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Abstract RTS,S/AS01E, the first approved malaria vaccine, demonstrated moderate efficacy during the phase 3 pediatric trial. We previously investigated cell-mediated immune (CMI) responses following the primary 3-dose immunization and now report responses to the booster dose given 18 months later. Thirty CMI markers were measured by Luminex in supernatants of peripheral blood mononuclear cells from 709 children and infants after RTS,S/AS01E antigen stimulation, and their associations with malaria risk and antibodies one month post-booster and one year later were assessed. IL-2, IFN-γ, IL-17, IL-5, and IL-13 were associated with RTS,S/AS01E booster vaccination, and IL-2 responses to the circumsporozoite protein (CSP) remained higher after one year. IL-2 was associated with reduced malaria risk in one site, and IL-10 was associated with increased risk in infants. Anti-CSP IgG and IL-2 were moderately correlated one year after booster. This study highlights the moderate cell-mediated immunogenicity of the RTS,S/AS01E booster dose that aligns with partial recovery of RTS,S/AS01E vaccine efficacy.

Abstract The malignant microenvironment plays a major role in the development of resistance to therapies and the occurrence of relapses in acute myeloid leukemia (AML). We previously showed that interactions of AML blasts with bone marrow macrophages (MΦ) shift their polarization towards a protumoral (M2-like) phenotype, promoting drug resistance; we demonstrated that inhibiting the colony-stimulating factor-1 receptor (CSF1R) repolarizes MΦ towards an antitumoral (M1-like) phenotype and that other factors may be involved. We investigated here macrophage migration inhibitory factor (MIF) as a target in AML blast survival and protumoral interactions with MΦ. We show that pharmacologically inhibiting MIF secreted by AML blasts results in their apoptosis. However, this effect is abrogated when blasts are co-cultured in close contact with M2-like MΦ. We next demonstrate that pharmacological inhibition of MIF secreted by MΦ, in the presence of granulocyte macrophage-colony stimulating factor (GM-CSF), efficiently reprograms MΦ to an M1-like phenotype that triggers apoptosis of interacting blasts. Furthermore, contact with reprogrammed MΦ relieves blast resistance to venetoclax and midostaurin acquired in contact with CD163+ protumoral MΦ. Using intravital imaging in mice, we also show that treatment with MIF inhibitor 4-IPP and GM-CSF profoundly affects the tumor microenvironment in vivo: it strikingly inhibits tumor vasculature, reduces protumoral MΦ, and slows down leukemia progression. Thus, our data demonstrate that MIF plays a crucial role in AML MΦ M2-like protumoral phenotype that can be reversed by inhibiting its activity and suggest the therapeutic targeting of MIF as an avenue towards improved AML treatment outcomes.

The advent of immunotherapy has revolutionised cancer therapeutics, but its application in the context of pancreatic ductal adenocarcinoma has been limited. Here authors explore the effect of innate trained responses to fungal β-glucan and assess its effect in a murine model of pancreatic ductal adenocarcinoma where they observe reduced tumour burden and enhanced survival.

Abstract Background Surveillance tools to estimate viral transmission dynamics in young populations are essential to guide recommendations for school opening and management during viral epidemics. Ideally, sensitive techniques are required to detect low viral load exposures among asymptomatic children. We aimed to estimate SARS-CoV-2 infection rates in children and adult populations in a school-like environment during the initial COVID-19 pandemic waves using an antibody-based field-deployable and non-invasive approach. Methods Saliva antibody conversion defined as ≥ 4-fold increase in IgM, IgA, and/or IgG levels to five SARS-CoV-2 antigens including spike and nucleocapsid constructs was evaluated in 1509 children and 396 adults by high-throughput Luminex assays in samples collected weekly in 22 summer schools and 2 pre-schools in 27 venues in Barcelona, Spain, from June 29th to July 31st, 2020. Results Saliva antibody conversion between two visits over a 5-week period was 3.22% (49/1518) or 2.36% if accounting for potentially cross-reactive antibodies, six times higher than the cumulative infection rate (0.53%) assessed by weekly saliva RT-PCR screening. IgG conversion was higher in adults (2.94%, 11/374) than children (1.31%, 15/1144) (p=0.035), IgG and IgA levels moderately increased with age, and antibodies were higher in females. Most antibody converters increased both IgG and IgA antibodies but some augmented either IgG or IgA, with a faster decay over time for IgA than IgG. Nucleocapsid rather than spike was the main antigen target. Anti-spike antibodies were significantly higher in individuals not reporting symptoms than symptomatic individuals, suggesting a protective role against COVID-19. Conclusion Saliva antibody profiling including three isotypes and multiplexing antigens is a useful and user-friendlier tool for screening pediatric populations to detect low viral load exposures among children, particularly while they are not vaccinated and vulnerable to highly contagious variants, and to recommend public health policies during pandemics.

Long-term characterisation of SARS-CoV-2 antibody kinetics is needed to understand the protective role of the immune response. Here the authors describe antibody levels and neutralisation activity in healthcare workers over seven months and investigate the role of immunity to endemic human coronaviruses.

The skin is the site of host invasion by the mosquito-borne Plasmodium parasite, which caused an estimated 229 million infections and 409,000 deaths in 2019 according to WHO World Malaria report 2020. In our previous studies, we have shown that skin scarification (SS) with a P. falciparum circumsporozoite (CS) peptide in the oil-in-water adjuvant AddaVax containing a combination of TLR 7/8 and TLR 9 agonists can elicit sporozoite neutralizing antibodies. SS with AddaVax + TLR agonists, but not AddaVax alone, elicited CD4+ Th1 cells and IgG2a/c anti-repeat antibody. To explore the innate immune responses that may contribute to development of adaptive immunity following SS, we examined the skin at 4h and 24h post priming with CS peptide in AddaVax with or without TLR agonists. H&E stained and IHC-labeled dorsal skin sections obtained 24h post SS demonstrated a marked difference in the pattern of infiltration with F4/80+, CD11b+ and Ly6G+ cells at the immunization site, with the lowest intensity noted following SS with AddaVax + TLR agonists. Serum collected at 4h post SS, had reproducible increases in IL-6, MIP-3α, IL-22 and IP-10 (CXCL10) following SS with AddaVax + TLR agonists, but not with AddaVax alone. To begin to decipher the complex roles of these pro-inflammatory cytokines/chemokines, we utilized IP-10 deficient (IP-10 -/-) mice to examine the role of this chemokine in the development of anti-repeat antibody response following SS. In the absence of IP-10, the levels of Th1-type IgG2a/c antibody and kinetics of the primary anti-repeat antibody response were reduced following prime and boost. The IP-10 chemokine, present as early as 4h post prime, may provide an early serological marker for rapid screening of adjuvant formulations and delivery platforms to optimize SS-induced humoral immunity to CS repeats as well as other pathogens.

Health care workers (HCW) are a high-risk population for SARS-CoV-2 infection. Here, the authors determine seroprevalence against SARS-CoV-2 in HCWs of a large Spanish reference hospital and find a cumulative prevalence of SARS-CoV-2 infection (presence of antibodies or past or current positive rRT-PCR) of 11%.

Objectives: To determine the potential for dose escalation to a biological equivalent dose BED10≅100 Gy in hypofractionated radiotherapy for locally advanced pancreatic cancer (LAPC). Materials and methods: Ten unselected LAPC patients were retrospectively included in the study. Two fractionation regimens were compared (5 and 15 fractions). The aim was to cover 95% of the Planning Target Volume (PTV) with a BED10 = 54 Gy (base dose = 33 Gy in 5 fractions, 42.5 Gy in 15 fractions) whilst respecting organs-at-risk (OAR) constraints. Once the highest PTV coverage was achieved dose escalation to a BED10≅100 Gy (escalated dose = 50 Gy in 5 fractions, 67.5 Gy in 15 fractions) was attempted, limiting the PTV maximum dose to 130% of the escalated dose. Results: In 5 fractions, 95% PTV coverage by both base and escalated doses could be achieved for one patient with PTV more than 1 cm away from OAR. 95% and 90% PTV coverage by the base dose was achieved in one and two patients respectively. In all other patients, coverage even by the base dose had to be compromised to comply with OAR constraints. In 15 fractions, 95% PTV coverage by the base dose was feasible for all patients except one. Dose escalation allowed improvement in target coverage by the base dose in both fractionation regimen whilst covering a sub-volume of the PTV with a BED10≅100 Gy. Both fractionation schemes were equivalent in terms of dose escalation potential. Conclusion: LAPC patients with OAR close to the PTV are generally not eligible for hypofractionation with dose escalation. However, this planning study shows that it is possible to cover PTV sub-volumes with a BED10≅100 Gy in addition to delivering a BED10 = 54 Gy to 90–95% of the PTV as commonly prescribed to this population. Combined with an adaptive approach, this may maximize PTV coverage by a high BED on days with favourable anatomy. Keywords: Pancreatic cancer, SBRT, Hypofractionation, Dose escalation, Treatment planning

Initially identified as a T lymphocyte-elicited inhibitor of macrophage motility, macrophage migration inhibitory factor (MIF) has since been found to be expressed by nearly every immune cell type examined and overexpressed in most solid and hematogenous malignant cancers. It is localized to both extracellular and intracellular compartments and physically interacts with more than a dozen different cell surface and intracellular proteins. Although classically associated with and characterized as a mediator of pro-inflammatory innate immune responses, more recent studies demonstrate that, in malignant disease settings, MIF contributes to anti-inflammatory, immune evasive, and immune tolerant phenotypes in both innate and adaptive immune cell types. This review will summarize the studies describing MIF in tumor-specific innate and adaptive immune responses and attempt to reconcile these various pleiotropic functions in normal physiology.

Background. The goal of treating chronic hepatitis C virus (HCV) infection is sustained virologic response (SVR). There is concern that despite achieving SVR, replication-competent HCV may be sequestered at low levels within the liver and could theoretically reactivate with immunosuppression. We report transplantation of a HCV-seropositive liver donor, who achieved SVR, into a seronegative patient without HCV reactivation despite profound immunosuppression. Method. Retrospective chart review. Results. We present a 21-year-old male who was HCV seronegative and received a liver transplant from a donor who had been treated for HCV and achieved SVR. The liver recipient, despite developing severe acute graft rejection and undergoing intense immunosuppression with T cell–depleting antibodies, did not become HCV RNA-positive with a follow up period of 8 months. The recipient was HCV seronegative before transplant, but became HCV seropositive immediately posttransplant. The antibodies were undetectable after 97 days, in keeping with a passive antibody transmission or B lymphocyte transmission with the graft. Conclusions. To the best of our knowledge, this is the first reported case of an HCV seropositive liver allograft transplanted into an HCV-negative recipient who subsequently received intense immunosuppression. This case, therefore, is an encouraging and novel step in liver transplantation, and demonstrates that SVR may be closer to a true “cure” of HCV in the donor population and that, even in circumstances of very potent immunosuppression in the recipient, this SVR is sustained.

Background. It is unclear if the availability of new techniques for removal of large colonic polyps has affected the use of segmental colon resection. We sought to evaluate the characteristics of polyps undergoing surgical resection, including involvement of therapeutic gastroenterologists (TG). Methods. 484 patients had a colonic resection; 165 (34%) were identified from the pathology database with polyp, adenoma, or mass in the clinical history field; these charts were reviewed. Results. 128 patients (mean age 68 yrs, 72% male) were included. The mean polyp size was 2.9 cm (0.4 cm–12.0 cm). Adenocarcinoma was diagnosed in 50 (39.1%). 97 (75.8%) patients had a polyp that was felt to be unresectable by EMR, and 31 (24.2%) underwent successful EMR followed by surgery for adenocarcinoma (n=29). The indication for surgery in those with unresectable polyps was variable and was not clearly documented in 51 (52.6%); only 17 of these patients (17.5%) had a TG involved. Conclusion. A high proportion of polyps managed by segmental resection did not contain adenocarcinoma. This data suggests that even in a tertiary care center where advanced endoscopic techniques are easily available, they are not always utilized. Educational endeavors to ensure that ideal pathways of intervention are utilized require implementation.

Myeloid-derived suppressor cells (MDSCs) are potently immunosuppressive innate immune cells that accumulate in advanced cancer patients and actively inhibit anti-tumor T lymphocyte responses [1]. Increased numbers of circulating MDSCs directly correlate with melanoma patient morbidity and reduced anti-tumor immune responses [2,3]. Previous studies have revealed that monocyte-derived macrophage migration inhibitory factor (MIF) is necessary for the immune suppressive function of MDSCs in mouse models of melanoma [4,5]. To investigate whether MIF participates in human melanoma-induced MDSC differentiation and/or suppressive function, we have established an in vitro MDSC induction model using primary, normal human monocytes co-cultured with human melanoma cell lines in the presence or absence of the MIF antagonist—4-IPP [4,6–9]. To identify potential mechanistic effectors, we have performed transcriptome analyses on cultured monocytes and on melanoma-induced MDSCs obtained from either untreated or 4-IPP-treated A375:monocyte co-cultures. Here, we present a detailed protocol, which can facilitate easy reproduction of the microarray results (NCBI GEO accession number GSE73333) published by Yaddanapudi et al. (2015) in Cancer Immunology Research [10]. Keywords: Melanoma, MDSC, MIF, Immunesuppression, Trancriptome analysis

Background. There is a high incidence of inconclusive cytopathology at initial EUS-FNA (endoscopic ultrasound-guided fine-needle aspiration) for suspected malignant pancreatic lesions. To obtain appropriate preoperative or palliative chemotherapy for pancreatic cancer, definitive cytopathology is often required. The utility of repeat EUS-FNA is not well established. Methods. A retrospective cohort study was conducted evaluating the yield of repeat EUS-FNA in determining a cytological diagnosis in patients who had undergone a prior EUS-FNA for diagnosis of suspected malignant pancreatic lesions with inconclusive cytopathology. The wait times to the second procedure and to decisions regarding therapy were calculated. Results. Overall, 45 repeat EUS-FNA procedures were performed over seven years for suspected malignant pancreatic lesions. Cytopathological class (I to IV) changed between first and second EUS-FNA in 32 patients (71%). Of 34 patients with an initially nonconclusive diagnosis, 20 had a conclusive diagnosis (59%) on repeat EUS-FNA. The cumulative yield after repeat EUS-FNA for definite pancreatic adenocarcinoma was 7 (16%). The median time interval between first and second EUS-FNA was 31 (7–175) days. Conclusions. A substantial number of patients had a definitive diagnosis of adenocarcinoma on repeat FNA and were, therefore, subsequently able to access appropriate care.

Background. Infliximab (IFX) therapeutic drug monitoring (TDM) allows for objective decision making in patients with inflammatory bowel disease (IBD) and loss of response. Questions remain about whether IFX TDM improves outcomes. Methods. Patients with IBD who had IFX TDM due to concerns for loss of response were considered for inclusion. Serum IFX trough concentration and anti-drug antibody (ADA) concentrations were measured. Patients were grouped by TDM results: group 1, low IFX/high ADA; group 2, low IFX/low ADA; group 3, therapeutic IFX. Changes in management were analyzed according to groupings; remission rates were assessed at 6 months. Results. 71 patients were included of whom 37% underwent an appropriate change in therapy. Groups 1 (67%) and 2 (83%) had high adherence compared to only 9% in group 3. At 6 months, 57% had achieved remission. More patients who underwent an appropriate change in therapy achieved remission, though this did not reach statistical significance (69% versus 49%; P=0.098). Conclusions. A trend towards increased remission rates was associated with appropriate changes in management following TDM results. Many patients with therapeutic IFX concentrations did not undergo an appropriate change in management, potentially reflecting a lack of available out-of-class options at the time of TDM or due to uncertainty of the meaning of the reported therapeutic range.