The role of B cells in antitumor immunity and their impact on emerging immunotherapies is increasingly gaining attention. B-cell effector functions include not only secretion of antibodies, but also presentation of antigens to T cells. A physiologic B-cell subset with immunostimulatory properties was described in humans, defined by a high expression of CD86 and downregulation of CD21. We used multicolor flow cytometry and IHC to elucidate abundance and spatial distribution of these antigen-presenting B cells (BAPC) in blood (peripheral blood mononuclear cells, PBMC) and tumor samples of 237 patients with cancer. Antigen-specific T-cell responses to cancer testis antigens were determined using tetramer staining and sorted BAPCs in FluoroSpot assays for selected patients. We found that BAPCs were increased in the tumor microenvironment of 9 of 10 analyzed cancer types with site-specific variation. BAPCs were not increased in renal cell carcinoma, whereas we found a systemic increase with elevated fractions in tumor-infiltrating lymphocytes (TIL) and PBMCs of patients with colorectal cancer and gastroesophageal adenocarcinoma. BAPCs were localized in lymphoid follicles of tertiary lymphoid structures (TLS) and were enriched in tumors with increased numbers of TLSs. BAPCs isolated from tumor-draining lymph nodes of patients with cancer showed increased percentages of tumor antigen–specific B cells and induced responses of autologous T cells in vitro. Our results highlight the relevance of BAPCs as professional antigen-presenting cells in tumor immunity and provide a mechanistic rationale for the observed correlation of B-cell abundance and response to immune checkpoint inhibition.

Purpose: BRCA1-deficient breast cancers carry a specific DNA copy-number signature ("BRCA1-like") and are hypersensitive to DNA double-strand break (DSB) inducing compounds. Here, we explored whether 1) EZH2 is overexpressed in human BRCA1-deficient breast tumors and might predict sensitivity to DSB-inducing drugs; 2) EZH2 inhibition potentiates cisplatin efficacy in Brca1-deficient murine mammary tumors. Experimental Design: EZH2 expression was analyzed in 497 breast cancers using immunohistochemistry or RNA sequencing. We classified 370 tumors by copy-number profiles as BRCA1-like or non-BRCA1-like and examined its association with EZH2 expression. Additionally, we assessed BRCA1-loss through mutation or promoter methylation status and investigated the predictive value of EZH2 expression in a study population of breast cancer patients treated with adjuvant high-dose platinum-based chemotherapy compared to standard anthracyline-based chemotherapy. To explore whether EZH2 inhibition by GSK126 enhances sensitivity to platinum drugs in EZH2-overexpressing breast cancers we used a Brca1-deficient mouse model. Results: The highest EZH2 expression was found in BRCA1-associated tumors harboring a BRCA1-mutation, BRCA1-promoter methylation or were classified as BRCA1-like. We observed a greater benefit from high-dose platinum-based chemotherapy in BRCA1-like and non-BRCA1-like patients with high EZH2 expression. Combined treatment with the EZH2 inhibitor GSK126 and cisplatin decreased cell proliferation and improved survival in Brca1-deficient mice in comparison to single agents. Conclusion: Our findings demonstrate that EZH2 is expressed at significantly higher levels in BRCA1-deficient breast cancers. EZH2 overexpression can identify breast cancer patients that benefit significantly from intensified DSB-inducing platinum-based chemotherapy independent of BRCA1-like status. EZH2 inhibition improves the antitumor effect of platinum drugs in Brca1-deficient breast tumors in vivo.

Introduction: Implant-based immediate breast reconstruction (IBR) is a common surgical procedure in breast cancer patients. Comparative analysis concerning the placement of implants is still lacking. Hence, we aimed to analyze pre- versus subpectoral IBR in breast cancer patients. Patients: A single-center experience with implant-based IBR following skin/nipple-sparing mastectomy was evaluated. Patient demographics, incidence of major complications, and quality of life assessed with BREAST-Q were compared between the pre- and subpectoral cohort. Results: A total of 63 patients were included in this analysis of whom 29 underwent subpectoral and 34 underwent prepectoral IBR. Median duration of surgery was prolonged in the subpectoral versus the prepectoral group (104 ± 28 vs. 80 ± 91 min; p < 0.05). The mean number of major complications was significantly increased in the subpectoral group (1.41 ± 1.76 vs. 0.47 ± 0.75 per patient; p < 0.05). Detailed analysis showed a significantly increased incidence of implant dislocation (p < 0.05) and a trend concerning capsular contracture (p = 0.086, not significant) and necrosis (p = 0.092, not significant) in the subpectoral group. Quality of life was equal in both groups. Conclusion: The mean number of major complications in the subpectoral group should be considered when IBR is indicated. Prepectoral IBR seems to be a feasible alternative surgical treatment option with less major complications in selected patients.

Purpose: More than 99% of cervical cancers and up to 40% of vulvar cancers are human papillomavirus (HPV) related. HPV 16 and 18 are the most relevant subtypes. Novel technologies allow the detection of minimal amounts of circulating cell-free HPV DNA (ccfHPV-DNA). The aim of this study was to evaluate ccfHPV-DNA assessed by droplet digital PCR (ddPCR) as a biomarker for molecular therapy monitoring in early, advanced, relapsed and metastatic HPV-driven cervical and vulvar cancer. Methods: Inclusion criteria of the study were histologically proven HPV 16/18-driven cervical and vulvar cancer with first diagnosed disease, newly diagnosed recurrence, or progression of disease. Blood samples were taken pre- and post-therapeutically. Circulating cell-free HPV DNA was quantified using ddPCR and the results were correlated with clinical data. Results: The mean copy number of ccfHPV-DNA was 838.6 (± 3089.1) in pretreatment and 2.3 (± 6.4) in post-treatment samples (p < 0.05). The copy number of ccfHPV-DNA increased with higher FIGO stages (p < 0.05), which are commonly used for clinical staging/assessment. Furthermore, we compared the distribution of copy numbers between T-stage 1 versus T-stage 2/3. We could show higher copy number level of ccfHPV-DNA in T-stage 2/3 (p < 0.05). Conclusions: Therapy monitoring with determination of ccfHPV-DNA by ddPCR with a small amount of plasma reflects response to therapy and appears feasible for patients in advanced cancer stages of cervical and vulvar cancer. This promising tool should be examined as marker of therapy monitoring in particular in novel HPV-directed therapies.