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Background: HIV pre-exposure prophylaxis (PrEP) has likely contributed to large decreases in HIV incidence among men who have sex with men (MSM) in several major cities. Berlin has seen a smaller decline, and affordable PrEP has been accessible through formal channels in Germany only since autumn 2017. We aimed to investigate knowledge and use of PrEP among MSM in Berlin, and factors predictive of a desire to use PrEP and history of PrEP use. Methods: Multicentre, paper-based, self-administered survey of adult MSM whose HIV status was negative or unknown at time of participation. Data were collected from 1 October 2017 to 2 April 2018. Results: 473 of 875 questionnaires were returned (response rate 54.1%; mean age 37.4 years, range 18–79). 90.0% of participants were aware of PrEP and, of these, 48.2% felt well informed about it. Among the 17.2% of participants reporting PrEP use, 59.3% indicated obtaining some or all of it from informal sources. 23.7% of those with no history of PrEP use reported having condomless anal intercourse (CAI) with two or more partners over the past six months. Worries about side effects, cost, not having a doctor who prescribes it, and a lack of information were the most frequently reported barriers to PrEP use. A desire to use PrEP and history of PrEP use were associated in our multivariable model with having multiple CAI partners. A history of PrEP use was associated with having a university degree, one or two parents born outside Germany, or friends living with HIV. Conclusions: We found high awareness of PrEP among MSM in Berlin, but also a strong need for more education on its pros, cons and proper use. The frequency of informal PrEP use was also high, raising urgent individual and public health concerns. Policy makers need to consider recent calls to improve access to PrEP and PrEP education through regular health services. [ABSTRACT FROM AUTHOR]

Background: Recent preclinical and clinical studies in the diagnosis and treatment of Alzheimer Disease (AD) focus on antibody based radioligands and therapeutics by targeting amyloid‐β (Aβ).1 So far, imaging brain targets with bispecific antibodies (using transferrin receptor protein1 as shuttling mechanism) has only been investigated using 124I.2 The disadvantages of 124I limit drastically its clinical potential.3 Therefore, 89Zr is suggested as more suitable positron emitter for labelling of antibodies4, especially in combination with DFO*, the next generation chelator candidate for clinical 89Zr‐immuno‐PET.5 In this study, we evaluated [89Zr]Zr‐DFO*‐NCS labeled bispecific Abeta‐mAb‐scFab8D3 and its mutated analogue Abeta‐mAb‐scFab8D3 T1/2 with faster pharmacokinetics for Aβ imaging and targeting in a preclinical Alzheimer mouse model. Method: Abeta‐mAb‐scFab8D3 ± T1/2 and the nonspecific isotype control B12‐mAb‐scFab8D3 ± T1/2 were modified with DFO*‐NCS, and subsequently radiolabeled with 89Zr.6 The radiolabeled biologicals (1 mg/kg) were intravenously injected in APP/PS1 transgenic mice as well as in littermates which served as controls (n=5 per group). Blood pharmacokinetics were determined up to 3 (T1/2) or 7 days post injection (p.i.). PET/CT and PET/MRI scans were acquired for 1h at different time points. Result: The PET images showed a clear brain uptake for the bispecific Abeta‐mAb‐scFab8D3 ± T1/2 in APP/PS1 mice, while the corresponding B12‐mAb‐scFab8D3 ± T1/2 in APP/PS1 mice, as well as Abeta‐mAb‐scFab8D3 ± T1/2 in the littermates showed no specific uptake. Abeta‐mAb‐scFab8D3 demonstrated 2‐fold higher brain uptake (2% ID/g) than Abeta‐mAb‐scFab8D3 T1/2 (1% ID/g). Conclusion: 89Zr‐DFO*‐immuno‐PET revealed high and specific uptake of the bispecific Abeta‐mAb‐scFab8D3 in the brain. In this context, we demonstrated that slow kinetics of the biologicals contribute to improve Aβ targeting. The new bispecific Abeta‐mAb‐scFab8D3 looks very promising and supports further development toward companion and complementary diagnostics for AD. References: 1. Selkoe, D. J. Nature Reviews Neurology 15, 365–366 (2019). 2. Sehlin, D. et al. Nat. Commun. 7, 10759 (2016). 3. Verel, I. et al. Cancer Biother. Radiopharm. 18, 655–661 (2003). 4. O'Brien, H. A. J. Radioimmunoimaging Radioimmunother. 17, (1983). 5. Chomet, M. et al. Eur. J. Nucl. Med. Mol. Imaging 1–14 (2020). doi:10.1007/s00259‐020‐05002‐7. 6. Vugts, D. J. et al. Eur. J. Nucl. Med. Mol. Imaging 44, 286–295 (2017). [ABSTRACT FROM AUTHOR]