Faculty Bibliography

BACKGROUND:Growing evidence suggests that the tumor immune microenvironment influences breast cancer development and prognosis. Density of tumor-infiltrating lymphocytes (TILs) within invasive breast cancer is correlated with response to therapy, especially in triple-negative disease. The clinical relevance and outcomes of TILs within ductal carcinoma in situ (DCIS) are less understood. METHODS:Our institutional database of 668 patients with pure DCIS from 2010 to 2018 was queried. TILs were evaluated by International TILs Working Group guidelines. Percentage of TILs was assessed from the densest focus (hotspot) in one high-power field of stroma touching the basement membrane. Statistical methods included cluster analyses (to define sparse versus dense TILs), logistic, and Cox regression models. RESULTS:Sixty-nine patients with DCIS and TILs were evaluated, of whom 54 (78%) were treated by breast-conserving surgery. Thirteen (19%) patients had ipsilateral recurrence. Each recurrence (n = 13) was matched to four controls (n = 56) based on date of surgery. Median follow-up was 6.7 years. TILs were defined as sparse (< 45%) or dense (≥ 45%). Dense TILs were associated with younger age (p = 0.045), larger tumor size (p < 0.001), high nuclear grade (p = 0.010), comedo histology (p = 0.033), necrosis (p = 0.027), estrogen receptor (ER) negativity (p = 0.037), and ipsilateral recurrence (p = 0.001). Nine patients with dense TILs had mean time to recurrence of 73.5 months compared with four patients with sparse TILs with mean time to recurrence of 97.9 months (p = 0.003). CONCLUSIONS:Dense TILs were significantly associated with age, tumor size, nuclear grade, comedo histology, necrosis, and ER status and was a significant predictor of recurrence in patients with pure DCIS.

Metaplastic breast carcinomas (MPBC) are rare, aggressive and relatively chemorefractory tumors with a high unmet need. While most are "triple negative" and lack expression of estrogen, progesterone and HER2 receptors, MPBC are associated with worse outcomes compared to conventional triple negative invasive tumors. MPBCs are genetically heterogeneous and harbor somatic mutations, most frequently in TP53, PIK3CA and PTEN, with emerging studies suggesting a role for novel targeted therapies. These tumors have also been associated with overexpression of PD-L1 and tumor-infiltrating lymphocytes suggesting an endogenous immune response and therefore a rationale for treatment with immunotherapies. Here, we focus on therapeutic options for this difficult to treat breast cancer subtype and encourage physicians to consider targeted therapies/immunotherapies as part of ongoing clinical trials.

Importance/UNASSIGNED:There is tremendous interest in using immunotherapy to treat breast cancer, as evidenced by the more than 290 clinical trials ongoing at the time of this narrative review. The objective of this review is to describe the current status of immunotherapy in breast cancer, highlighting its potential in both early-stage and metastatic disease. Observations/UNASSIGNED:After searching ClinicalTrials.gov on April 24, 2018, and PubMed up to June 30, 2018, to identify breast cancer immunotherapy trials, we found that immune checkpoint blockade (ICB) is the most investigated form of immunotherapy in breast cancer. Use of ICB as monotherapy has achieved objective responses in patients with breast cancer, with higher rates seen when administered in earlier lines of therapy. For responding patients, those responses are durable. More recent data suggest clinical efficacy when ICB is given in combination with chemotherapy. Ongoing studies are evaluating combination strategies pairing ICB with additional chemotherapeutic agents, targeted therapy, vaccines, and local ablative therapies to enhance response. To date, robust predictive biomarkers for response to ICB have not been established. Conclusions and Relevance/UNASSIGNED:It is anticipated that combination therapy strategies will be the way forward for immunotherapy in breast cancer, with an improved understanding of tumor, microenvironment, and host factors informing treatment combination decisions. Thoughtful study design incorporating appropriate end points and correlative studies will be critical in identifying optimal strategies for enhancing the immune response against breast tumors.

Imiquimod is a topical toll-like-receptor-7 agonist currently used for treating basal cell carcinoma. Recently, imiquimod has demonstrated tumor regression in melanoma and breast cancer skin metastases. However, the molecular perturbations induced by imiquimod in breast cancer metastases have not been previously characterized. Here, we describe transcriptomic profiles associated with responsiveness to imiquimod in breast cancer skin metastases. Baseline and post-treatment tumor samples from patients treated with imiquimod in a clinical trial were profiled using Nanostring technology. Through an integrative analytic pipeline, we showed that tumors from patients who achieved a durable clinical response displayed a permissive microenvironment, substantiated by the upregulation of transcripts encoding for molecules involved in leukocyte adhesion and migration, cytotoxic functions, and antigen presentation. In responding patients, Imiquimod triggered a strong T-helper-1 (Th-1)/cytotoxic immune response, characterized by the coordinated upregulation of Th-1 chemokines, migration of Th-1 and cytotoxic T cells into the tumor, and activation of immune-effector functions, ultimately mediating tumor destruction. In conclusion, we have shown that topical imiquimod can induce a robust immune response in breast cancer metastases, and this response is more likely to occur in tumors with a pre-activated microenvironment. In this setting, imiquimod could be utilized in combination with other targeted immunotherapies to increase therapeutic efficacy.

Background/UNASSIGNED:Standard first-line treatment for metastatic triple-negative breast cancer (mTNBC) is chemotherapy. However, outcomes are poor, and new treatment options are needed. In cohort B of the phase 2 KEYNOTE-086 study, we evaluated pembrolizumab as first-line therapy for patients with PD-L1-positive mTNBC. Patients and methods/UNASSIGNED:Eligible patients had centrally confirmed mTNBC, no prior systemic anticancer therapy for metastatic disease, measurable disease at baseline per RECIST v1.1 by central review, no radiographic evidence of central nervous system metastases, and a tumor PD-L1 combined positive score ≥1. Patients received pembrolizumab 200 mg intravenously every 3 weeks for up to 2 years. The primary endpoint was safety. Secondary end points included objective response rate (ORR), disease control rate (DCR; percentage of patients with complete or partial response or stable disease for ≥24 weeks), duration of response, progression-free survival (PFS) and overall survival (OS). Results/UNASSIGNED:All 84 patients enrolled were women, and 73 (86.9%) received prior (neo)adjuvant therapy. Fifty-three (63.1%) patients had treatment-related adverse events (AEs), including 8 patients (9.5%) with grade 3 severity; no patients experienced grade 4 AEs or died because of treatment-related AEs. Four patients had a complete response and 14 had a partial response, for an ORR of 21.4% (95% CI, 13.9-31.4). Of the 13 patients with stable disease, 2 had stable disease lasting ≥24 weeks, for a DCR of 23.8% (95% CI, 15.9-34.0). At data cutoff, 8 of 18 (44.4%) responses were ongoing, and median duration of response was 10.4 months (range, 4.2-19.2+). Median PFS was 2.1 months (95% CI, 2.0-2.2) and median OS was 18.0 months (95% CI, 12.9-23.0). Conclusions/UNASSIGNED:Pembrolizumab monotherapy had a manageable safety profile and showed durable antitumor activity as first-line therapy for patients with PD-L1-positive mTNBC. Clinical trial registration/UNASSIGNED:ClinicalTrials.gov, NCT02447003.

Importance/UNASSIGNED:The humanized monoclonal antibody atezolizumab targets programmed death-ligand 1 and has demonstrated durable single-agent activity in a subset of metastatic triple-negative breast cancers. To extend the observed activity, combinatorial approaches are being tested with standard cytotoxic chemotherapies known to induce immunogenic tumor cell death. Objective/UNASSIGNED:To examine the safety, tolerability, and preliminary clinical activity of atezolizumab plus nab-paclitaxel in metastatic triple-negative breast cancers. Design, Setting, and Participants/UNASSIGNED:This phase 1b multicohort study enrolled 33 women with stage IV or locally recurrent triple-negative breast cancers and 0 to 2 lines of prior chemotherapy in the metastatic setting from December 8, 2014, to April 30, 2017, at 11 sites in the United States. The median follow-up was 24.4 months (95% CI, 22.1-28.8 months). Interventions/UNASSIGNED:Patients received concurrent intravenous atezolizumab and intravenous nab-paclitaxel (minimum 4 cycles). Main Outcomes and Measures/UNASSIGNED:The primary end point was safety and tolerability. Secondary end points included best overall response rate by Response Evaluation Criteria in Solid Tumors, version 1.1; objective response rate; duration of response; disease control rate; progression-free survival; overall survival; and biomarker analyses. Results/UNASSIGNED:The 33 women had a median age of 55 years (range, 32-84 years) and received 1 or more doses of atezolizumab. All patients (100%) experienced at least 1 treatment-related adverse event, 24 patients (73%) experienced grade 3/4 adverse events, and 7 patients (21%) had grade 3/4 adverse events of special interest. No deaths were related to study treatment. The objective response rate was 39.4% (95% CI, 22.9%-57.9%), and the median duration of response was 9.1 months (95% CI, 2.0-20.9 months). The disease control rate was 51.5% (95% CI, 33.5%-69.2%). Median progression-free survival and overall survival were 5.5 months (95% CI, 5.1-7.7 months) and 14.7 months (95% CI, 10.1-not estimable), respectively. Concurrent nab-paclitaxel neither significantly changed biomarkers of the tumor immune microenvironment (programmed death-ligand 1, tumor-infiltrating lymphocytes, CD8) nor impaired atezolizumab systemic immune activation (expansion of proliferating CD8+ T cells, increase of CXCL10 chemokine). Conclusions and Relevance/UNASSIGNED:In this phase 1b trial for metastatic triple-negative breast cancers, the combination of atezolizumab plus nab-paclitaxel had a manageable safety profile. Antitumor responses were observed, including in patients previously treated with a taxane. Trial Registration/UNASSIGNED:ClinicalTrials.gov identifier: NCT01633970.

Background/UNASSIGNED:Treatment options for previously treated metastatic triple-negative breast cancer (mTNBC) are limited. In cohort A of the phase 2 KEYNOTE-086 study, we evaluated pembrolizumab as second or later line of treatment for patients with mTNBC. Patients and methods/UNASSIGNED:Eligible patients had centrally confirmed mTNBC, ≥1 systemic therapy for metastatic disease, prior treatment with anthracycline and taxane in any disease setting, and progression on or after the most recent therapy. Patients received pembrolizumab 200 mg intravenously every 3 weeks for up to 2 years. Primary endpoints were objective response rate (ORR) in the total and PD-L1-positive populations, and safety. Secondary endpoints included duration of response, disease control rate (DCR; percentage of patients with complete or partial response or stable disease for ≥24 weeks), progression-free survival (PFS), and overall survival (OS). Results/UNASSIGNED:All enrolled patients (N=170) were women, 61.8% had PD-L1-positive tumors, and 43.5% had received ≥3 previous lines of therapy for metastatic disease. ORR (95% CI) was 5.3% (2.7-9.9) in the total and 5.7% (2.4-12.2) in the PD-L1-positive populations. DCR (95% CI) was 7.6% (4.4-12.7) and 9.5% (5.1-16.8), respectively. Median duration of response was not reached in the total (range, 1.2+-21.5+) and in the PD-L1-positive (range, 6.3-21.5+) populations. Median PFS was 2.0 months (95% CI, 1.9-2.0), and the 6-month rate was 14.9%. Median OS was 9.0 months (95% CI, 7.7-11.2), and the 6-month rate was 69.1%. Treatment-related adverse events (AEs) occurred in 103 (60.6%) patients, including 22 (12.9%) with grade 3 or 4 AEs. There were no deaths due to AEs. Conclusions/UNASSIGNED:Pembrolizumab monotherapy demonstrated durable antitumor activity in a subset of patients with previously treated mTNBC and had a manageable safety profile. Clinical trial registration/UNASSIGNED:ClinicalTrials.gov, NCT02447003.

BACKGROUND:For primary triple-negative breast cancer (TNBC) treated with neoadjuvant chemotherapy (NAC), higher pretreatment tumor-infiltrating lymphocytes (TILs) correlates with increased pathologic complete response (pCR) rates, and improved survival. We evaluated the added prognostic value of residual disease (RD) TILs to residual cancer burden (RCB) in predicting survival post-NAC. PATIENTS AND METHODS:We combined four TNBC NAC patient cohorts who did not achieve pCR. RD TILs were investigated for associations with recurrence-free survival (RFS), and overall survival (OS) using Cox models with stromal TILs as a continuous variable (per 10% increment). The likelihood ratio test was used to evaluate added prognostic value of RD TILs. RESULTS:A total of 375 RD TNBC samples were evaluable for TILs and RCB. The median age was 50 years, with 62% receiving anthracycline/taxane chemotherapy. The RCB class after NAC was 11%, 50%, and 39% for I, II, and III, respectively. The median RD TIL level was 20% (IQR 10-40). There was a positive correlation between RD TIL levels and CD8+ T-cell density (ρ = 0.41). TIL levels were significantly lower with increasing post-NAC tumor (P = 0.005), nodal stage (P = 0.032), but did not differ by RCB class (P = 0.84). Higher RD TILs were significantly associated with improved RFS (HR: 0.86; 95% CI 0.79-0.92; P < 0.001), and improved OS (HR: 0.87; 95% CI 0.80-0.94; P < 0.001), and remained significant predictors in multivariate analysis (RFS P = 0.032; OS P = 0.038 for OS). RD TILs added significant prognostic value to multivariate models including RCB class (P < 0.001 for RFS; P = 0.021 for OS). The positive prognostic effect of RD TILs significantly differed by RCB class for RFS (PInt=0.003) and OS (PInt=0.008) with a greater magnitude of positive effect observed for RCB class II than class III. CONCLUSIONS:TIL levels in TNBC RD are significantly associated with improved RFS and OS and add further prognostic information to RCB class, particularly in RCB class II.

PURPOSE/OBJECTIVE:The aim of the current study was to conduct a pooled analysis of studies that have investigated the prognostic value of tumor-infiltrating lymphocytes (TILs) in early-stage triple negative breast cancer (TNBC). METHODS:Participating studies had evaluated the percentage infiltration of stromally located TILs (sTILs) that were quantified in the same manner in patient diagnostic samples of early-stage TNBC treated with anthracycline-based chemotherapy with or without taxanes. Cox proportional hazards regression models stratified by trial were used for invasive disease-free survival (iDFS; primary end point), distant disease-free survival (D-DFS), and overall survival (OS), fitting sTILs as a continuous variable adjusted for clinicopathologic factors. RESULTS:, 48.5 OS; P < .001). Each 10% increment in sTILs corresponded to an iDFS hazard ratio of 0.87 (95% CI, 0.83 to 0.91) for iDFS, 0.83 (95% CI, 0.79 to 0.88) for D-DFS, and 0.84 (95% CI, 0.79 to 0.89) for OS. In node-negative patients with sTILs ≥ 30%, 3-year iDFS was 92% (95% CI, 89% to 98%), D-DFS was 97% (95% CI, 95% to 99%), and OS was 99% (95% CI, 97% to 100%). CONCLUSION/CONCLUSIONS:This pooled data analysis confirms the strong prognostic role of sTILs in early-stage TNBC and excellent survival of patients with high sTILs after adjuvant chemotherapy and supports the integration of sTILs in a clinicopathologic prognostic model for patients with TNBC. This model can be found at www.tilsinbreastcancer.org .