Factors Associated With Laboratory Test Negativity Following a Transition in Specimen Collection in Microbial Keratitis Cases

PURPOSE

Negative laboratory results make targeting microbial keratitis treatment difficult. We investigated factors associated with laboratory negativity in patients with microbial keratitis in the context of a transition to a new specimen collection method.

METHODS

Microbial keratitis patients with associated laboratory tests were identified in the electronic health record of a tertiary care facility from August 2012 to April 2022. Patient demographics and laboratory results were obtained. Random sampling of 50% of charts was performed to assess the impact of the ocular history and pretreatment measures. The relationship between probability of negative laboratory results with demographics, ocular history, pretreatment measures, and utilization of a new specimen collection method (i.e. ESwab) was evaluated by multivariable logistic regression.

RESULTS

Of 3395 microbial keratitis patients identified, 31% (n = 1051) had laboratory tests. Laboratory testing increased over time (slope = 2.5% per year, p < 0.001; 19.6% in 2013 to 42.2% in 2021). Laboratory negative rate increased over time (slope = 2.2% per year, p = 0.022; 48.5% in 2013 to 62.3% in 2021). Almost one-third of patients (31.2%, n = 164) were pretreated with steroids. Over two-thirds of patients were pretreated with antibiotics (69.5%, n = 367). 56.5% (n = 297) of patients were outside referrals. In multivariable regression, patients with corticosteroid pretreatment had lower odds of negative laboratory results (odds ratio [OR] = 0.49, p = 0.001). There were higher odds of negative laboratory results for every additional antibiotic prescribed to a patient prior to presentation (OR = 1.30, p = 0.006) and for specimens collected using ESwabs (OR = 1.69, p = 0.005). Age, prior eye trauma, outside referrals, and contact lens wear were not significantly associated with negative laboratory results.

CONCLUSION

More microbial keratitis associated laboratory tests are being taken over time. Over 60% of tests were negative by 2022. Factors associated with negative laboratory test results included pretreatment with antibiotics and specimens collected with the new collection method.

Corneal Specialists' Confidence in Identifying Causal Organisms of Microbial Keratitis

PURPOSE

Microbial keratitis (MK) is a potentially blinding corneal disease caused by an array of microbial etiologies. However, the lack of early organism identification is a barrier to optimal care. We investigated clinician confidence in their diagnosis of organism type on initial presentation and the relationship between confidence and presenting features.

METHODS

This research presents secondary data analysis of 72 patients from the Automated Quantitative Ulcer Analysis (AQUA) study. Cornea specialists reported their confidence in organism identification. Presenting sample characteristics were recorded including patient demographics, health history, infection morphology, symptoms, and circumstances of infection. The association between confidence and presenting characteristics was investigated with 2-sample t-tests, Wilcoxon tests, and Chi-square or Fisher's exact tests.

RESULTS

Clinicians reported being "confident or very confident" in their diagnosis of the causal organism in MK infections for 39 patients (54%) and "not confident" for 33 patients (46%). Confidence was not significantly associated with patient demographics, morphologic features, or symptoms related to MK. MK cases where clinicians reported they were confident, versus not confident in their diagnosis, showed significantly smaller percentages of previous corneal disease (0% versus 15%, p = 0.017), were not seen by an outside provider first (69% versus 94%, p = 0.015), or had no prior labs drawn (8% versus 33%, p = 0.046), and a significantly larger percentage of cases wore contact lenses (54% versus 28%, p = 0.029).

CONCLUSION

In almost half of MK cases, cornea specialists reported lack of confidence in identifying the infection type. Confidence was related to ocular history and circumstances of infection but not by observable signs and symptoms or patient demographics. Tools are needed to assist clinicians with early diagnosis of MK infection type to expedite care and healing.

A Comparison of Culture Results and Visual Acuity in Contact Lens Related Microbial Keratitis

PURPOSE

Evaluate the effect of corneal and contact lens-related (CLR) culture results on visual acuity (VA) in patients with microbial keratitis (MK).

METHODS

MK patients with corneal and CLR cultures were identified in the University of Michigan electronic health record from August 2012 to April 2022. Test results were classified as laboratory-positive or laboratory-negative. Linear regression was used to examine trends of VA and associations between changes in VA (differences of VA at 90-day and baseline VA) and corneal and CLR culture results, after adjustment for baseline VA. One-sample t-tests were used to test if the slope estimates were different from zero.

RESULTS

MK patients (n = 50) were on average 49 years old (standard deviation = 20.9), 56% female, and 90% White. Positive corneal and CLR cultures were reported in 60% and 64% of patients, respectively, and 38% reported both. The agreement rate between corneal and CLR culture results was 30% (n = 15/50). LogMAR VA improved over time in patients with positive corneal and CLR cultures (Estimate=-0.19 per 10-day increase, p = 0.002), and in those with negative corneal and positive CLR cultures (Estimate= -0.17 per 10-day increase, p = 0.004). Compared to patients with negative corneal and CLR cultures, there was a trend toward improvement in VA for patients with positive corneal and CLR cultures (Estimate=-0.68, p = 0.068), and those with negative corneal and positive CLR cultures (Estimate= -0.74, p = 0.059), after adjusting for baseline VA.

CONCLUSIONS

Positive CLR cultures are associated with significant improvement in VA over time. These additional cultures can provide guidance on appropriate antimicrobial selection, especially when corneal cultures are negative.

Circulating tumor DNA association with residual cancer burden after neoadjuvant chemotherapy in triple-negative breast cancer in TBCRC 030

BACKGROUND

We aimed to examine circulating tumor DNA (ctDNA) and its association with residual cancer burden (RCB) using an ultrasensitive assay in patients with triple-negative breast cancer (TNBC) receiving neoadjuvant chemotherapy.

PATIENTS AND METHODS

We identified responders (RCB 0/1) and matched non-responders (RCB 2/3) from the phase II TBCRC 030 prospective study of neoadjuvant paclitaxel versus cisplatin in TNBC. We collected plasma samples at baseline, 3 weeks and 12 weeks (end of therapy). We created personalized ctDNA assays utilizing MAESTRO mutation enrichment sequencing. We explored associations between ctDNA and RCB status and disease recurrence.

RESULTS

Of 139 patients, 68 had complete samples and no additional neoadjuvant chemotherapy. Twenty-two were responders and 19 of those had sufficient tissue for whole-genome sequencing. We identified an additional 19 non-responders for a matched case-control analysis of 38 patients using a MAESTRO ctDNA assay tracking 319-1000 variants (median 1000 variants) to 114 plasma samples from 3 timepoints. Overall, ctDNA positivity was 100% at baseline, 79% at week 3 and 55% at week 12. Median tumor fraction (TFx) was 3.7 × 10-4 (range 7.9 × 10-7-4.9 × 10-1). TFx decreased 285-fold from baseline to week 3 in responders and 24-fold in non-responders. Week 12 ctDNA clearance correlated with RCB: clearance was observed in 10 of 11 patients with RCB 0, 3 of 8 with RCB 1, 4 of 15 with RCB 2 and 0 of 4 with RCB 3. Among six patients with known recurrence, five had persistent ctDNA at week 12.

CONCLUSIONS

Neoadjuvant chemotherapy for TNBC reduced ctDNA TFx by 285-fold in responders and 24-fold in non-responders. In 58% (22/38) of patients, ctDNA TFx dropped below the detection level of a commercially available test, emphasizing the need for sensitive tests. Additional studies will determine whether ctDNA-guided approaches can improve outcomes.

A Consortium for Analytic Standardization in Immunohistochemistry

CONTEXT.—

The authors announce the launch of the Consortium for Analytic Standardization in Immunohistochemistry, funded with a grant from the National Cancer Institute. As with other laboratory testing, analytic standards are important for many different stakeholders: commercial vendors of instruments and reagents, biopharmaceutical firms, pathologists, scientists, clinical laboratories, external quality assurance organizations, and regulatory bodies. Analytic standards are customarily central to assay development, validation, and method transfer into routine assays, and are critical quality assurance tools.

OBJECTIVE.—

To improve immunohistochemistry (IHC) test accuracy and reproducibility by integrating analytic standards into routine practice. To accomplish this mission, the consortium has 2 mandates: (1) to experimentally determine analytic sensitivity thresholds (lower and upper limits of detection) for selected IHC assays, and (2) to inform IHC stakeholders of what analytic standards are, why they are important, and how and for what purpose they are used. The consortium will then publish the data and offer analytic sensitivity recommendations where appropriate. These mandates will be conducted in collaboration and coordination with clinical laboratories, external quality assurance programs, and pathology organizations.

DATA SOURCES.—

Literature review and published external quality assurance data.

CONCLUSIONS.—

Integration of analytic standards is expected to (1) harmonize and standardize IHC assays; (2) improve IHC test accuracy and reproducibility, both within and between laboratories; and (3) dramatically simplify and improve methodology transfer for new IHC protocols from published literature or clinical trials to clinical IHC laboratories.

Ocular examinations, findings, and toxicity in children taking vigabatrin

BACKGROUND

The antiepileptic medication vigabatrin has been associated with ocular toxicity, and close ophthalmic monitoring has been recommended; however, there is no clear consensus regarding the value and feasibility of such monitoring in children. We describe ophthalmic assessments in children in a real-world clinical setting, the incidence of vigabatrin-related ocular toxicity, and the utility of regular screening or ancillary testing in children taking vigabatrin.

METHODS

The medical records of children taking vigabatrin with one or more ophthalmic assessments at Children's Hospital of Philadelphia or University of California, San Francisco, between May 2010 and May 2021, were reviewed retrospectively. Abnormalities on ophthalmic examination, visual field (VF), electroretinogram (ERG), and optical coherence tomography (OCT) were reviewed and categorized as attributable to vigabatrin, possibly attributable to vigabatrin, or not attributable to vigabatrin.

RESULTS

A total of 1,281 assessments of 284 children (mean age, 2.09 years) were included. Of these, 283 (99.6%) had funduscopic examination(s), 37 (13.0%) had ERG, 19 (6.7%) had OCT, and 6 (2.1%) had formal VF. Rate of examinations and ERGs per child decreased over the 10-year study period. Two children (0.7%) had definite vigabatrin-related ocular toxicity, both identified on ERG. An additional 4 children (1.4%) had optic atrophy of unclear relation to vigabatrin, categorized as possible toxicity. The remaining 278 children did not have abnormal examination or testing findings attributable to vigabatrin.

CONCLUSIONS

The incidence of vigabatrin-related ocular toxicity in children was low in our cohort. Ocular and neurologic comorbidities and limited examinations in children make identification of such toxicity challenging and the value of screening is unclear.

Inflammatory breast cancer defined: proposed common diagnostic criteria to guide treatment and research

Purpose

Inflammatory breast cancer is a deadly and aggressive type of breast cancer. A key challenge relates to the need for a more detailed, formal, objective definition of IBC, the lack of which compromises clinical care, hampers the conduct of clinical trials, and hinders the search for IBC-specific biomarkers and treatments because of the heterogeneity of patients considered to have IBC.

Methods

Susan G. Komen, the Inflammatory Breast Cancer Research Foundation, and the Milburn Foundation convened patient advocates, clinicians, and researchers to review the state of IBC and to propose initiatives to advance the field. After literature review of the defining clinical, pathologic, and imaging characteristics of IBC, the experts developed a novel quantitative scoring system for diagnosis.

Results

The experts identified through consensus several “defining characteristics” of IBC, including factors related to timing of onset and specific symptoms. These reflect common pathophysiologic changes, sometimes detectable on biopsy in the form of dermal lymphovascular tumor emboli and often reflected in imaging findings. Based on the importance and extent of these characteristics, the experts developed a scoring scale that yields a continuous score from 0 to 48 and proposed cut-points for categorization that can be tested in subsequent validation studies.

Conclusion

To move beyond subjective ‘clinical diagnosis’ of IBC, we propose a quantitative scoring system to define IBC, based on clinical, pathologic, and imaging features. This system is intended to predict outcome and biology, guide treatment decisions and inclusion in clinical trials, and increase diagnostic accuracy to aid basic research; future validation studies are necessary to evaluate its performance.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-021-06434-x.

Abstract GS6-05: The impact of breast cancer surgery on quality of life: Long term results from E5103

Background: Breast cancer (BC) treatment, including surgery, can impact not only short-term health outcomes but may also affect longer term health-related and psychosocial quality of life (QOL). We sought to describe the impact of BC surgery on QOL among breast cancer survivors followed in a large randomized trial.

Methods: The ECOG-ACRIN protocol E5103 was a phase III trial that randomized BC patients (pts) who had undergone definitive BC surgery to receive adjuvant doxorubicin, cyclophosphamide, and paclitaxel with either bevacizumab (bev) or placebo. Telephone based surveys were administered to all pts enrolled between 01/Jan/10 and 08/Jun/10 as part of a Decision-Making/QOL component until 18 mos post enrollment. Functional/psychosocial QOL domains were assessed by the EQ-5D-3L and the FACT B+G. Fisher's exact test compared categorical and Wilcoxon rank sum test compared continuous variables between subgroups. Multivariable regression was used to evaluate factors in addition to primary surgery at enrollment (age, race, ER/PgR status, tumor size, nodal status) associated with overall FACT score at 18 mos.

Results: Patient reported outcomes at 18 mos were available from 89.6% (465/519) pts. At enrollment, 57% (266/465) had a mastectomy; 43% (199/465) breast conserving surgery (BCS). Median age at enrollment was 52 (range: 25-76) years. There were no differences in QOL between bev vs placebo treatment arms (EQ-5D-3L Index Score p=0.65; FACT B+G Score p=0.23) at 18 mos so groups were combined. Using EQ-5D-3L, over half of the pts (58%) reported at least some pain/discomfort; 38% symptoms of anxiety/depression. A higher proportion of mastectomy pts reported problems with usual activities compared to BCS pts (Table). Compared to BCS pts, mastectomy pts had lower average EQ5D-3L scores 0.80 vs. 0.84, p=0.04 and FACT B+G scores 109 vs. 114, p=0.01, indicating worse QOL. In univariate analyses, non-white race (p=0.03), ER/PgR+ status (p=0.04) and mastectomy as primary surgery (p=0.01) were significantly associated with worse QOL (lower FACT B+G scores). In multivariable analyses, non-white race (p=0.02) and ER/PgR+ status (p=0.05) remained associated with worse QOL; mastectomy was borderline significant (p=0.06).

Conclusions: Among women participating in a contemporary adjuvant BC chemotherapy trial, a substantial proportion of survivors experience symptoms that may be amenable to intervention, including referral to physical rehabilitation, especially among pts undergoing more extensive surgery. Attention to psychosocial health is also essential both during and after completion of active treatment to optimize QOL outcomes.

 N(%) reporting problems*  5 DimensionsBCSMastectomyOverallp**Mobility44(23)59(23)103(23)1.00Self-care11(6)23(9)34(7)0.21Usual activities49(25)90(34)139(30)0.04Pain/discomfort104(53)161(61)265(58)0.08Anxiety/depression70(36)105(40)175(38)0.44*3L: 3 possible answers: 1) no problems 2) some/moderate problems 3) problems; responses then collapsed into no problems vs. any problems' (=some/moderate problems and problems). ** Fisher's exact test p-value.

Citation Format: Rosenberg SM, O'Neill A, Sepucha K, Miller KD, Dang CT, Northfelt DW, Sledge GW, Schneider BP, Partridge AH. The impact of breast cancer surgery on quality of life: Long term results from E5103 [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 GS6-05.

Abstract OT3-06-02: An initial safety study of gedatolisib plus PTK7-ADC for metastatic triple-negative breast cancer

Background: The PI3K pathway is dysregulated in the majority of triple-negative breast cancer (TNBCs). Contrary to the theory of oncogene addiction, single agent inhibition of the PI3K pathway in TNBC has had only modest activity. Our group has demonstrated preclinically that when PI3K is inhibited, an immediate compensatory up-regulation of the Wnt pathway occurs. The Wnt pathway is known known for its role in cancer metastases and can confer resistance to initial PI3K inhibition. Simultaneous dual targeting of both pathways is highly synergistic against TNBC models in vitro and in vivo.

We have initiated a Phase I clinical trial using Gedatolisib (PI3K/mTOR inhibitor) and PTK7-ADC (Wnt pathway) for patients with metastatic TNBC (NCT03243331). Gedatolisib is a pan-class I isoform PI3K/mTOR inhibitor, and PTK7-ADC is an antibody-drug conjugate against the cell-surface PTK7 protein (Wnt pathway co-receptor) with an Auristatin payload. PTK7 is an attractive second target due to its up-regulation after PI3K inhibition and its known overexpression in TNBC. Further data has shown that the PTK7-payload, Auristatin, is in itself synergistic with Gedatolisib. The combination of using both of these drugs suggests a unique concept of “double synergy”. Where Gedatolisib increases the expression of the target of PTK7-ADC leading to one mechanism of synergy, and the Auristatin payload on PTK7-ADC is synergistic with Gedatolisib providing a second mechanism.

Study Design: This is an open-label, Phase I, dose-escalation study with a 3 + 3 cohort design. The trial will enroll 12-18 patients. 3 cohorts of at least 3 patients will receive Gedatolisib (weekly) & PTK-ADC (q3w) at 110mg+1.4mg/kg, 180mg+1.4mg/kg, and 180mg+2.8mg/kg dose levels.

Eligibility Criteria: This trial enrolls patients with metastatic triple negative (ER-, PgR-, HER2-) or low estrogen expressing (ER and PgR &lt;5%, HER2-) breast cancer. Patients must have received at least one prior chemotherapy for advanced disease and have adequate hematologic, renal, and hepatic function. Patients with previously treated CNS involvement are eligible. Patients with uncontrolled diabetes are excluded, given the potential for hyperglycemia with Gedatolisib. Patients must have disease amenable and consent to biopsy for correlative endpoints.

Objectives: The primary objective is to evaluate the safety of Gedatolisib plus PTK7-ADC. The secondary objective is to evaluate efficacy as determined by objective response rate, clinical benefit at 18 weeks, and progression free survival (PFS). Exploratory objectives will evaluate efficacy in patients with genomic aberrations in the PI3K pathway; and association of tumor DNA, RNA, plasma and circulating tumor cell sequencing with clinical efficacy to identify putative biomarkers.

Correlative Sciences: We are collecting matched pre-/post-treatment tumor biopsies and serial blood samples to determine biomarkers of clinical response to inform subsequent trials. We plan to evaluate: 1) PI3K activity; 2) genomic aberrations in the PI3K pathway; 3) baseline PTK7 expression; 4) PTK7 upregulation after Gedatolisib treatment; and 5) mutations in plasma circulating tumor DNA.

Supported by the BCRF, 100 Voices of Hope, Catherine Peachey Foundation, and Pfizer.

Citation Format: Radovich M, Solzak JP, Hancock BA, Storniolo AMV, Schneider BP, Miller KD. An initial safety study of gedatolisib plus PTK7-ADC for metastatic triple-negative 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 OT3-06-02.

Abstract P5-16-02: Variance between experts and community practitioners in treatment of metastatic breast cancer

Background

New treatment options continue to improve outcomes for patients with metastatic breast cancer (MBC). However, clinicians' lack of clinical experience using new agents, a complex treatment landscape, and the broad treatment recommendations in available guidelines can make the choice of an optimal treatment for individual patients with MBC challenging. An online treatment decision support tool was developed to overcome these challenges and provide recommendations from multiple experts for specific MBC patient scenarios. Here we report data comparing expert treatment recommendations with the intended treatment indicated by clinicians using the tool.

Methods

In October 2016, 5 breast cancer experts provided treatment consultation for 492 unique MBC case scenarios based on a simplified set of variables: disease phenotype, previous systemic therapy, visceral crisis (yes/no), and rate of disease progression. These patient and disease characteristics along with expert treatment consultation were used to develop the treatment decision tool. Clinicians used drop-down menus to enter patient and disease factors along with their intended treatment plan. When completed, the experts' treatment recommendations for that specific patient case were shown to the clinicians, at which point the users were asked to indicate if the expert recommendations changed their planned treatment.

Results

From December 2016 through April 2017, 619 healthcare providers entered 1018 patient case scenarios in the online MBC tool representing the following phenotypes: HR+/HER2- (53%), HR-/HER2+ (10%), HR+/HER2+ (14%), and triple-negative breast cancer (23%). A comparison of expert and community oncologist treatment choices in select patient case scenarios with expert consensus is shown in the table. Among participating oncologists whose initial intended treatment of MBC differed from the experts, 51% indicated that they would change their choice of therapy.

Conclusions

MBC therapy continues to evolve with new agents having a large impact on how experts treat MBC. Data from the online MBC treatment decision support tool indicate variance in expert and oncologist treatment choices for many case scenarios. Moreover, consensus expert recommendations in this online tool changed the intended treatment plan of many using it and, therefore, can help optimize the care of patients with MBC. A detailed analysis of self-identified practice trends among those using the online tool, along with a comparison of expert and participating oncologist treatment choices for different MBC case scenarios, will be presented.

MBC Case ScenarioMajority Consensus Recommendation Among Experts, %Tool Cases Where Oncologist Intended Treatment Matched the Expert Consensus Recommendation, %HR+/HER2- (no visceral crisis)•De novoPalbociclib + letrozole: 10023•Previous (neo)adjuvant AIPalbociclib + fulvestrant: 9219•Previous palbociclib + letrozoleFulvestrant: 820•Previous palbociclib + fulvestrantEverolimus + exemestane: 8750HR-/HER2+•De novoTHP: 10068•Previous pertuzumabT-DM1: 10066Triple-negative breast cancer•Visceral crisisCombination CT: 9139•No visceral crisis, fast progressionSingle-agent CT: 7250AI, aromatase inhibitor; CT, chemotherapy.

Citation Format: Quill TA, Blackwell KL, Hurvitz S, Miller KD, Robert N, Obholz KL, Jahanzeb M. Variance between experts and community practitioners in treatment of 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 P5-16-02.

Abstract PD3-16: Clinical safety and efficacy of the aurora and angiogenic kinase inhibitor ENMD-2076 in previously treated, locally advanced or metastatic triple-negative breast cancer

Background: Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype defined by the lack of expression of the estrogen and progesterone receptors and lack of HER2 over-expression. ENMD-2076 is an orally bioavailable small molecule inhibitor of Aurora and angiogenic kinases with pro-apoptotic and antiproliferative activity in preclinical models of TNBC.

Methods: This two institution, single-arm, two-stage, phase II clinical trial enrolled patients with locally advanced or metastatic TNBC refractory to 1-3 prior lines of chemotherapy in the advanced setting. Patients had ECOG PS ≤ 1, measureable disease by RECIST 1.1 and no evidence of brain metastasis. Patients were treated with ENMD-2076 250 mg PO daily with continuous dosing in 4-week cycles until disease progression or unacceptable toxicity occurred. The primary end point was 6-month clinical benefit rate (6-CBR) and secondary endpoints included time to progression (TTP), PK profile, safety and biologic correlatives in archival and fresh serial tumor biopsies in a subset of patients.

Results: Between July 2012 and October 2016, 41 patients were enrolled (median age 54; range 30-73; female 40; male 1). Patients received a mean 1.7 prior lines of chemotherapy for locally advanced unresectable or metastatic disease and 80.5% received prior neoadjuvant or adjuvant chemotherapy (N=33). Thirty-six patients were evaluable per protocol for the primary efficacy analysis. Five patients (12.2%) were not included in the efficacy analysis due to: adverse events (AE) leading to discontinuation prior to objective efficacy assessment (N=3), not meeting eligibility criteria on day 1 (N=1) and withdraw of consent in cycle 1 (N=1). The study proceeded to the second stage of enrollment based on observing three 6-CBR events in Stage 1 (N=18 patients). The 6-CBR in the overall trial was 16.7% (95% exact CI: 6%-32.8%; 2 patients with PR and 4 patients with SD &gt; 6 mos). The median duration of response or clinical benefit in these patients was 32 weeks (8 cycles). 4-CBR was 27.8% (95% exact CI: 14%-45.2%). Dose reduction occurred in 8 patients (20%) for fatigue, hypertension and proteinuria. The most common grade 3 treatment-related adverse events were hypertension (37.5%) and fatigue (10%). One patient experienced grade 4 hypertension. Analysis of serial tumor biopsies prior to and following 2 weeks of ENMD-2076 (N=8 patients), demonstrated a treatment-induced decrease in cellular proliferation (Ki-67) and microvessel density (CD34) as assessed by IHC. Immunofluorescence performed on a subset of samples demonstrated an increase in p53-family member expression following treatment, consistent with changes observed in preclinical TNBC patient-derived tumor xenograft models.

Conclusions: ENMD-2076 has durable clinical activity in a subset of patients with pretreated, advanced or metastatic triple-negative breast cancer. Predictive biomarker development using archival and fresh tumor tissue is underway. Exploration of lower doses of ENMD-2076 in future clinical trials may improve tolerability.

Citation Format: Diamond JR, Eckhardt SG, Pitts TM, van Bokhoven A, Aisner D, Gustafson DL, Capasso A, Elias AD, Storniolo AM, Schneider BP, Gao D, Tentler JJ, Borges VF, Miller KD. Clinical safety and efficacy of the aurora and angiogenic kinase inhibitor ENMD-2076 in previously treated, locally advanced or metastatic triple-negative 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 PD3-16.

Abstract P2-07-04: Molecular regulators of resistance and relapse in chemorefractory triple-negative breast cancers

Triple-Negative Breast Cancer (TNBC) accounts for approximately one-fifth of breast cancer incidence but disproportionately high mortality. Two-thirds of early-stage TNBCs are resistant to pre-surgical chemotherapy and highly prone to relapse within 3 years. Morever, no advanced therapies are indicated for patients with these cancers. We have embarked on a comprehensive genomic analysis of chemoresistant TNBC to gain an in-depth understanding of molecular entities driving chemoresistance and relapse. By collecting somatic mutation and copy number, RNA-sequencing, and outcome data in the context of a phase II post-neoadjuvant clinical trial, we have uncovered several molecular mechanisms behind these aggressive cancers. Through the analysis of matched pairs sampled before and after chemotherapy, we have discovered multiple means by which tumors are able to overcome the effects of chemotherapy including clonal evolution of high-level oncogene amplification, repression of the in situ immune system, and upregulation of the stem cell-related MEK-ERK and JAK-STAT pathways. Investigation into factors related to prognosis revealed important correlations between relapse and immune and JAK-STAT signaling. Finally, using a novel method of demarcating loss-of-function of p53, which we have termed graduated inactivation, we discovered additional associations between p53 loss and relapse, mortality, and MYC signalling.

Citation Format: Hancock BA, Chen Y-H, Solzak JP, Ahmad MN, Wedge DC, Brinza D, Scafe C, Veitch J, Gottimukkala R, Short W, Atale RV, Ivan M, Badve SS, Schneider BP, Miller KD, Radovich M. Molecular regulators of resistance and relapse in chemorefractory triple-negative breast cancers [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 P2-07-04.

Abstract PD3-14: Phase 1 study of the antibody-drug conjugate SGN-LIV1A in patients with heavily pretreated triple-negative metastatic breast cancer

Background

LIV-1, a transmembrane protein and downstream target of STAT3, is highly expressed in breast cancer cells. It is associated with lymph node involvement and metastatic progression. SGN-LIV1A is an anti-LIV-1 antibody conjugated via a protease-cleavable linker to monomethyl auristatin E (MMAE). Upon binding to cell-surface LIV-1, SGN-LIV1A is internalized and releases MMAE, which disrupts microtubulin and induces apoptosis.

Methods

This ongoing, phase 1 study evaluates safety, tolerability, pharmacokinetics, and antitumor activity of SGN-LIV1A (q3wks IV) in women with LIV-1-positive, unresectable, locally advanced or metastatic breast cancer (LA/MBC) (NCT01969643). Patients (pts) with measurable disease and ≥2 prior cytotoxic regimens for LA/MBC are eligible. Pts with ≥ Grade 2 neuropathy are excluded. Response is assessed per RECIST v1.1; pts with stable disease (SD) or better can continue treatment until disease progression or intolerable toxicity. At completion of dose escalation in hormone receptor-positive/HER2-negative (HR+/HER2–) and triple-negative (TN) pts, expansion cohorts were opened to further evaluate safety and antitumor activity of monotherapy in TN pts. Tumor biopsies are evaluated for LIV-1 expression.

Results

To date, 69 pts (18 HR+/HER2–, 51 TN) have received a median of 3 cycles (range, 1–12) of SGN-LIV1A at doses of 0.5–2.8 mg/kg. Median age was 56 yrs. Pts had a median of 3 prior cytotoxic regimens for LA/MBC; 58 had visceral disease and 37 had bone metastases. No dose-limiting toxicities (DLTs) occurred in 19 DLT-evaluable pts; maximum tolerated dose was not exceeded at 2.8 mg/kg. Expansion cohorts of TN pts were opened at 2.0 and 2.5 mg/kg. Treatment-emergent adverse events (AEs) reported in ≥25% of pts were fatigue (59%), nausea (51%), peripheral neuropathy (44%), alopecia (36%), decreased appetite (33%), constipation (30%), abdominal pain, diarrhea, and neutropenia (25% each). Most AEs were Grade 1/2; AEs ≥ Grade 3 included neutropenia (25%) and anemia (15%). Febrile neutropenia occurred in 2 pts whose total dose exceeded 200 mg per cycle, including 1 treatment-related death due to sepsis. No other treatment-related deaths occurred on-study. Seven pts discontinued treatment due to AEs. In dose escalation, activity was observed in 17 efficacy evaluable (EE) HR+/HER2- pts, with a disease control rate (DCR= CR+PR+SD) of 59% (10 SD), including 1 pt with SD ≥24 wks. Among the 44 EE TN pts (dose escalation plus expansion cohorts), the objective response rate (ORR) was 32% (14 PR) with a confirmed PR rate of 21%, DCR was 64% (14 PR, 14 SD), and clinical benefit rate (CBR=CR+PR+SD ≥24 wks) was 36% (16 pts). For TN pts, median PFS was 11.3 wks (95% CI: 6.1, 17.1); 10 pts remain on treatment.

Of 631 MBC tumor samples of all clinical subtypes evaluated for LIV-1, 91% were positive; 75% had moderate-to-high expression (H-score ≥100).

Conclusions

LIV-1 is expressed in almost all MBC tumors. SGN-LIV1A monotherapy was generally well tolerated and showed encouraging antitumor activity in heavily pretreated TN MBC, with a PR rate of 32%, confirmed PR rate of 21%, and CBR (≥24 wks) of 36%. Response duration data continue to evolve. Enrollment continues in the TN monotherapy expansion cohort.

Citation Format: Modi S, Pusztai L, Forero A, Mita M, Miller KD, Weise A, Krop I, Burris III H, Kalinsky K, Tsai M, Liu MC, Hurvitz SA, Wilks S, Ademuyiwa F, Diab S, Han HS, Kato G, Nanda R, O'Shaughnessy J, Kostic A, Li M, Specht J. Phase 1 study of the antibody-drug conjugate SGN-LIV1A in patients with heavily pretreated triple-negative 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 PD3-14.

Abstract P6-07-08: Dual TGFβ/BMP inhibition allows in vitro expansion of multiple cell types from normal and cancerous breast

Functional modeling of breast epithelial hierarchy and stromal-epithelial cell interactions has been difficult due to inability to obtain sufficient stem-progenitor-mature epithelial cells and stromal cells. The recently developed epithelial reprogramming assay has partially overcome this limitation, allowing propagation of epithelial cells with stem, luminal progenitor and mature cell features. However, characterizing stromal cells using this assay is difficult because irradiated fibroblasts which can be difficult to distinguish from stromal cells are needed as feeder layer. A recent study demonstrated expansion of airway basal stem cells without a feeder layer through pharmacologic inhibition of TGFβ/BMP/SMAD signaling. We sought to develop this method for culture and expansion of cells from normal and cancerous breast samples. With appropriate modifications to growth media, we were able to obtain normal and stromal cells from breast biopsies of healthy women. The expanded cell population included CD10+/EpCAM- basal/myoepithelial cells, CD49f+/EpCAM+ luminal progenitor cells, CD49f-/EpCAM+ mature luminal cells, CD73+/EpCAM+/CD90- rare endogenous pluripotent somatic stem cells, CD73+/CD90+/EpCAM- mesenchymal stem cells, ALCAM (CD166)+/EpCAM+ cells, CD44+/CD24- cells, CD44+/CD24+ cells and ALDFLUOR+ stem/luminal progenitor cells. Epithelial cells were KRT14+, KRT19+ or both further documenting heterogeneity within epithelial cell population. We have extended this technique to grow breast epithelial cells from high-risk patients including BRCA1 mutant-carriers, tumor-adjacent normal and tumor cells from the same patient, pleural effusions and liver metastasis from breast cancer patients. Phenotypic characterization showed differences in the differentiation state of adjacent-normal and tumor cells. Tumor cells from pleural effusions showed remarkable phenotypic heterogeneity with a fraction of these cells expressing estrogen receptor. The assay described here, therefore, is versatile and provides resources to model epithelial-stromal interactions under normal and cancerous conditions as well as for genomics and screening of drugs to target metastasis on an individual level.

Susan G. Komen for the Cure and Department of Defense supported this work.

Citation Format: Nakshatri H, Ananappa M, Prasad MS, Kumar B, Liu Y, Storniolo AM, Miller KD, Bhat-Nakshatri P. Dual TGFβ/BMP inhibition allows in vitro expansion of multiple cell types from normal and cancerous breast [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 P6-07-08.

Abstract PD5-06: Adjuvant palbociclib plus endocrine therapy for hormone receptor positive/HER2 negative breast cancer: A phase II feasibility study

Background:

The CDK4/6 inhibitor palbociclib (P) combined with endocrine therapy (ET) prolongs progression-free survival in previously untreated and treated hormone receptor positive/HER2 negative (HR+/HER2-) metastatic breast cancer (MBC). The most common toxicity with P is neutropenia, typically non-cumulative and uncomplicated. Given observed benefits of P in metastatic BC, this single arm phase II trial was designed to determine the feasibility and toxicity of combination adjuvant P and ET for HR+/HER2- early BC (EBC).

Methods:

Eligible patients (pts) had HR+/HER2- stage II (not T2N0)-III EBC, with prior completion of 3-24 mo of ET (either AI or tamoxifen) without significant adverse events (AE). Pts received P at 125 mg daily, 3 wk on/1 wk off in a 28d cycle, plus continuous ET, for planned duration 2 yrs. Pts were removed from study for toxicity, non-adherence, or other events related to tolerability; pts who recurred or completed 2 yrs of therapy were censored for the primary endpoint. The primary objective was to evaluate the treatment discontinuation rate at 2 yrs; a rate of &gt;50%, would indicated a non-feasible treatment duration (null hypothesis). Discontinuation rates at 2 yrs are estimated by Kaplan Meier with 95% confidence bands. A sample size of 160 pts provided 92% power to reject the null hypothesis using a one-sided alpha = 0.025 if the true rate of discontinuation is &lt;33.3%, and accounting for a censoring rate of up to 20% over the 2 yrs. Secondary endpoints include toxicity, adherence, QOL, and pharmacogenomics.

Results:

Between 3/2014 and 11/2015, 162 pts initiated P; the majority had stage III EBC (52%) and received prior chemotherapy (63%). As of 05/2017, 120 (74%) have completed at least 1 yr of P + ET, and 50 (31%) have completed 2 yrs of P + ET. Early discontinuation of protocol treatment was reported for 59 pts (36%), including 49 events (30%) related to protocol-mandated (9%) and non-mandated (21%) tolerability. The cumulative rate of all discontinuations was 15.1% at 6 mos, 20.9% at 12 mos and 27.8% at 18 mos. Half of all non-mandated discontinuations occurred within the first 6 mos of initiation of therapy, and the rate decreased with greater provider and pt education. Median duration of pts still on treatment is 20 mos (inter-quartile range: 18 to 21 mos). The rate of grade 3/4 neutropenia was 77%, with 0 cases of febrile neutropenia. Other common all-grade P-related AE &gt; 20% included fatigue 65%, alopecia 25%, mucositis 24%, and anemia 24%. 32% of pts required one dose reduction, 16% required two. There have been 2 BC recurrence events and 1 chemotherapy-related AML. Updated data for the primary analysis of feasibility and tolerability, as well as pharmacogenomics, QOL, and adherence, will be presented.

Conclusions:

In this single arm phase II trial, the majority of pts have completed at least 1 year of adjuvant P + ET therapy, with no new toxicity signals. Non-protocol discontinuations have decreased with education. Updated results for the primary analysis will be presented. As in the MBC setting, extended duration palbociclib appears feasible and tolerable for most pts. The efficacy of 2 years of P and ET will be addressed by the phase III PALLAS trial (NCT NCT02513394).

Citation Format: Mayer EL, DeMichele AM, Guo H, Miller KD, Rugo HS, Schneider B, Waks AG, Come SE, Mulvey T, Huang Bartlett C, Koehler M, Barry W, Winer EP, Burstein HJ. Adjuvant palbociclib plus endocrine therapy for hormone receptor positive/HER2 negative breast cancer: A phase II feasibility study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD5-06.

A system for detecting high impact-low frequency mutations in primary tumors and metastases

Tumor complexity and intratumor heterogeneity contribute to subclonal diversity. Despite advances in next-generation sequencing (NGS) and bioinformatics, detecting rare mutations in primary tumors and metastases contributing to subclonal diversity is a challenge for precision genomics. Here, in order to identify rare mutations, we adapted a recently described epithelial reprograming assay for short-term propagation of epithelial cells from primary and metastatic tumors. Using this approach, we expanded minor clones and obtained epithelial cell-specific DNA/RNA for quantitative NGS analysis. Comparative Ampliseq Comprehensive Cancer Panel sequence analyses were performed on DNA from unprocessed breast tumor and tumor cells propagated from the same tumor. We identified previously uncharacterized mutations present only in the cultured tumor cells, a subset of which has been reported in brain metastatic but not primary breast tumors. In addition, whole-genome sequencing identified mutations enriched in liver metastases of various cancers, including Notch pathway mutations/chromosomal inversions in 5/5 liver metastases, irrespective of cancer types. Mutations/rearrangements in FHIT, involved in purine metabolism, were detected in 4/5 liver metastases, and the same four liver metastases shared mutations in 32 genes, including mutations of different HLA-DR family members affecting OX40 signaling pathway, which could impact the immune response to metastatic cells. Pathway analyses of all mutated genes in liver metastases showed aberrant tumor necrosis factor and transforming growth factor signaling in metastatic cells. Epigenetic regulators including KMT2C/MLL3 and ARID1B, which are mutated in >50% of hepatocellular carcinomas, were also mutated in liver metastases. Thus, irrespective of cancer types, organ-specific metastases may share common genomic aberrations. Since recent studies show independent evolution of primary tumors and metastases and in most cases mutation burden is higher in metastases than primary tumors, the method described here may allow early detection of subclonal somatic alterations associated with metastatic progression and potentially identify therapeutically actionable, metastasis-specific genomic aberrations.

Abstract OT3-04-01: BRE12-158: A phase II randomized controlled trial of genomically directed therapy after preoperative chemotherapy in patients with triple negative breast cancer (TNBC)

Background: About 1/3 of patients with TNBC who receive preoperative therapy will experience a pathological complete response (pCR). Patients with residual disease have a markedly inferior overall survival (OS) compared to those who experience pCR. Recently, the CREATE-X trial demonstrated an improvement in disease free survival (DFS) and OS for post-neoadjuvant capecitebine; although the addition of capecitebine to standard therapy has not previously improved outcome across other non-selected adjuvant or neo-adjuvant trials. Prior data have also demonstrated that the residual tumors are genomically diverse and that these genetic changes are reflected at time of relapse.

Trial Design: This trial is a randomized phase II trial to determine whether a genomically guided therapy in the setting of incomplete response to standard neoadjuvant therapy will improve outcomes compared to standard of care. DNA from archived tumor samples collected at the time of surgery will be extracted and sequenced. The sequencing data will be interrogated for known genomic drivers of sensitivity or resistance to existing FDA approved agents. A cancer genomic tumor board (CGTB) will consider the genomic data along with the patient's prior treatment history, toxicities, and comorbidities and select the optimal therapy. Participants with a CGTB recommendation will be randomized to Experimental Arm A (genomically directed monotherapy) or Control Arm B (standard of care). Participants may have no CGTB recommendation either because sequencing did not identify a matched drug or because the drug was contraindicated and will be assigned to Control Arm B.

Eligibility criteria: Patients must have histologically confirmed TNBC with completion of all definitive local therapy and no evidence of metastatic disease. There must be significant residual disease characterized by &gt;2cm primary tumor, or lymph node positivity or RCB classification II or III. An FFPE tumor block with tumor cellularity &gt;20% is required. All patients must have completed preoperative chemotherapy including a taxane or anthracycline or both.

Specific aims: The Primary Aim is to compare 2-year DFS with a genomically directed therapy vs. standard of care. Secondary Aims include 1-year DFS, 5-year OS, collection of archival specimens for correlative studies, and to describe toxicities. Exploratory Aims are to describe the evolution of genomically directed therapies during the course of the study and to evaluate the drug specific effect on efficacy and toxicity.

Statistical methods: In order to detect an improvement in the fraction of patients free from disease at 2-year from 40% in the control Arm B to 63.2% in the genomically directed Experimental Arm A (corresponding to an HR=0.5), 136 participants will have 80% power to detect a difference in DFS using a two-side log-rank test with 0.05 level of significance.

Present accrual/target accrual: 38 accrued of 136 to be randomized.

Citation Format: Schneider B, Miller KD, Badve S, O'Neil B, Helft P, Chitambar C, Falkson C, Nanda R, McCormick M, Danso M, Blaya M, Langdon R, Lippman M, Paplomata E, Walling R, Thompson M, Robin E, Aggarwal L, Shalaby I, Canfield V, Adesunloye B, Lee T, Daily K, Ma C, Erban J, Radhakrishnan N, Bruetman D, Graham M, Reddy NA, Lynce FC, Radovich M. BRE12-158: A phase II randomized controlled trial of genomically directed therapy after preoperative chemotherapy in patients with triple negative breast cancer (TNBC) [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 OT3-04-01.

Abstract OT2-01-17: A Phase II randomized trial of pembrolizumab with carboplatin and gemcitabine for treatment of patients with metastatic triple-negative breast cancer (mTNBC)

Background: Treatment for mTNBC is limited, and significant challenges persist in treating this disease, as outcomes remain largely dependent on chemotherapy without any effective targeted treatment. Pembrolizumab (MK-3475) is a highly selective, humanized monoclonal antibody against PD-1, blocking the negative immune regulatory signaling of the PD-1 receptor that is usually expressed by T-cells. Recent data showed that some patients with mTNBC may benefit from immune-based therapies (PD-1 or PD-L1 antibodies). Cumulative evidence suggest that stromal tumor infiltrating lymphocytes (sTILs) have a prognostic and predictive role in response to treatment in subsets of TNBC, particularly in response to carboplatin use. Preclinical data revealed that blocking PD-1/PD-L1 pathway in combination with platinum containing cytotoxic therapy improved response rates and survival. High levels of sTILs and an increased PD-L1 expression make mTNBC a candidate for PD-1–targeted therapy. As studies showed that the subset of TNBC with better response rates to carboplatin are heavily infiltrated with sTILs, pembrolizumab, becomes a very attractive drug to be tested in combination with carboplatin, with the goal of improving outcomes in mTNBC. A Phase II multicenter, randomized, trial has been initiated to evaluate the efficacy and safety of combining pembrolizumab with carboplatin and gemcitabine in patients with mTNBC.

Methods: A safety run-in will assess the safety and tolerability of combining pembrolizumab with carboplatin and gemcitabine in patients with mTNBC. Following the completion of the safety run-in, patients will be randomized 2:1 to receive pembrolizumab (200 mg IV) on day 1 along with carboplatin (AUC 2, day 1 and day 8, IV) plus gemcitabine (800 mg/m2, day 1 and day 8, IV) of a 21-day cycle, or carboplatin plus gemcitabine (same aforementioned dose) alone. Patients will have histologically documented unresectable mTNBC. Prior systemic therapy for mTNBC, for up to 2 lines is allowed, and patients will have ECOG PS 0–2 and measurable disease (RECIST v1.1). Prior carboplatin/gemcitabine or cisplatin therapy is allowed in the adjuvant or neoadjuvant setting, as long as it occurred more than 12 months from the beginning of their enrollment. Subjects whose tumors progressed while on treatment with carboplatin or cisplatin are excluded. Known CNS disease (except asymptomatic treated metastases), autoimmune disease or prior immune checkpoint blockade therapy is an exclusion to enrollment on this trial. Primary endpoint is assessing the objective response rate according to RECIST v1.1 . Other endpoints include clinical benefit rate (CBR), progression-free survival (PFS), overall survival (OS), duration of response (DOR), and safety. Tumor biopsies will be obtained at baseline and just prior to initiation of cycle 3 to assess biomarkers of response and immune escape. PD-L1 expression will be evaluated in exploratory analysis with a planned assessment of response based on PD-L1 status. This trial will enroll 6-12 patients in the safety run-in portion, and 75 patients in the randomized part, at 7 sites in the United States. Clinical trial information: NCT02755272 www.clinicaltrials.gov.

Citation Format: Obeid E, Miller KD, Sparano JA, Blackwell K, Goldstein LJ. A Phase II randomized trial of pembrolizumab with carboplatin and gemcitabine for treatment of patients with metastatic triple-negative breast cancer (mTNBC) [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 OT2-01-17.

Abstract P6-11-03: A phase 2 open-label study of lucitanib in patients (pts) with FGF aberrant metastatic breast cancer (MBC)

BACKGROUND: Lucitanib is a potent, oral antiangiogenic tyrosine kinase inhibitor of Vascular Endothelial Growth Factor Receptors 1-3 (VEGFR1-3), Platelet-Derived Growth Factor Receptors alpha and beta (PDGFRα/β), and Fibroblast Growth Factor Receptors 1-3 (FGFR1-3). FGF aberrancies (amplification of FGFR1,or 11q[amplicon containing FGF ligands 3, 4, and 19]), are genomic alterations observed in over 20% of breast cancer pts and promote cancer proliferation and survival.

METHODS: MBC pts who had received at least 1 metastatic line of therapy were randomized 1:1 to 10 or 15 mg QD of lucitanib. Stratification was based on local assessment of FGF aberrancy; pts with both FGFR1 and 11q-amplified tumors were stratified as FGFR1 amplified. Central confirmation of FGFR1 or 11q amplification was done using Abbott FISH probes (FGFR1 or 11q copy number ≥ 6 and a ratio of FGFR1 or 11q to centromere ≥ 2). Investigator-assessed progression-free survival (PFS) was the primary endpoint. Secondary endpoints included objective response rate (ORR) per RECIST 1.1, disease control rate (DCR), duration of response (DR), and incidence of treatment-emergent adverse events (TEAE).

RESULTS: Enrollment completed in 3/2016; 178 pts that received at least 1 dose of lucitanib are included in this analysis (baseline characteristics in Table 1). Due to grade 3 hypertension in the 15 mg group (46% vs 37% in 10 mg group), enrollment to the 15 mg group was halted. Overall, most pts (97%) experienced at least 1 TEAE, with the most frequently (≥ 30%) occurring events being hypertension (73%), fatigue (48%), nausea (43%), hypothyroidism (40%), and headache (33%). Grade ≥ 3 TEAEs occurred in 66% of pts, with hypertension as the most frequent event (40%) followed by proteinuria and hyponatremia (both 6%). AEs were manageable with dose interruption or reduction, with approximately 8% of pts ending treatment due to an AE. Current median PFS is 3.5 mos (95% CI 2.8-4.6; range 0.62-12.95) and 2.6 mos (95% CI 1.8-2.9; range 0.82-18.87) respectively for the 10 mg and 15 mg treatment groups. No differences in clinical activity were observed by treatment group, FGF aberrancy, hormone receptor or HER2 status. Of the 168 evaluable pts, confirmed ORR was 3%; overall DCR was 27% (32% for pts in the 10 mg group compared to 20% for the 15 mg group); overall mean (standard deviation) DR of 3.3 (1.8) mos.

Baseline Characteristics 10 mg QD15 mg QD N=109N=69Age (years)Median5653Range27-8227-80SexFemale109 (100%)67 (97%)Male02 (3%)ECOG PSmissing5 (5%)2 (3%)051 (47%)30 (43%)153 (49%)37 (54%)Number of prior anticancer therapies in the metastatic setting&gt; 332 (29%)21 (30%)3-648 (44%)32 (46%)&gt; 629 (27%)16 (23%)Endocrine/HER2 statusmissing7 (6%)1 (1%)ER+ or PR+74 (68%)50 (73%)HER2+12 (11%)7 (10%)TNBC16 (15%)11 (16%)FGFR aberrancyFGFR1 amplified54 (49%)29 (42%)11q amplified31 (28%)24 (35%)FGFR1 and 11q amplified13 (12%)9 (13%)FGFR1 and 11q non-amplified11 (10%)7 (10%)

CONCLUSION: At 10 mg QD, lucitanib has modest activity with manageable toxicity in this heavily pretreated pt population. Future clinical development for lucitanib may focus on alternative biomarkers to identify sensitive tumors and rational combinations with other anti-cancer drugs.

Citation Format: Mayer IA, Arteaga CL, Nanda R, Miller KD, Jhaveri K, Brufsky AM, Rugo H, Yardley DA, Vahdat LT, Sadeghi S, Audeh MW, Rolfe L, Litten J, Knox A, Raponi M, Tankersley C, Isaacson J, Wride K, Morganstern DE, Vogel C, Connolly RM, Gradishar WJ, Patel R, Pusztai L, Abu-Khalaf M. A phase 2 open-label study of lucitanib in patients (pts) with FGF aberrant metastatic breast cancer (MBC) [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 P6-11-03.

Abstract P2-08-23: TP53 mutation is a biomarker for prognosis in triple-negative breast cancer patients treated with post-neoadjuvant cisplatin

Introduction: Patients with Triple-Negative Breast Cancer (TNBC) who have residual disease (RD) after neoadjuvant chemotherapy are at an increased risk of relapse and have a poor prognosis. No adjuvant therapies are currently indicated for this group. BRE09-146 was a Phase II post-neoadjuvant clinical trial testing Cisplatin or Cisplatin + Rucaparib in TNBC patients with RD after neoadjuvant chemotherapy. As TP53 is mutated in 70-80% of TNBCs, and is well known to play a role in the DNA damage response, we sought to determine the prognostic capability of mutated TP53 in BRE09-146.

Methods: We performed full sequence and copy number analysis of 134 genes in 76 tumors from BRE09-146 using the Oncomine Research Panel along with Ion Proton Next Generation Sequencing. All patients included had RD. Somatic mutations were called by identifying mutations that were present in the tumor that were not present in the germ line DNA from a normal blood sample. Mutations were annotated using the IARC TP53 somatic mutation database. Gene copy numbers in tumors were identified using the Ion Reporter system from Thermo-Fisher Scientific and called as copy number loss, normal, or gain based upon a comparison to a reference range established from the normal blood samples. Survival analyses were generated using the Log-Rank and Kaplan-Meier methods.

Results: 84% (64/76) of our TNBC tumors harbored a somatic mutation in the TP53 gene. The majority were missense mutations (particularly in the DNA binding and tetramerization domains) followed by frameshift insertions/deletions, and copy number loss. Patients whose tumors harbored somatic TP53 mutations were observed to have a significantly inferior disease free survival (DFS) compared to non-mutated tumors (events = 29/64 vs. 1/12; median = 25.9 mos vs. NR (Not Reached); p=0.021, HR=7.28 (95% C.I.: 2.98-17.79). The same was observed for overall survival (OS) (events = 23/64 vs. 0/12, median = 33.78 vs. NR; p=0.017, HR = Not evaluable). There was no difference in DFS or OS when comparing the nature of the mutation (point mutation vs. indel vs. copy loss) at a p=0.88 and p=0.91, respectively. We then sought to determine if clonal status of TP53 mutations was also associated with survival. Cases were divided into non-mutated, subclonal (mutations present in a fraction of cells), or truncal (mutation present in most or all cells). Interestingly, tumors that harbored subclonal TP53 mutations had a superior OS compared to truncal mutations (events = 1/9 vs. 22/55; median = NR vs. 29.1, p=0.036, HR =0.16 (95% C.I.:0.06-0.42). OS for subclonal mutations was highly similar to non-mutated tumors (p=0.25).

Conclusions: While RD after neoadjuvant chemotherapy in TNBC is a well-known risk factor for poor prognosis, in our study, we observed a subset of RD patients defined by a lack of TP53 mutation or presence of a subclonal mutation that portended a superior survival outcome after post-neoadjuvant Cisplatin. If validated, these results reveal that the presence and clonal status of TP53 mutations is important to accurate prognostication and should be considered in decision-making algorithms for this patient population.

Citation Format: Hancock BA, Chen Y-H, Solzak JP, Miller KD, Radovich M. TP53 mutation is a biomarker for prognosis in triple-negative breast cancer patients treated with post-neoadjuvant cisplatin. [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 P2-08-23.

Abstract P5-11-02: Survival benefit needed to undergo chemotherapy: Patients and physicians preferences

Background: Data regarding patients (pts) and physicians' preferences for modern adjuvant chemotherapy (CT) are limited. Prior studies suggested that most pts with early stage breast cancer were willing to receive 6 months of adjuvant cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) for modest survival benefits (e.g. most women would have accepted 3-6 months extension of life).

Methods: E5103 was a phase III trial which randomized node positive or high risk node negative breast cancer pts to receive adjuvant CT (doxorubicin, cyclophosphamide and paclitaxel) with either placebo or bevacizumab. Telephone based surveys were administered to all pts enrolled on E5103 between 01/Jan/10 and 08/Jun/10, as part of a Decision-Making/Quality of Life component. Results presented here are part of the 18 months post-enrollment follow-up. Pts were asked to rate the survival benefit needed to justify 6 months of CT. A complementary survey was sent to all physicians who registered at least one pt on E5103.

Results: 465 out of 519 eligible pts (90%) responded to this survey at 18 months. Main reasons for non response were: inability to reach the patient (6%) or patient refusal (2%). Median pts age was 51 (25-76); 42% of pts had at least a college degree. The majority had at least Stage II cancer.

179 (16%) physicians participated, among whom median age was 50 (35-70). The median years in practice was 17 (3-38); 78% of physicians worked on large size practices, 72% saw at least 5 new breast cancer pts/month, and 77% enroll between 1-4 pts on trials/month.

We found considerable variation in pts preferences particularly for modest survival benefits: a substantial minority of pts (24%) would consider 6 months of CT definitely worthwhile for 1 month survival benefit, 18% would possibly consider it and 56% would not. The percentage considering CT definitely worthwhile increased with greater benefit, but did not reach 100%, even with 24 months survival benefit. About half of pts considered 6 months of CT definitely worthwhile for 9 months benefit, 70% for 12 months and 84% for 24 months.

Physicians were less likely to accept CT for a small chance of benefit (34% of pts vs. 5% of physicians would definitely consider CT worthwhile for 2 months of benefit). For longer benefit, pts and physicians choices were similar (84% of pts vs. 92% of physicians would definitely consider CT worthwhile for 24 months benefit).

Table Yes, definitely worthwhileYes, maybeNo, not worthwhileNo answerConsider 6 months of CT to live:PtsPhysiciansPtsPhysiciansPtsPhysiciansPts/Physicians*1 month longer24%3%18%15%56%80%2%2 months longer34%5%23%32%41%60%2%6 months longer44%32%35%54%19%12%2%9 months longer53%51%34%42%11%5%2%12 months longer70%75%23%22%5%1%2%24 months longer84%92%12%5%2%1%2%n Pts= 465; n Physicians= 179; * equal results in both groups

Conclusions: This subgroup of pts who had undergone modern adjuvant CT in a large multicenter randomized controlled trial and these physicians who registered pts on the same trial had different cutoffs for acceptable levels of benefits and risks when considering adjuvant chemotherapy. It is important to engage pts in determining whether CT is or is not a "reasonable" option for treatment.

Citation Format: Vaz Luis I, O'Neill A, Sepucha K, Miller KD, Baker E, Dang CT, Northfelt DW, Winer EP, Sledge GW, Schneider BP, Partridge A. Survival benefit needed to undergo chemotherapy: Patients and physicians preferences. [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 P5-11-02.

Novel Anti-Nicotine Vaccine Using a Trimeric Coiled-Coil Hapten Carrier

Tobacco addiction represents one of the largest public health problems in the world and is the leading cause of cancer and heart disease, resulting in millions of deaths a year. Vaccines for smoking cessation have shown considerable promise in preclinical models, although functional antibody responses induced in humans are only modestly effective in preventing nicotine entry into the brain. The challenge in generating serum antibodies with a large nicotine binding capacity is made difficult by the fact that this drug is non-immunogenic and must be conjugated as a hapten to a protein carrier. To circumvent the limitations of traditional carriers like keyhole limpet hemocyanin (KLH), we have synthesized a short trimeric coiled-coil peptide (TCC) that creates a series of B and T cell epitopes with uniform stoichiometry and high density. Here we compared the relative activities of a TCC-nic vaccine and two control KLH-nic vaccines using Alum as an adjuvant or GLA-SE, which contains a synthetic TLR4 agonist formulated in a stable oil-in-water emulsion. The results showed that the TCC's high hapten density correlated with a better immune response in mice as measured by anti-nicotine Ab titer, affinity, and specificity, and was responsible for a reduction in anti-carrier immunogenicity. The Ab responses achieved with this synthetic vaccine resulted in a nicotine binding capacity in serum that could prevent >90% of a nicotine dose equivalent to three smoked cigarettes (0.05 mg/kg) from reaching the brain.

Genetic variant predicts bevacizumab-induced hypertension in ECOG-5103 and ECOG-2100

BACKGROUND

Bevacizumab has broad anti-tumour activity, but substantial risk of hypertension. No reliable markers are available for predicting bevacizumab-induced hypertension.

METHODS

A genome-wide association study (GWAS) was performed in the phase III bevacizumab-based adjuvant breast cancer trial, ECOG-5103, to evaluate for an association between genotypes and hypertension. GWAS was conducted in those who had experienced systolic blood pressure (SBP) >160 mm Hg during therapy using binary analysis and a cumulative dose model for the total exposure of bevacizumab. Common toxicity criteria (CTC) grade 3-5 hypertension was also assessed. Candidate SNP validation was performed in the randomised phase III trial, ECOG-2100.

RESULTS

When using the phenotype of SBP>160 mm Hg, the most significant association in SV2C (rs6453204) approached and met genome-wide significance in the binary model (P=6.0 × 10(-8); OR=3.3) and in the cumulative dose model (P=4.7 × 10(-8); HR=2.2), respectively. Similar associations with rs6453204 were seen for CTC grade 3-5 hypertension but did not meet genome-wide significance. Validation study from ECOG-2100 demonstrated a statistically significant association between this SNP and grade 3/4 hypertension using the binary model (P-value=0.037; OR=2.4).

CONCLUSIONS

A genetic variant in SV2C predicted clinically relevant bevacizumab-induced hypertension in two independent, randomised phase III trials.

Abstract P1-12-01: Clinical impact of internet-based tools to help guide therapeutic decisions for metastatic breast cancer (MBC)

Background: Clinical practice guidelines are an important resource to help guide management of patients with MBC. However, guidelines are sometimes difficult to apply to individual patients, particularly when there are 2 or more treatment options with similar levels of evidence. We sought to determine whether expert recommendations on MBC treatment, delivered via an interactive, online decision support tool, would change or confirm the treatment decisions of community practitioners. We further sought to analyze changes in practice patterns and expert recommendations over time by comparing data from the current tool (2013) with data from a similar tool developed previously (2012).

Methods: Both online decision support tools were developed based on input from a panel of 5 experts. Each expert provided treatment recommendations for more than 400 patient scenarios based on a simplified set of variables: disease phenotype (HR status, HER2 status), previous therapy, visceral crisis (yes/no), and rate of disease progression. Users of the tool are prompted to enter specific patient criteria, and are asked to state their intended management approach for that particular patient case. The tool then shows the recommendations of the 5 MBC experts for the specific patient case that the user entered. Finally, the user is prompted to indicate whether the experts’ recommendation confirmed or changed their intended management approach. An analysis of expert recommendations and user-selected treatments was performed to compare results of the 2013 and 2012 tools.

Results: The 2012 decision support tool was utilized by 697 individuals who entered more than 1000 patient case scenarios. Users indicated that the experts’ recommendations changed their intended management approach for 30% of the cases, confirmed their approach for 36%, and did not impact their intended approach for 34%. Utilization data for the 2013 tool are pending. Expert recommendations in the 2012 vs 2013 tools changed to reflect emerging developments in guidelines, evidence, and clinical practice. For example, in 2012 there was no expert consensus on use of everolimus + hormonal therapy for HR+, HER2- patient cases, whereas in 2013, everolimus-based therapy was recommended by the majority of experts (3 out of 5) for 12 different HR+, HER2- cases. There was no consensus among the experts on the use of pertuzumab + trastuzumab and a taxane for HER2+ MBC in 2012, whereas in 2013 at least 3 out of 5 experts recommended it for a total of 36 HER2+ cases. At least 3 of 5 experts recommended trastuzumab emtansine for 96 different HER2+ cases in 2013 vs 0 in 2012. In both 2012 and 2013, the greatest variability in expert treatment recommendations was observed for HR-, HER2- cases.

Conclusions: An online tool providing expert advice on specific MBC patient scenarios either confirmed or changed the clinical approach for a majority of community practitioners. Decision support tools may increase the number of clinicians who make optimal treatment decisions for patients with MBC, especially when new data, agent indications, and guideline updates must be incorporated. Detailed comparisons of expert and user responses from the 2012 and 2013 decision support tools will be presented.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-12-01.

Abstract P5-17-01: Bevacizumab (B) in the adjuvant treatment of breast cancer - first toxicity results from Eastern Cooperative Oncology Group trial E5103

Background: A previous feasibility trial (E2104 – Ann Oncol 23(2):331–7,2012) suggested incorporation of B into anthracycline-containing adjuvant therapy was feasible but ongoing cardiac monitoring was required to define the true impact of B on cardiac function.

Methods: Patients (pts) were assigned 1:2:2 to one of three treatment arms. In addition to doxorubicin and cyclophosphamide followed by weekly paclitaxel, patients received either placebo (Arm A – AC&gt;T) or B during chemotherapy (Arm B - BAC&gt;BT), or B during chemotherapy followed by B monotherapy (15 mg/kg q3wk) for an additional 10 cycles (Arm C – BAC&gt;BT&gt;B). Randomization was stratified and B dose adjusted for choice of AC schedule (classical q3wk − 15 mg/kg; dose dense(dd) q2 wk − 10 mg/kg). When indicated, radiation and hormonal therapy were administered concurrently with B (for Arm C pts). The primary cardiac endpoint was the incidence of clinically apparent cardiac dysfunction (CHF)defined as symptomatic decline in left ventricular ejection fraction (LVEF) to below the lower limit of normal (LLN) or symptomatic diastolic dysfunction as assessed by independent review. Cumulative toxicity data as of Jan 23, 2012 are presented.

Results: From 11.07 to 2.11, 4994 pts were enrolled. Median age was 52; 80% received ddAC. Chemotherapy associated toxicities including myelosuppression (Grade 4 neutropenia 16/20/19%) and neuropathy (Grade ≥ 3 8/8/8%) were similar across all arms. Grade ≥ 3 hypertension/thrombosis/proteinuria/hemorrhage was reported by 7/3/&lt;1/&lt;1% of B-treated pts. 99 pts developed CHF, most commonly reported at the post-AC or post-T evaluation. After a median follow-up of 26 months, the cumulative incidence of clinical CHF at 15 months from randomization in Arm A/B/C was 1.0/1.7/2.9% respectively. Median age of CHF pts was 57; median baseline LVEF of CHF pts was 60.

OT3-01-05: PARP Inhibition after Preoperative Chemotherapy in Patients with Triple-Negative Breast Cancer (TNBC) or Known BRCA 1/2 Mutations: Hoosier Oncology Group BRE09-146

Background

Based on recently reported I-SPY trial, TNBC patients who had residual disease category II or III had 2-year disease free survival (DFS) of only ∼40% (J Clin Oncol 2009;27:18s). Currently, no standard systemic therapy exists for this high-risk group. It represents a real opportunity to explore the potential impact of novel therapies. Recent laboratory and early clinical studies (Nature 2005;434:913) identified a unique sensitivity to DNA-damaging chemotherapy and PARP inhibition. We initiated a randomized phase II trial of DNA-damaging chemotherapy (cisplatin) or PARP-inhibition + cisplatin in TNBC patients with substantial residual invasive disease after standard anthracycline and/or taxane containing neoadjuvant chemotherapy.

Methods: To ensure a high-risk population, patients must have residual disease category 0–2 based on the Miller-Payne classification system, residual cancer burden classification II or III, residual lymph node involvement, or at least 2 cm of residual invasive disease in the breast. After completion of standard radiation therapy (when indicated), patients are randomized 1:1 to cisplatin (75 mg/M2 IV Day 1 every 3 weeks x 4 cycles) alone or in combination with PARP inhibition (PF-01367338 — 24 mg IV D1, 2, 3 of each 3 week cycle with a single dose escalation to 30 mg in the absence of significant toxicity in cycle 1 followed by maintenance PARP inhibition weekly x 24 weeks). The primary objective is 2-year DFS. To detect an improvement in 2-year DFS from 40% with cisplatin alone to 63.2% in the cisplatin + PF-01367338 arm (corresponding to HR=0.5), with 80% power using a one-side log-rank test with 0.10 level of significance, 102 patients are required in the primary analysis. Secondary objectives include safety, 1-year DFS, overall survival, and biomarkers of tumor recurrence, resistance to chemotherapy and/or PARP inhibition. Two dose escalation safety cohorts (N=13) were completed without dose limiting toxicity; the randomized portion began enrolment in 11/2010 has enrolled 20 patients as of 05/2011.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT3-01-05.

P1-08-01: Survival in Metastatic Breast Cancer (MBC): No Evidence for Improved Survival Following Distant Recurrence after Adjuvant Chemotherapy

Population-based studies have suggested improved survival for patients diagnosed with MBC in recent years, presumably due to the availability of new and more effective therapies (Chia et al. Cancer 2007; Dawood et al. JCO, 2008). The objective of this analysis was to determine if survival improved for patients who participated in Eastern Cooperative Oncology Group (ECOG) adjuvant trials and later developed MBC.

Methods: Adjuvant trials coordinated by the ECOG that accrued patients between 1978 and 2002 were reviewed (n=12), which included followup until 2010. Cytotoxic and biologic agents approved for MBC during this time included paclitaxel (1994), capecitabine and trastuzumab (1998), docetaxel and gemcitabine (2004), lapatinib and ixabepilone (2007), and bevacizumab (2008). Survival following distant recurrence was estimated for 4 time periods ranging from 6–10 years, and adjusted for baseline covariates in a Cox proportional hazards model. Because distant relapse free interval (DRFI) was the covariate most strongly associated with survival after recurrence, and the potential for “gap time” bias this could introduce, logrank tests for other covariates and estimates of effects were computed stratified on DRFI (0-3, &gt;3-6, &gt; 6 years). HER2 status was not routinely available and thus not included.

Results: The 12 trials included 14,752 patients (93% received adjuvant chemotherapy); 3711 (25.2%) developed distant recurrence. Median survival after distant recurrence was 20 months; the estimated 5 and 10-year survival rates were 16.3% and 6.1%, respectively. Median survival by time period is shown in the table, stratified by DRFI. Median survival did not significantly change over time by DRFI (≤3 years, p=0.15; &gt;3 yr, p=0.57). In a Cox proportional hazards model, factors associated with inferior survival after adjusting for other covariates included shorter DRFI (&lt;3 years vs. 3–6 years — hazard ratio [HR] 1.60, p&lt;0.001, and &gt; 6 vs. &lt; 3 years — HR 2.23, p &lt;0.001), ER-negative disease (HR 1.30, p&lt;0.001), PR-negative disease (HR 1.36, P&lt;0.0001), number of positive axillary nodes at diagnosis (1-3 vs. 0 nodes — HR 1.28, 4–9 vs. 0 nodes — HR 1.51, &gt; 9 vs. 0 nodes — HR 1.51, p&lt;0.0001), and black vs. white race (HR 1.29, p=0.0003), but not age at recurrence (p=0.07). When the year of recurrence was added to the Cox proportional hazards model using the intervals shown in the table below, it was not significantly associated with survival. Results were similar when 1978–2010 was assessed by 5–6 year intervals.

Conclusions: In contrast to reports from population-based studies, we do not observe any improvement in survival over time for patients who develop distant recurrence after adjuvant chemotherapy. There remains a critical unmet need for new therapies for MBC, especially for those who recur after adjuvant chemotherapy.

OT3-02-04: TBCRC 012: ABCDE, a Phase II Randomized Study of Adjuvant Bevacizumab, Metronomic Chemotherapy (CM), Diet and Exercise after Preoperative Chemotherapy for Breast Cancer

Background Patients (pts) with residual breast cancer after neoadjuvant chemotherapy are at increased risk of recurrence; no proven risk-reduction strategies exist, supporting exploration of novel therapies in the post-preoperative setting. Bevacizumab (B) combined with chemotherapy is active in metastatic disease; ongoing studies are exploring the efficacy of adjuvant combination chemotherapy and B. DFCI 05–055 (Mayer et al, ASCO 2007, 2008) demonstrated the feasibility of 1 year B after preoperative chemotherapy. Also, increasing data support risk reduction through lifestyle interventions (Segal, Ligibel et al, ASCO 2011). The ABCDE trial was designed to evaluate extended adjuvant B in a high risk post-preoperative cohort, and also assess the contribution of exercise to a dietary intervention.

Eligibility Criteria Eligible pts have HER2− breast cancer and have received preoperative anthracycline and/or taxane-based chemotherapy with residual invasive disease at surgery. Acceptable stages include: triple negative if preop stages I-III, or ER+/PR+ if stage III preop or IIB postop. Acceptable organ function and standard B exclusions apply. Registration must occur between 28–180 days after last surgery.

Specific Aims Primary endpoint is recurrence-free survival at a median follow-up of 6 years. Secondary endpoints include B pharmacogenomics, evaluation of the impact of exercise on quality of life and biomarkers associated with recurrence, and prospective examination of cardiac toxicity. Residual tissue-based predictors of outcome will be extensively explored, including PAM50, Ki67, and VEGF hypoxia signature.

Methods This is a 2 × 2 randomized study with a first randomization to 6 months (mo) B 15 mg/kg every 3 weeks (wks) plus 6 mo CM (C 50 mg daily, M 2.5 mg twice daily days 1, 2 each wk), followed by 2.5 years B 15 mg/kg every 6–8 wks, versus observation. A second randomization is to a 1 year telephone-based lifestyle intervention, offering dietary modification alone, or in combination with a structured exercise program.

Statistical Methods and Accrual Total sample size is 660 pts within the Translational Breast Cancer Research Consortium. Overall power is 0.80 to detect a hazard ratio of 0.59−0.68, depending on pt population. Accrual initiated early 2011 and is expected to continue for the next 36 months.

Conclusions Patients with residual disease after preoperative chemotherapy are at high risk of recurrence and have unmet medical needs. To our knowledge, this is the only trial testing a prolonged but less intensive adjuvant B schedule in this clinical setting. Results of this study could have critical implications for the management of this patient population and for the design of future clinical trials with anti-angiogenic agents.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT3-02-04.

A phase II pilot trial incorporating bevacizumab into dose-dense doxorubicin and cyclophosphamide followed by paclitaxel in patients with lymph node positive breast cancer: a trial coordinated by the Eastern Cooperative Oncology Group

BACKGROUND

E2104 was designed to evaluate the safety of two different strategies incorporating bevacizumab into anthracycline-containing adjuvant therapy as a precursor to a definitive randomized phase III trial.

PATIENTS AND METHODS

Patients were sequentially assigned to one of two treatment arms. In addition to dose-dense doxorubicin and cyclophosphamide followed by paclitaxel (Taxol) (ddAC→T), all patients received bevacizumab (10 mg/kg every 2 weeks × 26) initiated either concurrently with AC (Arm A: ddBAC→BT→B) or with paclitaxel (Arm B: ddAC→BT→B). The primary end point was incidence of clinically apparent cardiac dysfunction (CHF).

RESULTS

Patients enrolled were 226 in number (Arm A 104, Arm B 122). Grade 3 hypertension, thrombosis, proteinuria and hemorrhage were reported for 12, 2, 2 and <1% of patients, respectively. Two patients developed grade 3 or more cerebrovascular ischemia. Three patients in each arm developed CHF. There was no significant difference between arms in the proportion of patients with an absolute decrease in left ventricular ejection fraction of >15% or >10% to below the lower limit of normal post AC or post bevacizumab.

CONCLUSIONS

Incorporation of bevacizumab into anthracycline-containing adjuvant therapy does not result in prohibitive cardiac toxicity. The definitive phase III trial (E5103) was activated with systematic and extensive cardiac monitoring to define the true impact of bevacizumab on cardiac function.

Synergistic capture of Clostridium botulinum type A neurotoxin by scFv antibodies to novel epitopes

A non-immune library of human single chain fragment variable (scFv) antibodies displayed on Saccharomyces cerevisiae was screened for binding to the Clostridium botulinum neurotoxin serotype A binding domain [BoNT/A (Hc)] with the goal of identifying scFv to novel epitopes. To do this, an antibody-mediated labeling strategy was used in which antigen-binding yeast clones were selected after labeling with previously characterized monoclonal antibodies (MAbs) specific to the Hc. Twenty unique scFv clones were isolated that bound Hc. Of these, 3 also bound to full-length BoNT/A toxin complex with affinities ranging from 5 to 48 nM. Epitope binning showed that the three unique clones recognized at least two epitopes distinct from one another as well as from the detection MAbs. After production in E. coli, scFv were coupled to magnetic particles and tested for their ability to capture BoNT/A holotoxin using an Endopep-MS assay. In this assay, toxin captured by scFv coated magnetic particles was detected by incubation of the complex with a peptide containing a BoNT/A-specific cleavage sequence. Mass spectrometry was used to detect the ratio of intact peptide to cleavage products as evidence for toxin capture. When tested individually, each of the scFv showed a weak positive Endopep-MS result. However, when the particles were coated with all three scFv simultaneously, they exhibited significantly higher Endopep-MS activity, consistent with synergistic binding. These results demonstrate novel approaches toward the isolation and characterization of scFv antibodies specific to unlabeled antigens. They also provide evidence that distinct scFv antibodies can work synergistically to increase the efficiency of antigen capture onto a solid support.

Developing recombinant antibodies for biomarker detection

Monoclonal antibodies (mAbs) have an essential role in biomarker validation and diagnostic assays. A barrier to pursuing these applications is the reliance on immunization and hybridomas to produce mAbs, which is time-consuming and may not yield the desired mAb. We recommend a process flow for affinity reagent production that utilizes combinatorial protein display systems (e.g., yeast surface display or phage display) rather than hybridomas. These systems link a selectable phenotype--binding conferred by an antibody fragment--with a means for recovering the encoding gene. Recombinant libraries obtained from immunizations can produce high-affinity antibodies (<10 nM) more quickly than other methods. Non-immune libraries provide an alternate route when immunizations are not possible, or when suitable mAbs are not recovered from an immune library. Directed molecular evolution (DME) is an integral part of optimizing mAbs obtained from combinatorial protein display, but can also be used on hybridoma-derived mAbs. Variants can easily be obtained and screened to increase the affinity of the parent mAb (affinity maturation). We discuss examples where DME has been used to tailor affinity reagents to specific applications. Combinatorial protein display also provides an accessible method for identifying antibody pairs, which are necessary for sandwich-type diagnostic assays.

Flow cytometry-based methods for assessing soluble scFv activities and detecting antigens in solution

Novel methods are reported for evaluating and utilizing single chain fragment variable (scFv) antibodies derived from yeast-display libraries. Yeast-display was used to select scFv specific to invariant surface glycoproteins (ISG) of Trypanosoma brucei. A limiting step in the isolation of scFv from non-immune libraries is the conversion of highly active yeast-displayed scFv into soluble antibodies that can be used in standard immunoassays. Challenges include limited solubility or activity following secretion and purification of scFv. For this reason, few scFv derived from yeast-display platforms have moved into development and implementation as diagnostic reagents. To address this problem, assays were developed that employ both yeast-displayed and -secreted scFv as analytical reagents. The first is a competitive inhibition flow cytometry (CIFC) assay that detects secreted scFv by virtue of their ability to competitively inhibit the binding of biotinylated antigen to yeast-displayed scFv. The second is an epitope binning assay that uses secreted scFv to identify additional yeast-displayed scFv that bind non-overlapping or non-competing epitopes on an antigen. The epitope binning assay was used not only to identify sandwich assay pairs with yeast-displayed scFv, but also to identify active soluble scFv present in low concentration in a crude expression extract. Finally, a CIFC assay was developed that bypasses entirely the need for soluble scFv expression, by using yeast-displayed scFv to detect unlabeled antigen in samples. These methods will facilitate the continued development and practical implementation of scFv derived from yeast-display libraries.

Renewable surface fluorescence sandwich immunoassay biosensor for rapid sensitive botulinum toxin detection in an automated fluidic format

A renewable surface biosensor for rapid detection of botulinum neurotoxin serotype A is described based on fluidic automation of a fluorescence sandwich immunoassay, using a recombinant protein fragment of the toxin heavy chain ( approximately 50 kDa) as a structurally valid simulant. Monoclonal antibodies AR4 and RAZ1 bind to separate non-overlapping epitopes of the full botulinum holotoxin ( approximately 150 kDa). Both of the targeted epitopes are located on the recombinant fragment. The AR4 antibody was covalently bound to Sepharose beads and used as the capture antibody. A rotating rod flow cell was used to capture these beads delivered as a suspension by a sequential injection flow system, creating a 3.6 microL column. After perfusing the bead column with sample and washing away the matrix, the column was perfused with Alexa 647 dye-labeled RAZ1 antibody as the reporter. Optical fibers coupled to the rotating rod flow cell at a 90 degrees angle to one another delivered excitation light from a HeNe laser (633 nm) using one fiber and collected fluorescent emission light for detection with the other. After each measurement, the used Sepharose beads are released and replaced with fresh beads. In a rapid screening approach to sample analysis, the toxin simulant was detected to concentrations of 10 pM in less than 20 minutes using this system.

A pilot study of vascular endothelial growth factor inhibition with bevacizumab in patients with lymphedema following breast cancer treatment

Abstract #6142

Purpose: Lymphedema is a significant long-term complication of primary therapy for breast cancer but little is known regarding its etiology and persistence other than relation to the number of lymph nodes (LN) removed. We suggest the following model: Mechanical disruption of normal lymphatic drainage leads to increased back pressure on lymphatic vessels producing an increase in interstitial fluid pressure (IFP). The increased in IFP triggers local production of VEGF-C to stimulate compensatory lymphangiogenesis. As VEGF-A (and to a lesser extent –C) also increases vascular permeability, the consequent increase in interstitial fluid and edema predominate. Anecdotally, several patients (pts) with metastatic disease treated with bevacizumab monotherapy noted improvement in long-standing lymphedema. This pilot study was conducted to explore these observations prospectively.&#x2028; Methods: We used an existing biospecimen bank to conduct a case-control study to compare VEGF-A, -C, -D and VEGFR-3 serum concentrations in breast cancer pts with and without lymphedema (matched for age and LN status). In a separate pilot trial, pts with significant unilateral lymphedema receive bevacizumab, 15 mg/kg every 3 weeks. Baseline assessments include arm volume, interstitial fluid pressure (IFP), extracellular fluid volume by lymphometer (ECF), quality of life (QOL) and plasma VEGF-C, -D, and R-3. IFP is measured serially for 24 hours after the first treatment; arm volume, ECF, QOL, and plasma VEGF-C/D/R-3 are assessed at 3 and 6 weeks.&#x2028; Results: Samples were available for 16 pts with chronic lymphedema and 24 matched controls. Median VEGF-C levels were significantly increased in pts with lymphedema (6895 pg/ml vs. 5349 pg/ml, p=0.001). Median VEGF-A levels were slightly higher in pts with lymphedema (375 pg/ml vs.250 pg/ml, p=NS). Eight pts have been enrolled in the pilot trial thus far. Median duration of lymphedema was 4.4 years (2.2-16.6) Median time since surgery was 7.1 years (3.4-17.6); median time since radiation (n=7) was 4.4 years (2.3-7.9). Complete IFP data is available in 5 pts. Baseline IFP was significantly higher in the affected compared to unaffected arm (9.04 vs. -2.07 mmHg; p=0.0017). Median IFP in the affected arm decreased an average of 42.6% 24 hours after bevacizumab infusion (11.1 vs. 6.9 mmHg; p=0.09). Total arm circumference decreased by an average of 2.8 cm three weeks after initial treatment.&#x2028; Conclusions: Preliminary data supports the hypothesis that VEGF plays a central role in the development and persistence of lymphedema after local therapy for breast cancer. Inhibiting VEGF acutely decreases IFP and may be an effective treatment. Treatment and accrual to the pilot trial continues; full data will be available by December 2008.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6142.

Dual targeting of EphA2 and ER restores tamoxifen sensitivity in ER/EphA2-positive breast cancer

Abstract #3020

Background: Overexpression and altered function of EphA2 receptor tyrosine kinase are critical in the progression of breast cancer and provide a novel target for breast cancer therapy. We have previously demonstrated that EphA2 overexpression decreases estrogen dependence and tamoxifen sensitivity both in vitro and in vivo. EA5, a novel monoclonal antibody that mimicks the binding of ephrin A to EphA2, reverses the effect of EphA2 overexpression and restores tamoxifen sensitivity in EphA2-transfected MCF-7 cells (MCF-7EphA2) in vitro. Here we report the impact of EA5 on in vivo tumor growth and its ability to overcome in vivo tamoxifen resistance in MCF-7EphA2 xenografts. Furthermore, we investigated the mechanisms by which EphA2 overexpression decreases the estrogen dependence and contributes to tamoxifen resistance in ER+ breast cancer models.&#x2028; Material and Methods: MCF-7 cells transfected with vector (MCF-7neo) or EphA2 (MCF-7EphA2) were implanted in the right and left mammary fat pads of athymic mice. Treatment with EA5 (5 mg/kg/i.p./5 days/week), vehicle, tamoxifen (1 mg/oral gavage/5 days/week), or EA5 and tamoxifen in combination was initiated once tumors were established. To explore the role of EphA2 overexpression on ER-dependent mechanisms, we used two different ER+/EphA2-transfected cell line models (MCF-7neo/ MCF-7EphA2 and T47Dneo/ T47DEphA2). We measured ER activity and expression of ER-dependent proteins in response to 17β-estradiol (E2;10-10 M), 4-hydroxy-tamoxifen (10-6 M, and EA5 antibody (3μg/mL). Interaction of ER and EphA2 was investigated using GST-pulldown and co-immunoprecipitation approaches. Gene array studies suggested that EphA2 may impact ER via noncanonical pathways, leading to an investigation of focal adhesion kinase (FAK) signaling.&#x2028; Results: EA5 inhibits primary tumor growth and restores tamoxifen sensitivity in the MCF-7EphA2 in vivo model;EA5 had no impact on in vivo tumor growth in MCF-7neo xenografts. Using T47DEphA2 in vitro model, we verified that EphA2 decreases ER activation in response to E2 stimulation consistent with our earlier results in MCF-7EphA2 model. We found no direct interaction between ER and EphA2 and no difference in expression of canonical ER-dependent proteins, ER coactivators or corepressors. However, E2 stimulation phosphorylates FAKTyr925 in ER+/EphA2+ cell lines but not in ER+/EphA2- cell lines. Treatment of T47DEphA2 cells with EA5 and tamoxifen leads to dephosphorylation of FAKTyr925 in the presence of E2 stimulation.&#x2028; Conclusion: Our data demonstrate that dual targeting of EphA2 and ER is a promising approach for delaying resistance to tamoxifen. The data support our hypothesis that EphA2 impacts ER function via a FAK dependent pathway.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3020.

Construction and screening of antigen targeted immune yeast surface display antibody libraries

These protocols describe a yeast surface display-based process for the rapid selection of antibodies from immunized mice, eliminating the need for creating and screening hybridoma fusions. A yeast surface display library of single-chain antibody fragments (scFvs) is created from antigen-binding B cells from the splenocytes of immunized mice. The antigen targeted library is then screened for antigen specific scFv by magnetic-activated cell sorting (MACS) and fluorescence-activated cell sorting (FACS). Library construction and screening can be accomplished in as little as 2 weeks, resulting in a panel of scFvs specific for the target antigen.

Immobilization strategies for single-chain antibody microarrays

Sandwich ELISA microarrays have great potential for validating disease biomarkers. Each ELISA relies on robust-affinity reagents that retain activity when immobilized on a solid surface or when labeled for detection. Single-chain antibodies (scFv) are affinity reagents that have greater potential for high-throughput production than traditional IgG. Unfortunately, scFv are typically less active than IgG following immobilization on a solid surface and not always suitable for use in sandwich ELISAs. We therefore investigated different immobilization strategies and scFv constructs to determine a more robust strategy for using scFv as ELISA reagents. Two promising strategies emerged from these studies: (i) the precapture of epitope-tagged scFv using an antiepitope antibody and (ii) the direct printing of a thioredoxin (TRX)/scFv fusion protein on glass slides. Both strategies improved the stability of immobilized scFv and increased the sensitivity of the scFv ELISA microarray assays, although the antiepitope precapture method introduced a risk of reagent transfer. Using the direct printing method, we show that scFv against prostate-specific antigen (PSA) are highly specific when tested against 21 different IgG-based assays. In addition, the scFv microarray PSA assay gave comparable quantitative results (R(2) = 0.95) to a commercial 96-well ELISA when tested using human serum samples. In addition, we find that TRX-scFv fusions against epidermal growth factor and toxin X have good LOD. Overall, these results suggest that minor modifications of the scFv construct are sufficient to produce reagents that are suitable for use in multiplex assay systems.

RA8, a human anti-CD25 antibody against human Treg cells

Although anti-CD25 antibodies exist for clinical use in patients, there is a need for the development of a human Treg antibody that will abrogate the immunosuppressive function of this small but critical T cell subtype. Based upon mounting evidence that the level of Treg cells in the tumor microenvironment correlates with clinical prognosis and stage in man, it appears that Treg cells play an important role in the tumor's ability to overcome host immune responses. In mice, the rat anti-mouse CD25 antibody PC61 causes depletion of CD25-bearing Treg cells both peripherally in lymphatic tissues and in the tumor microenvironment, without inducing symptoms of autoimmunity. A similar antibody, though with the ability to delete Treg cells specifically, would be an important new tool for reversing tumor escape associated with Treg immunosuppression in man. To begin to generate such a reagent, we now describe the development of a human anti-CD25 antibody using a novel yeast display library. The target antigen CD25-Fc was constructed and used for five rounds of selection using a non-immune yeast display library that contained as many as 10(9) single chain variable fragments (scFv). Two unique clones with low K(D) values (RA4 and RA8) were then selected to construct fully human anti-CD25 antibodies (IgG1/kappa) for stable expression. One antibody, RA8, showed excellent binding to human CD25(+) cell lines and to human Treg cells and appears to be an excellent candidate for the generation of a human reagent that may be used in man for the immunotherapy of cancer.

Production, purification, and characterization of human scFv antibodies expressed in Saccharomyces cerevisiae, Pichia pastoris, and Escherichia coli

Single chain (scFv) antibodies are used as affinity reagents for diagnostics, therapeutics, and proteomic analyses. The antibody discovery platform we use to identify novel antigen binders involves discovery, characterization, and production. The discovery and characterization components have previously been characterized but in order to fully utilize the capabilities of affinity reagents from our yeast surface display library, efforts were focused on developing a production component to obtain purified, soluble, and active scFvs. Instead of optimizing conditions to achieve maximum yield, efforts were focused on using a system that could quickly and easily produce and process hundreds of scFv antibodies. Heterologous protein expression in Saccharomyces cerevisiae, Pichia pastoris, and Escherichia coli were evaluated for their ability to rapidly, efficaciously, and consistently produce scFv antibodies for use in downstream proteomic applications. Following purification, the binding activity of several scFv antibodies were quantified using a novel Biacore assay. All three systems produced soluble scFv antibodies which ranged in activity from 0 to 99%. scFv antibody yields from Saccharomyces, Pichia, and E. coli were 1.5-4.2, 0.4-7.3, and 0.63-16.4 mgL(-1) culture, respectively. For our purposes, expression in E. coli proved to be the quickest and most consistent way to obtain and characterize purified scFv for downstream applications. The E. coli expression system was subsequently used to study three scFv variants engineered to determine structure-function relationships.

Review of Growth Inhibitory Peptide as a biotherapeutic agent for tumor growth, adhesion, and metastasis

This review surveys the biological activities of an alpha-fetoprotein (AFP) derived peptide termed the Growth Inhibitory Peptide (GIP), which is a synthetic 34 amino acid segment produced from the full length 590 amino acid AFP molecule. The GIP has been shown to be growth-suppressive in both fetal and tumor cells but not in adult terminally-differentiated cells. The mechanism of action of this peptide has not been fully elucidated; however, GIP is highly interactive at the plasma membrane surface in cellular events such as endocytosis, cell contact inhibition and cytoskeleton-induced cell shape changes. The GIP was shown to be growth-suppressive in nine human tumor types and to suppress the spread of tumor infiltrates and metastases in human and mouse mammary cancers. The AFP-derived peptide and its subfragments were also shown to inhibit tumor cell adhesion to extracellular matrix (ECM) proteins and to block platelet aggregation; thus it was expected that the GIP would inhibit cell spreading/migration and metastatic infiltration into host tissues such as lung and pancreas. It was further found that the cyclic versus linear configuration of GIP determined its biological and anti-cancer efficacy. Genbank amino acid sequence identities with a variety of integrin alpha/beta chain proteins supported the GIP's linkage to inhibition of tumor cell adhesion and platelet aggregation. The combined properties of tumor growth suppression, prevention of tumor cell-to-ECM adhesion, and inhibition of platelet aggregation indicate that tumor-to-platelet interactions present promising targets for GIP as an anti-metastatic agent. Finally, based on cholinergic studies, it was proposed that GIP could influence the enzymatic activity of membrane acetylcholinesterases during tumor growth and metastasis. It was concluded that the GIP derived from full-length AFP represents a growth inhibitory motif possessing instrinsic properties that allow it to interfere in cell surface events such as adhesion, migration, metastasis, and aggregation of tumor cells.

Directed evolution for the development of conformation-specific affinity reagents using yeast display

Yeast display is a powerful tool for increasing the affinity and thermal stability of scFv antibodies through directed evolution. Mammalian calmodulin (CaM) is a highly conserved signaling protein that undergoes structural changes upon Ca(2+) binding. In an attempt to generate conformation-specific antibodies for proteomic applications, a selection against CaM was undertaken. Flow cytometry-based screening strategies to isolate easily scFv recognizing CaM in either the Ca(2+)-bound (Ca(2+)-CaM) or Ca(2+)-free (apo-CaM) states are presented. Both full-length scFv and single-domain VH only clones were isolated. One scFv clone having very high affinity (K(d) = 0.8 nM) and specificity (>1000-fold) for Ca(2+)-CaM was obtained from de novo selections. Subsequent directed evolution allowed the development of antibodies with higher affinity (K(d) = 1 nM) and specificity (>300-fold) for apo-CaM from a parental single-domain clone with both a modest affinity and specificity for that particular isoform. CaM-binding activity was unexpectedly lost upon conversion of both conformation-specific clones into soluble fragments. However, these results demonstrate that conformation-specific antibodies can be quickly and easily isolated by directed evolution using the yeast display platform.

Selection bias in clinical trials

All research is subject to bias that may systematically distort results. Though over 50 types of bias in analytical research have been identified and many classification schemes proposed, this review focuses on the special problem of selection bias in clinical trials. We demonstrate the systematic nature of selection bias in clinical research. We describe the common sources of selection bias in clinical trials including the (inappropriate) use of historical controls, stage migration, inclusion/exclusion criteria, the use of multiple subset analyses, and investigator bias. We then move from the general to the specific, using the recent experience of high dose chemotherapy for breast cancer as an illustrative example. Finally, we suggest means to avoid falling into the many selection bias traps that often confront clinical researchers.

Automated robotic liquid handling/laser-based nephelometry system for high throughput measurement of kinetic aqueous solubility

The ability to rapidly and consistently measure aqueous solubility in a preclinical environment is critical to the successful identification of promising discovery compounds. The advantage of an early solubility screen is timely attrition of compounds likely to fail due to poor absorption or low bioavailability before more costly screens are performed. However, due to the large number of compounds and limited sample amounts, thermodynamic solubility measurements are not feasible at this stage. A kinetic solubility measurement is an alternative to thermodynamic measurements at the discovery stage that provides a rank listing of solubility values with minimal sample requirements. A kinetic solubility measurement is attractive from an automation vantage because it features rapid data acquisition and is amenable to multi-well formats. We describe the use of a robotic liquid/plate handler coupled to nephelometry detection for the measurement of kinetic solubility. We highlight the liquid handling validation, serial dilution parameters, and a comparison to the previous method. Experiments to further enhance throughput, or increase confidence in the automation steps, are described and the effects of these experiments are presented. In our integrated nephelometry method, we observe rapid liquid handling with an error of less than 10%, after a series of validation studies, and a sample throughput up to 1800 compounds per week. We compare the nephelometry method with our semi-thermodynamic flow-injection analysis (FIA) method, and find a 75% bin agreement between the methods.

Effects of handling intensity and live weight on blood acid-base status in finishing pigs

The objective of this study was to determine the effect of live weight on the plasma acid-base response of pigs subjected to various handling intensities. Eighty pigs (equal numbers of barrows and gilts) were used in a completely randomized block design with a 2 x 2 x 2 factorial arrangement of the following treatments: 1) live weight (light [104 kg] vs. heavy [128 kg]), 2) handling intensity (low vs. high), and 3) gender (barrows vs. gilts). Before the handling test, pigs were weighed, venous blood samples were taken to establish baseline levels, and rectal temperature was measured. Pigs were allowed to rest for 2 h before being subjected to the handling treatments, which consisted of moving the pigs through a course (12.2 m long x 0.91 m wide), for a total of eight laps. Animals on the high-intensity treatment were moved rapidly through the course and subjected to a total of 16 single shocks (two shocks per lap) with an electric livestock goad, whereas pigs on the low-intensity treatment were moved at their own pace using a moving panel and a paddle. Rectal temperature and a venous blood sample were taken immediately after handling and at 2 h after handling. Blood plasma was assayed for pH, partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2), saturated oxygen (SO2), total carbon dioxide (TCO2), bicarbonate (HCO3), base excess, and lactate. Live weight had no effect on the baseline measurements. After handling, light pigs had higher (P < 0.05) blood SO2 (65.6 vs. 57.2+/-2.80%) and showed a greater (P < 0.05) increase in PO2 from baseline to post-handling than heavy pigs (15.6 vs. 8.3+/-2.63 mmHg). Post-handling, pigs on the high- compared with the low-intensity handling treatment had greater (P < 0.001) lactate (19.1 vs. 4.9+/-0.56 mmol/L) and PO2 (51.6 vs. 36.5+/-2.44 mmHg) with lower (P < 0.001) TCO2 (18.6 vs. 34.7+/-0.64 mmol/L), pH (7.02 vs. 7.36+/-0.015), HCO3 (16.7 vs. 33.0+/-0.62 mmol/L), and base excess (-14.2 vs. 7.5+/-0.75) values. There were no effects of gender on blood measurements or rectal temperatures. Results from this study highlight a major effect of pig handling intensity, a limited effect of live weight, and no effect of gender on blood acid-base responses to handling.

Tracking neurons recorded from tetrodes across time

Tetrodes allow isolation of multiple neurons at a single recording site by clustering spikes. Due to electrode drift and perhaps due to time-varying neuronal properties, positions and shapes of clusters change in time. As data is typically collected in sequential files, to track neurons across files one has to decide which clusters from different files belong to the same neuron. We report on a semi-automated neuron tracking procedure that uses computed similarities between the mean spike waveforms of the clusters. The clusters with the most similar waveforms are assigned to the same neuron, provided their similarity exceeds a threshold. To set this threshold, we calculate two distributions: of within-file similarities, and of best matches in the across adjacent file similarities. The threshold is set to the value that optimally separates the two distributions. We compare different measures of similarity (metrics) by their ability to separate these distributions. We find that these metrics do not differ drastically in their performance, but that taking into account the cross-channel noise correlation significantly improves performance of all metrics. We also demonstrate the method on an independent dataset and show that neurons, as assigned by the procedure, have consistent physiological properties across files.

Probing feature selectivity of neurons in primary visual cortex with natural stimuli

One way to characterize neural feature selectivity is to model the response probability as a nonlinear function of the output of a set of linear filters applied to incoming signals. Traditionally these linear filters are measured by probing neurons with correlated Gaussian noise ensembles and calculating correlation functions between incoming signals and neural responses. It is also important to derive these filters in response to natural stimuli, which have been shown to have strongly non-Gaussian spatiotemporal correlations. An information-theoretic method has been proposed recently for reconstructing neural filters using natural stimuli in which one looks for filters whose convolution with the stimulus ensemble accounts for the maximal possible part of the overall information carried the sequence of neural responses. Here we give a first-time demonstration of this method on real neural data, and compare responses of neurons in cat primary visual cortex driven with natural stimuli, noise ensembles, and moving gratings. We show that the information-theoretic method achieves the same quality of filter reconstruction for natural stimuli as that of well-established white-noise methods. Major parameters of neural filters derived from noise ensembles and natural stimuli, as well as from moving gratings are consistent with one another. We find that application of the reverse correlation method to natural stimuli ensembles leads to significant distortions in filters for a majority of studied cells with non-zero reverse-correlation filter.