In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Q: Context: To provide optimal treatment of heterogeneous triple negative breast cancer (TNBC), we need biomarkers that can predict the chemotherapy response.', 'We retrospectively investigated BRCAness in 73 patients with breast cancer who had been treated with taxane- and/or anthracycline-based neoadjuvant chemotherapy (NAC). Using multiplex, ligation-dependent probe amplification on formalin-fixed core needle biopsy (CNB) specimens before NAC and surgical specimens after NAC. BRCAness status was assessed with the assessor unaware of the clinical information.', 'We obtained 45 CNB and 60 surgical specimens from the 73\xa0patients. Of the 45 CNB specimens, 17 had BRCAness (38.6% of all subtypes). Of the 23 TNBC CNB specimens, 14\xa0had BRCAness (61% of TNBC cases). The clinical response rates were significantly lower for BRCAness than for non-BRCAness tumors, both for all tumors (58.8% vs. 89.3%, P\xa0= .03) and for TNBC (50% vs. 100%, P\xa0= .02). All tumors that progressed with taxane therapy had BRCAness. Of the patients with TNBC, those with non-BRCAness cancer had pathologic complete responses significantly more often than did those with BRCAness tumors (77.8%\xa0vs. 14.3%, P\xa0= .007). After NAC, the clinical response rates were significant lower for BRCAness than for non-BRCAness tumors in all subtypes (P\xa0= .002) and in TNBC cases (P\xa0= .008). After a median follow-up of 26.4 months, 6 patients-all with BRCAness-had developed recurrence. Patients with BRCAness had shorter progression-free survival than did those with non- BRCAness (P\xa0=\xa0.049).\Question: Does bRCAness predict resistance to taxane-containing regimens in triple negative breast cancer during neoadjuvant chemotherapy?

A: Identifying BRCAness can help predict the response to taxane, and changing regimens for BRCAness TNBC might improve patient survival. A larger prospective study is needed to further clarify this issue.
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Q: Context: Transport across the blood-brain barrier (BBB) is an important mediator of beta-amyloid (Aβ) accumulation in the brain and a contributing factor in the pathogenesis of Alzheimer's disease (AD). One of the receptors responsible for the transport of Aβ in the BBB is the low density lipoprotein receptor-related protein 1 (LRP1). LRP1 is susceptible to proteolytic shedding at the cell surface, which prevents endocytic transport of ligands. Previously, we reported a strong inverse correlation between LRP1 shedding in the brain and Aβ transit across the BBB. Several proteases contribute to the ectodomain shedding of LRP1 including the α-secretase, a desintegrin and metalloproteinase domain containing protein 10 (ADAM10).", 'The role of ADAM10 in the shedding of LRP1 and Aβ BBB clearance was assessed through pharmacological inhibition of ADAM10 in an in vitro model of the BBB and through the use of ADAM10 endothelial specific knock-out mice. In addition, an acute treatment paradigm with an ADAM10 inhibitor was also tested in an AD mouse model to assess the effect of ADAM10 inhibition on LRP1 shedding and Aβbrain accumulation.', 'In the current studies, inhibition of ADAM10 reduced LRP1 shedding in brain endothelial cultures and increased Aβ42 transit across an in vitro model of the BBB. Similarly, transgenic ADAM10 endothelial knockout mice displayed lower LRP1 shedding in the brain and significantly enhanced Aβ clearance across the BBB compared to wild-type animals. Acute treatment with the ADAM10-selective inhibitor GI254023X in an AD mouse model substantially reduced brain LRP1 shedding and increased Aβ40 levels in the plasma, indicating enhanced Aβ transit from the brain to the periphery. Furthermore, both soluble and insoluble Aβ40 and Aβ42 brain levels were decreased following GI254023X treatment, but these effects lacked statistical significance.\Question: Does inhibition of ADAM10 promote the clearance of Aβ across the BBB by reducing LRP1 ectodomain shedding?

A: These studies demonstrate a role for ADAM10 in the ectodomain shedding of LRP1 in the brain and the clearance of Aβ across the BBB, which may provide a novel strategy for attenuating Aβ accumulation in the AD brain.
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Q: Context: Nonviral vectors based on polyethylenimine (PEI) usually contain an excess of PEI that is not complexed to DNA. Since unbound PEI contributes to cellular and systemic toxicity, purification of polyplexes from unbound PEI is desirable.', 'Size exclusion chromatography (SEC) was used to purify PEI polyplexes of free PEI. Transfection properties of purified polyplexes and the effect of free PEI on gene delivery were studied in vitro and in vivo after systemic application into mice.', 'SEC did not change the size and zeta-potential of polyplexes. Independent of the amount of PEI used for complex formation, purified PEI polyplexes had the same final PEI nitrogen/DNA phosphate ratio of 2.5. Notably, purified PEI polyplexes demonstrated low cellular and systemic toxicity. High transfection efficiency was achieved with purified polyplexes at high DNA concentrations (8-15 microg/ml). At low DNA concentrations (2-4 microg/ml) gene transfer with purified particles was less efficient than with polyplexes containing free PEI both in vitro and in vivo. Mechanistic studies showed that free PEI partly blocked cellular association of DNA complexes but was essential for the following intracellular gene delivery. Adding free PEI to cells treated with purified particles with a delay of up to 4 h resulted in significantly enhanced transfection efficiency compared with non-purified particles or purified particles without free PEI.\Question: Does purification of polyethylenimine polyplexes highlight the role of free polycations in gene transfer?

A:
This study presents an efficient method to remove free PEI from PEI polyplexes by SEC. Our results from transfection experiments demonstrate that free PEI substantially contributes to efficient gene expression but also mediates toxic effects in a dose-dependent manner. Purified polyplexes without free PEI have to be applied at increased concentrations to achieve high transfection levels, but exhibit a greatly improved toxicity profile.
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