This demonstrated for the first time that androgen receptor antagonists act in concert in an additive fashion in fish and that existing mixture methodology is effective in predicting the outcome, based on concentration-response data for individual chemicals. The sensitivity range of the AFSS assay lies within the range of anti-androgenicity reported in rivers across many locations internationally. The approach taken in our study lays the foundations for understanding how androgen receptor antagonists work together in fish and is essential in informing risk assessment methods for complex anti-androgenic mixtures in the aquatic environment.

An insight into the reproductive biology of the bearded goby Sufflogobius bibarbatus

Preliminary results obtained from histological analyses of the male reproductive organs, supplemented with field and behavioural data, indicate that Sufflogobius bibarbatus, a small, slow growing gobiid exhibiting low fecundity, which plays an important role in the food web off Namibia, where large areas of the shelf are hypoxic, spawns demersally. Large males defend benthic nests, possibly at the edge of the hypoxic shelf. Male reproductive strategy appears to be flexible, and tentative evidence to suggest that polygyny and sneaking may also occur is presented.

Triploidy alters brain morphology in pre-smolt Atlantic salmon Salmo salar: possible implications for behaviour

Total brain mass and the volumes of five specific brain regions in diploid and triploid Atlantic salmon Salmo salar pre-smolts were measured using digital images. There were no significant differences (P > 0·05) in total brain mass when corrected for fork length, or the volumes of the optic tecta or hypothalamus when corrected for brain mass, between diploids and triploids. There was a significant effect (P < 0·01) of ploidy on the volume of the olfactory bulb, with it being 9·0% larger in diploids compared with triploids. The cerebellum and telencephalon, however, were significantly larger, 17 and 8% respectively, in triploids compared with diploids. Sex had no significant effect (P > 0·05) on total brain mass or the volumes of any measured brain region. As the olfactory bulbs, cerebellum and telencephalon are implicated in a number of functions, including foraging ability, aggression and spatial cognition, these results may explain some of the behavioural differences previously reported between diploids and triploids.

P1-17-02: A Phase 1/2 Study of SAR245408 (S08) in Combination with Trastuzumab (T) or Paclitaxel (P) and T in Patients with HER2+ Metastatic Breast Cancer (MBC) Who Progressed on a Previous T-Based Regimen

BACKGROUND: Most HER2+ MBC patients (pts) treated with a combination of T+P progress within 1 year. Activation of downstream pathways through either deficiency in PTEN or mutations in the PI3K pathway has been implicated in the development of resistance to T. S08 is a potent, orally bioavailable, pan-PI3K inhibitor that inhibits phosphorylation of multiple downstream components of the PI3K/PTEN signaling pathway and has demonstrated activity as a single agent and in combination with other anticancer agents (Edelman G, et al., ASCO 2010; Traynor AM, et al. ASCO 2010).

PATIENTS and METHODS: This ongoing, open-label multicenter phase 1/2 study (NCT01042925) was designed to assess safety and tolerability of S08 in combination with either T or T+P. Eligible female pts were ≥18 yrs, ECOG PS 0–2, with adequate organ and marrow function and had advanced or recurrent HER2+ MBC disease refractory to T. Pts have received, and progressed on at least 1 prior T-containing regimen for metastatic disease. Pts were allocated to Arm 1 or Arm 2 and received different dose levels of S08 (starting dose 200 mg PO, daily) in combination with either T 8/6 mg/kg IV on Day (D) 1 q3w (Arm 1) or T 8/6 mg/kg IV on D1 + P 80 mg/m2 on D 1, 8, and 15 q3w (Arm 2). In phase 1, a standard ascending 3 + 3 dose escalation design was used in each arm to evaluate safety/tolerability of the combinations. Following establishment of preliminary maximal tolerated doses (MTDs) for each combination, subsequent pts will be accrued to the phase 2 portion. Approximately 25 additional pts will be enrolled in each arm to further evaluate the safety and estimate the overall response rate (ORR) in each arm.

RESULTS: As of June 1st 2011, 33 pts median age 55 yrs were enrolled; 18 to Arm 1 and 15 to Arm 2. Based on preliminary data of the study, in Arm 1, the most common treatment emergent adverse events (TEAEs) regardless of relationship include rash, diarrhea, fatigue, nausea, vomiting; in Arm 2 were neutropenia, diarrhea, fatigue, nausea, hyporexia, hypokalemia, peripheral neuropathy, rash and hyperglycemia. SAEs reported in Arm 1 (3 subjects) included Gr3 dehydration (2 cases), Gr3 epigastric pain and Gr2 dyspnea; those SAEs in Arm 2 (4 subjects) included Gr4 neutropenia, Gr3 anorexia, Gr3 dehydration, Gr3 epigastric pain, Gr3 thromboembolism, Gr2 nausea, Gr2 pneumonitis and Gr2 headache. A total of 4 DLTs were reported; 2 in Arm 1 [Gr3 skin rash (S08; 400 mg dose)] and 2 in Arm 2 [Gr4 neutropenia (S08; 200mg dose)] (table 1). With phase I nearly complete, the MTD for arm 1 is S08 300 mg PO daily and T 8/6 mg/kg D1 q3w. The data for Arm 2 (current dose level ongoing at the maximum allowed per protocol) will be completed in August 2011. Preliminary PK data did not show interactions between S08 and either T or T+P.

A Phase Ib Trial of Erlotinib, an EGFR Inhibitor, and Everolimus (RAD001), an mTOR Inhibitor, in Patients with Metastatic Breast Cancer

Background: The EGFR and the PI3K pathways have been implicated in breast cancer's prognosis and mechanisms of resistance to conventional therapies. Preclinical data have shown synergy between EGFR and PI3K/Akt pathway blockade. Therefore, we conducted a phase Ib trial to determine the maximum tolerated dose (MTD) and antitumor activity of Erlotinib, an oral EGFR tyrosine kinase inhibitor, and Everolimus (RAD001), an oral mTOR inhibitor, given daily to patients with metastatic breast cancer.Materials and Methods: This was an open-label, phase I dose-escalation study. Everolimus was started at 2.5 mg/d and Erlotinib was started at 100 mg/d on a 28-day treatment cycle. Doses were escalated over 6 levels (Everolimus 2.5, 5 or 10 mg daily with Erlotinib 100 or 150 mg daily). Treatment was continued until consistent dose-limiting toxicity (DLT) was observed or until progression of disease. All toxicities were documented using the NCI CTC v.3. Disease assessment was done every 2 months after initiation of therapy.Results: A total of 14 patients were enrolled on the first 2 dose levels (Erlotinib 100 mg with Everolimus 2.5 mg [level I] and 5 mg [level II] daily). Eight patients were enrolled on level I and 6 patients were enrolled on level II. The median age of all patients enrolled was 55 years of age, and 92% of them had visceral disease. Half of the patients had ER+ disease, 35% had HER2 + disease, and 15% had triple-negative disease. The median number of previous chemotherapy regimens in the metastatic setting was 4. Two patients on the level II cohort discontinued trial due to grade 3 stomatitis prior to their first disease assessment. Of the remaining 13 patients, 11 progressed at the time of their first disease assessment, and 1 patient on the dose level I cohort had a partial response that lasted for 7 months. The most common toxicities were rash (16%), transaminase elevation (15%), stomatitis (13%), fatigue (7%) and diarrhea (5%). Grade 3 and 4 toxicities were overall uncommon (3.5%), and mostly consisted of stomatitis, transaminase elevation and rash. Stomatitis was the only DLT, and was seen at dose level II. The MTD was determined to be Erlotinib 100 mg and Everolimus 2.5 mg daily.Discussion: In patients with metastatic HER2-negative breast cancer the combination of Erlotinib and Everolimus was overall well tolerated, but clinically ineffective from a tumor activity point of view in this heavily pre-treated patient population. Stomatitis was one of the most common toxicities and also the DLT in the cohort treated with dose level II. In view of the plethora of novel active agents currently in clinical trials in breast cancer, we do not believe the above combination warrants further testing in this disease.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3094.

Effective atomic orbitals for fuzzy atoms

The method of extracting effective atomic orbitals and effective minimal basis sets from molecular wave function characterizing the state of an atom in a molecule is developed in the framework of the "fuzzy" atoms. In all cases studied, there were as many effective orbitals that have considerable occupation numbers as orbitals in the classical minimal basis. That is considered to be of high conceptual importance.