FcγR Polymorphisms Research Articles

Microbiological aspects of cancer progression: A systematic review conducted according to the PRISMA 2020 guidelines and the Cochrane Handbook for Systematic Reviews of Interventions.

The complex interplay between the gut microbiota, cancer treatments and patient characteristics has emerged as a significant area of research. This study sought to examine these relationships in the context of colorectal cancer (CRC).A comprehensive search of relevant studies was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines and the Cochrane Handbook for Systematic Reviews of Interventions. The studies included a variety of treatment modalities and microbiological parameters. A data extraction form, designed specifically for this review, was used to assess a range of variables across all studies.The analysis revealed a multifaceted interaction between the gut microbiota, genetic factors and treatment outcomes. Elderly patients with CRC frequently received single-agent chemotherapy, with outcomes that were comparable to those of younger patients. The presence of tumorigenic bacteria, including Escherichia coli and Bacteroides fragilis, was associated with early colon neoplasia. Additionally, an abundance of Fusobacterium spp. was observed in colonic adenomas, contributing to a pro-inflammatory environment. Although the FcγRIIIa-158 V/V genotype was associated with higher cetuximab-mediated antibodydependent cellular cytotoxicity (ADCC), no direct influence of FcγR polymorphisms on treatment response was noted. Furthermore, the combination of programmed cell death protein-1 (PD-1), BRAF and MEK inhibition showed favorable response rates. The gut microbiome, especially the presence of Fusobacterium spp., had a notable influence on the therapeutic response in CRC.These findings underscore the role of the gut microbiota and genetic factors in cancer treatment outcomes, emphasizing the potential of a holistic approach to cancer management. Future research should exploit these findings in order to develop microbiota-modulating strategies and personalized medicine approaches for the purpose of improving the efficacy of cancer treatment.

Defining genetic diversity of rhesus macaque Fcγ receptors with long-read RNA sequencing.

Fcγ receptors (FcγRs) are membrane-bound glycoproteins that bind to the fragment crystallizable (Fc) constant regions of IgG antibodies. Interactions between IgG immune complexes and FcγRs can initiate signal transduction that mediates important components of the immune response including activation of immune cells for clearance of opsonized pathogens or infected host cells. In humans, many studies have identified associations between FcγR gene polymorphisms and risk of infection, or progression of disease, suggesting a gene-level impact on FcγR-dependent immune responses. Rhesus macaques are an important translational model for most human health interventions, yet little is known about the breadth of rhesus macaque FcγR genetic diversity. This lack of knowledge prevents evaluation of the impact of FcγR polymorphisms on outcomes of preclinical studies performed in rhesus macaques. In this study we used long-read RNA sequencing to define the genetic diversity of FcγRs in 206 Indian-origin Rhesus macaques, Macaca mulatta. We describe the frequency of single nucleotide polymorphisms, insertions, deletions, frame-shift mutations, and isoforms. We also index the identified diversity using predicted and known rhesus macaque FcγR and Fc-FcγR structures. Future studies that define the functional significance of this genetic diversity will facilitate a better understanding of the correlation between human and macaque FcγR biology that is needed for effective translation of studies with antibody-mediated outcomes performed in rhesus macaques.

Abstract P5-02-40: Anthracycline improves the outcome of neoadjuvant trastuzumab-treated breast cancer patients with FcγRIIIA F/F genotype by decreasing the ratios of CD8+PD1+ and CD68+PDL1+ cells

Abstract Background: Antibody-dependent cell-mediated cytotoxicity (ADCC) is one of the most important mechanisms of trastuzumab. Fragment C Gamma receptor (FcγR) IIA and IIIA polymorphisms influence the affinity of immunoglobin G (IgG). Recently, FcγRIIA and FcγRIIIA polymorphisms have identified with the efficacy of trastuzumab. However, whether FcγR polymorphisms are associated with the efficacy of trastuzumab in the neoadjuvant setting was unclear. Patients and methods: We retrospectively enrolled 101 patients with HER2-positive breast cancer receiving chemotherapy plus trastuzumab at least four cycles as neoadjuvant therapy and mastectomy in Sun Yat-sen university cancer center from May 2015 to March 2021. Among them, twenty patients were excluded because lacking of blood samples. Polymorphisms of FcγRIIA(rs1801274) and FcγRIIIA(rs396991) were examined by nested polymerase chain reaction (PCR) and sanger sequencing. Lastly, we performed multiple immunohistochemistry (mIHC) to examine the expressions of CD8, CD68, CD57, PD1 and PDL1. Results: Blood samples (n=81) were successfully detected. No significant differences between FcγRIIA/FcγRIIIA genotypes and clinical characteristics, including age, clinical stages, menstrual status, molecular subtyping, treatment and pathological complete response (pCR) rate. In paclitaxel-based treatment subgroup (n=34), FcγRIIIA polymorphism was significantly correlated with pCR rate (P< 0.05,Table1), moreover, the disease-free survivals (DFS) in FcγRIIIA-158V carriers subgroup (high affinity) were significantly longer than that in FcγRIIIA-158 F/F genotype group (low affinity) (P=0.036), while that was not significant difference in patients with anthracycline-based treatment (n=47, P=0.248), indicating that anthracycline enhanced the efficacy of neoadjuvant therapy in patients with FcγRIIIA F/F genotype(low affinity). So far, there is no recurrence events in paclitaxel-based treatment group with FcγRIIIA-158V carriers genotype. The mIHC showed that the ratios of stroma CD8+PD1+ and CD68+PDL1+ cells were significantly higher in anthracycline-based treatment group (Table 2), respectively, indicating that anthracycline improved the efficacy of neoadjuvant targeted therapy by decreasing the ratios of exhausted immune cells. Conclusions: FcγRIIIA-158V genotype is associated with better outcome in HER2-positive breast cancer patients who received paclitaxel combined with trastuzumab as neoadjuvant therapy. Anthracycline improves the outcome of neoadjuvant trastuzumab-treated breast cancer patients with FcγRIIIA F/F genotype by decreasing the ratios of CD8+PD1+ and CD68+PDL1+ cells. Correlation between FcγRIIIA and pCR Correlation between FcγRIIIA and pCR in total population and paclitaxel-based treatment population. Ratios of immune cells Ratios of immune cells in anthracycline-based and paclitaxel-based treatment group. Citation Format: Kaping Lee, Rongzhen Luo, Qianyi Lu, Shusen Wang, Fei Xu. Anthracycline improves the outcome of neoadjuvant trastuzumab-treated breast cancer patients with FcγRIIIA F/F genotype by decreasing the ratios of CD8+PD1+ and CD68+PDL1+ cells [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-02-40.

Associations between KIR/KIR-ligand genotypes and clinical outcome for patients with advanced solid tumors receiving BEMPEG plus nivolumab combination therapy in the PIVOT-02 trial

Bempegaldesleukin (BEMPEG), a CD122-preferential IL2 pathway agonist, has been shown to induce proliferation and activation of NK cells. NK activation is dependent on the balance of inhibitory and excitatory signals transmitted by NK receptors, including Fc-gamma receptors (FCγRs) and killer immunoglobulin-like receptors (KIRs) along with their KIR-ligands. The repertoire of KIRs/KIR-ligands an individual inherits and the single-nucleotide polymorphisms (SNPs) of FCγRs can influence NK function and affect responses to immunotherapies. In this retrospective analysis of the single-arm PIVOT-02 trial, 200 patients with advanced solid tumors were genotyped for KIR/KIR-ligand gene status and FCγR SNP status and evaluated for associations with clinical outcome. Patients with inhibitory KIR2DL2 and its ligand (HLA-C1) observed significantly greater tumor shrinkage (TS, median change −13.0 vs. 0%) and increased PFS (5.5 vs. 3.3 months) and a trend toward improved OR (31.2 vs. 19.5%) compared to patients with the complementary genotype. Furthermore, patients with KIR2DL2 and its ligand together with inhibitory KIR3DL1 and its ligand (HLA-Bw4) had improved OR (36.5 vs. 19.6%), greater TS (median change −16.1 vs. 0%), and a trend toward prolonged PFS (8.4 vs. 3.6 months) as compared to patients with the complementary genotype. FCγR polymorphisms did not influence OR/PFS/TS.These data show that clinical response to BEMPEG plus nivolumab treatment in the PIVOT-02 trial may be associated with the repertoire of KIR/KIR-ligands an individual inherits. Further investigation and validation of these results may enable KIR/KIR-ligand genotyping to be utilized prospectively for identifying patients likely to benefit from certain cancer immunotherapy regimens.

Assessment of the influence of Fc-γ receptor polymorphisms on biologics' pharmacokinetics in Tunisian rheumatoid arthritis patients.

This study aims to determine whether a modification in Fc-γ receptors' (FcgRs) affinity to Fc portion, caused by single nucleotide polymorphisms such as rs1801274-R131H FcgRIIa, rs396991-F158V FcgRIIIa and NA1/NA2-FcgRIIIb, might impact clearance of therapeutic monoclonal antibodies and thus serum drug levels and the development of anti-drug antibodies. A cross sectional, multicentral and noninterventional study was conducted in Tunisian RA patients treated with rituximab (RTX), etanercept (ETA), infliximab (IFX) and adalimumab (ADL). Serum drug level (SDL) of the different biologics and ADA against them were measured. All patients were genotyped for the 3 FcgR single nucleotide polymorphisms. A total of 81 patients were included: 47 were under tumour necrosis factor inhibitors (18 ETA, 13 ADL and 16 IFX), and 34 were under RTX. Regardless of the type of biotherapy, SDL was in therapeutic range, in 35 patients (43.2%), of whom only 1 was treated with RTX. Fourteen patients (22.2%) developed ADA, but none of the patients treated with ETA had detectable ADA levels. There was no association between SDL positivity and FcgR polymorphisms. However, the high affinity FcgR2A 131 H/H receptor was statistically more prevalent in patients with detectable ADA treated with ADL, IFX and RTX (P = .018). The same result was obtained in the monoclonal antibody tumour necrosis factor inhibitor subgroup (n = 29, P = .022) as well as in patients treated only with IFX (n = 16, P = .029). Our work supports the hypothesis of an impact of FcgR single nucleotide polymorphisms on biologics' immunogenicity, particularly FcgR R131H polymorphism, but further studies with larger cohorts need to be undertaken to confirm these results.

The Role of Fc Gamma Receptors in Antibody-Mediated Rejection of Kidney Transplants.

For the past decades, complement activation and complement-mediated destruction of allograft cells were considered to play a central role in anti-HLA antibody-mediated rejection (AMR) of kidney transplants. However, also complement-independent mechanisms are relevant in the downstream immune activation induced by donor-specific antibodies, such as Fc-gamma receptor (FcγR)-mediated direct cellular activation. This article reviews the literature regarding FcγR involvement in AMR, and the potential contribution of FcγR gene polymorphisms to the risk for antibody mediated rejection of kidney transplants. There is large heterogeneity between the studies, both in the definition of the clinical phenotypes and in the technical aspects. The study populations were generally quite small, except for two larger study cohorts, which obviates drawing firm conclusions regarding the associations between AMR and specific FcγR polymorphisms. Although FcγR are central in the pathophysiology of AMR, it remains difficult to identify genetic risk factors for AMR in the recipient’s genome, independent of clinical risk factors, independent of the donor-recipient genetic mismatch, and in the presence of powerful immunosuppressive agents. There is a need for larger, multi-center studies with standardised methods and endpoints to identify potentially relevant FcγR gene polymorphisms that represent an increased risk for AMR after kidney transplantation.

Relevance of Fc Gamma Receptor Polymorphisms in Cancer Therapy With Monoclonal Antibodies.

Therapeutic monoclonal antibodies (mAbs), including immune checkpoint inhibitors (ICIs), are an important breakthrough for the treatment of cancer and have dramatically changed clinical outcomes in a wide variety of tumours. However, clinical response varies among patients receiving mAb-based treatment, so it is necessary to search for predictive biomarkers of response to identify the patients who will derive the greatest therapeutic benefit. The interaction of mAbs with Fc gamma receptors (FcγR) expressed by innate immune cells is essential for antibody-dependent cellular cytotoxicity (ADCC) and this binding is often critical for their in vivo efficacy. FcγRIIa (H131R) and FcγRIIIa (V158F) polymorphisms have been reported to correlate with response to therapeutic mAbs. These polymorphisms play a major role in the affinity of mAb receptors and, therefore, can exert a profound impact on antitumor response in these therapies. Furthermore, recent reports have revealed potential mechanisms of ICIs to modulate myeloid subset composition within the tumour microenvironment through FcγR-binding, optimizing their anti-tumour activity. The purpose of this review is to highlight the clinical contribution of FcγR polymorphisms to predict response to mAbs in cancer patients.

Fragement C Gamma receptor IIIa polymorphism is predictive of trastuzumab efficacy in the neoadjuvant setting of HER2-positive breast cancer patients.

e12607 Background: Antibody-dependent cell-mediated cytotoxicity (ADCC) is one of the most important mechanisms of Trastuzumab. Fragement C Gamma receptor (FcγR) IIA and IIIA polymorphisms influence the affinity of immunoglobin G (IgG). Recently, FcγRIIA and FcγRIIIA polymorphisms have identified with the efficacy of trastuzumab. However, whether FcγR polymorphisms are associated with the efficacy of trastuzumab in the neoadjuvant setting was unclear. Methods: We retrospectively enrolled 101 patients with HER2-positive breast cancer receiving chemotherapy plus trastuzumab as neoadjuvant therapy and mastectomy in Sun Yat-sen university cancer center from May 2015 to March 2021. Among them, twenty patients were excluded because lacking of blood samples. Clinical and pathological characteristics, treatments and outcomes of patients were collected. We purified the genomic DNA from peripheral blood samples, performed nested polymerase chain reaction (PCR) and sanger sequencing to identify the polymorphisms of FcγRIIA(rs1801274) and FcγRIIIA(rs396991). Results: Patient samples (n=81) were successfully detected. No significant differences between FcγRIIA/FcγRIIIA genotypes and clinical characteristics, including age, clinical stage, menstrual status, molecular subtyping, treatment and pathological complete response (pCR) rate. In subgroup analyses, FcγRIIIA polymorphism was significantly correlated with pCR rate in the population who received paclitaxel plus trastuzumab therapy (n=34, P<0.05). The Kaplan-Meier analyses showed that no significant difference in disease-free survivals (DFS) between FcγRIIA-131 H/H and R carriers genotype groups ( P=0.24), either that in the FcγRIIIA-158 F/F and V carriers genotype groups ( P=0.60). But the DFS in FcγRIIIA-158 V carriers genotype group were significant longer than that in FcγRIIIA-158 F/F genotype group in subgroup who received paclitaxel plus trastuzumab therapy (n=34, P=0.036), while that was not significant difference in patients with anthracycline-based treatment (n=47, P=0.248). DFS has not yet been reached. Conclusions: FcγRIIIA polymorphism is predictive of trastuzumab efficacy in the neoadjuvant setting of HER2-positive breast cancer patients who received paclitaxel plus trastuzumab therapy. Anthracycline-based treatment may improve the outcomes of HER2 positive breast cancer patients with FcγRIIIA-158 F/F genotype.[Table: see text]

A Quantitative Approach to Unravel the Role of Host Genetics in IgG-FcγR Complex Formation After Vaccination.

Fc-mediated immune functions have been correlated with protection in the RV144 HIV vaccine trial and are important for immunity to a range of pathogens. IgG antibodies (Abs) that form complexes with Fc receptors (FcRs) on innate immune cells can activate Fc-mediated immune functions. Genetic variation in both IgGs and FcRs have the capacity to alter IgG-FcR complex formation via changes in binding affinity and concentration. A growing challenge lies in unraveling the importance of multiple variations, especially in the context of vaccine trials that are conducted in homogenous genetic populations. Here we use an ordinary differential equation model to quantitatively assess how IgG1 allotypes and FcγR polymorphisms influence IgG-FcγRIIIa complex formation in vaccine-relevant settings. Using data from the RV144 HIV vaccine trial, we map the landscape of IgG-FcγRIIIa complex formation predicted post-vaccination for three different IgG1 allotypes and two different FcγRIIIa polymorphisms. Overall, the model illustrates how specific vaccine interventions could be applied to maximize IgG-FcγRIIIa complex formation in different genetic backgrounds. Individuals with the G1m1,17 and G1m1,3 allotypes were predicted to be more responsive to vaccine adjuvant strategies that increase antibody FcγRIIIa affinity (e.g. glycosylation modifications), compared to the G1m-1,3 allotype which was predicted to be more responsive to vaccine boosting regimens that increase IgG1 antibody titers (concentration). Finally, simulations in mixed-allotype populations suggest that the benefit of boosting IgG1 concentration versus IgG1 affinity may be dependent upon the presence of the G1m-1,3 allotype. Overall this work provides a quantitative tool for rationally improving Fc-mediated functions after vaccination that may be important for assessing vaccine trial results in the context of under-represented genetic populations.

59 Associations between KIR/KIR-ligand genotypes and clinical outcome for patients with advanced solid tumors receiving BEMPEG plus nivolumab combination therapy in the PIVOT-02 trial

BackgroundHigh-dose IL2 therapy has shown clinical benefit in metastatic melanoma and renal cell carcinoma, however only in a select subset of patients. Bempegaldesleukin (BEMPEG), a novel CD122-preferential IL2 pathway agonist, preferentially binds the heterodimeric IL2βγR predominantly expressed on NK and CD8 T cells and minimizes binding to the IL2αR expressed on immunosuppressive Tregs. BEMPEG monotherapy in Phase I clinical trials induced proliferation and activation of NK cells in the blood and tumor microenvironment.1 NK activation is dependent on the balance of inhibitory and excitatory signals transmitted by NK receptors, including Fc-gamma receptors (FCγRs) and killer immunoglobulin-like receptors (KIRs) along with their KIR-ligands. The repertoire of KIRs/KIR-ligands an individual inherits and the single-nucleotide polymorphisms (SNPs) of FCγRs can influence NK cell function and affect responses to immunotherapies.2–4 Thus, we sought to investigate whether distinct immunogenotypes are associated with clinical response of patients enrolled in PIVOT-02, a Phase II study of BEMPEG plus nivolumab.Methods200 patients with advanced solid tumors enrolled in PIVOT-02 who were not previously treated with immunotherapy (immunotherapy-naïve, ‘IO’) had DNA available for genotyping and clinical data for correlative analyses. All patients received 0.006mg/kg BEMPEG plus 360mg nivolumab every 3 weeks.5 KIR/KIR-ligand gene status was assessed by real-time SYBR green PCR melt-curve analyses and PCR-SSP. FCγR SNP status was determined using Taqman primers/probes for FCγR2A, and FCγR3A and FCγR2C were determined using RNaseH primers/probes.6 Clinical outcome parameters included objective response rate (ORR), progression-free survival (PFS), and tumor shrinkage (TS, defined as best objective response <0% by RECIST). Preliminary statistical analyses were done using a chi-square test, log-rank test, and Wilcoxon rank-sum test, respectively.ResultsKIR2DL2+/C1+ IO patients observed significantly greater TS (p=0.015) and a trend towards improved ORR (p=0.060) and increased PFS (p=0.058) compared to IO patients who were not KIR2DL2+/C1+. IO patients who were KIR2DL2+/C1+/KIR3DL1+/Bw4+ showed significantly improved ORR (p=0.014) and greater TS (p=0.044) compared to IO patients who were not KIR2DL2+/C1+/KIR3DL1+/Bw4+, with no significance found for PFS in these patients. FCγR polymorphisms did not influence ORR/PFS/TS.ConclusionsNK cells may play an important role in the anti-tumor efficacy of BEMPEG plus nivolumab, and NK activation is influenced by certain immunogenotypes. Similar to previous findings,2–4 the status of KIR2DL2+/C1+ and KIR2DL2+/C1+/KIR3DL1+/Bw4+ was associated with the response to BEMPEG plus nivolumab treatment in the PIVOT-02 trial. The potential to utilize these genotypes in clinical decision-making for immunotherapy treatment requires further investigation.Trial RegistrationClinicalTrialsgov NCT02983045ReferencesBentebibel S-E, et al. A first-in-human study and biomarker analysis of NKTR-214, a Novel IL2βγ-Biased cytokine, in patients with advanced or metastatic solid tumors. Cancer Discov 2019;9:711–21.Erbe AK, et al. Follicular lymphoma patients with KIR2DL2 and KIR3DL1 and their ligands (HLA-C1 and HLA-Bw4) show improved outcome when receiving rituximab. J Immunother Cancer 2019;7(1):70.Erbe AK, et al. Neuroblastoma patients’ KIR and KIR-Ligand genotypes influence clinical outcome for dinutuximab-based immunotherapy: A report from the Children’s Oncology Group. Clin Cancer Res 2018;24(1):189–96.Erbe AK, et al. FCGR polymorphisms influence response to IL2 in metastatic renal cell carcinoma. Clin Cancer Res 2017;23(9):2159–68.Diab A, et al. Bempegaldesleukin (NKTR-214) plus nivolumab in patients with advanced solid tumors: Phase I dose-escalation study of safety, efficacy, and immune activation (PIVOT-02). Cancer Discov 2020;10:1–16.Erbe AK, et al. Genotyping single nucleotide polymorphisms and copy number variability of the FCGRs expressed on NK cells. Methods Mol Biol 2016;1441:43–56.Ethics ApprovalThe study was conducted in accordance with Good Clinical Practice guidelines and the Declaration of Helsinki. The Protocol (online only) was approved by independent ethics committees and the relevant institutional review board at each site. All patients provided written informed consent.

Functional Fc Gamma Receptor Gene Polymorphisms and Long-Term Kidney Allograft Survival

The functional Fc gamma receptor (FcγR) IIIA polymorphism FCGR3A-V/F158 was earlier suggested to determine the potential of donor-specific HLA antibodies to trigger microcirculation inflammation, a key lesion of antibody-mediated renal allograft rejection. Associations with long-term transplant outcomes, however, have not been evaluated to date. To clarify the impact of FCGR3A-V/F158 polymorphism on kidney transplant survival, we genotyped a cohort of 1,940 recipient/donor pairs. Analyzing 10-year death-censored allograft survival, we found no significant differences in relation to FCGR3A-V/F158. There was also no independent survival effect in a multivariable Cox model. Similarly, functional polymorphisms in two other activating FcγR, FCGR2A-H/R131 (FcγRIIA) and FCGR3B-NA1/NA2 (FcγRIIIB), were not associated with outcome. There were also no significant survival differences among patient subgroups at increased risk of rejection-related injury, such as pre-sensitized recipients (> 0% panel reactivity; n = 438) or recipients treated for rejection within the first year after transplantation (n = 229). Our study results suggest that the earlier shown association of FcγR polymorphism with microcirculation inflammation may not be strong enough to exert a meaningful effect on graft survival.

Are Fc Gamma Receptor Polymorphisms Important in HIV-1 Infection Outcomes and Latent Reservoir Size?

Fc gamma receptors (FcγR) are cell surface glycoproteins which trigger specific effector-cell responses when cross-linked with the Fc portions of immunoglobulin (IgG) antibodies. During HIV-1 infection, the course of disease progression, ART response, and viral reservoir size vary in different individuals. Several factors may account for these differences; however, Fc gamma receptor gene polymorphisms, which influence receptor binding to IgG antibodies, are likely to play a key role. FcγRIIa (CD32) was recently reported as a potential marker for latent HIV reservoir, however, this assertion is still inconclusive. Whether FcγR polymorphisms influence the size of the viral reservoir, remains an important question in HIV cure studies. In addition, potential cure or viral suppression methods such as broadly neutralizing antibody (bNAbs) may depend on FcγRs to control the virus. Here, we discuss the current evidence on the potential role played by FcγR polymorphisms in HIV-1 infection, treatment and vaccine trial outcomes. Importantly, we highlight contrasting findings that may be due to multiple factors and the relatively limited data from African populations. We recommend further studies especially in sub-Saharan Africa to confirm the role of FcγRIIa in the establishment of latent reservoir and to determine their influence in therapies involving bNAbs.

Susceptibility to Plasmodium falciparum Malaria: Influence of Combined Polymorphisms of IgG3 Gm Allotypes and Fc Gamma Receptors IIA, IIIA, and IIIB.

The binding of immunoglobulin (Ig) to Fc gamma receptors (FcgR) at the immune cell surface is an important step to initiate immunological defense against malaria. However, polymorphisms in receptors and/or constant regions of the IgG heavy chains may modulate this binding. Here, we investigated whether polymorphisms located in FcgR and constant regions of the heavy chain of IgG are associated with susceptibility to P. falciparum malaria. For this purpose, a clinical and parasitological follow-up on malaria was conducted among 656 infants in southern Benin. G3m allotypes (from total IgG3) were determined by a serological method of hemagglutination inhibition. FcgRIIA 131R/H and FcgRIIIA 176F/V genotypes were determined using the TaqMan method and FcgRIIIB NA1/NA2 genotypes were assessed by polymerase chain reaction using allele-specific primers. Association analyses between the number of malaria infections during the follow-up and polymorphisms in IgG G3m allotypes and FcgR were studied independently by zero inflated binomial negative regression. The influence of combinations of G3m allotypes and FcgRIIA/FcgRIIIA/FcgRIIIB polymorphisms on the number of P. falciparum infections, and their potential interaction with environmental exposure to malaria was assessed by using the generalized multifactor dimensionality reduction (GMDR) method. Results showed that individual carriage of G3m24 single allotype and of G3m5,6,10,11,13,14,24 phenotype was independently associated with a high risk of malaria infection. A risk effect for G3m6 was observed only under high environmental exposure. FcgRIIIA 176VV single genotype and combined carriage of FcgRIIA 131RH/FcgRIIIA 176VV/FcgRIIIB NA1NA2, FcgRIIA 131HH/FcgRIIIA 176FF/FcgRIIIB NA1NA1, FcgRIIA 131HH/FcgRIIIA 176VV/FcgRIIIB NA2NA2 and FcgRIIA 131HH/FcgRIIIA 176VV/FcgRIIIB NA1NA2 genotypes were related to a high number of malaria infections. The risk was accentuated for FcgRIIIA 176VV when considering the influence of environmental exposure to malaria. Finally, the GMDR analysis including environmental exposure showed strengthened associations with a malaria risk when FcgRIIA/FcgRIIIA/FcgRIIIB genotypes were combined to G3m5,6,11,24 and G3m5,6,10,11,13,15,24 phenotypes or G3m10 and G3m13 single allotypes. Our results highlight the relevance of studying IgG heavy chain and FcgR polymorphisms, independently as well as in combination, in relation to the individual susceptibility to P. falciparum infection. The intensity of individual exposure to mosquito bites was demonstrated to impact the relationships found.

Abstract 2278: CTLA-4 targeted engineered toxin bodies designed to deplete regulatory T cells (Tregs)

Abstract Tumor resident regulatory T cells (Tregs) are important mediators of an immunosuppressive tumor microenvironment (TME) promoting tumor immune evasion. The presence of Tregs, and a higher ratio of Tregs to effector T cells in the TME, are associated with poor prognosis. The depletion of Tregs in the TME is expected to re-expose the tumor to the immune system to allow for tumor control. CLTA-4 is expressed on the cell surface of Tregs and is a clinically validated target. Better responses to CTLA-4 monoclonal antibody (mAb) treatment are correlated with stronger ADCC-mediated Treg depletion in preclinical models, and patient FcγR polymorphism has been reported to correlate with response to CTLA-4 mAb therapy. Towards improving on current therapies, many efforts to increase effective depletion of Tregs (such as by Fc effector modification) are being pursued. Engineered toxin bodies (ETBs) are comprised of a proprietarily engineered form of Shiga-like Toxin A subunit (SLT-A) genetically fused to antibody-like binding domains. ETBs work through novel mechanisms of action and are capable of forcing internalization, self-routing through intracellular compartments to the cytosol, and inducing potent cell-kill via the enzymatic and permanent inactivation of ribosomes. Targeted ETBs are being developed to specifically target and destroy CTLA-4 expressing cells. In vitro, cells expressing CTLA-4 are effectively and specifically killed by targeted ETBs. This direct cell kill activity of the ETB has the potential to deplete Tregs in the TME without a requirement for ADCC mechanisms. ETBs have been designed to bind various CTLA-4 epitopes, and to comprise of different targeting domains formats, including monomeric and diabody single chain variable fragments (scFvs) as well as single domain and biparatopic antibody fragments. The development of a CTLA-4 targeted ETB is ongoing. The entry of a protein with direct cell kill properties into the therapeutic space represents a differentiated mechanism of action to deplete Tregs for ultimate re-invigoration of the anti-tumor immune response, and has the potential to provide benefit to patients, including in the relapsed or refractory setting. Citation Format: Aimee Iberg, Edith Acquaye-Seedah, Lilia A. Rabia, Garrett L. Robinson, Hilario J. Ramos, Joseph D. Dekker, Jay Zhao, Erin K. Willert. CTLA-4 targeted engineered toxin bodies designed to deplete regulatory T cells (Tregs) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2278.

Aberrant FcγRIIb and FcγRIII expression on monocytes from patients with Behçet's disease

Behçet's disease (BD) patients have abnormal FcγR polymorphisms, the implication of which remains elusive. We examined FcγRIIb expression on neutrophils, monocytes, B cells, natural killer cells, dendritic cells and T cells, and FcγRI and FcγRIII expression on monocytes in BD patients and healthy controls using flow cytometry. We further stimulated monocytes with IgG and (or) lipopolysaccharide (LPS) and measured IL-6 and TNF-α production by enzyme-linked immunosorbent assay. We found that BD monocytes expressed a lower level of FcγRIIb and a higher level of FcγRIII, which were correlated with erythrocyte sedimentation rate and C-reactive protein and were rescued after treatment. Furthermore, LPS- and IgG-stimulated BD monocytes produced higher levels of IL-6 and TNF-α than HC monocytes. In summary, we found that BD monocytes downregulated FcγRIIb expression and upregulated FcγRIII expression, which were correlated with disease activity and potentially contributed to monocyte hyperactivation in BD.

Fc-gamma IIIa-V158F receptor polymorphism contributes to the severity of Guillain-Barré syndrome.

ObjectiveGuillain‐Barré syndrome (GBS) is a rare, life‐threatening disorder of the peripheral nervous system. Immunoglobulin G Fc‐gamma receptors (FcγRs) mediate and regulate diverse effector functions and are involved in the pathogenesis of GBS. We investigated whether the FcγR polymorphisms FcγRIIa H/R131 (rs1801274), FcγRIIIa V/F158 (rs396991), and FcγRIIIb NA1/NA2, and their haplotype patterns affect the affinity of IgG‐FcγR interactivity and influence GBS susceptibility and severity.MethodsWe determined FcγR polymorphisms in 303 patients with GBS and 302 ethnically matched healthy individuals from Bangladesh by allele‐specific polymerase chain reaction. Pairwise linkage disequilibrium and haplotype patterns were analyzed based on D ´statistics and the genotype package of R statistics, respectively. Logistic regression analysis and Fisher’s exact test with corrected P (Pc) values were employed for statistical comparisons.ResultsFcγRIIIa‐V158F was associated with the severe form of GBS compared to the mild form (P = 0.005, OR = 2.24, 95% CI = 1.28–3.91; Pc = 0.015); however, FcγR genotypes and haplotype patterns did not show any association with GBS susceptibility compared to healthy controls. FcγRIIIa‐V/V158 and FcγRIIIb‐NA2/2 were associated with recent Campylobacter jejuni infection (P ≤ 0.001, OR = 0.36, 95% CI = 0.23–0.56; Pc ≤ 0.003 and P = 0.004, OR = 1.70, 95% CI = 1.18–2.44; Pc ≤ 0.012, respectively). Haplotype 1 (FcγRIIa‐H131R‐ FcγRIIIa‐V158F‐ FcγRIIIb‐NA1/2) and the FcγRIIIb‐NA2/2 genotype were more prevalent among anti‐GM1 antibody‐positive patients (P = 0.031, OR = 9.61, 95% CI = 1.24–74.77, Pc = 0.279; P = 0.027, OR = 1.62, 95% CI = 1.06–2.5, Pc = 0.081, respectively).InterpretationFcγR polymorphisms and haplotypes are not associated with susceptibility to GBS, though the FcγRIIIa‐V158F genotype is associated with the severity of GBS.

Functional Attributes of Antibodies, Effector Cells, and Target Cells Affecting NK Cell-Mediated Antibody-Dependent Cellular Cytotoxicity.

Ab-dependent cellular cytotoxicity (ADCC) is one of the most important effector mechanisms of tumor-targeting Abs in current immunotherapies. In ADCC and other Ab-dependent activation of myeloid effector cells, close cell-cell contact (between effector and target cell) and formation of immunological synapses are required. However, we still lack basic knowledge on the principal factors influencing ADCC potential by therapeutic Abs. In this study we investigated the combined roles of five factors affecting human NK cell-mediated ADCC, namely: 1) Ag density, 2) target cell membrane composition, 3) IgG FcγR polymorphism, 4) FcγR-blocking cytophilic Abs, and 5) Ab fucosylation. We demonstrate that the magnitude of NK cell-mediated ADCC responses is predominantly influenced by Ag density and Ab fucosylation. Afucosylation consistently induced efficient ADCC, even at very low Ag density, where fucosylated target Abs did not elicit ADCC. On the side of the effector cell, the FcγRIIIa-Val/Phe158 polymorphism influenced ADCC potency, with NK cells expressing the Val158 variant showing more potent ADCC. In addition, we identified the sialic acid content of the target cell membrane as an important inhibitory factor for ADCC. Furthermore, we found that the presence and glycosylation status of aspecific endogenous Abs bound to NK cell FcγRIIIa (cytophilic Abs) determine the blocking effect on ADCC. These five parameters affect the potency of Abs in vitro and should be further tested as predictors of in vivo capacity.

Herceptin: A First Assault on Oncogenes that Launched a Revolution

This year's Lasker Clinical Research Award honors H. Michael Shepard, Dennis J. Slamon, and Axel Ullrich for their invention of Herceptin, the first monoclonal antibody that blocks a cancer-causing protein, and for its development as a life-saving therapy for women with breast cancer.

PTPN22, CTLA4, FcγRIIa, FcγRIIIa and FcγRIIIb polymorphisms in Tunisian patients with systemic lupus erythematosus

Background: Pathogenesis of systemic lupus erythematosus (SLE) involves both T cell tolerance breakdown and pathogenic autoantibodies. Polymorphisms in T cell regulatory proteins (PTPN22 and CTLA-4) and IgG receptors (FcγR) genes could impact their functions. Consequently, we aimed to study the role of PTPN22, CTLA-4, FcγRII and FcγRIII polymorphisms on either SLE susceptibility or its severity. Methods: Consequently, PTPN22 rs2476601 (R620W), CTLA-4 rs231775 (+49 A/G), FcγRIIa rs1801274 (R131H), FcγRIIIa rs396991 (F158V) and FcγRIIIb Na1/Na2 polymorphisms were examined in 137 SLE patients and 100 healthy blood donors matched in age, gender and ethnic origin. Results: The PTPN22-620*W mutant allele was significantly more prevalent in SLE patients comparatively to controls; p=0.001, OR [95% CI] = 7.8 [1.73-48.85]. Inversely, the frequency of the CTLA-4*G/G homozygous genotype was significantly lower in patients (35%) than in controls; p=0.02, OR [95% CI] = 0.54 [0.31-0.94]. Regarding to FcγR polymorphisms, while the FcγRIIIa*V allele was more prevalent in case of SLE (0.562 vs 0.35); p=0.001, OR [95% CI] = 2.77 [1.38-5.68], FcγRIIa and FcγRIIIb did not show any association with SLE. Analytic results showed that the prevalence of anti-dsDNA autoantibody was significantly higher in patients carrying PTPN22*W allele p=0.038. Otherwise, no correlation was found between the five studied polymorphisms and either clinical or biological patients characteristics. Conclusion: PTPN22 R620W, CTLA-A +49 A/G and FcγRIIIa F158V polymorphisms seem to be related to SLE susceptibility in Tunisian.

Fcγ-receptor polymorphisms associated with clinical symptoms in patients with immunoglobulin G subclass deficiency

Background: Immunoglobulin G subclass deficiencies (IgGsd) are associated with recurrent respiratory tract infections. Immunoglobulin substitution therapy may be needed to prevent chronic lung tissue damage but tools for identifying the patients that will benefit from this treatment are still insufficient. Some FcγR polymorphisms seem to predispose for an increased risk for infections. In this study we wanted to evaluate if the FcγR-profile differs between individuals with IgGsd and a control population.Methods: Single nucleotide polymorphisms (SNPs) of FcγRIIa, FcγRIIIa and FcγRIIc in 36 IgGsd patients and 192 controls with similar sex and geographical distribution were analyzed by TaqMan allelic discrimination assay or Sanger sequencing.Results: In the IgGsd-group, homozygous frequency for FcγRIIa-R/R131 (low-binding capacity isoform) was higher (p = .03) as well as for non-classical FcγRIIc-ORF (p = .03) and classical FcγRIIc-ORF tended (p = .07) to be more common compared to the controls. There was no difference between the groups regarding FcγRIIIa.Conclusion: The gene for classical FcγRIIc-ORF tended to be more frequent in individuals with immunoglobulin G subclass deficiency and the genes for non-classical FcγRIIc-ORF as well as low-binding capacity receptor FcγRIIa-R/R131 were more frequent. Further studies on the FcγR polymorphisms may pave way for identifying individuals that will benefit from immunoglobulin substitution.