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Bacterial dysbiosis accompanies carcinogenesis in malignancies such as colon and liver cancer, and has recently been implicated in the pathogenesis of pancreatic ductal adenocarcinoma (PDA) 1 . However, the mycobiome has not been clearly implicated in tumorigenesis. Here we show that fungi migrate from the gut lumen to the pancreas, and that this is implicated in the pathogenesis of PDA. PDA tumours in humans and mouse models of this cancer displayed an increase in fungi of about 3,000-fold compared to normal pancreatic tissue. The composition of the mycobiome of PDA tumours was distinct from that of the gut or normal pancreas on the basis of alpha- and beta-diversity indices. Specifically, the fungal community that infiltrated PDA tumours was markedly enriched for Malassezia spp. in both mice and humans. Ablation of the mycobiome was protective against tumour growth in slowly progressive and invasive models of PDA, and repopulation with a Malassezia species—but not species in the genera Candida , Saccharomyces or Aspergillus —accelerated oncogenesis. We also discovered that ligation of mannose-binding lectin (MBL), which binds to glycans of the fungal wall to activate the complement cascade, was required for oncogenic progression, whereas deletion of MBL or C3 in the extratumoral compartment—or knockdown of C3aR in tumour cells—were both protective against tumour growth. In addition, reprogramming of the mycobiome did not alter the progression of PDA in Mbl - (also known as Mbl2 ) or C3 -deficient mice. Collectively, our work shows that pathogenic fungi promote PDA by driving the complement cascade through the activation of MBL. In humans and mouse models, the mycobiome of pancreatic ductal adenocarcinoma tumours is markedly enriched in Malassezia species compared to that of normal pancreas, which implicates these pathogenic fungi in oncogenesis.

Activation of dectin-1-dependent signaling in macrophages through ligation by galectin 9 promotes an immunosuppressive, protumorigenic microenvironment in pancreatic adenocarcinoma (PDA). Blocking dectin 1 ligation restores anti-tumor immunity and delays tumor growth, thus offering a novel strategy for improving the effectiveness of immunotherapy in patients with PDA. The progression of pancreatic oncogenesis requires immune-suppressive inflammation in cooperation with oncogenic mutations. However, the drivers of intratumoral immune tolerance are uncertain. Dectin 1 is an innate immune receptor crucial for anti-fungal immunity, but its role in sterile inflammation and oncogenesis has not been well defined. Furthermore, non-pathogen-derived ligands for dectin 1 have not been characterized. We found that dectin 1 is highly expressed on macrophages in pancreatic ductal adenocarcinoma (PDA). Dectin 1 ligation accelerated the progression of PDA in mice, whereas deletion of Clec7a —the gene encoding dectin 1—or blockade of dectin 1 downstream signaling was protective. We found that dectin 1 can ligate the lectin galectin 9 in mouse and human PDA, which results in tolerogenic macrophage programming and adaptive immune suppression. Upon disruption of the dectin 1–galectin 9 axis, CD4 + and CD8 + T cells, which are dispensable for PDA progression in hosts with an intact signaling axis, become reprogrammed into indispensable mediators of anti-tumor immunity. These data suggest that targeting dectin 1 signaling is an attractive strategy for developing an immunotherapy for PDA.

The gut microbiome shapes local and systemic immunity. The liver is presumed to be a protected sterile site. As such, a hepatic microbiome has not been examined. Here, we showed a liver microbiome in mice and humans that is distinct from that of the gut and is enriched in Proteobacteria. It undergoes dynamic alterations with age and is influenced by the environment and host physiology. Fecal microbial transfer experiments revealed that the liver microbiome is populated from the gut in a highly selective manner. Hepatic immunity is dependent on the microbiome, specifically the bacteroidetes species. Targeting bacteroidetes with oral antibiotics reduced hepatic immune cells by approximately 90%, prevented antigen-presenting cell (APC) maturation, and mitigated adaptive immunity. Mechanistically, our findings are consistent with presentation of bacteroidetes-derived glycosphingolipids to NKT cells promoting CCL5 signaling, which drives hepatic leukocyte expansion and activation, among other possible host-microbe interactions. Collectively, we reveal a microbial/glycosphingolipid/NKT/CCL5 axis that underlies hepatic immunity.

Background The National Comprehensive Cancer Network guidelines consider pancreatic cancer with celiac axis (CA), proper hepatic artery (PHA), and superior mesenteric artery (SMA) involvement unresectable. Thus, technical reports and video illustrations of these operations are rare. We report the stepwise management of multivascular reconstruction for Mayo Clinic class IIIb CA resections at New York University Langone Health, a dedicated center of excellence in pancreatic surgery. Methods We illustrated the management of a 56-year-old patient with biopsy-confirmed pancreatic ductal adenocarcinoma arising from the pancreatic body and involving the CA, PHA, SMA, and mesentericoportal venous axis. Perioperative management The preoperative stepwise considerations include: 1) mandatory patient selection; 2) planning vascular reconstructability; 3) tailoring risk assessment while carefully considering the need for total pancreatectomy, total gastrectomy, and mesenteric/hepatic revascularization; and 4) 3D-reconstruction for arterial evaluation. The key intraoperative considerations include: 1) selective and sequential clamping for vascular reconstruction in a “domino” fashion, to minimize warm ischemic time 2) a combined multi-surgeon approach to comprehensively tackle vascular reconstructions; 3) a low threshold for total pancreatectomy to avoid pancreatic leak; and 4) two-stage surgery to reassess the blood supply to the liver and stomach for on-demand gastric preservation instead of a theoretically advised total gastrectomy. Conclusion Liver, stomach, and bowel vascularization present life-threatening risks that require an extensive preoperative evaluation and a multidisciplinary approach. Our stepwise management for these extensive operations includes total pancreatectomy, “domino” vascular reconstruction, and two-stage surgery.

The COVID-19 pandemic strained healthcare systems worldwide, delaying breast cancer screening and surgery. In 2019, approximately 80% of breast cancers in the U.S. were diagnosed on screening examinations, with 76.4% of eligible Medicare patients undergoing screening at least every two years. Since the start of the pandemic, many women have been reluctant to seek elective screening mammography, even with the lifting of pandemic-related restrictions in access to routine healthcare. We describe the effect of the COVID-19 pandemic on breast cancer presentation at a tertiary academic medical center greatly impacted by the pandemic.

Programmed cell death protein 1 (PD-1) ligation delimits immunogenic responses in T cells. However, the consequences of programmed cell death 1 ligand 1 (PD-L1) ligation in T cells are uncertain. We found that T cell expression of PD-L1 in cancer was regulated by tumor antigen and sterile inflammatory cues. PD-L1 + T cells exerted tumor-promoting tolerance via three distinct mechanisms: (1) binding of PD-L1 induced STAT3-dependent ‘back-signaling’ in CD4 + T cells, which prevented activation, reduced T H 1-polarization and directed T H 17-differentiation. PD-L1 signaling also induced an anergic T-bet − IFN-γ − phenotype in CD8 + T cells and was equally suppressive compared to PD-1 signaling; (2) PD-L1 + T cells restrained effector T cells via the canonical PD-L1–PD-1 axis and were sufficient to accelerate tumorigenesis, even in the absence of endogenous PD-L1; (3) PD-L1 + T cells engaged PD-1 + macrophages, inducing an alternative M2-like program, which had crippling effects on adaptive antitumor immunity. Collectively, we demonstrate that PD-L1 + T cells have diverse tolerogenic effects on tumor immunity. PD-L1 on tumor cells exerts an important dampening effect on T cells via their expression of PD-1. Miller and colleagues find that PD-L1 ‘back-signaling’ into T cells and macrophages can also dampen immune responses within the tumor microenvironment.

Background Breast conserving surgery (BCS) is well established for the management of ductal carcinoma in situ (DCIS), but neither randomized trials nor guidelines address management of ipsilateral breast tumor recurrence (IBTR) after BCS for DCIS. Patients and Methods We identified women treated with BCS for DCIS who developed IBTR as a first event. Between those treated with mastectomy versus re-BCS, we compare the clinicopathologic characteristics, the use of adjuvant radiotherapy (RT) both upfront (“primary RT”) and post IBTR (“secondary RT”), of tamoxifen, the rate of third events (local, regional, distant), and both breast cancer specific (BCSS) and overall survival (OS). Results Of 3001 women treated with BCS for DCIS (1978–2010), 383 developed an IBTR as a first event (1983–2023) and were treated by mastectomy (51%) versus re-BCS (49%). Compared with re-BCS, mastectomy patients at initial treatment were higher grade (74% versus 59%, p = 0.004), with more frequent primary RT (61% versus 21%, p < 0.001). Third local events were more frequent for re-BCS than mastectomy (16% versus 3%, p = 0.001), but there were no differences in breast cancer specific or overall survival. Conclusions For isolated IBTR following BCS for DCIS and treated by mastectomy versus re-BCS (1) mastectomy was associated with less favorable initial pathology and more frequent use of primary RT, (2) re- recurrence was more frequent with re-BCS, and (3) BCSS and OS were comparable. Our data suggest a wider role for re-BCS and further study of the relationship between secondary RT and the rate of third breast events.

The drivers and the specification of CD4 T cell differentiation in the tumor microenvironment and their contributions to tumor immunity or tolerance are incompletely understood. Using models of pancreatic ductal adenocarcinoma (PDA), we show that a distinct subset of tumor-infiltrating dendritic cells (DC) promotes PDA growth by directing a unique T -program. Specifically, CD11b CD103 DC predominate in PDA, express high IL-23 and TGF-β, and induce FoxP3 tumor-promoting IL-10 IL-17 IFNγ regulatory CD4 T cells. The balance between this distinctive T program and canonical FoxP3 T is unaffected by pattern recognition receptor ligation and is modulated by DC expression of retinoic acid. This T -signature is mimicked in human PDA where it is associated with immune-tolerance and diminished patient survival. Our data suggest that CD11b CD103 DC promote CD4 T cell tolerance in PDA which may underscore its resistance to immunotherapy.