Objective. Men who have sex with men (MSM) have a high risk of lifelong anal cancer caused by high-risk human papillomavirus (HR HPV) infections. The aim of this study was to investigate the prevalence of anal canal HR HPV infection among men who have sex with men (MSM) with and without HIV infection in Moscow (Russia). We evaluated associations of some HIV coinfections (HSV and CMV) and HPV distribution among MSM with and without HIV infection. Methods. Two groups of HIV-positive (n = 60) and HIV-negative (n = 60) MSM were evaluated in the study. Fourteen high-risk (HR) HPV types, HSV1/2, and CMV were investigated in men anal swabs. Results. HR HPVs were found with nearly the same frequency of 66.7% in both groups: HIV-positive and HIV-negative MSM. HIV-positive status was statistically associated with the presence of several (more than two) HPV types ( p = 0.044 ). The most prevalent HR HPV genotypes were HPV18, HPV16, HPV56, and HPV33 for HIV-positive MSM and HPV56, HPV51, HPV66, and HPV16 for HIV-negatives. We found a statistically significant association of five HR HPV types with HIV status of MSM: HPV16 ( p = 0.028 ), HPV18 ( p = 0.00006 ), HPV58 ( p = 0.003 ), HPV33 ( p = 0.019 ), and HPV39 ( p = 0.026 ). The frequency of HSV1 (1.7%) and HSV2 (10%) infections and CMV (3.3%) infection was evaluated in the group of HIV-positive MSM. The frequency of HSV1 (5%) and HSV2 (6.7%) infections and CMV (0%) infection was evaluated, as well, in the group of HIV-negative MSM. Conclusion. Multiple HPV genotypes were detected significantly more often than single HPV genotype in the group of HIV-positive MSM. According to our data, 25% of HIV-positive MSM have HPV39; this is the only one of the five types of HR HPV (16, 18, 58, 33, and 39) associated with this group of MSM that has not yet been included in the HPV vaccines available on the market.

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49 Background: Gastrointestinal stromal tumours (GISTs) contain oncogenic KIT or PDGFRA tyrosine kinase (TK) mutations leading to disturbance of downstream signaling pathways that contribute to GIST pathogenesis. Additional genetic aberrations were found in GISTs, demonstrating the involvement of other genes important in tumor progression. The aim of the study was to evaluate the prognostic relevance of different TK mutations in GISTs and to analyze the additional genetic aberrations in GISTs according to mutational status. Methods: 180 GIST patients were examined for KIT (9, 11, 13, 17 exons) and PDGFRA mutations (12, 14, 18 exons) by direct sequencing of DNA obtained from microdissected tumor sections. Tumor tissue DNA from 44 GISTs patients was screened for loss of heterozygosity (LOH) at 11 microsatellite loci on 1p, 9p, 14q, 15q and 22q arms. Results: KIT and PDGFRA mutations were identified in 76.1% and 10% of GISTs, respectively. 13.9% GISTs had no mutations (wild type). Most of KIT mutations were located in exon 11 (65%) and exon 9 (9.4%). Prognostic significance of TK mutations was evaluated. There was a trend of better survival for patients with PDGFRA mutation then with KIT mutation or wild type GISTs. The higher overall survival prior to target therapy was shown for patients with duplication or point mutation in KIT exon 11 in comparison to exon 11 deletion. Analysis of LOH revealed allelic deletions in 85% of GISTs, more frequently at 14q arm. There was a different LOH pattern in subgroups of GISTs. GISTs with PDGFRA mutation and with KIT exon 11 point mutation had LOH at 14q, while GISTs with KIT exon 11 deletions revealed high LOH frequency also on 22q, 15q and 1p arms. LOH in wild type GISTs occurred on all chromosomes with low frequency. LOH on 9p was found exclusively in metastatic and recurrent GISTs. Specific gene loci of frequent LOH were identified on 9p, 15q and 22q that may be contributed to GIST progression. Conclusions: Specific mutations are associated with GISTs prognosis. Tumors with point mutations and duplications in KIT exon 11 are associated with a better survival then GISTs with other KIT mutations. Specific pattern of allelic deletions was identified in subgroups of GISTs according to type of mutation and tumor progression. No significant financial relationships to disclose.

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