Human serous cavity macrophages and dendritic cells possess counterparts in the mouse with a distinct distribution between species.

In mouse peritoneal and other serous cavities, the transcription factor GATA6 drives the identity of the major cavity resident population of macrophages, with a smaller subset of cavity-resident macrophages dependent on the transcription factor IRF4. Here we showed that GATA6+ macrophages in the human peritoneum were rare, regardless of age. Instead, more human peritoneal macrophages aligned with mouse CD206+ LYVE1+ cavity macrophages that represent a differentiation stage just preceding expression of GATA6. A low abundance of CD206+ macrophages was retained in C57BL/6J mice fed a high-fat diet and in wild-captured mice, suggesting that differences between serous cavity-resident macrophages in humans and mice were not environmental. IRF4-dependent mouse serous cavity macrophages aligned closely with human CD1c+CD14+CD64+ peritoneal cells, which, in turn, resembled human peritoneal CD1c+CD14-CD64- cDC2. Thus, major populations of serous cavity-resident mononuclear phagocytes in humans and mice shared common features, but the proportions of different macrophage differentiation stages greatly differ between the two species, and dendritic cell (DC2)-like cells were especially prominent in humans.

Hallmarks of response, resistance, and toxicity to immune checkpoint blockade.

Unprecedented advances have been made in cancer treatment with the use of immune checkpoint blockade (ICB). However, responses are limited to a subset of patients, and immune-related adverse events (irAEs) can be problematic, requiring treatment discontinuation. Iterative insights into factors intrinsic and extrinsic to the host that impact ICB response and toxicity are critically needed. Our understanding of the impact of host-intrinsic factors (such as the host genome, epigenome, and immunity) has evolved substantially over the past decade, with greater insights on these factors and on tumor and immune co-evolution. Additionally, we are beginning to understand the impact of acute and cumulative exposures-both internal and external to the host (i.e., the exposome)-on host physiology and response to treatment. Together these represent the current day hallmarks of response, resistance, and toxicity to ICB. Opportunities built on these hallmarks are duly warranted.

The response to and repair of RAG-mediated DNA double-strand breaks.

Developing lymphocytes must assemble antigen receptor genes encoding the B cell and T cell receptors. This process is executed by the V(D)J recombination reaction, which can be divided into DNA cleavage and DNA joining steps. The former is carried out by a lymphocyte-specific RAG endonuclease, which mediates DNA cleavage at two recombining gene segments and their flanking RAG recognition sequences. RAG cleavage generates four broken DNA ends that are repaired by nonhomologous end joining forming coding and signal joints. On rare occasions, these DNA ends may join aberrantly forming chromosomal lesions such as translocations, deletions and inversions that have the potential to cause cellular transformation and lymphoid tumors. We discuss the activation of DNA damage responses by RAG-induced DSBs focusing on the component pathways that promote their normal repair and guard against their aberrant resolution. Moreover, we discuss how this DNA damage response impacts processes important for lymphocyte development.

Androgen receptor blockade promotes response to BRAF/MEK-targeted therapy.

Treatment with therapy targeting BRAF and MEK (BRAF/MEK) has revolutionized care in melanoma and other cancers; however, therapeutic resistance is common and innovative treatment strategies are needed1,2. Here we studied a group of patients with melanoma who were treated with neoadjuvant BRAF/MEK-targeted therapy ( NCT02231775 , n = 51) and observed significantly higher rates of major pathological response (MPR; ≤10% viable tumour at resection) and improved recurrence-free survival (RFS) in female versus male patients (MPR, 66% versus 14%, P = 0.001; RFS, 64% versus 32% at 2 years, P = 0.021). The findings were validated in several additional cohorts2-4 of patients with unresectable metastatic melanoma who were treated with BRAF- and/or MEK-targeted therapy (n = 664 patients in total), demonstrating improved progression-free survival and overall survival in female versus male patients in several of these studies. Studies in preclinical models demonstrated significantly impaired anti-tumour activity in male versus female mice after BRAF/MEK-targeted therapy (P = 0.006), with significantly higher expression of the androgen receptor in tumours of male and female BRAF/MEK-treated mice versus the control (P = 0.0006 and P = 0.0025). Pharmacological inhibition of androgen receptor signalling improved responses to BRAF/MEK-targeted therapy in male and female mice (P = 0.018 and P = 0.003), whereas induction of androgen receptor signalling (through testosterone administration) was associated with a significantly impaired response to BRAF/MEK-targeted therapy in male and female patients (P = 0.021 and P < 0.0001). Together, these results have important implications for therapy.

Immune Checkpoint Blockade across the Cancer Care Continuum.

Four studies recently reported in the New England Journal of Medicine highlight advances in treatment with immune checkpoint blockade across the cancer care continuum. These findings demonstrate efficacy of these agents in the treatment of early and late-stage disease, as monotherapy or in combination, and in addition to-or in place of-standard front-line therapy.

B cells and tertiary lymphoid structures promote immunotherapy response.

Treatment with immune checkpoint blockade (ICB) has revolutionized cancer therapy. Until now, predictive biomarkers1-10 and strategies to augment clinical response have largely focused on the T cell compartment. However, other immune subsets may also contribute to anti-tumour immunity11-15, although these have been less well-studied in ICB treatment16. A previously conducted neoadjuvant ICB trial in patients with melanoma showed via targeted expression profiling17 that B cell signatures were enriched in the tumours of patients who respond to treatment versus non-responding patients. To build on this, here we performed bulk RNA sequencing and found that B cell markers were the most differentially expressed genes in the tumours of responders versus non-responders. Our findings were corroborated using a computational method (MCP-counter18) to estimate the immune and stromal composition in this and two other ICB-treated cohorts (patients with melanoma and renal cell carcinoma). Histological evaluation highlighted the localization of B cells within tertiary lymphoid structures. We assessed the potential functional contributions of B cells via bulk and single-cell RNA sequencing, which demonstrate clonal expansion and unique functional states of B cells in responders. Mass cytometry showed that switched memory B cells were enriched in the tumours of responders. Together, these data provide insights into the potential role of B cells and tertiary lymphoid structures in the response to ICB treatment, with implications for the development of biomarkers and therapeutic targets.

Repeat Cytoreduction and Hyperthermic Intraperitoneal Chemotherapy for Recurrent Mucinous Appendiceal Adenocarcinoma: A Viable Treatment Strategy with Demonstrable Benefit.

INTRODUCTION: Many patients with mucinous appendiceal adenocarcinoma experience peritoneal recurrence despite complete cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Prior work has demonstrated that repeat CRS/HIPEC can prolong survival in select patients. We sought to validate these findings using outcomes from a high-volume center. PATIENTS AND METHODS: Patients with mucinous appendiceal adenocarcinoma who underwent CRS/HIPEC at MD Anderson Cancer Center between 2004 and 2021 were stratified by whether they underwent CRS/HIPEC for recurrent disease or as part of initial treatment. Only patients who underwent complete CRS/HIPEC were included. Initial and recurrent groups were compared. RESULTS: Of 437 CRS/HIPECs performed for mucinous appendiceal adenocarcinoma, 50 (11.4%) were for recurrent disease. Patients who underwent CRS/HIPEC for recurrent disease were more often treated with an oxaliplatin or cisplatin perfusion (35%/44% recurrent vs. 4%/1% initial, p < 0.001), had a longer operative time (median 629 min recurrent vs. 511 min initial, p = 0.002), and had a lower median length of stay (10 days repeat vs. 13 days initial, p < 0.001). Thirty-day complication and 90-day mortality rates did not differ between groups. Both cohorts enjoyed comparable recurrence free survival (p = 0.82). Compared with patients with recurrence treated with systemic chemotherapy alone, this select cohort of patients undergoing repeat CRS/HIPEC enjoyed better overall survival (p < 0.001). CONCLUSIONS: In appropriately selected patients with recurrent appendiceal mucinous adenocarcinoma, CRS/HIPEC can provide survival benefit equivalent to primary CRS/HIPEC and that may be superior to that conferred by systemic therapy alone in select patients. These patients should receive care at a high-volume center in the context of a multidisciplinary team.

Treatment Variation and Long-Term Outcomes of Low-Grade Appendiceal Neoplasms.

BACKGROUND: Heterogenous nomenclature describing appendiceal neoplasms has added to uncertainty around their appropriate treatment. Although a recent consensus has established the term low-grade appendiceal neoplasm (LAMN), we hypothesize that significant variation remains in the treatment of LAMNs. METHODS: We retrospectively reviewed our prospectively maintained appendiceal registry, identifying patients with LAMNs from 2009 to 2019. We assessed variability in treatment, including whether patients underwent colectomy, spread of disease at presentation, and long-term outcomes. RESULTS: Of 136 patients with LAMNs, 88 (35%) presented with localized disease and 48 (35%) with disseminated peritoneal disease. Median follow-up was 2.9 years (IQR 1.9-4.4), and 120 (88%) patients underwent pre-referral surgery. Among 26 pre-referral colectomy patients, 23 (88%) were performed for perceived oncologic need/nodal evaluation; no nodal metastases were identified. In patients with resected LAMNs without radiographic evidence of disseminated disease, 41 (47%) underwent second look diagnostic laparoscopy (DL) to evaluate for occult metastases. No peritoneal metastases were identified. Patients with disseminated disease were treated with cytoreductive surgery/heated intraperitoneal chemotherapy (CRS/HIPEC). For patients undergoing CRS/HIPEC, 5-year recurrence-free survival was 94% (95% CI 81-98%). For patients with localized disease, 5-year RFS was 98% (95% CI 85-99%). CONCLUSIONS: Significant variation exists in treatment patterns for LAMNs, particularly prior to referral to a high-volume center. Patients frequently underwent colectomy without apparent oncologic benefit. In the current era of high-quality cross sectional imaging, routine use of DL has low yield and is not recommended. Recurrence in this population is rare, and low-intensity surveillance can be offered. Overall prognosis is excellent, even with peritoneal disease.

Community-based management of acute malnutrition for infants under 6 months of age is safe and effective: analysis of operational data.

OBJECTIVE: To assess the effectiveness of outpatient management with ready-to-use and supplementary foods for infants under 6 months (u6m) of age who were unable to be treated as inpatients due to social and economic barriers. DESIGN: Review of operational acute malnutrition treatment records. SETTING: Twenty-one outpatient therapeutic feeding clinics in rural Malawi. PARTICIPANTS: Infants u6m with acute malnutrition treated as outpatients because of barriers to inpatient treatment. The comparison group consisted of acutely malnourished children 6-9 months of age who were being treated at the same time in the same location in the context of two different randomised clinical trials. RESULTS: A total of 323 infants u6m were treated for acute malnutrition (130 severe and 193 moderate). A total of 357 infants 6-9 months old with acute malnutrition (seventy-four severe and 283 moderate) were included as contemporaneous controls. Among infants u6m with severe acute malnutrition, 98 (75·4 %) achieved nutritional recovery; in comparison, 56 (75·7 %) of those with severe acute malnutrition 6-9 months old recovered. Among infants u6m with moderate acute malnutrition, 157 (81·3 %) recovered; in comparison, 241 (85·2 %) of those aged 6-9 months recovered. CONCLUSIONS: In a rural Malawian population of infants u6m who had generally already stopped exclusive breast-feeding and were now acutely malnourished, treatment with therapeutic or supplementary foods under the community management of acute malnutrition model was safe and effective. In settings where social and financial factors make hospital admission challenging, consideration should be given to lowering the recommended age of ready-to-use therapeutic and supplementary foods to infants u6m.

Regulation of hematopoietic stem cell differentiation by a single ubiquitin ligase-substrate complex.

Hematopoietic stem cell (HSC) differentiation is regulated by cell-intrinsic and cell-extrinsic cues. In addition to transcriptional regulation, post-translational regulation may also control HSC differentiation. To test this hypothesis, we visualized the ubiquitin-regulated protein stability of a single transcription factor, c-Myc. The stability of c-Myc protein was indicative of HSC quiescence, and c-Myc protein abundance was controlled by the ubiquitin ligase Fbw7. Fine changes in the stability of c-Myc protein regulated the HSC gene-expression signature. Using whole-genome genomic approaches, we identified specific regulators of HSC function directly controlled by c-Myc binding; however, adult HSCs and embryonic stem cells sensed and interpreted c-Myc-regulated gene expression in distinct ways. Our studies show that a ubiquitin ligase-substrate pair can orchestrate the molecular program of HSC differentiation.

What is the Risk for Peritoneal Metastases and Survival Afterwards in T4 Colon Cancers?

BACKGROUND: Patients with T4 colon adenocarcinomas have an increased risk of peritoneal metastases (PM) but the histopathologic risk factors for its development are not well-described. OBJECTIVE: The purpose of this study was to determine factors associated with PM, time to recurrence, and survival after recurrence among patients with T4 colon cancer. PATIENTS AND METHODS: Patients with pathologic T4 colon cancer who underwent curative resection from 2005 to 2017 were identified from a prospectively maintained institutional database and classified by recurrence pattern: (a) none - 68.8%; (b) peritoneal only - 7.9%; (c) peritoneal and extraperitoneal - 9.9%; and (d) extraperitoneal only - 13.2%. Associations between PM development and patient, primary tumor, and treatment factors were assessed. RESULTS: Overall, 151 patients were analyzed, with a median follow-up of 66.2 months; 27 patients (18%) developed PM (Groups B and C) and 20 (13%) patients recurred at non-peritoneal sites only (Group D). Median time to developing metastases was shorter for Groups B and C compared with Group D (B and C: 13.7 months; D: 46.7 months; p = 0.022). Tumor deposits (TDs) and nodal stage were associated with PM (p < 0.05), and TDs (p = 0.048) and LVI (p = 0.015) were associated with additional extraperitoneal recurrence. Eleven (41%) patients with PM underwent salvage surgery, and median survival after recurrence was associated with the ability to undergo cytoreduction (risk ratio 0.20, confidence interval 0.06-0.70). CONCLUSION: PM risk after resection of T4 colon cancer is independently associated with factors related to lymphatic spread, such as N stage and TDs. Well-selected patients can undergo cytoreduction with long-term survival. These findings support frequent postoperative surveillance and aggressive early intervention, including cytoreduction.

Toxicity of Immune Checkpoint Inhibitors: Considerations for the Surgeon.

BACKGROUND: The use of immunotherapeutic agents, specifically immune checkpoint inhibitors (ICIs) for solid malignancies, is rapidly rising, and many new agents and treatment combinations are in development. However, ICIs have a unique side-effect profile of immune-related adverse events (irAEs) compared with chemotherapeutic agents or targeted therapies. METHODS: In this report the diverse spectrum of irAEs is highlighted using two patients with metastatic melanoma undergoing treatment with ICIs. We supplement these case reports with a brief literature review of the data regarding the safety of surgical intervention in patients taking irAEs. RESULTS: The report describes the basic approach to the detection and management of irAEs, notes important perioperative considerations, and discusses the safety of surgical intervention for these patients. CONCLUSIONS: Overall, these irAEs represent a diverse group of pathologies with variable timing and sometimes subtle presentation requiring careful monitoring and heightened clinical suspicion for potential toxicity by all providers, including surgeons.

Modulating the microbiome to improve therapeutic response in cancer.

Although novel therapies, including immunotherapy, have dramatically improved outcomes for many patients with cancer, overall outcomes are heterogeneous and existing biomarkers do not reliably predict response. To date, predictors of response to cancer therapy have largely focused on tumour-intrinsic features; however, there is growing evidence that other host factors (eg, host genomics and the microbiome) can substantially affect therapeutic response. The microbiome, which refers to microbiota within a host and their collective genomes, is becoming increasingly recognised for its influence on host immunity, as well as therapeutic responses to cancer treatment. Importantly, microbiota can be modified via several different strategies, affording new angles in cancer treatment to improve outcomes. In this Review, we examine the evidence on the role of the microbiome in cancer and therapeutic response, factors that influence and shape host microbiota, strategies to modulate the microbiome, and present key unanswered questions to be addressed in ongoing and future research.

H2AX prevents CtIP-mediated DNA end resection and aberrant repair in G1-phase lymphocytes.

DNA double-strand breaks (DSBs) are generated by the recombination activating gene (RAG) endonuclease in all developing lymphocytes as they assemble antigen receptor genes. DNA cleavage by RAG occurs only at the G1 phase of the cell cycle and generates two hairpin-sealed DNA (coding) ends that require nucleolytic opening before their repair by classical non-homologous end-joining (NHEJ). Although there are several cellular nucleases that could perform this function, only the Artemis nuclease is able to do so efficiently. Here, in vivo, we show that in murine cells the histone protein H2AX prevents nucleases other than Artemis from processing hairpin-sealed coding ends; in the absence of H2AX, CtIP can efficiently promote the hairpin opening and resection of DNA ends generated by RAG cleavage. This CtIP-mediated resection is inhibited by γ-H2AX and by MDC-1 (mediator of DNA damage checkpoint 1), which binds to γ-H2AX in chromatin flanking DNA DSBs. Moreover, the ataxia telangiectasia mutated (ATM) kinase activates antagonistic pathways that modulate this resection. CtIP DNA end resection activity is normally limited to cells at post-replicative stages of the cell cycle, in which it is essential for homology-mediated repair. In G1-phase lymphocytes, DNA ends that are processed by CtIP are not efficiently joined by classical NHEJ and the joints that do form frequently use micro-homologies and show significant chromosomal deletions. Thus, H2AX preserves the structural integrity of broken DNA ends in G1-phase lymphocytes, thereby preventing these DNA ends from accessing repair pathways that promote genomic instability.