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During the maturation of pre-B cells, the recombination activating gene 1 and 2 (RAG1/2) endonuclease complex plays a crucial role in coordinating V(D)J recombination by introducing DNA breaks in immunoglobulin (Ig) loci. Dysregulation of RAG1/2 has been linked to the onset of B cell malignancies, yet the mechanisms controlling RAG1/2 in pre-B cells exposed to excessive DNA damage are not fully understood. In this study, we show that DNA damage–induced activation of p53 initiates a negative-feedback loop which rapidly downregulates RAG1 levels. This feedback loop involves ataxia telangiectasia mutated activation, subsequent stabilization of p53, and modulation of microRNA-34a (miR-34a) levels, which is one of the p53 targets. Notably, this loop incorporates transcription factor forkhead box P1 as a downstream effector. The absence of p53 resulted in an increased proportion of IgM+ cells prompted to upregulate RAG1/2 and to undergo Ig light chain recombination. Similar results were obtained in primary pre-B cells with depleted levels of miR-34a. We propose that in pre-B cells undergoing Ig gene recombination, the DNA breaks activate a p53/miR-34a/forkhead box P1-mediated negative-feedback loop that contributes to the rapid downregulation of RAG. This regulation limits the RAG-dependent DNA damage, thereby protecting the stability of the genome during V(D)J rearrangement in developing B cells. [ABSTRACT FROM AUTHOR]

Recently, an update on the analyses of the immunoglobulin heavy variable region chain (IGHV-IGHD-IGHJ) gene rearrangements of a comprehensive cohort, now containing 29 856 cases of chronic lymphocytic leukaemia (CLL), was reported by the European Research Initiative on CLL (ERIC) consortium.1 Within this collection, as many as 2195 stereotyped B-cell receptor (BCR) subsets have been defined ranging in size from 2 to 764 IGHV sequences. ht 1 Stereotyped rheumatoid factors (RFs) expressed by MALT lymphomas (MALT-L) have been described previously.8 The numbers of stereotyped RFs expressed by salivary gland MALT-L have been updated. Higher-order of chronic lymphocytic leukaemia (CLL) classification: shared antigenic specificities of stereotyped B-cell receptor subsets as defined by the European Research Initiative on CLL consortium Identification of a novel stereotypic IGHV4-59/IGHJ5-encoded B-cell receptor subset expressed by various B-cell lymphomas with high affinity rheumatoid factor activity. [Extracted from the article]

Aims: The discovery of somatic genetic alterations established many histiocytic disorders as haematologic neoplasms. We aimed to investigate the demographic characteristics and additional haematologic cancers of patients diagnosed with histiocytic disorders in The Netherlands. Methods and results: We retrieved data on histiocytosis patients from the Dutch Nationwide Pathology Databank (Palga). During 1993 to 2022, more than 4000 patients with a pathologist‐assigned diagnosis of a histiocytic disorder were registered in Palga. Xanthogranulomas were the most common subtype, challenging the prevailing assumption that Langerhans cell histiocytosis (LCH) is the most common histiocytic disorder. LCH and juvenile xanthogranuloma (JXG) had a peak incidence in the first years of life; males were overrepresented among all histiocytosis subgroups. 118 patients had a histiocytic disorder and an additional haematologic malignancy, including 107 (91%) adults at the time of histiocytosis diagnosis. In 16/118 patients, both entities had been analysed for the same genetic alteration(s). In 11 of these 16 patients, identical genetic alterations had been detected in both haematologic neoplasms. This included two patients with PAX5 p.P80R mutated B cell acute lymphoblastic leukaemia and secondary histiocytic sarcoma, further supporting that PAX5 alterations may predispose (precursor) B cells to differentiate into the myeloid lineage. All 4/11 patients with myeloid neoplasms as their additional haematologic malignancy had shared N/KRAS mutations. Conclusions: This population‐based study highlights the frequency of xanthogranulomas. Furthermore, our data add to the growing evidence supporting clonal relationships between histiocytic/dendritic cell neoplasms and additional myeloid or lymphoid malignancies. Particularly adult histiocytosis patients should be carefully evaluated for the development of these associated haematologic cancers. [ABSTRACT FROM AUTHOR]

Despite this high miss-rate, advanced lesions were however rare and none of the patients developed appendiceal carcinoma, implying that appendiceal lesions in SPS patients are of limited clinical relevance. Furthermore, we evaluated how often endoscopists detected (non)advanced appendiceal lesions in: (i) SPS patients who underwent colonoscopies only during the (pre)clearance phase (described below); and (ii) patients who additionally received endoscopic surveillance and did not undergo colorectal surgery including the appendix (Fig. The rate of interval post-colonoscopy CRC (i. e. cancer that develops after a colonoscopy negative for CRC) can be considered as a proxy for missed lesions in SPS patients under strict surveillance. [Extracted from the article]

Presents the case of a Caucasian woman who developed graft-versus-host disease of the skin after treatment of pancytopenia due to bone marrow infiltration. Achievement of complete remission after induction treatment; Development of graft-versus-host disease; Findings of the skin biopsy.

Background: Circulating tumor DNA (ctDNA) has predictive and prognostic value in localized and metastatic cancer. This study analyzed the prognostic value of baseline and on-treatment ctDNA in metastatic gastroesophageal cancer (mGEC) using a region-specific next generation sequencing (NGS) panel. Methods: Cell free DNA was isolated from plasma of patients before start of first-line palliative systemic treatment and after 9 and 18 weeks. Two NGS panels were designed comprising the most frequently mutated genes and targetable mutations in GEC. Tumor-derived mutations in matched metastatic biopsies were used to validate that the sequencing panels assessed true tumor-derived variants. Tumor volumes were calculated from baseline CT scans and correlated to variant allele frequency (VAF). Survival analyses were performed using univariable and multivariable Cox-regression analyses. Results: ctDNA was detected in pretreatment plasma in 75% of 72 patients and correlated well with mutations in metastatic biopsies (86% accordance). The VAF correlated with baseline tumor volume (Pearson's R 0.53, p < 0.0001). Detection of multiple gene mutations at baseline in plasma was associated with worse overall survival (OS, HR 2.16, 95% CI 1.10–4.28; p = 0.027) and progression free survival (PFS, HR 2.71, 95% CI 1.28–5.73; p = 0.009). OS and PFS were inferior in patients with residual detectable ctDNA after 9 weeks of treatment (OS: HR 4.95, 95% CI 1.53–16.04; p = 0.008; PFS: HR 4.08, 95% CI 1.31–12.75; p = 0.016). Conclusion: Based on our NGS panel, the number of ctDNA mutations before start of first-line chemotherapy has prognostic value. Moreover, residual ctDNA after three cycles of systemic treatment is associated with inferior survival. [ABSTRACT FROM AUTHOR]

Simple Summary: This review summarizes gene-expression profiling insights into the background and origination of diffuse large B-cell lymphomas (DLBCL). To further unravel the molecular biology of these lymphomas, a consortium panel called BLYM-777 was designed including genes important for subtype classifications, genetic pathways, tumor-microenvironment, immune response and resistance to targeted therapies. This review proposes to combine this transcriptomic method with genomics, proteomics, and patient characteristics to facilitate diagnostic classification, prognostication, and the development of new targeted therapeutic strategies in DLBCL. Gene-expression profiling (GEP) is used to study the molecular biology of lymphomas. Here, advancing insights from GEP studies in diffuse large B-cell lymphoma (DLBCL) lymphomagenesis are discussed. GEP studies elucidated subtypes based on cell-of-origin principles and profoundly changed the biological understanding of DLBCL with clinical relevance. Studies integrating GEP and next-generation DNA sequencing defined different molecular subtypes of DLBCL entities originating at specific anatomical localizations. With the emergence of high-throughput technologies, the tumor microenvironment (TME) has been recognized as a critical component in DLBCL pathogenesis. TME studies have characterized so-called "lymphoma microenvironments" and "ecotypes". Despite gained insights, unexplained chemo-refractoriness in DLBCL remains. To further elucidate the complex biology of DLBCL, we propose a novel targeted GEP consortium panel, called BLYM-777. This knowledge-based biology-driven panel includes probes for 777 genes, covering many aspects regarding B-cell lymphomagenesis (f.e., MYC signature, TME, immune surveillance and resistance to CAR T-cell therapy). Regarding lymphomagenesis, upcoming DLBCL studies need to incorporate genomic and transcriptomic approaches with proteomic methods and correlate these multi-omics data with patient characteristics of well-defined and homogeneous cohorts. This multilayered methodology potentially enhances diagnostic classification of DLBCL subtypes, prognostication, and the development of novel targeted therapeutic strategies. [ABSTRACT FROM AUTHOR]

Background: In non-small cell lung cancer (NSCLC), PD-L1 expression on either tumor cells (TC) or both TC and tumor-infiltrating immune cells (IC) is currently the most used biomarker in cancer immunotherapy. However, the mechanisms involved in PD-L1 regulation are not fully understood. To provide better insight in these mechanisms, a multiangular analysis approach was used to combine protein and mRNA expression with several clinicopathological characteristics. Patients and methods: Archival tissues from 640 early stage, resected NSCLC patients were analyzed with immunohistochemistry for expression of PD-L1 and CD8 infiltration. In addition, mutational status and expression of a selection of immune genes involved in the PD-L1/PD-1 axis and T-cell response was determined. Results: Tumors with high PD-L1 expression on TC or on IC represent two subsets of NSCLC with minimal overlap. We observed that PD-L1 expression on IC irrespective of expression on TC is a good marker for inflammation within tumors. In the tumors with the highest IC expression and absent TC expression an association with reduced IFNγ downstream signaling in tumor cells was observed. Conclusions: These results show that PD-L1 expression on TC and IC are both independent hallmarks of the inflamed phenotype in NSCLC, and TC-negative/IC-high tumors can also be categorized as inflamed. The lack of correlation between PD-L1 TC and IC expression in this subgroup may be caused by impaired IFNγ signaling in tumor cells. These findings may bring a better understanding of the tumor-immune system interaction and the clinical relevance of PD-L1 expression on IC irrespective of PD-L1 expression on TC. [ABSTRACT FROM AUTHOR]

The recombination activating gene (RAG) 1 and RAG2 protein complex introduces DNA breaks at Tcr and Ig gene segments that are required for V(D)J recombination in developing lymphocytes. Proper regulation of RAG1/2 expression safeguards the ordered assembly of Ag receptors and the development of lymphocytes, while minimizing the risk for collateral damage. The ataxia telangiectasia mutated (ATM) kinase is involved in the repair of RAG1/2-mediated DNA breaks and prevents their propagation. The simultaneous occurrence of RAG1/2-dependent and -independent DNA breaks in developing lymphocytes exposed to genotoxic stress increases the risk for aberrant recombinations. In this study, we assessed the effect of genotoxic stress on RAG1/2 expression in pre–B cells and show that activation of the DNA damage response resulted in the rapid ATM-dependent downregulation of RAG1/2 mRNA and protein expression. We show that DNA damage led to the loss of FOXO1 binding to the enhancer region of the RAG1/2 locus (Erag) and provoked FOXO1 cleavage. We also show that DNA damage caused by RAG1/2 activity in pre–B cells was able to downmodulate RAG1/2 expression and activity, confirming the existence of a negative feedback regulatory mechanism. Our data suggest that pre–B cells are endowed with a protective mechanism that reduces the risk for aberrant recombinations and chromosomal translocations when exposed to DNA damage, involving the ATM-dependent regulation of FOXO1 binding to the Erag enhancer region. [ABSTRACT FROM AUTHOR]

The recombination activating gene (RAG) 1 and RAG2 protein complex introduces DNA breaks at Ter and Ig gene segments that are required for V(D)J recombination in developing lymphocytes. Proper regulation of RAG1/2 expression safeguards the ordered assembly of Ag receptors and the development of lymphocytes, while minimizing the risk for collateral damage. The ataxia telangiectasia mutated (ATM) kinase is involved in the repair of RAGl/2-mediated DNA breaks and prevents their propagation. The simultaneous occurrence of RAGl/2-dependent and -independent DNA breaks in developing lymphocytes exposed to genotoxic stress increases the risk for aberrant recombinations. In this study, we assessed the effect of genotoxic stress on RAG1/2 expression in pre-B cells and show that activation of the DNA damage response resulted in the rapid ATM-dependent downregulation of RAG 1/2 mRNA and protein expression. We show that DNA damage led to the loss of FOXOI binding to the enhancer region of the RAG1/2 locus (Erag) and provoked FOXOI cleavage. We also show that DNA damage caused by RAG1/2 activity in pre-B cells was able to downmodulate RAG1/2 expression and activity, confirming the existence of a negative feedback regulatory mechanism. Our data suggest that pre-B cells are endowed with a protective mechanism that reduces the risk for aberrant recombinations and chromosomal translocations when exposed to DNA damage, involving the ATM-dependent regulation of FOXOI binding to the Erag enhancer region. [ABSTRACT FROM AUTHOR]

In developing lymphocytes, expression and activity of the recombination activation gene protein 1 (RAG1) and RAG2 endonuclease complex is tightly regulated to ensure ordered recombination of the immunoglobulin genes and to avoid genomic instability.Aberrant RAG activity has been implicated in the generation of secondary genetic events in human B-cell acute lymphoblastic leuκemias (B-ALLs), illustrating the oncogenic potential of the RAG complex. Several layers of regulation prevent collateral genomic DNA damage by restricting RAG activity to the G1 phase of the cell cycle. In this study, we show a novel pathway that suppresses RAG expression in cycling-transformed mouse pre-B cells and human pre-B B-ALL cells that involves the negative regulation of FOXO1 by nuclear factor κB (NF-κB). Inhibition of NF-κB in cycling pre-B cells resulted in upregulation of RAG expression and recombination activity, which provoκed RAG-dependent DNA damage. In agreement, we observe a negative correlation between NF-κB activity and the expression of RAG1,RAG2,andTdTinB-ALL patients.Our data suggest that targetingNF-κBinB-ALL increases the risκof RAG-dependent genomic instability. [ABSTRACT FROM AUTHOR]

BACKGROUND: High-grade anal intraepithelial neoplasia (AIN) is present in many human immunodeficiency virus (HIV)-positive men who have sex with men. The major etiologic factor is infection with an oncogenic human papillomavirus (HPV) genotype. We investigated whether individual components of high-grade AIN are caused by single HPV types. METHODS: DNA was isolated from whole-tissue sections of 31 high-grade AIN that were recovered from 21 HIV-positive men who have sex with men. The SPF10 PCR/LiPA25 HPV genotyping system was used for DNA analysis. In whole-tissue sections with multiple HPV types, polymerase chain reaction was repeated in regions of AIN sampled by laser-capture microdissection. The results were compared with HPV types in anal swabs. RESULTS: A single HPV type was observed in 15 (48%) of 31 whole-tissue sections. In an additional 14 whole-tissue sections, 1 HPV type was found in each lesion sample evaluated by laser-capture microdissection. Consequently, in 29 of 31 biopsy specimens (94%), a single HPV type was found in each lesional component studied. Two whole-tissue sections contained collision regions, each with 2 HPV types. HPV16 was presumed to be causative in 14 of 31 biopsy specimens (45%). More than half of the anal swabs did not contain all causative HPV types. CONCLUSIONS: Individual components of high-grade AIN are caused by single HPV types (the so-called one lesion, one virus concept). HPV16 is causative in <50% of cases. Anal swabs are not useful for detecting lesion-specific HPV types. [ABSTRACT FROM AUTHOR]

Colon cancer is a clinically diverse disease. This heterogeneity makes it difficult to determine which patients will benefit most from adjuvant therapy and impedes the development of new targeted agents. More insight into the biological diversity of colon cancers, especially in relation to clinical features, is therefore needed. We demonstrate, using an unsupervised classification strategy involving over 1,100 individuals with colon cancer, that three main molecularly distinct subtypes can be recognized. Two subtypes have been previously identified and are well characterized (chromosomal-instable and microsatellite-instable cancers). The third subtype is largely microsatellite stable and contains relatively more CpG island methylator phenotype-positive carcinomas but cannot be identified on the basis of characteristic mutations. We provide evidence that this subtype relates to sessile-serrated adenomas, which show highly similar gene expression profiles, including upregulation of genes involved in matrix remodeling and epithelial-mesenchymal transition. The identification of this subtype is crucial, as it has a very unfavorable prognosis and, moreover, is refractory to epidermal growth factor receptor-targeted therapy. [ABSTRACT FROM AUTHOR]

The pathogenesis of classical Hodgkin lymphoma (cHL), the most common lymphoma in the young, is still enigmatic, largely because its Hodgkin and Reed-Sternberg (HRS) tumor cells are rare in the involved lymph node and therefore difficult to analyze. Here, by overcoming this technical challenge and performing, for the first time, a genome-wide transcriptional analysis of microdissected HRS cells compared with other B-cell lymphomas, cHL lines, and normal B-cell subsets, we show that they differ extensively from the usually studied cHL cell lines, that the lost B-cell identity of cHLs is not linked to the acquisition of a plasma cell-like gene expression pro gram, and that Epstein-Barr virus infection of HRS cells has a minor transcriptional influence on the established cHL clone. Moreover, although cHL appears a distinct lymphoma entity overall, HRS cells of its histologic subtypes diverged in their similarity to other related lymphomas. Unexpectedly, we identified 2 molecular subgroups of cHL associated with differential strengths of the transcription factor activity of the NOTCH1, MYC, and IRF4 proto-oncogenes. Finally, HRS cells display deregulated expression of several genes potentially highly relevant to lymphoma pathogenesis, including silencing of the apoptosis-inducer BIK and of INPP5D, an inhibitor of the PI3K-driven oncogenic pathway. [ABSTRACT FROM AUTHOR]

In gastric cancer, a new epigenetic mechanism of tumour suppressor loss has been suggested where the histone methyltransferase enhancer of zeste homolog 2 (EZH2) is responsible for loss of expression of RUNX3. This is consistent with EZH2 upregulation in multiple cancer types being associated with poor prognosis. We investigated whether EZH2 influences the expression of RUNX3 in colorectal cancer (CRC) and whether this is independent of methylation. We determined protein and messenger RNA (mRNA) levels of EZH2 and RUNX3 and assessed RUNX3 methylation with methylation- specific polymerase chain reaction using 72 human CRCs and 8 CRC cell lines. We assessed the effect of efficient RNA interference-mediated knockdown of EZH2 on RUNX3 levels, cell viability and H3K27 trimethylation of the RUNX3 promoter using chromatin immunoprecipitation. Despite higher levels of EZH2 and lower levels of RUNX3 in CRC specimens in general, no inverse correlation between EZH2 and RUNX3 in paired samples was found arguing against a major role for histone methylation in silencing RUNX3 in CRC. Conversely, downregulation of RUNX3 mRNA in the same tumours was associated with RUNX3 DNA methylation (P < 0.05). In cell lines, knockdown of EZH2 removed the repressive chromatin marks from RUNX3 but did not result in RUNX3 re-expression. However, it prevented the re-silencing of RUNX3 after the removal of demethylating agents. In conclusion, DNA methylation is primarily responsible for the transcriptional silencing of RUNX3 in CRC, but EZH2 and histone methylation are necessary for its methylation-dependent re-silencing after the removal of demethylating agents. These results would predict that inhibitors of EZH2 and histone methylation would enhance the effects of demethylating agents in cancer therapy. [ABSTRACT FROM AUTHOR]

BACKGROUND AND AIMS: Patients with hyperplastic polyposis syndrome (HPS) receive endoscopic surveillance to prevent malignant progression of polyps. However, the optimal treatment and surveillance protocol for these patients is unknown. The aim of this study was to describe the clinical and pathological features of a large HPS cohort during multiple years of endoscopic surveillance. METHODS: Databases were searched for patients with HPS, who were analysed retrospectively. Endoscopy reports and histopathology reports were collected to evaluate frequency of endoscopic surveillance and to obtain information regarding polyp and the presence of colorectal cancer (CRC). RESULTS: In 77 patients with HPS, 1984 polyps were identified during a mean follow-up period of 5.6 years (range: 0.5–26.6). In 27 (35%) patients CRC was detected of which 22 (28.5%) at initial endoscopy. CRC was detected during surveillance in five patients (cumulative incidence: 6.5%) after a median follow-up time of 1.3 years and a median interval of 11 months. Of these interval CRCs, 4/5 were detected in diminutive serrated polyps (range: 4–16 mm). The cumulative risk of CRC under surveillance was 7% at 5 years. At multivariate logistic regression, an increasing number of hyperplastic polyps (OR 1.05, p=0.013) and serrated adenomas (OR 1.09, p=0.048) was significantly associated with CRC presence. CONCLUSIONS: HPS patients undergoing endoscopic surveillance have an increased CRC risk. The number of serrated polyps is positively correlated with the presence of CRC in HPS, thus supporting a ‘serrated pathway’ to CRC. To prevent malignant progression, adequate detection and removal of all polyps seems advisable. If this is not feasible, surgical resection should be considered. [ABSTRACT FROM AUTHOR]

CD20 was the first B cell differentiation antigen identified, and CD20-specific mAbs are commonly used for the treatment of B cell malignancies and autoantibody-mediated autoimmune diseases. Despite this the role of CD20 in human B cell physiology has remained elusive. We describe here a juvenile patient with CD20 deficiency due to a homozygous mutation in a splice junction of the CD20 gene (also known as MS4A1) that results in "cryptic" splicing and nonfunctional mRNA species. Analysis of this patient has led us to conclude that CD20 has a central role in the generation of T cell-independent (TI) antibody responses. Key evidence to support this conclusion was provided by the observation that although antigen-independent B cells developed normally in the absence of CD20 expression, antibody formation, particularly after vaccination with TI antigens, was strongly impaired in the patient. Consistent with this, TI antipolysaccharide B cell responses were severely impeded in CD20-deficient mice. Our study therefore identifies what we believe to be a novel type of humoral immunodeficiency caused by CD20 deficiency and characterized by normal development of antigen-independent B cells, along with a reduced capacity to mount proper antibody responses. [ABSTRACT FROM AUTHOR]

The article focuses on a study which aimed to determine whether and where bone morphogenetic protein (BMP) signaling is disrupted during the adenoma-carcinoma sequence of colorectal cancer (CRC) formation. A tissue microarray and immunohistochemistry of BMP receptors and signal transduction elements in adenomas and CRC specimens were used to elucidate the role of BMP signalling in CRC carcinogenesis. The results of the study showed that the loss of BMP signalling correlates with progression of adenomas to cancer occurs during cancer progression.

Background: Kaposi's Sarcoma (KS) is a proliferation of aberrant vascular structures lined by spindle cells, and is caused by a gammaherpes virus (HHV8/KSHV). Its course is aggravated by coinfection with HIV-1, where the timing of infection with HIV-1 and HHV8 is important for the clinical outcome. Methods: In order to better understand the pathogenesis of KS, we have analysed tissue from two AIDS-KS lesions, and from normal skin by serial analysis of gene expression (SAGE). Semi-quantitative RT-PCR was then used to validate the results. Results: The expression profile of AIDS-related KS (AIDS-KS) reflects an active process in the skin. Transcripts of HHV8 were found to be very low, and HIV-1 mRNA was not detected by SAGE, although it could be found using RT-PCR. Comparing the expression profile of AIDS-KS tissue with publicly available SAGE libraries suggested that AIDS-KS mRNA levels are most similar to those in an artificially mixed library of endothelial cells and leukocytes, in line with the description of KS lesions as containing spindle cells with endothelial characteristics, and an inflammatory infiltrate. At least 64 transcripts were found to be significantly elevated, and 28 were statistically downregulated in AIDS-KS compared to normal skin. Five of the upregulated mRNAs, including Tie 1 and sialoadhesin/CD169, were confirmed by semi-quantitative PCR to be elevated in additional AIDS-KS biopsies. Antibodies to sialoadhesin/CD169, a known marker of activated macrophages, were shown to specifically label tumour macrophages. Conclusion: The expression profile of AIDS-KS showed 64 genes to be significantly upregulated, and 28 genes downregulated, compared with normal skin. One of the genes with increased expression was sialoadhesin (CD169). Antibodies to sialoadhesin/CD169 specifically labelled tumour-associated macrophages, suggesting that macrophages present in AIDS-KS lesions belong to a subset of human CD169+ macrophages. [ABSTRACT FROM AUTHOR]

Objective:Anal Intraepithelial Neoplasia (AIN) is present in the majority of HIV+ men who have sex with men (MSM) and routine AIN-screening is subject of discussion. In this study we analysed a wide range of potential risk factors for AIN in order to target screening programs. Methods:We screened 311 HIV+ MSM by high resolution anoscopy, with biopsies of suspect lesions. HIV-parameters, previous sexual transmitted infections (STI’s), anal pathology, sexual practices and substance use were analysed in relation to AIN by uni- and multivariable logistic regression. Results:AIN (any grade) was found in 175/311 MSM (56%), high grade (HG)AIN in 30%. In the univariable analysis, years since HIV diagnosis, years of antiretroviral therapy (cART) and anal XTC use decreased AIN risk, while a history of anogenital warts and use of GHB (γ-hydroxybutyric acid) increased this risk. In the multivariable analysis three parameters remained significant: years of cART (OR=0.92 per year, p=0.003), anal XTC use (OR=0.10, p=0.002) and GHB use (OR=2.60, p=0.003). No parameters were significantly associated with HGAIN, but there was a trend towards increased risk with anal enema use prior to sex (>50 times ever; p=0.07) and with a history of AIN (p=0.06). CD4 count, STI’s, anal pathology, smoking, number of sex partners and anal fisting were not associated with (HG)AIN. Conclusion:GHB use increases the risk for AIN, while duration of cART and anal XTC use are negatively correlated with AIN. Given the high prevalence of AIN in HIV+ MSM, these associations are not helpful to guide a screening program. [ABSTRACT FROM AUTHOR]