Cytotoxic chemotherapy is an effective treatment for invasive breast cancer. However, experimental studies in mice also suggest pro-metastatic effects of chemotherapy. Primary tumours release extracellular vesicles (EVs), including exosomes, that can facilitate the seeding and growth of metastatic cancer cells in distant organs, but the effects of chemotherapy on tumour-derived EVs remain unclear. Here we show that two classes of cytotoxic drugs broadly employed in pre-operative (neoadjuvant) breast cancer therapy, taxanes and anthracyclines, elicit tumour-derived EVs with enhanced pro-metastatic capacity. Chemotherapy-elicited EVs are enriched in annexin-A6 (ANXA6), a Ca2+-dependent protein that promotes NF-kB-dependent endothelial cell activation, Ccl2 induction, and Ly6C+CCR2+ monocyte expansion in the pulmonary pre-metastatic niche to facilitate the establishment of lung metastasis. Genetic inactivation of Anxa6 in cancer cells, or Ccr2 in host cells, blunts the pro-metastatic effects of chemotherapy-elicited EVs. ANXA6 is detected, and potentially enriched, in the circulating EVs of breast cancer patients undergoing neoadjuvant chemotherapy.

Purpose:While various studies have highlighted the prognostic significance of pathologic complete response (pCR) after neoadjuvant chemotherapy (NAT), the impact of additional adjuvant therapy after pCR is not known.Experimental Design:PubMed was searched for studies with NAT for breast cancer and individual patient-level data was extracted for analysis using plot digitizer software. HRs, with 95% probability intervals (PI), measuring the association between pCR and overall survival (OS) or event-free survival (EFS), were estimated using Bayesian piece-wise exponential proportional hazards hierarchical models including pCR as predictor.Results:Overall, 52 of 3,209 publications met inclusion criteria, totaling 27,895 patients. Patients with a pCR after NAT had significantly better EFS (HR = 0.31; 95% PI, 0.24–0.39), particularly for triple-negative (HR = 0.18; 95% PI, 0.10–0.31) and HER2+ (HR = 0.32; 95% PI, 0.21–0.47) disease. Similarly, pCR after NAT was also associated with improved survival (HR = 0.22; 95% PI, 0.15–0.30). The association of pCR with improved EFS was similar among patients who received subsequent adjuvant chemotherapy (HR = 0.36; 95% PI, 0.19–0.67) and those without adjuvant chemotherapy (HR = 0.36; 95% PI, 0.27–0.54), with no significant difference between the two groups (P = 0.60).Conclusions:Achieving pCR following NAT is associated with significantly better EFS and OS, particularly for triple-negative and HER2+ breast cancer. The similar outcomes with or without adjuvant chemotherapy in patients who attain pCR likely reflects tumor biology and systemic clearance of micrometastatic disease, highlighting the potential of escalation/deescalation strategies in the adjuvant setting based on neoadjuvant response.See related commentary by Esserman, p. 2771

IMPORTANCE Estrogen receptor-positive (ER+) tumors of the breast are generally highly responsive to endocrine treatment. Although endocrine therapy is the mainstay of adjuvant treatment for ER+ breast cancer, the role of endocrine therapy in the neoadjuvant setting is unclear. OBJECTIVE To evaluate the effect of neoadjuvant endocrine therapy (NET) on the response rate and the rate of breast conservation surgery (BCS) for ER+ breast cancer. DATA SOURCES Based on PRISMA guidelines, a librarian-led search of PubMed and Ovid MEDLINE was performed to identify eligible trials published from inception to May 15, 2015. The search was performed in May 2015. STUDY SELECTION Inclusion criteria were prospective, randomized, neoadjuvant clinical trials that reported response rates with at least 1 arm incorporating NET (n = 20). Two authors independently analyzed the studies for inclusion. DATA EXTRACTION AND SYNTHESIS Pooled odds ratios (ORs), 95% CIs, and P values were estimated for end points using the fixed- and random-effects statistical model. RESULTS The analysis included 20 studies with 3490 unique patients. Compared with combination chemotherapy, NET as monotherapy with aromatase inhibitors had a similar clinical response rate (OR, 1.08; 95% CI, 0.50–2.35; P = .85; n = 378), radiological response rate (OR, 1.38; 95% CI, 0.92–2.07; P = .12; n = 378), and BCS rate (OR, 0.65; 95% CI, 0.41–1.03; P = .07; n = 334) but with lower toxicity. Aromatase inhibitors were associated with a significantly higher clinical response rate (OR, 1.69; 95% CI, 1.36–2.10; P < .001; n = 1352), radiological response rate (OR, 1.49; 95% CI, 1.18–1.89; P < .001; n = 1418), and BCS rate (OR, 1.62; 95% CI, 1.24–2.12; P < .001; n = 918) compared with tamoxifen. Dual combination therapy with growth factor pathway inhibitors was associated with a higher radiological response rate (OR, 1.59; 95% CI, 1.04–2.43; P = .03; n = 355), but not clinical response rate (OR, 0.76; 95% CI, 0.54–1.07; P = .11; n = 537), compared with endocrine monotherapy. The incidence of pathologic complete response was low (<10%). CONCLUSIONS AND RELEVANCE Neoadjuvant endocrine therapy, even as monotherapy, is associated with similar response rates as neoadjuvant combination chemotherapy but with significantly lower toxicity, suggesting that NET needs to be reconsidered as a potential option in the appropriate setting. Additional research is needed to develop rational NET combinations and predictive biomarkers to personalize the optimal neoadjuvant strategy for ER+ breast cancer.

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This is the first clinical report to describe the emergence of somatic RB1 mutations after exposure to palbociclib or ribociclib, in patients with metastatic breast cancer. Further research is needed to validate these findings, identify how these mutations temporally emerge under selective pressure of CDK 4/6 inhibitor, and develop rational therapeutic strategies.

Purpose of Review: To describe the clinical role of CDK 4/6 inhibitors in hormone receptor-positive (HR+) metastatic breast cancer (HR+ MBC) as well as current controversies and evolving areas of research. Recent Findings: Palbociclib, ribociclib, and abemaciclib are each approved in combination with an aromatase inhibitor or fulvestrant for HR+ MBC. Abemaciclib is also approved as monotherapy for pre-treated patients. Key questions in the field include whether all patients with HR+ MBC should receive a CDK 4/6 inhibitor up front versus later line, impact on overall survival, role of continued CDK 4/6 blockade, mechanism of clinical resistance, and treatment sequencing. Summary: The development of CDK 4/6 inhibitors has changed the therapeutic management of HR+ MBC. Additional research is needed to determine optimal treatment sequencing, understand mechanisms governing resistance, and develop novel therapeutic strategies to circumvent or overcome clinical resistance and further improve the outcomes of patients with MBC.

Medical Education 2011:45: 867–877 OBJECTIVES  Many medical schools are currently undergoing curriculum reform. When considering the means by which students will be evaluated in a revised curriculum, the need to reduce the prevalences of depression and anxiety associated with academic stress must be weighed against the importance of academic outcomes. Pass/fail evaluation, as compared with tiered grading, is commonly presented as a means to adequately assess student performance while minimising stress and anxiety. The purpose of this literature review was to determine the impact of pass/fail grading on medical student well‐being and academic outcomes. METHODS  A systematic search was performed of the available literature published between January 1980 and August 2010, using the PubMed, Ovid Medline, Ovid PsycINFO and ERIC databases. Eligible papers assessed the impact of pass/fail grading on medical student well‐being, academic outcomes or both. Academic outcomes included but were not limited to objective measures, such as performance on the US Medical Licensing Examination, and subjective measures, such as student desirability by residency programmes. Reference lists in identified papers were searched and all identified papers were run through a citation index. RESULTS  Four papers met the inclusion criteria for both well‐being and academic outcomes. An additional five papers met the inclusion criteria for academic outcomes only. The four papers that focused on well‐being reported improvement in specified areas. No significant difference was identified in any of the five papers examining objective academic outcomes or in those papers that examined the quality of residency programmes attained. Results from two studies suggested that some programme directors believe pass/fail grading creates disadvantages for students in attaining a residency, whereas a third study yielded mixed results about its impact on residency attainment. CONCLUSIONS  Student well‐being is enhanced and objective academic performance is not adversely affected by a pass/fail evaluation system, but students’ ability to obtain a desired residency programme may be hindered by individual programme directors’ preferences for tiered grading systems. There is an overall paucity of literature on this topic and additional study is needed.

This review article reports the clinical management of potential toxicities and drug interactions seen with the use of CDK4/6 inhibitors in breast cancer, with a focus on palbociclib and ribociclib, and summarizes practical management strategies for the oncologist.