Faculty Bibliography

PURPOSE/OBJECTIVE:The functional composition and diversity of the gut microbiome may affect breast cancer risk by modulation of systemic sex hormones. Gut bacteria with β-glucuronidase enzymatic activity may deconjugate estrogens, leading to increased estrogen reabsorption into the circulation thereby increasing breast cancer risk. We investigated the relationship between the gut bacterial microbiome and endogenous estrogens and related sex hormones in women with hormone receptor-positive breast cancer compared to healthy control women. The goal was to determine if the estrobolome (i.e., bacteria capable of modulating the body's circulated estrogen levels) was altered in those with breast cancer compared with controls. METHODS:In this prospective case-control study, postmenopausal women (n = 46) with newly diagnosed stage I-III estrogen and/or progesterone receptor-positive breast cancer were compared with healthy postmenopausal female controls (n = 22). Bacterial composition of the gut microbiome was analyzed by 16S rRNA gene sequencing from fecal specimens. Plasma and urine sex hormones were quantified using high-performance liquid chromatography/mass spectrometry. RESULTS:We found evidence that some β-glucuronidase positive bacteria were enriched in the breast cancer patients compared to healthy controls, whereas abundances of some β-glucuronidase negative bacteria were reduced. There was also a wide distribution of prevalence of β-glucuronidase positive taxa in both breast cancer subjects and healthy controls, as well as higher probability of breast cancer subjects having higher average β-glucuronidase levels. Significant differences were found in endogenous progesterone levels between the breast cancer patients and healthy controls. CONCLUSION/CONCLUSIONS:This pilot study showed differences in the gut microbiome and endogenous progesterone levels among postmenopausal women with hormone receptor-positive breast cancer compared with healthy controls. These interesting findings may have implications for breast cancer risk and prevention and warrant further exploration.

Breast tumors harbor dynamic microenvironments, with multiple immune cell types playing opposing roles during tumor progression and/or response to therapy. Tumor-associated macrophages promote mammary tumorigenesis, whereas the role of mammary tissue macrophages (MTMs) remains incompletely understood. High-dimensional immunostaining of murine mammary tumor progression revealed that MTMs were localized in the peritumoral stroma and associated with eosinophils, which were previously shown to facilitate antitumor T cell responses. The depletion of MTMs accelerated tumorigenesis in both spontaneous and orthotopically transplanted mammary tumor models. Upon induction of a productive antitumor response via the depletion of regulatory T cells, MTMs assumed an alternatively activated state and expressed eotaxins, thereby attracting eosinophils to peritumoral regions. MTMs expressed the receptor for the alarmin IL-33, which induced both MTM activation and eosinophil recruitment. These results suggest that MTMs can sense IL-33 and recruit eosinophils to facilitate antitumor immunity, a mechanism that may operate during tumor progression and be further enhanced during productive antitumor responses.

BACKGROUND:Toll-like receptor (TLR) agonists and radiation therapy hold promise for cancer immunotherapy. We conducted a phase I/II trial combining topical imiquimod (IMQ, a TLR-7 agonist) and local radiotherapy (RT) in patients with metastatic breast cancer accompanied by longitudinal transcriptional analysis of tumor biopsies. METHODS:The primary objective of the trial (NCT01421017) was to assess systemic responses by immune-related response criteria (irRC) after an 8-week cycle of topical IMQ and concurrent local RT (cohort 1). An amendment to the trial added two cohorts, both received one dose of cyclophosphamide (CTX) administered 1 week before study treatment initiation, IMQ/RT/CTX (cohort 2) and RT/CTX control (cohort 3). Cutaneous metastases were prospectively assigned to treatment with IMQ and RT (area A) or IMQ alone (area B). Secondary objectives were safety (Common Terminology Criteria for Adverse Events criteria) and local response in skin metastases. In all IMQ cohorts, tumors were biopsied before treatment and at 2 and 3 weeks. RESULTS:31 patients were enrolled (n=12, n=12, and n=7, in cohort 1, 2, and 3, respectively), with 4 out of 24 patients in the IMQ cohorts showing systemic tumor responses (two complete responses (CR) and two partial responses (PR)). No objective responses were observed in the seven patients enrolled in the control arm (RT alone). The treatment was well-tolerated, no grade 4-5 treatment-related adverse events occurred and grade 3 AEs were manageable (anemia, local pain, and local ulceration, n=1 each). Local objective responses were observed in 19/24 (9 CR and 10 PR) and 5/24 (5 PR) in areas treated with combined IMQ-RT and IMQ alone, respectively (p<0.001). All 24 patients treated with IMQ underwent serial biopsies, and 84 samples yielded sufficient material for transcriptional analyses. These revealed that the presence of a T-helper 1 functional orientation of the tumor microenvironment paralleled by the downregulation of DNA-repair genes was associated with CR after IMQ+RT, but not after IMQ alone. No post-treatment activation of immune-effector functions was observed in stable and progressing lesions. CONCLUSIONS:Our findings support the safety and clinical efficacy of combining topical IMQ with local RT for recurrent breast cancer, with evidence of local and occasional systemic antitumor activity. TRIAL REGISTRATION NUMBER/BACKGROUND:NCT01421017.

Leptomeningeal carcinomatosis (LC) is a severe complication of metastatic breast cancer (mBC), with rising incidence. The prognosis for patients with LC has been poor, with a median overall survival of approximately four months. However, recent therapeutic advances, in particular the introduction of trastuzumab deruxtecan have dramatically changed the landscape of CNS metastases and improved outcomes. Here, we present the case of a 42-year-old woman with recurrent HER2+ breast cancer who developed extensive LC after multiple lines of treatment. Despite progressive disease, the patient exhibited a sustained response to trastuzumab deruxtecan, a novel antibody-drug conjugate (ADC), for 15 months, which was further extended by adding tucatinib. This case underscores the potential of ADCs, like trastuzumab deruxtecan, in controlling both brain metastases and leptomeningeal disease, offering hope for prolonged survival in patients with aggressive HER2+ mBC. Additionally, we highlight the evolving role of clinical trials, molecular profiling, and interdisciplinary care in managing this challenging condition. Ongoing trials continue to investigate new therapeutic options for HER2+ mBC with CNS involvement, promising to further improve outcomes and quality of life for patients facing this devastating disease.

IMPORTANCE/UNASSIGNED:The absolute benefit of chemotherapy for all patients with stage I triple-negative breast cancer (TNBC) is unclear, and biomarkers are not currently available for selecting patients with an excellent outcome for whom neoadjuvant or adjuvant chemotherapy may have negligible benefit. High levels of stromal tumor-infiltrating lymphocytes (sTILs) are associated with favorable survival in TNBC, but data solely in stage I TNBC are lacking. OBJECTIVE/UNASSIGNED:To examine the outcomes of patients of all ages with stage I TNBC solely and who received neither neoadjuvant nor adjuvant chemotherapy, according to centrally reviewed sTIL levels at prespecified cutoffs. DESIGN, SETTING, AND PARTICIPANTS/UNASSIGNED:This cohort study used the Netherlands Cancer Registry to identify patients diagnosed with stage I TNBC between January 1, 2005, and December 31, 2015, who were not treated with chemotherapy. Only patients who did not receive neoadjuvant and/or adjuvant chemotherapy were selected. The clinical data were matched with their corresponding pathology data provided by the Dutch Pathology Registry. Data analysis was performed between February and October 2023. MAIN OUTCOMES AND MEASURES/UNASSIGNED:The primary end point was breast cancer-specific survival (BCSS) at 5, 10, and 15 years for the prespecified sTIL level cutoffs of 30%, 50%, and 75%. Hematoxylin and eosin-stained slides were used for central review of histologic subtype, grade, and lymphovascular invasion. The International Immuno-Oncology Biomarker Working Group guidelines were used to score the sTIL levels; these levels were determined for 1041 patients. RESULTS/UNASSIGNED:Of a total of 4511 females with stage I TNBC, patients who were not treated with chemotherapy were selected and tissue blocks requested; sTILs were scored in 1041 patients (mean [SD] age at diagnosis, 64.4 [11.1] years, median follow-up 11.4 [95% CI, 10.9-11.9] years) who were included in the analyses.. Most tumors (952 [91.5%]) were invasive carcinomas of nonspecial histologic subtype. Most patients (548 [52.6%]) had pT1cN0 tumors. Median (range) sTIL level was 5% (1%-99%). A total of 775 patients (74.4%) had sTIL levels below 30%, 266 (25.6%) had 30% or greater, 203 (19.5%) had 50% or greater, and 141 (13.5%) had 75% or greater. Patients with pT1abN0 tumors had a more favorable outcome vs patients with pT1cN0 tumors, with a 10-year BCSS of 92% (95% CI, 89%-94%) vs 86% (95% CI, 82%-89%). In the overall cohort, sTIL levels of at least 30% were associated with better BCSS compared with sTIL levels less than 30% (96% and 87%, respectively; hazard ratio [HR], 0.45; 95% CI, 0.26-0.77). High sTIL levels of 50% or greater were associated with a better outcome than low sTIL levels of less than 50% (HR, 0.27; 95% CI, 0.10-0.74) in patients with pT1C tumors, with a 10-year BCSS of 95% increasing to 98% with sTIL levels of 75% or greater. CONCLUSIONS AND RELEVANCE/UNASSIGNED:Results of this study showed that patients with stage I TNBC and high level of sTILs who did not receive neoadjuvant or adjuvant chemotherapy had excellent 10-year BCSS. The findings further support the role of sTILs as integral biomarkers in prospective clinical trials of therapy optimization for this patient population.

PURPOSE/OBJECTIVE:The time required for in-clinic drug administration can substantially affect breast cancer patients' quality of life. Subcutaneous (SC) drug administration, as opposed to intravenous (IV), may reduce this time commitment. This study sought to estimate the difference in time burden between IV and SC administration of trastuzumab and pertuzumab (HP). METHODS:SC). RESULTS:< .0001). CONCLUSION/CONCLUSIONS:SC administration of HP shortened patient time burden by approximately 1 hour. SC drug administration can facilitate faster workflows for health care professionals and improve patients' breast cancer treatment experience.

PURPOSE/OBJECTIVE:Although ongoing studies are assessing the efficacy of new systemic therapies for patients with triple negative breast cancer (TNBC), the overwhelming majority have excluded patients with brain metastases (BM). Therefore, we aim to characterize systemic therapies and outcomes in a cohort of patients with TNBC and BM managed with stereotactic radiosurgery (SRS) and delineate predictors of increased survival. METHODS:We used our prospective patient registry to evaluate data from 2012 to 2023. We included patients who received SRS for TNBC-BM. A competing risk analysis was conducted to assess local and distant control. RESULTS:Forty-three patients with 262 tumors were included. The median overall survival (OS) was 16 months (95% CI 13-19 months). Predictors of increased OS after initial SRS include Breast GPA score > 1 (p < 0.001) and use of immunotherapy such as pembrolizumab (p = 0.011). The median time on immunotherapy was 8 months (IQR 4.4, 11.2). The median time to new CNS lesions after the first SRS treatment was 17 months (95% CI 12-22). The cumulative rate for development of new CNS metastases after initial SRS at 6 months, 1 year, and 2 years was 23%, 40%, and 70%, respectively. Thirty patients (70%) underwent multiple SRS treatments, with a median time of 5 months (95% CI 0.59-9.4 months) for the appearance of new CNS metastases after second SRS treatment. CONCLUSIONS:TNBC patients with BM can achieve longer survival than might have been previously anticipated with median survival now surpassing one year. The use of immunotherapy is associated with increased median OS of 23 months.

PURPOSE/OBJECTIVE:Our institution was an early adopter of 5-fraction accelerated partial breast irradiation (ABPI) to treat women with early-stage breast cancer. This study reports long-term oncologic and cosmetic outcomes. METHODS:We included patients receiving APBI 600 cGy × 5 fx delivered every other day or every day between 2010 and 2022. Logistic regression models were used to identify factors associated with development of late toxicities, clinician, and patient-rated cosmesis. Kaplan-Meier methodology was used to calculate overall survival (OS), disease-free survival (DFS), and locoregional recurrence-free survival (LR-RFS). RESULTS:442 patients received APBI either daily (56%) or every other day (44%) in the prone position (92%). At a median follow-up of 48 months (range: 5.96-155 months), 12 (2.7%) patients developed a local recurrence (LR). Out of 258 patients with > 3-month toxicity data available, the most common late grade ≥ 2 adverse event was breast fibrosis (6.2%). On multivariate analysis, daily APBI treatment (vs every other day) did not correlate with an increased risk of any late grade ≥ 2 toxicity though it did correlate with a lower risk of any late grade ≥ 2 fibrosis. Overall, at a median follow-up of 80 months, the rates of good-excellent physician and patient-rated cosmesis were 95% and 85%, respectively, with no difference between patients treated on consecutive vs. every other day. On multivariate analysis, patients who did not receive any adjuvant therapy were at increased risk of developing a LR. Five-year OS, LRFS, and DFS were 97.2%, 97.7%, and 89.5%, respectively. CONCLUSIONS:Five-fraction APBI delivered primarily in the prone position either daily or every other day was effective with low rates of local recurrence, minimal toxicity, and excellent cosmesis at long-term follow-up.

Recent advances in the field of immuno-oncology have brought transformative changes in the management of cancer patients. The immune profile of tumours has been found to have key value in predicting disease prognosis and treatment response in various cancers. Multiplex immunohistochemistry and immunofluorescence have emerged as potent tools for the simultaneous detection of multiple protein biomarkers in a single tissue section, thereby expanding opportunities for molecular and immune profiling while preserving tissue samples. By establishing the phenotype of individual tumour cells when distributed within a mixed cell population, the identification of clinically relevant biomarkers with high-throughput multiplex immunophenotyping of tumour samples has great potential to guide appropriate treatment choices. Moreover, the emergence of novel multi-marker imaging approaches can now provide unprecedented insights into the tumour microenvironment, including the potential interplay between various cell types. However, there are significant challenges to widespread integration of these technologies in daily research and clinical practice. This review addresses the challenges and potential solutions within a structured framework of action from a regulatory and clinical trial perspective. New developments within the field of immunophenotyping using multiplexed tissue imaging platforms and associated digital pathology are also described, with a specific focus on translational implications across different subtypes of cancer. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.