BRCA1-mediated homologous recombination is an important DNA repair mechanism that is the target of FDA-approved PARP inhibitors, yet details of BRCA1-mediated functions remain to be fully elucidated. ...Similarly, immune checkpoint molecules are targets of FDA-approved cancer immunotherapies, but the biological and mechanistic consequences of their application are incompletely understood. We show here that the immune checkpoint molecule PD-L1 regulates homologous recombination in cancer cells by promoting BRCA1 nuclear foci formation and DNA end resection. Genetic depletion of tumor PD-L1 reduced homologous recombination, increased nonhomologous end joining, and elicited synthetic lethality to PARP inhibitors olaparib and talazoparib in vitro in some, but not all, BRCA1 wild-type tumor cells. In vivo, genetic depletion of tumor PD-L1 rendered olaparib-resistant tumors sensitive to olaparib. In contrast, anti-PD-L1 immune checkpoint blockade neither enhanced olaparib synthetic lethality nor improved its efficacy in vitro or in wild-type mice. Tumor PD-L1 did not alter expression of BRCA1 or its cofactor BARD1 but instead coimmunoprecipitated with BARD1 and increased BRCA1 nuclear accumulation. Tumor PD-L1 depletion enhanced tumor CCL5 expression and TANK-binding kinase 1 activation in vitro, similar to known immune-potentiating effects of PARP inhibitors. Collectively, these data define immune-dependent and immune-independent effects of PARP inhibitor treatment and genetic tumor PD-L1 depletion. Moreover, they implicate a tumor cell-intrinsic, immune checkpoint-independent function of PD-L1 in cancer cell BRCA1-mediated DNA damage repair with translational potential, including as a treatment response biomarker.
PD-L1 upregulates BRCA1-mediated homologous recombination, and PD-L1-deficient tumors exhibit BRCAness by manifesting synthetic lethality in response to PARP inhibitors, revealing an exploitable therapeutic vulnerability and a candidate treatment response biomarker. See related commentary by Hanks, p. 2069.
In Europe and elsewhere, health inequalities among HIV-positive individuals are of concern. We investigated late HIV diagnosis and late initiation of combination antiretroviral therapy (cART) by ...educational level, a proxy of socioeconomic position.
We used data from nine HIV cohorts within COHERE in Austria, France, Greece, Italy, Spain and Switzerland, collecting data on level of education in categories of the UNESCO/International Standard Classification of Education standard classification: non-completed basic, basic, secondary and tertiary education. We included individuals diagnosed with HIV between 1996 and 2011, aged at least 16 years, with known educational level and at least one CD4 cell count within 6 months of HIV diagnosis. We examined trends by education level in presentation with advanced HIV disease (AHD) (CD4 <200 cells/μl or AIDS within 6 months) using logistic regression, and distribution of CD4 cell count at cART initiation overall and among presenters without AHD using median regression.
Among 15 414 individuals, 52, 45,37, and 31% with uncompleted basic, basic, secondary and tertiary education, respectively, presented with AHD (P trend <0.001). Compared to patients with tertiary education, adjusted odds ratios of AHD were 1.72 (95% confidence interval 1.48-2.00) for uncompleted basic, 1.39 (1.24-1.56) for basic and 1.20 (1.08-1.34) for secondary education (P < 0.001). In unadjusted and adjusted analyses, median CD4 cell count at cART initiation was lower with poorer educational level.
Socioeconomic inequalities in delayed HIV diagnosis and initiation of cART are present in European countries with universal healthcare systems and individuals with lower educational level do not equally benefit from timely cART initiation.
Many migrants face adverse socioeconomic conditions and barriers to health services that can impair timely HIV diagnosis and access to life-saving treatments. We aimed to assess the differences in ...overall mortality by geographical origin in HIV-positive men and women using data from COHERE, a large European collaboration of HIV cohorts from 1997 to 2013.
In this observational cohort study, we included HIV-positive, antiretroviral-naive people accessing care in western Europe from COHERE. Individuals were eligible if enrolled in a cohort that collected information on geographical origin or ethnic origin from Jan 1, 1997, to March 19, 2013, aged 18-75 years, they had available information about sex, they were not infected perinatally or after the receipt of clotting factor concentrates, and were naive to combination antiretroviral therapy at cohort entry. Migrants' origins were grouped into seven regions: western Europe and similar countries (Australia, Canada, New Zealand, and the USA); eastern Europe; North Africa and the Middle East; sub-Saharan Africa; Latin America; the Caribbean; and Asia and the rest of Oceania (excluding Australia and New Zealand). Crude and adjusted mortality rate ratios were calculated by use of Poisson regression stratified by sex, comparing each group with the native population. Multiple imputation with chained equations was used to account for missing values.
Between Oct 25, 1979, and March 19, 2013, we recruited 279 659 individuals to the COHERE collaboration in EuroCoord. Of these 123 344 men and 45 877 women met the inclusion criteria. Our data suggested effect modification by transmission route (pinteraction=0·12 for men; pinteraction=0·002 for women). No significant difference in mortality was identified by geographical origin in men who have sex with men. In heterosexual populations, most migrant men had mortality lower than or equal to that of native men, whereas no group of migrant women had mortality lower than that in native women. High mortality was identified in heterosexual men from Latin America (rate ratio RR 1·46, 95% CI 1·00-2·12, p=0·049) and heterosexual women from the Caribbean (1·48, 1·29-1·70, p<0·0001). Compared with that in the native population, mortality in injecting drug users was similar or low for all migrant groups.
Characteristics of and risks faced by migrant populations with HIV differ for men and women and for populations infected heterosexually, by sex between men, or by injecting drug use. Further research is needed to understand how inequalities are generated and maintained for the groups with higher mortality identified in this study.
EuroCoord.
Discusses ethical behaviour in the OT and beyond through its characters, its varying portrayals of God and humanity in mutual dialogue and through its authors.
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