IMPORTANCEApproximately 25% of patients with early-stage breast cancer who receive (neo)adjuvant chemotherapy experience a recurrence within 5 years. Improvements in therapy are greatly needed.OBJECTIVE To determine if pembrolizumab plus neoadjuvant chemotherapy (NACT) in early-stage breast cancer is likely to be successful in a 300-patient, confirmatory randomized phase 3 neoadjuvant clinical trial. DESIGN, SETTING, AND PARTICIPANTSThe I-SPY2 study is an ongoing open-label, multicenter, adaptively randomized phase 2 platform trial for high-risk, stage II/III breast cancer, evaluating multiple investigational arms in parallel. Standard NACT serves as the common control arm; investigational agent(s) are added to this backbone. Patients with ERBB2 (formerly HER2)-negative breast cancer were eligible for randomization to pembrolizumab between November 2015 and November 2016.INTERVENTIONS Participants were randomized to receive taxane-and anthracycline-based NACT with or without pembrolizumab, followed by definitive surgery. MAIN OUTCOMES AND MEASURESThe primary end point was pathologic complete response (pCR). Secondary end points were residual cancer burden (RCB) and 3-year event-free and distant recurrence-free survival. Investigational arms graduated when demonstrating an 85% predictive probability of success in a hypothetical confirmatory phase 3 trial. RESULTSOf the 250 women included in the final analysis, 181 were randomized to the standard NACT control group (median [range] age, 47 [24.77] years). Sixty-nine women (median [range] age, 50 [27-71] years) were randomized to 4 cycles of pembrolizumab in combination with weekly paclitaxel followed by AC; 40 hormone receptor (HR)-positive and 29 triple-negative. Pembrolizumab graduated in all 3 biomarker signatures studied. Final estimated pCR rates, evaluated in March 2017, were 44% vs 17%, 30% vs 13%, and 60% vs 22% for pembrolizumab vs control in the ERBB2-negative, HR-positive/ERBB2-negative, and triple-negative cohorts, respectively. Pembrolizumab shifted the RCB distribution to a lower disease burden for each cohort evaluated. Adverse events included immune-related endocrinopathies, notably thyroid abnormalities (13.0%) and adrenal insufficiency (8.7%). Achieving a pCR appeared predictive of long-term outcome, where patients with pCR following pembrolizumab plus chemotherapy had high event-free survival rates (93% at 3 years with 2.8 years' median follow-up).CONCLUSIONS AND RELEVANCE When added to standard neoadjuvant chemotherapy, pembrolizumab more than doubled the estimated pCR rates for both HR-positive/ERBB2negative and triple-negative breast cancer, indicating that checkpoint blockade in women with early-stage, high-risk, ERBB2-negative breast cancer is highly likely to succeed in a phase 3 trial. Pembrolizumab was the first of 10 agents to graduate in the HR-positive/ERBB2-negative signature.

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Purpose: The G 1 -S checkpoint of the cell cycle is frequently dysregulated in breast cancer. Palbociclib (PD0332991) is an oral inhibitor of CDK4/6. Based upon preclinical/phase I activity, we performed a phase II, single-arm trial of palbociclib in advanced breast cancer.Experimental Design: Eligible patients had histologically confirmed, metastatic breast cancer positive for retinoblastoma (Rb) protein and measureable disease. Palbociclib was given at 125 mg orally on days 1 to 21 of a 28-day cycle. Primary objectives were tumor response and tolerability. Secondary objectives included progression-free survival (PFS) and assessment of Rb expression/localization, KI-67, p16 loss, and CCND1 amplification.Results: Thirty-seven patients were enrolled; 84% hormonereceptor (HR) þ /Her2 À

The diagnosis and management of breast cancer are undergoing a paradigm shift from a one-size-fits-all approach to an era of personalized medicine. Sophisticated diagnostics, including molecular imaging and genomic expression profiles, enable improved tumor characterization. These diagnostics, combined with newer surgical techniques and radiation therapies, result in a collaborative multidisciplinary approach to minimizing recurrence and reducing treatment-associated morbidity. This article reviews the diagnosis and treatment of breast cancer, including screening, staging, and multidisciplinary management. In this article, we address current approaches to breast cancer diagnosis and management. These approaches include screening recommendations; diagnostic imaging and pathologic assessment to determine the extent of disease; surgery and radiation treatment; and an array of systemic options, such as chemotherapy, endocrine therapy, and targeted agents (Fig. 1). We also consider the potential contribution of functional imaging to a new era of personalized, tumor-specific treatment. BREAST CANCER DIAGNOSIS ScreeningBreast cancer is generally diagnosed through either screening or a symptom (e.g., pain or a palpable mass) that prompts a diagnostic exam. Screening of healthy women is associated with the detection of tumors that are smaller, have lower odds of metastasis, are more amenable to breast-conserving and limited axillary surgery, and are less likely to require chemotherapy (1). This scenario translates to reduced treatment-related morbidity and improved survival.The only screening modality proven to reduce breast cancerspecific mortality is mammography (2). Screening mammography leads to a 19% overall reduction in breast cancer mortality (3), with less benefit for women in their 40s (15%) and more benefit for women in their 60s (32%). As a result, screening mammography is recommended by the American Cancer Society beginning at age 45, or sooner depending on individual preference. The potential negative aspects of screening mammography are falsepositive examinations, radiation exposure, pain, anxiety, and other negative psychologic effects. Mammography has a 61% chance of a false-positive result over a 10-y period for women commencing screening between the ages of 40 y and 50 y. The risk of a falsepositive examination decreases with older age (3). The US Preventative Task Force cited a 15% breast cancer-related mortality reduction for women who were 39-49 y old and a mortality-related benefit from screening between ages 39 and 69. However, the task force released a controversial report recommending only biennial screening mammography for women who were 50-74 y old, excluding younger women to a large extent because of the high rate of false-positive results (4). Mammography for women in the 39-to 49-y-old age group was recommended if indicated after the use of a risk-based model of breast cancer screening, such as the models developed by the Population-Based Research Optimizing Screening Through Personalized Re...