Modification of bacterial microcompartments with target biomolecules via post-translational SpyTagging.

Bacterial microcompartments (BMCs) are proteinaceous organelle-like structures formed within bacteria, often encapsulating enzymes and cellular processes, in particular, allowing toxic intermediates to be shielded from the general cellular environment. Outside of their biological role they are of interest, through surface modification, as potential drug carriers and polyvalent antigen display scaffolds. Here we use a post-translational modification approach, using copper free click chemistry, to attach a SpyTag to a target protein molecule for attachment to a specific SpyCatcher modified BMC shell protein. We demonstrate that a post-translationally SpyTagged material can react with a SpyCatcher modified BMC and show its presence on the surface of BMCs, enabling future investigation of these structures as polyvalent antigen display scaffolds for vaccine development. This post-translational 'click' methodology overcomes the necessity to genetically encode the SpyTag, avoids any potential reduction in expression yield and expands the scope of SpyTag/SpyCatcher vaccine scaffolds to form peptide epitope vaccines and small molecule delivery agents.

Phosphatidylinositol 3-kinase pathway activation in breast cancer brain metastases.

INTRODUCTION: Activation status of the phosphatidylinositol 3-kinase (PI3K) pathway in breast cancer brain metastases (BCBMs) is largely unknown. We examined expression of phospho(p)-AKT, p-S6, and phosphatase and tensin homologue (PTEN) in BCBMs and their implications for overall survival (OS) and survival after BCBMs. Secondary analyses included PI3K pathway activation status and associations with time to distant recurrence (TTDR) and time to BCBMs. Similar analyses were also conducted among the subset of patients with triple-negative BCBMs. METHODS: p-AKT, p-S6, and PTEN expression was assessed with immunohistochemistry in 52 BCBMs and 12 matched primary BCs. Subtypes were defined as hormone receptor (HR)+/HER2-, HER2+, and triple-negative (TNBC). Survival analyses were performed by using a Cox model, and survival curves were estimated with the Kaplan-Meier method. RESULTS: Expression of p-AKT and p-S6 and lack of PTEN (PTEN-) was observed in 75%, 69%, and 25% of BCBMs. Concordance between primary BCs and matched BCBMs was 67% for p-AKT, 58% for p-S6, and 83% for PTEN. PTEN- was more common in TNBC compared with HR+/HER2- and HER2+. Expression of p-AKT, p-S6, and PTEN- was not associated with OS or survival after BCBMs (all, P > 0.06). Interestingly, among all patients, PTEN- correlated with shorter time to distant and brain recurrence. Among patients with TNBC, PTEN- in BCBMs was associated with poorer overall survival. CONCLUSIONS: The PI3K pathway is active in most BCBMs regardless of subtype. Inhibition of this pathway represents a promising therapeutic strategy for patients with BCBMs, a group of patients with poor prognosis and limited systemic therapeutic options. Although expression of the PI3K pathway did not correlate with OS and survival after BCBM, PTEN- association with time to recurrence and OS (among patients with TNBC) is worthy of further study.

Impact of breast cancer molecular subtypes on locoregional recurrence in patients treated with neoadjuvant chemotherapy for locally advanced breast cancer.

BACKGROUND: Gene expression studies have identified distinct breast cancer subtypes, including luminal A, luminal B, Her2-enriched, and Basal-like, which differ in survival. The impact of subtypes on locoregional recurrence (LRR) after neoadjuvant chemotherapy for locally advanced breast cancer is unknown. METHODS: A total of 149 patients with stage II and III breast cancer with known ER, PR, and HER2 who underwent neoadjuvant chemotherapy from 1991 to 2005 were analyzed. We used clinical assays to distinguish luminal A (ER or PR+/HER2-, n = 55), luminal B (ER or PR+/HER2+, n = 25), HER2 (ER and PR-/HER2+, n = 20), and Basal-like (ER, PR, and HER2-, n = 49) subtypes. Covariates associated with LRR were evaluated by logistic regression and differences between subtypes tested using Wald χ(2). RESULTS: Median follow-up was 55 months. Forty-nine (33%) patients had breast conservation (BCT) with radiation, 82 (55%) had a mastectomy with radiation, and 18 (12%) had a mastectomy alone. Eighty-eight (59%) were clinically node positive. A pathologic complete response was seen in 39 (26%) patients. LRR was identified in 11 (7%) patients: 2 after BCT (4%) and 9 after mastectomy (9%). LRR rates by subtype are as follows: luminal A 2 of 55 (4%), luminal B 1 of 25 (4%), Her2 1 of 20 (5%), and basal-like 7 of 49 (14%). Compared with all other subtypes, basal-like patients were more likely to have a LRR (7/49 (14%) vs. 4/100 (4%), p = 0.03). CONCLUSIONS: Molecular subtype predicts LRR with basal-like patients more likely to develop LRR. These patients may be candidates for investigation with novel chemotherapy regimens and radiation sensitizing agents, which may offer improvement in local control.

Use of a Nutrition Behavior Change Counseling Tool: Lessons from a Rapid Qualitative Assessment in Eastern Zambia.

The U.S. Agency for International Development Feed the Future Mawa Project - led by Catholic Relief Services - aims to improve food and economic security for farming households in Zambia's Eastern Province. Mawa employs social and behavior change (SBC) strategies with households and communities to improve nutrition and reduce stunting among children under two (CU2). To support these strategies, sub-partner University Research Co., LLC employed a participatory process to develop a series of 35 action cards, each illustrating one project-promoted behavior, that are used at household and community group levels. Caregivers of CU2 are given a full set of action cards to promote household dialogue and support for the promoted behaviors. As a final step in the action card tool development process, a qualitative rapid assessment was conducted 1 month after implementation to investigate preliminary ways action cards were being used, and if the methods of using the cards had the potential to impact behavior change. The research team conducted nine key informant interviews and four focus group discussions with Mawa staff and administered 41 qualitative interview questionnaires with project participants in the Chipata and Lundazi districts. Although not based on a representative sampling frame, the assessment produced valuable results for program improvement purposes. It also provided a feedback mechanism for community-based staff and project participants, a crucial step in the participatory tool development process. The assessment found that Mawa staff at every level use action cards combined with at least one other social behavior change tool for each nutrition intervention. Our results suggest that Mawa staff and project participants share a common understanding of the cards' purpose. Each group noted that the cards provide a visual cue for action and reinforce previous Mawa nutrition messages. Intended uses confirmed by the assessment include encouraging household cooperation, negotiating behavior change, telling stories, and integrating messages with other project sectors. Based on the findings, recommendations for future project activities include aligning efforts against a theory of change to optimize use of all SBC tools; leveraging action card use to strengthen cross-sectoral integration within Mawa; and specific ongoing monitoring of action card use to improve activity implementation.

TBCRC 001: randomized phase II study of cetuximab in combination with carboplatin in stage IV triple-negative breast cancer.

PURPOSE: Epidermal growth factor receptor (EGFR) is a targetable receptor frequently overexpressed in basal-like breast cancer, which comprises most triple-negative breast cancers (TNBCs), the only subtype without established targeted therapy. PATIENTS AND METHODS: In this randomized phase II trial, patients with metastatic TNBC received anti-EGFR antibody cetuximab (400 mg/m(2) load then 250 mg/m(2) per week intravenously [IV]) alone, with carboplatin (area under the curve of 2, once per week IV) added after progression or as concomitant therapy from the beginning. Response rate (RR) was the primary end point; others included time to progression (TTP), overall survival (OS), and toxicity. Embedded correlative studies included molecular subtyping on archival tissue. Fresh tumor tissue before and after 7 to 14 days of therapy was used for microarray analyses exploring EGFR pathway activity and inhibition. RESULTS: In 102 patients with TNBC, RRs were 6% (two of 31) to cetuximab and 16% (four of 25) to cetuximab plus carboplatin after progression. RR to those treated from the beginning with cetuximab plus carboplatin was 17% (12 of 71); 31% of patients responded or had prolonged disease stabilization. The cetuximab plus carboplatin regimen was well tolerated, but both TTP and OS were short at 2.1 months (95% CI, 1.8 to 5.5 months) and 10.4 months (95% CI, 7.7 to 13.1 months), respectively. Of 73 patients with archival tissue for analysis, 74% had basal-like molecular subtype. Sixteen patients had tumor biopsies before and 1 week after therapy; genomic patterns of the EGFR pathway showed activation in 13 and inhibition by therapy in five. CONCLUSION: Despite strong preclinical data, combination cetuximab plus carboplatin in metastatic TNBC produced responses in fewer than 20% of patients. EGFR pathway analysis showed that most TNBCs involved activation. However, cetuximab blocked expression of the EGFR pathway in only a minority, suggesting that most had alternate mechanisms for pathway activation.

Young women with locally advanced breast cancer who achieve breast conservation after neoadjuvant chemotherapy have a low local recurrence rate.

Women with locally advanced breast cancer (LABC) who are breast conservation (BCT) candidates after neoadjuvant chemotherapy have the best long-term outcome and low local-regional recurrence (LRR) rates. However, young women are thought to have a higher risk of LRR based on historical data. This study sought to evaluate LRR rates in young women who undergo BCT after neoadjuvant chemotherapy. We identified 122 women aged 45 years or younger with American Joint Committee on Cancer (AJCC) Stage II to III breast cancer, excluding T4d, treated with neoadjuvant chemotherapy from 1991 to 2007 from a prospective, Institutional Review Board-approved, single-institution database. Data were analyzed using Fisher eExact test, Wilcoxon tests, and the Kaplan-Meier method. Median follow-up was 6.4 years. Fifty-four (44%) patients had BCT and 68 (56%) mastectomy. Forty-six per cent were estrogen receptor-positivity and 28 per cent overexpressed Her2. Mean pretreatment T size was 5.6 cm in the BCT group and 6.7 cm in the mastectomy group (P = 0.04). LRR rates were no different after BCT compared with mastectomy (13 vs 18%, P = 0.6). Higher posttreatment N stage (P < 0.001) and AJCC stage (P = 0.008) were associated with LRR but not pretreatment staging. Disease-free survival was better for patients achieving BCT, with 5-year disease-free survival rates of 82 per cent (95% CI, 69 to 90%) compared with 58 per cent (95% CI, 45 to 69%) for mastectomy (P = 0.03). Young women with LABC who undergo BCT after neoadjuvant chemotherapy appear to have similar LRR rates compared with those with mastectomy. This suggests that neoadjuvant chemotherapy may identify young women for whom BCT may have an acceptable risk of LRR.

The prognostic contribution of clinical breast cancer subtype, age, and race among patients with breast cancer brain metastases.

BACKGROUND: Brain metastases (BM) arising from triple-negative breast cancer (TNBC) portend a poor prognosis. TNBC is more common in premenopausal and African-American (AA) patients; both of these characteristics also confer a poor prognosis. In a single-institution cohort study, the authors attempted to determine whether the inferior outcome noted with TNBC brain metastases is more reflective of a higher risk population or the subtype itself. METHODS: The University of North Carolina Breast Cancer Database identified patients with BC brain metastases who were diagnosed between 1988 and 2008. BC subtype was assigned by immunohistochemistry: hormone receptor (HR) positive (+);(HR, estrogen receptor [ER]+ and/or progesterone receptor [PR]+)/human epidermal growth factor receptor 2 (HER2) negative (-), HR+/HER2+, HR-/HER2+, and TN (ER-/PR-/HER2-). Survival and disease recurrence patterns were evaluated by subtype, patient age (<40 years vs ≥40 years), and race (AA vs non-AA) using the Kaplan-Meier method and Cox regression analysis. RESULTS: Among 119 patients with BC brain metastases, 33% were AA and 31% were aged <40 years. BC subtype was confirmed in 98 patients (30% with HR+/HER2-, 21% with HR+/HER2+, 18% with HR-/HER2+, and 31% with TNBC). Survival after BM was found to be impacted by subtype (P = .002), and was shortest for patients with TNBC (0.24 years; 95% confidence interval, 0.17 years-0.48 years). There were no age-specific (P = .84) or race-specific (P = .09) differences in survival noted after brain metastases; stratification of BC subtypes by age and race revealed no difference (all, P > .1). The receipt of systemic therapy after BC brain metastases was found to be an important predictor of survival after BC brain metastases (hazard ratio, 0.29; P = .002) when adjusted for race, age, number of central nervous system lesions, and BC subtype. CONCLUSIONS: TNBC confers a high risk of death after brain metastases regardless of patient race and age, supporting the need for novel agents capable of controlling both intracranial and extracranial TNBC across all races and ages.