Melanoma Clonal Heterogeneity Leads to Secondary Resistance after Adoptive Cell Therapy with Tumor-Infiltrating Lymphocytes.

Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TIL) is effective in patients with melanoma, although long-term responses seem restricted in patients who have complete remissions. Many patients develop secondary resistance to TIL-ACT but the involved mechanisms are unclear. In this study, we describe a case of secondary resistance to TIL-ACT possibly due to intratumoral heterogeneity and selection of a resistant tumor cell clone by the transferred T cells. To the best our knowledge, this is the first case of clonal selection of a pre-existing nondominant tumor cell clone; this report demonstrates the mechanism involved in secondary resistance to TIL-ACT that can potentially change current clinical practice because it advocates for T-cell collection from multiple tumor sites and analysis of tumor heterogeneity before treatment with TIL-ACT.

Pathologist Computer-Aided Diagnostic Scoring of Tumor Cell Fraction: A Swiss National Study.

Tumor cell fraction (TCF) estimation is a common clinical task with well-established large interobserver variability. It thus provides an ideal test bed to evaluate potential impacts of employing a tumor cell fraction computer-aided diagnostic (TCFCAD) tool to support pathologists' evaluation. During a National Slide Seminar event, pathologists (n = 69) were asked to visually estimate TCF in 10 regions of interest (ROIs) from hematoxylin and eosin colorectal cancer images intentionally curated for diverse tissue compositions, cellularity, and stain intensities. Next, they re-evaluated the same ROIs while being provided a TCFCAD-created overlay highlighting predicted tumor vs nontumor cells, together with the corresponding TCF percentage. Participants also reported confidence levels in their assessments using a 5-tier scale, indicating no confidence to high confidence, respectively. The TCF ground truth (GT) was defined by manual cell-counting by experts. When assisted, interobserver variability significantly decreased, showing estimates converging to the GT. This improvement remained even when TCFCAD predictions deviated slightly from the GT. The standard deviation (SD) of the estimated TCF to the GT across ROIs was 9.9% vs 5.8% with TCFCAD (P < .0001). The intraclass correlation coefficient increased from 0.8 to 0.93 (95% CI, 0.65-0.93 vs 0.86-0.98), and pathologists stated feeling more confident when aided (3.67 ± 0.81 vs 4.17 ± 0.82 with the computer-aided diagnostic [CAD] tool). TCFCAD estimation support demonstrated improved scoring accuracy, interpathologist agreement, and scoring confidence. Interestingly, pathologists also expressed more willingness to use such a CAD tool at the end of the survey, highlighting the importance of training/education to increase adoption of CAD systems.

Composite haemangioendothelioma in the heart: a case report.

Background: Primary cardiac neoplasm is rare and generally benign. Epithelioid haemangioendothelioma, a potentially malignant tumour of vascular origin, has been occasionally described in the heart. Composite haemangioendothelioma, characterized by a heterogeneous architecture of vascular components and usually located in soft tissue of the extremities, has only been reported twice in the heart. We herein report another case of this extremely uncommon cardiac tumour. Case summary: Comprehensive cardiac examination of a 59-year-old female patient with palpitations and personal history of Hodgkin's lymphoma and chest radiation revealed a mass in the left atrium. After surgical resection, histopathological and immunohistochemical analysis identified a composite haemangioendothelioma. After two years, repeated imaging revealed neither signs of local relapse nor metastasis. Conclusions: Composite haemangioendothelioma, a very uncommon form of potentially malignant vascular tumour, can also be encountered in the heart. In this present case, the outcome was favourable two years after surgical resection without adjuvant therapy.

Targeting cancer glycosylation repolarizes tumor-associated macrophages allowing effective immune checkpoint blockade.

Immune checkpoint blockade (ICB) has substantially improved the prognosis of patients with cancer, but the majority experiences limited benefit, supporting the need for new therapeutic approaches. Up-regulation of sialic acid-containing glycans, termed hypersialylation, is a common feature of cancer-associated glycosylation, driving disease progression and immune escape through the engagement of Siglec receptors on tumor-infiltrating immune cells. Here, we show that tumor sialylation correlates with distinct immune states and reduced survival in human cancers. The targeted removal of Siglec ligands in the tumor microenvironment, using an antibody-sialidase conjugate, enhanced antitumor immunity and halted tumor progression in several murine models. Using single-cell RNA sequencing, we revealed that desialylation repolarized tumor-associated macrophages (TAMs). We also identified Siglec-E as the main receptor for hypersialylation on TAMs. Last, we found that genetic and therapeutic desialylation, as well as loss of Siglec-E, enhanced the efficacy of ICB. Thus, therapeutic desialylation represents an immunotherapeutic approach to reshape macrophage phenotypes and augment the adaptive antitumor immune response.

Loss of Lymphotoxin Alpha-Expressing Memory B Cells Correlates with Metastasis of Human Primary Melanoma.

Activated antigen-experienced B cells play an unexpected complex role in anti-tumor immunity in human melanoma patients. However, correlative studies between B cell infiltration and tumor progression are limited by the lack of distinction between functional B cell subtypes. In this study, we examined a series of 59 primary and metastatic human cutaneous melanoma specimens with B cell infiltration. Using seven-color multiplex immunohistochemistry and automated tissue imaging and analysis, we analyzed the spatiotemporal dynamics of three major antigen-experienced B cell subpopulations expressing lymphotoxin alpha (LTA/TNFSF1) or interleukin-10 (IL-10) outside tertiary lymphoid structures. The expression of both LTA and IL-10 was not restricted to a particular B cell subtype. In primary melanomas, these cells were predominantly found at the invasive tumor-stroma front and, in metastatic melanomas, they were also found in the intratumoral stroma. In primary melanomas, decreased densities of LTA+ memory-like and, to a lesser extent, activated B cells were associated with metastasis. Compared with metastatic primary tumors, B cell infiltrates in melanoma metastases were enriched in both LTA+ memory-like and LTA+ activated B cells, but not in any of the IL-10+ B cell subpopulations. Melanoma disease progression shows distinct dynamics of functional B cell subpopulations, with the regulation of LTA+ B cell numbers being more significant than IL-10+ B cell subpopulations.

A Standardized Analysis of Tertiary Lymphoid Structures in Human Melanoma: Disease Progression- and Tumor Site-Associated Changes With Germinal Center Alteration.

There is increasing evidence that tertiary lymphoid structures (TLS) control not only local adaptive B cell responses at melanoma tumor sites but also the cellular composition and function of other immune cells. In human melanoma, however, a comprehensive analysis of TLS phenotypes, density and spatial distribution at different disease stages is lacking. Here we used 7-color multiplex immunostaining of whole tissue sections from 103 human melanoma samples to characterize TLS phenotypes along the expression of established TLS-defining molecular and cellular components. TLS density and spatial distribution were determined by referring TLS counts to the tissue area within defined intra- and extratumoral perimeters around the invasive tumor front. We show that only a subgroup of primary human melanomas contains TLS. These TLS rarely formed germinal centers and mostly located intratumorally within 1 mm distance to the invasive tumor front. In contrast, melanoma metastases had a significantly increased density of secondary follicular TLS. They appeared preferentially in stromal areas within an extratumoral 1 mm distance to the invasive tumor front and their density varied over time and site of metastasis. Interestingly, secondary follicular TLS in melanoma often lacked BCL6+ lymphatic cells and canonical germinal center polarity with the formation of dark and light zone areas. Our work provides an integrated qualitative, quantitative and spatial analysis of TLS in human melanoma and shows disease progression- and site-associated changes in TLS phenotypes, density and spatial distribution. The frequent absence of canonical germinal center polarity in melanoma TLS highlights the induction of TLS maturation as a potential additive to future immunotherapy studies. Given the variable evaluation strategies used in previous TLS studies of human tumors, an important asset of this study is the standardized quantitative evaluation approach that provides a high degree of reproducibility.

18F-FDG PET/CT compared with ultrasound and biopsy for detection of vasculitis of the temporal artery branches.

AIMS: To describe the feasibility and diagnostic accuracy of 18F-FDG positron emission tomography-computed tomography (PET/CT) of the temporal artery compared with temporal artery ultrasound and histology of the temporal artery in patients with suspicion of having giant cell arteritis (GCA). MATERIALS AND METHODS: Patients with suspected GCA were included. PET/CT standard uptake value ratios and the compression sign on ultrasound were assessed for the trunk, and parietal and frontal branches of the temporal artery. Temporal artery biopsies were systematically re-assessed, if available. RESULTS: In 17/34 patients, GCA was confirmed. Temporal artery PET/CT confirmed vasculitis in 9/17 patients and was negative in all 17 controls. Nineteen of 34 subjects had a temporal artery biopsy, which was positive in 7 patients. Five of these seven were negative in the preceding PET/CT. Ultrasound confirmed vasculitis in 9/17 patients and was negative in 16/17 controls. In 7/17 patients, PET/CT and ultrasound were positive for temporal arteritis. Two patients had positive findings only on temporal artery PET/CT and two patients showed vasculitis only on temporal artery ultrasound. No temporal artery segments <1.4 mm were positive on PET/CT. The parietal branches were PET/CT-positive in two patients only. In contrast, on ultrasound vasculitic findings were equally distributed amongst all branches. Sensitivity and specificity for identification of temporal artery involvement was 53% and 100% for PET/CT, and 53% and 94% for ultrasound, respectively. CONCLUSIONS: Assessment of the temporal artery with PET/CT is a valuable extension in the diagnostic workup for GCA. PET/CT and ultrasound have comparable diagnostic accuracy, but differ on a segment and a patient level and may thus be used as complementary tests. PET/CT has a lower sensitivity for the parietal branch than ultrasound and histology.

Malignant melanoma metastasis in the gallbladder. A case report of an unusual metastatic site.

INTRODUCTION: Malignant melanoma is a neoplasia with the ability to metastasize to all organs. Most frequently, metastases derives from a skin primary. A solitary metastasis in the gallbladder is rarely mentioned in current literature. PRESENTATION OF CASE: We present the case of a 62-year-old female patient with the unusual metastatic spread of malignant melanoma into the gallbladder. The lesion was detected during routine follow up appointment six years after the initial surgical and radio-chemotherapeutic treatment of a malignant melanoma on the back. Following multidisciplinary team meeting, it was decided to perform a laparoscopic cholecystectomy to remove the gallbladder metastasis. DISCUSSION: New occurrence of a melanoma metastasis in the gallbladder is extremely rare, especially in stable disease. The therapeutical concept must be discussed extensively in the present of this metastasized tumor. CONCLUSION: In otherwise stable disease, palliative surgery for metastasis in the gallbladder is a possible option to prevent biliary complications. In a palliative setting always weigh up the risks and benefits while maintaining the quality of life.

Cholecystokinin 2 Receptor Agonist 177Lu-PP-F11N for Radionuclide Therapy of Medullary Thyroid Carcinoma: Results of the Lumed Phase 0a Study.

Treatment of patients with advanced medullary thyroid carcinoma (MTC) is still a challenge. For more than 2 decades, it has been known that the cholecystokinin 2 receptor is a promising target for the treatment of MTC with radiolabeled minigastrin analogs. Unfortunately, kidney toxicity has precluded their therapeutic application so far. In 6 consecutive patients, we evaluated with advanced 3-dimensional dosimetry whether improved minigastrin analog 177Lu-DOTA-(d-Glu)6-Ala-Tyr-Gly-Trp-Nle-Asp-PheNH2 (177Lu-PP-F11N) is a suitable agent for the treatment of MTC. Methods: Patients received 2 injections of about 1 GBq (∼80 µg) of 177Lu-PP-F11N with and without a solution of succinylated gelatin (SG, a plasma expander used for nephroprotection) in a random crossover sequence to evaluate biodistribution, pharmacokinetics, and tumor and organ dosimetry. An electrocardiogram was obtained and blood count and blood chemistry were measured up to 12 wk after the administration of 177Lu-PP-F11N to assess safety. Results: In all patients, 177Lu-PP-F11N accumulation was visible in tumor tissue, stomach, and kidneys. Altogether, 13 tumors were eligible for dosimetry. The median absorbed doses for tumors, stomach, kidneys, and bone marrow were 0.88 (interquartile range [IQR]: 0.85-1.04), 0.42 (IQR: 0.25-1.01), 0.11 (IQR: 0.07-0.13), and 0.028 (IQR: 0.026-0.034) Gy/GBq, respectively. These doses resulted in median tumor-to-kidney dose ratios of 11.6 (IQR: 8.11-14.4) without SG and 13.0 (IQR: 10.2-18.6) with SG; these values were not significantly different (P = 1.0). The median tumor-to-stomach dose ratio was 3.34 (IQR: 1.14-4.70). Adverse reactions (mainly hypotension, flushing, and hypokalemia) were self-limiting and not higher than grade 1. Conclusion:177Lu-PP-F11N accumulates specifically in MTC at a dose that is sufficient for a therapeutic approach. With a low kidney and bone marrow radiation dose, 177Lu-PP-F11N shows a promising biodistribution. The dose-limiting organ is most likely the stomach. Further clinical studies are necessary to evaluate the maximum tolerated dose and the efficacy of 177Lu-PP-F11N.

Nivolumab in chemotherapy-resistant cervical cancer: report of a vulvitis as a novel immune-related adverse event and molecular analysis of a persistent complete response.

BACKGROUND: Treatment options for advanced cervical cancer are limited and patients experiencing recurrence after first-line cisplatin-based chemotherapy and bevacizumab have a poor prognosis. A recent phase II study in advanced cervical cancer has demonstrated a disease control rate of 68.4% with the immune checkpoint inhibitor nivolumab. By blocking immune checkpoints, immunotherapy puts the immune system into a state of hyper-activation that can cause immune-related adverse events. We present the clinical, pathological and molecular data of a patient with metastatic cervical cancer and progressive disease after second-line therapy. We report on the therapeutic response under third-line immunotherapy with nivolumab, the immune-related adverse events (IRAE), and their successful management. CASE PRESENTATION: We report the case of a 62-year-old woman who was diagnosed with advanced squamous cell carcinoma of the cervix with paraaortic lymph node metastases. After an initial combined radio-chemotherapy with cisplatin, she developed local and nodal (supraclavicular) recurrence. Second-line chemotherapy with 6 cycles of carboplatin, paclitaxel, and bevacizumab resulted in a partial response for 6 months. Checkpoint inhibition with nivolumab was started due to progression, leading to persistent complete remission. Immunotherapy was well tolerated for 8 months until the patient presented with an immune-related isolated vulvitis, which was successfully managed with topical corticosteroids. CONCLUSIONS: The persistent complete response after third-line treatment for relapsed chemotherapy-resistant cervical cancer presented in this case highlights the potential of immunotherapy for patients with advanced cervical cancer impressively. To our knowledge, this is the first report of an isolated immune-related vulvitis under nivolumab. This adverse event might be underdiagnosed and mistreated, however, it is of importance due to its impact on quality of life, sexual wellbeing and compliance of patients. Successful IRAE management may enable prolonged immune checkpoint inhibitor therapy. In the future, routine molecular tumour profiling is likely to aid in the stratification of cervical cancer patients for immunotherapy. Here, we provide the methylome data of a case with complete response.

B cells sustain inflammation and predict response to immune checkpoint blockade in human melanoma.

Tumor associated inflammation predicts response to immune checkpoint blockade in human melanoma. Current theories on regulation of inflammation center on anti-tumor T cell responses. Here we show that tumor associated B cells are vital to melanoma associated inflammation. Human B cells express pro- and anti-inflammatory factors and differentiate into plasmablast-like cells when exposed to autologous melanoma secretomes in vitro. This plasmablast-like phenotype can be reconciled in human melanomas where plasmablast-like cells also express T cell-recruiting chemokines CCL3, CCL4, CCL5. Depletion of B cells in melanoma patients by anti-CD20 immunotherapy decreases tumor associated inflammation and CD8+ T cell numbers. Plasmablast-like cells also increase PD-1+ T cell activation through anti-PD-1 blockade in vitro and their frequency in pretherapy melanomas predicts response and survival to immune checkpoint blockade. Tumor associated B cells therefore orchestrate and sustain melanoma inflammation and may represent a predictor for survival and response to immune checkpoint blockade therapy.

Proteomic Landscape of Aldosterone-Producing Adenoma.

Primary aldosteronism is a disease of excessive production of adrenal steroid hormones and the most common cause of endocrine hypertension. Primary aldosteronism results mainly from bilateral adrenal hyperplasia or unilateral aldosterone-producing adenoma (APA). Primary aldosteronism cause at the molecular level is incompletely understood and a targeted treatment preventing excessive adrenal steroid production is not available. Here, we perform deep quantitative proteomic and phosphoproteomic profiling of 6 pairs of APA and adjacent nontumoral adrenal cortex. We show that increased steroidogenesis in APA is accompanied by upregulation of steroidogenic enzymes (HSD3B2, CYP21A2, CYP11B2) and of proteins involved in cholesterol uptake (LSR). We demonstrate that HSD3B2 is phosphorylated at Ser95 or 96 and identify a novel phosphorylation site, Ser489, in CYP21A2, suggesting that steroidogenic enzymes are regulated by phosphorylation. Our analysis also reveals altered ECM (extracellular matrix) composition in APA that affects ECM-cell surface interactions and actin cytoskeleton rearrangements. We show that RHOC, a GTPase controlling actin organization in response to extracellular stimuli, is upregulated in APA and promotes expression of the aldosterone synthase gene CYP11B2. Our data also indicate deregulation of protein N-glycosylation and GABAergic signaling in APAs. Finally, we find that mTORC1 (mammalian target of rapamycin complex 1) signaling is the major pathway deregulated in APA. Our study provides a rich resource for future research on the molecular mechanisms of primary aldosteronism.

Renal cell carcinoma metastases to the maxillary sinus.

Metastasis of renal cell carcinoma (RCC) to the head and neck region is rare. We report the case of a 65-year-old man with history of RCC, presented 7 years after nephrectomy, adrenalectomy and lung metastasectomy for his primary tumour, with symptoms of nasal obstruction, postnasal drip, productive cough and pressure sensation in the left maxillary sinus. CT revealed a unilateral, irregular opacification in the left maxillary sinus with bony erosion of the infraorbital canal wall. A yellow cystic lesion was completely removed from the maxillary sinus during functional endoscopic sinus surgery and histopathological analysis confirmed the diagnosis of a metastatic RCC. Patient continued to be managed with his pre-existing treatment for advanced RCC.

Control of angiogenesis and host response by modulating the cell adhesion properties of an Elastin-Like Recombinamer-based hydrogel.

The control of the in vivo vascularization of engineered tissue substitutes is essential in order to obtain either a rapid induction or a complete inhibition of the process (e.g. in muscles and hyaline-cartilage, respectively). Among the several polymers available, Elastin-Like Recombinamers (ELR)-based hydrogel stands out as a promising material for tissue engineering thanks to its viscoelastic properties, non-toxicity, and non-immunogenicity. In this study, we hypothesized that varying the cell adhesion properties of ELR-hydrogels could modulate the high angiogenic potential of adipose tissue-derived stromal vascular fraction (SVF) cells, predominantly composed of endothelial/mural and mesenchymal cells. Human SVF cells, embedded in RGD-REDV-bioactivated or unmodified ELR-hydrogels, were implanted in rat subcutaneous pockets either immediately or upon 5-day-culture in perfusion-bioreactors. Perfusion-based culture enhanced the endothelial cell cord-like-organization and the release of pro-angiogenic factors in functionalized constructs. While in vivo vascularization and host cell infiltration within the bioactivated gels were highly enhanced, the two processes were strongly inhibited in non-functionalized SVF-based hydrogels up to 28 days. ELR-based hydrogels showed a great potential to determine the successful integration of engineered substitutes thanks to their capacity to finely control the angiogenic/inflammation process at the recipient site, even in presence of SVF cells.

Transforming growth factor-ß-dependent Wnt secretion controls myofibroblast formation and myocardial fibrosis progression in experimental autoimmune myocarditis.

AIMS: Myocardial fibrosis critically contributes to cardiac dysfunction in inflammatory dilated cardiomyopathy (iDCM). Activation of transforming growth factor-ß (TGF-ß) signalling is a key-step in promoting tissue remodelling and fibrosis in iDCM. Downstream mechanisms controlling these processes, remain elusive. METHODS AND RESULTS: Experimental autoimmune myocarditis (EAM) was induced in BALB/c mice with heart-specific antigen and adjuvant. Using heart-inflammatory precursors, as well as mouse and human cardiac fibroblasts, we demonstrated rapid secretion of Wnt proteins and activation of Wnt/ß-catenin pathway in response to TGF-ß signalling. Inactivation of extracellular Wnt with secreted Frizzled-related protein 2 (sFRP2) or inhibition of Wnt secretion with Wnt-C59 prevented TGF-ß-mediated transformation of inflammatory precursors and cardiac fibroblasts into pathogenic myofibroblasts. Inhibition of T-cell factor (TCF)/ß-catenin-mediated transcription with ICG-001 or genetic loss of ß-catenin also prevented TGF-ß-induced myofibroblasts formation. Furthermore, blocking of Smad-independent TGF-ß-activated kinase 1 (TAK1) pathway completely abrogated TGF-ß-induced Wnt secretion. Activation of Wnt pathway in the absence of TGF-ß, however, failed to transform precursors into myofibroblasts. The critical role of Wnt axis for cardiac fibrosis in iDCM is also supported by elevated Wnt-1/Wnt-5a levels in human samples from hearts with myocarditis. Accordingly, and as an in vivo proof of principle, inhibition of Wnt secretion or TCF/ß-catenin-mediated transcription abrogated the development of post-inflammatory fibrosis in EAM. CONCLUSION: We identified TAK1-mediated rapid Wnt protein secretion as a novel downstream key mechanism of TGF-ß-mediated myofibroblast differentiation and myocardial fibrosis progression in human and mouse myocarditis. Thus, pharmacological targeting of Wnts might represent a promising therapeutic approach against iDCM in the future.

The prognostic and predictive value of sstr2-immunohistochemistry and sstr2-targeted imaging in neuroendocrine tumors.

PURPOSE: Our aim was to assess the prognostic and predictive value of somatostatin receptor 2 (sstr2) in neuroendocrine tumors (NETs). METHODS: We established a tissue microarray and imaging database from NET patients that received sstr2-targeted radiopeptide therapy with yttrium-90-DOTATOC, lutetium-177-DOTATOC or alternative treatment. We used univariate and multivariate analyses to identify prognostic and predictive markers for overall survival, including sstr2-imaging and sstr2-immunohistochemistry. RESULTS: We included a total of 279 patients. In these patients, sstr2-immunohistochemistry was an independent prognostic marker for overall survival (HR: 0.82, 95 % CI: 0.67 - 0.99, n = 279, p = 0.037). In DOTATOC patients, sstr2-expression on immunohistochemistry correlated with tumor uptake on sstr2-imaging (n = 170, p < 0.001); however, sstr2-imaging showed a higher prognostic accuracy (positive predictive value: +27 %, 95 % CI: 3 - 56 %, p = 0.025). Sstr2-expression did not predict a benefit of DOTATOC over alternative treatment (p = 0.93). CONCLUSIONS: Our results suggest sstr2 as an independent prognostic marker in NETs. Sstr2-immunohistochemistry correlates with sstr2-imaging; however, sstr2-imaging is more accurate for determining the individual prognosis.

Fast Diagnostics of BRAF Mutations in Biopsies from Malignant Melanoma.

According to the American skin cancer foundation, there are more new cases of skin cancer than the combined incidence of cancers of the breast, prostate, lung, and colon each year, and malignant melanoma represents its deadliest form. About 50% of all cases are characterized by a particular mutation BRAF(V600E) in the BRAF (Rapid Acceleration of Fibrosarcoma gene B) gene. Recently developed highly specific drugs are able to fight BRAF(V600E) mutated tumors but require diagnostic tools for fast and reliable mutation detection to warrant treatment efficiency. We completed a preliminary clinical trial applying cantilever array sensors to demonstrate identification of a BRAF(V600E) single-point mutation using total RNA obtained from biopsies of metastatic melanoma of diverse sources (surgical material either frozen or fixated with formalin and embedded in paraffin). The method is faster than the standard Sanger or pyrosequencing methods and comparably sensitive as next-generation sequencing. Processing time from biopsy to diagnosis is below 1 day and does not require PCR amplification, sequencing, and labels.

SCS macrophages suppress melanoma by restricting tumor-derived vesicle-B cell interactions.

Tumor-derived extracellular vesicles (tEVs) are important signals in tumor-host cell communication, yet it remains unclear how endogenously produced tEVs affect the host in different areas of the body. We combined imaging and genetic analysis to track melanoma-derived vesicles at organismal, cellular, and molecular scales to show that endogenous tEVs efficiently disseminate via lymphatics and preferentially bind subcapsular sinus (SCS) CD169(+) macrophages in tumor-draining lymph nodes (tdLNs) in mice and humans. The CD169(+) macrophage layer physically blocks tEV dissemination but is undermined during tumor progression and by therapeutic agents. A disrupted SCS macrophage barrier enables tEVs to enter the lymph node cortex, interact with B cells, and foster tumor-promoting humoral immunity. Thus, CD169(+) macrophages may act as tumor suppressors by containing tEV spread and ensuing cancer-enhancing immunity.

Trastuzumab emtansine (T-DM1) renders HER2+ breast cancer highly susceptible to CTLA-4/PD-1 blockade.

Targeted drug delivery with antibody-drug conjugates such as the HER2-directed ado-trastuzumab emtansine (T-DM1) has emerged as a powerful strategy for cancer therapy. We show that T-DM1 is particularly effective in eliciting antitumor immunity in patients with early breast cancer (WSG-ADAPT trial) and in a HER2-expressing orthotopic tumor model. In the latter, despite primary resistance to immunotherapy, combined treatment with T-DM1 and anti-CTLA-4/PD-1 (cytotoxic T lymphocyte-associated protein-4/programmed cell death protein-1) was curative because it triggered innate and adaptive immunity. Tumor rejection was accompanied by massive T cell infiltration, TH1 (T helper 1) cell polarization, and, notably, a substantial increase in regulatory T cells. Depletion of regulatory T cells resulted in inflammation and tissue damage, implying their essential role in protecting the host during therapy. This study provides insights into the mechanisms of T-DM1's therapeutic activity and a rationale for potential therapeutic combination strategies with immunotherapy.