AIDS-defining events among people living with HIV who have been under continuous antiretroviral therapy for more than one year, a German cohort study 1999-2018.

PURPOSE: This study examined the characteristics, incidence and prognostic factors of the first AIDS-defining condition developed after more than one year of continuous antiretroviral therapy (ART) among people living with HIV (PLHIV). METHODS: We used data from two multicentre observational cohorts of PLHIV in Germany between 1999 and 2018. Our outcome was the first AIDS-defining event that occurred during follow-up after more than one year of continuous ART. Descriptive analyses at ART initiation, at the time of the AIDS event and of the most frequently observed types of AIDS-defining illnesses were performed. We calculated the incidence rate (IR) per 1000 person-years (PY) and used a bootstrap stepwise selection procedure to identify predictors of the outcome. RESULTS: A total of 12,466 PLHIV were included in the analyses. 378 developed the outcome, constituting an overall IR of 5.6 (95% CI 5.1-6.2) AIDS events per 1000 PY. The majority of PLHIV was virally suppressed at the time of the event. Oesophageal candidiasis and wasting syndrome were the most frequently diagnosed AIDS-defining illnesses. We found a low CD4 count at ART initiation, a previous AIDS-defining condition and transmission through intravenous drug use to be meaningful prognostic factors of the outcome. CONCLUSION: The overall rate of AIDS-defining events among PLHIV under long-term ART was low, highlighting the importance of continuous treatment. PLHIV who started ART with indicators of impaired immune functioning were more susceptible to disease progression, suggesting that the public health response should continue to focus on early and sustained treatment for all PLHIV.

AIDS in the era of antiretroviral therapy: Changes in incidence rates and predictors of AIDS among people living with HIV under clinical care in Germany, a cohort study 1999-2018.

OBJECTIVES: This study examined the incidence rates and predictive utility of established prognostic factors for the progression to AIDS among people living with HIV under clinical care. METHODS: We used data from two observational cohorts of people living with HIV in Germany between 1999 and 2018. The outcome measure was the first AIDS-defining event that occurred during follow-up. Incidence rates (IRs) per 1000 person-years (PY) were calculated by years of follow-up and calendar periods. We used Cox models in our prediction analyses, including CD4 count, viral load, and age at baseline to estimate the predictive performance. Additionally, we included transmission mode to examine its predictive utility. RESULTS: A total of 23 299 people living with HIV were included in the analyses. Of these, 1832 developed a first AIDS event during follow-up, constituting an overall rate of 14.6/1000 PY (95% confidence interval [CI] 13.9-15.2). IRs were highest in the first year of follow-up (45.6/1000 PY, 95% CI 42.6-48.8) and then declined continuously. IRs were highest among people living with HIV who enrolled between 1999 and 2003 (36.1/1000 PY, 95% CI 32.6-40.0). A low CD4 count, high viral load, and older age at baseline increased the likelihood of progressing to AIDS. Adding transmission mode to the models did not improve the predictive performance. CONCLUSIONS: The rates of a first AIDS event among people living with HIV have continuously declined in Germany. Health outcomes depend on a person's CD4 count, viral load, and age but not on transmission mode. To further reduce the number of AIDS cases, the focus should be on groups more likely to present in progressed stages of their HIV infection.

Monkeypox in-patients with severe anal pain.

Berlin is amongst the cities most affected by the current monkeypox outbreak. Here, we report clinical characteristics of the first patients with confirmed monkeypox admitted to our center. We analyzed anamnestic, clinical, and laboratory data. Within a period of 2 weeks, six patients were hospitalized in our unit. All were MSM and had practiced condomless receptive anal intercourse in the weeks preceding admission. The chief complaint in all patients but one was severe anal pain unprecedented in severity. Investigations revealed proctitis, as well as anal and rectal ulcers with detection of monkeypox virus. Our findings support the hypothesis that sexual transmission plays a role in the current outbreak.

M ycobacterium tuberculosis-specific CD4 T-cell scoring discriminates tuberculosis infection from disease.

BACKGROUND: Rapid and reliable diagnostic work-up of tuberculosis (TB) remains a major healthcare goal. In particular, discrimination of TB infection from TB disease with currently available diagnostic tools is challenging and time consuming. This study aimed at establishing a standardised blood-based assay that rapidly and reliably discriminates TB infection from TB disease based on multiparameter analysis of TB antigen-reactive CD4+ T-cells acting as sensors for TB stage-specific immune status. METHODS: 157 HIV-negative subjects with suspected TB infection or TB disease were recruited from local tertiary care hospitals in Berlin (Germany). Peripheral blood mononuclear cells were analysed for CD4+ T-cells reactive to the Mycobacterium tuberculosis antigens purified protein derivative and early secretory antigenic target 6 kDa/culture filtrate protein 10. The activation state of TB antigen-reactive T-cells, identified by surface expression of CD154, was evaluated according to the expression profile of proliferation marker Ki-67 and activation markers CD38 and HLA-DR. Using data from 81 subjects with clinically confirmed TB infection (n=34) or culture-proven pulmonary or extrapulmonary TB disease (n=47), 12 parameters were derived from the expression profile and integrated into a scoring system. RESULTS: Using the scoring system, our assay (TB-Flow Assay) allowed reliable discrimination of TB infection from both pulmonary and extrapulmonary TB disease with high sensitivity (90.9%) and specificity (93.3%) as was confirmed by Monte-Carlo cross-validation. CONCLUSION: With low time requirement, ease of sample collection, and high sensitivity and specificity both for pulmonary and extrapulmonary TB disease, we believe this novel standardised TB-Flow Assay will improve the work-up of patients with suspected TB disease, supporting rapid TB diagnosis and facilitating treatment decisions.

HIV transmission by human bite: a case report and review of the literature-implications for post-exposure prophylaxis.

We report a case of a probable HIV-1 transmission by human bite. The analyzed data from ten previously reported  suspected or allegedly confirmed HIV transmissions revealed a deep bleeding bite wound as the primary risk factor. A high HIV plasma viral load and bleeding oral lesions are present most of the time during HIV transmission by bite. HIV post-exposure prophylaxis (PEP) should be recommended in case of a bleeding wound resulting from a bite of an HIV-infected person. PEP was missed in this presented case.

Treatment modification after starting cART in people living with HIV: retrospective analysis of the German ClinSurv HIV Cohort 2005-2017.

OBJECTIVE: Combination antiretroviral therapy (cART) has markedly increased survival and quality of life in people living with HIV. With the advent of new treatment options, including single-tablet regimens, durability and efficacy of first-line cART regimens are evolving. METHODS: We analyzed data from the prospective multicenter German Clinical Surveillance of HIV Disease (ClinSurv) cohort of the Robert-Koch Institute. Kaplan-Meier and Cox proportional hazards models were run to examine the factors associated with treatment modification. Recovery after treatment initiation was analyzed comparing pre-cART viral load and CD4+ T-cell counts with follow-up data. RESULTS: We included 8788 patients who initiated cART between 2005 and 2017. The sample population was predominantly male (n = 7040; 80.1%), of whom 4470 (63.5%) were reporting sex with men as the transmission risk factor. Overall, 4210 (47.9%) patients modified their first-line cART after a median time of 63 months (IQR 59-66). Regimens containing integrase strand transfer inhibitors (INSTI) were associated with significantly lower rates of treatment modification (adjusted hazard ratio 0.44; 95% CI 0.39-0.50) compared to protease inhibitor (PI)-based regimens. We found a decreased durability of first-line cART significantly associated with being female, a low CD4+ T-cell count, cART initiation in the later period (2011-2017), being on a multi-tablet regimen (MTR). CONCLUSIONS: Drug class and MTRs are significantly associated with treatment modification. INSTI-based regimens showed to be superior compared to PI-based regimens in terms of durability.

Studying the pathophysiology of coronavirus disease 2019: a protocol for the Berlin prospective COVID-19 patient cohort (Pa-COVID-19).

PURPOSE: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide causing a global health emergency. Pa-COVID-19 aims to provide comprehensive data on clinical course, pathophysiology, immunology and outcome of COVID-19, to identify prognostic biomarkers, clinical scores, and therapeutic targets for improved clinical management and preventive interventions. METHODS: Pa-COVID-19 is a prospective observational cohort study of patients with confirmed SARS-CoV-2 infection treated at Charité - Universitätsmedizin Berlin. We collect data on epidemiology, demography, medical history, symptoms, clinical course, and pathogen testing and treatment. Systematic, serial blood sampling will allow deep molecular and immunological phenotyping, transcriptomic profiling, and comprehensive biobanking. Longitudinal data and sample collection during hospitalization will be supplemented by long-term follow-up. RESULTS: Outcome measures include the WHO clinical ordinal scale on day 15 and clinical, functional, and health-related quality-of-life assessments at discharge and during follow-up. We developed a scalable dataset to (i) suit national standards of care, (ii) facilitate comprehensive data collection in medical care facilities with varying resources, and (iii) allow for rapid implementation of interventional trials based on the standardized study design and data collection. We propose this scalable protocol as blueprint for harmonized data collection and deep phenotyping in COVID-19 in Germany. CONCLUSION: We established a basic platform for harmonized, scalable data collection, pathophysiological analysis, and deep phenotyping of COVID-19, which enables rapid generation of evidence for improved medical care and identification of candidate therapeutic and preventive strategies. The electronic database accredited for interventional trials allows fast trial implementation for candidate therapeutic agents. TRIAL REGISTRATION: Registered at the German registry for clinical studies (DRKS00021688).

Distribution and Activation of CD8+ T Cells in the Duodenal Mucosa before and after HIV Seroconversion.

CD8+ T cells in the intestinal mucosa influence the HIV-associated pathogenesis, but little is known about the dynamics of mucosal CD8+ T cell counts and activation of these cells during the course of infection. In this study, mucosal CD8+ T cells in the duodenum were studied at different stages of HIV infection, starting from the seronegative phase. In seronegative acute HIV infection, CD8+ T cell counts increased in the epithelium, but not in the lamina propria. Infiltration of the lamina propria by peripherally expanded CD8+ T cells was observed after seroconversion. Highest increase in the expression of perforin, the rate-limiting molecule for cytotoxic CD8+ T cell activity, was evident in the lamina propria of seronegative acutely HIV-infected patients. The number of perforin-expressing cells in the lamina propria of acutely HIV-infected patients was positively associated with biomarkers of enterocyte damage and microbial translocation. After seroconversion, perforin expression was downregulated in the lamina propria, but not in the epithelium. In conclusion, our findings demonstrate that intraepithelial and lamina propria CD8+ T cells exhibit different dynamics of numerical alteration and cytotoxic activity in HIV-infected patients. Moreover, our results suggest that perforin-dependent cytotoxic mechanisms by CD8+ T cells could impair the intestinal mucosal barrier already in the seronegative phase of acute HIV infection, thereby inducing microbial translocation as one of the earliest pathological events in HIV infection.

Cystic echinococcosis in unaccompanied minor refugees from Afghanistan and the Middle East to Germany, July 2016 through June 2017.

Cystic echinococcosis (CE) is not covered by current refugee screening protocols. After we had detected CE among several refugees attending our clinic from Afghanistan and the Middle East, serological examinations for CE were performed for apparently healthy unaccompanied minor refugees from these regions.

Immediate versus deferred antiretroviral therapy in HIV-infected patients presenting with acute AIDS-defining events (toxoplasmosis, Pneumocystis jirovecii-pneumonia): a prospective, randomized, open-label multicenter study (IDEAL-study).

BACKGROUND: To evaluate clinical outcomes after either immediate or deferred initiation of antiretroviral therapy in HIV-1-infected patients, presenting late with pneumocystis pneumonia (PCP) or toxoplasma encephalitis (TE). METHODS: Phase IV, multicenter, prospective, randomized open-label clinical trial. Patients were randomized into an immediate therapy arm (starting antiretroviral therapy (ART) within 7 days after initiation of OI treatment) versus a deferred arm (starting ART after completing the OI-therapy). All patients were followed for 24 weeks. The rates of clinical progression (death, new or relapsing opportunistic infections (OI) and other grade 4 clinical endpoints) were compared, using a combined primary endpoint. Secondary endpoints were hospitalization rates after completion of OI treatment, incidence of immune reconstitution inflammatory syndrome (IRIS), virologic and immunological outcome, adherence to proteinase-inhibitor based antiretroviral therapy (ART) protocol and quality of life. RESULTS: 61 patients (11 patients suffering TE, 50 with PCP) were enrolled. No differences between the two therapy groups in all examined primary and secondary endpoints could be identified: immunological and virologic outcome was similar in both groups, there was no significant difference in the incidence of IRIS (11 and 10 cases), furthermore 9 events (combined endpoint of death, new/relapsing OI and grade 4 events) occurred in each group. CONCLUSIONS: In summary, this study supports the notion that immediate initiation of ART with a ritonavir-boosted proteinase-inhibitor and two nucleoside reverse transcriptase inhibitors is safe and has no negative effects on incidence of disease progression or IRIS, nor on immunological and virologic outcomes or on quality of life.

Indwelling pleural catheters for malignancy-associated pleural effusion: report on a single centre's ten years of experience.

INTRODUCTION: Recurrent pleural effusion is a common cause of dyspnoea, cough and chest pain during the course of malignant diseases. Chemical pleurodesis had been the only definitive treatment option until two decades ago. Indwelling pleural catheters (IPC) emerged as an alternative, not only assuring immediate symptom relief but also potentially leading to pleurodesis in the absence of sclerosing agents. METHODS: In this single-centre retrospective observational study patient characteristics, procedural variables and outcome in a large population of patients with IPC in malignancy were evaluated and prognostic factors for pleurodesis were identified. RESULTS: From 2006 to 2016, 395 patients received 448 IPC, of whom 121 (30.6%) had ovarian, 91 (23.0%) lung and 45 (11.4%) breast cancer. The median length of IPC remaining in place was 1.2 months (IQR, 0.5-2.6), the median survival time after insertion 2.0 months (IQR, 0.6-6.4). An adequate symptom relief was achieved in 94.9% of all patients, with no need for subsequent interventions until last visit or death. In patients surviving ≥30 days after IPC insertion, pleurodesis was observed in 44.5% and was more common in patients < 60 years (HR, 1.72; 95% CI, 1.05-2.78; p = 0.03). The use of an additional talc slurry via the IPC was highly predictive for pleurodesis (HR 6.68; 95% CI, 1.44-31.08; p = 0.02). Complications occurred in 13.4% of all procedures (n = 60), 41.8% concerning infections (local infections at the tunnel/exit site (n = 14) and empyema (n = 11)), and 98.3% being low or mild grade (n = 59). Complication rates were higher in men than women (18.6 vs. 12.4%, p = 0.023). CONCLUSION: High efficacy in symptom relief and a favourable safety profile confirm IPC as suitable first line option in most malignant pleural effusions. The study presents the largest dataset on IPC in gynaecologic cancer to date. Gender-specific differences in complication rates warrant further study.

Antiviral Activity, Safety, and Exposure-Response Relationships of GSK3532795, a Second-Generation Human Immunodeficiency Virus Type 1 Maturation Inhibitor, Administered as Monotherapy or in Combination With Atazanavir With or Without Ritonavir in a Phase 2a Randomized, Dose-Ranging, Controlled Trial (AI468002).

BACKGROUND: GSK3532795 is a second-generation human immunodeficiency virus type 1 (HIV-1) maturation inhibitor that targets HIV-1 Gag, inhibiting the final protease cleavage between capsid protein p24 and spacer protein-1, producing immature, noninfectious virions. METHODS: This was a phase 2a, randomized, dose-ranging multipart trial. In part A, subtype B-infected subjects received 5-120 mg GSK3532795 (or placebo) once daily for 10 days. In part B, subtype B-infected subjects received 40 mg or 80 mg GSK3532795 once daily with atazanavir (ATV) with or without (±) ritonavir (RTV) or standard of care (SOC) (tenofovir disoproxil fumarate 300 mg, emtricitabine 200 mg, and ATV/RTV 300 mg/100 mg) for 28 days. In part C, subtype C-infected subjects received 40 mg or 120 mg GSK3532795 once daily (or placebo) for 10 days. Endpoints included change in HIV-1 RNA from baseline on day 11 (parts A/C) or day 29 (part B). RESULTS: A >1 log10 median decline in HIV-1 RNA was achieved by day 11 in parts A and C and day 29 in part B at GSK3532795 doses ≥40 mg; part B subjects receiving GSK3532795 and ATV ± RTV achieved similar declines to those receiving SOC. Median of the maximum declines in HIV-1 RNA were similar for the 40-120 mg once-daily dose groups regardless of baseline Gag polymorphisms. There were no deaths, adverse events leading to discontinuation, or serious adverse events. CONCLUSIONS: GSK3532795 demonstrated potent antiviral activity against subtype B (monotherapy or with ATV ± RTV) and subtype C, and was generally well tolerated, which supported continued development of GSK3532795 in subjects with HIV-1 subtype B or subtype C. CLINICAL TRIALS REGISTRATION: NCT01803074.

Safety and immunogenicity of an adjuvanted herpes zoster subunit candidate vaccine in HIV-infected adults: a phase 1/2a randomized, placebo-controlled study.

BACKGROUND: Human immunodeficiency virus (HIV)-infected individuals are at increased risk of herpes zoster (HZ), even in the antiretroviral therapy (ART) era. Because concerns exist about the use of live-attenuated vaccines in immunocompromised individuals, a subunit vaccine may be an appropriate alternative. METHODS: This phase 1/2, randomized, placebo-controlled study evaluated the immunogenicity and safety of an investigational HZ subunit vaccine (HZ/su). Three cohorts of HIV-infected adults aged ≥18 years were enrolled: 94 ART recipients with a CD4(+) T-cell count of ≥200 cells/mm(3), 14 ART recipients with a CD4(+) T-cell count of 50-199 cells/mm(3), and 15 ART-naive adults with a CD4(+) T-cell count of ≥500 cells/mm(3). Subjects received 3 doses of HZ/su (50 µg varicella-zoster virus glycoprotein E [gE] combined with AS01B adjuvant) or 3 doses of saline at months 0, 2, and 6. RESULTS: One month after dose 3, serum anti-gE antibody concentrations and frequencies of gE-specific CD4(+) T cells were higher following HZ/su vaccination than after receipt of saline (P < .0001). Median cell-mediated immune responses peaked after dose 2. Humoral and cell-mediated immune responses persisted until the end of the study (month 18). No vaccination-related serious adverse events were reported. No sustained impact on HIV load or CD4(+) T-cell count was noted following vaccinations. CONCLUSIONS: HZ/su was immunogenic and had a clinically acceptable safety profile in HIV-infected adults. CLINICAL TRIALS REGISTRATION: NCT01165203.

Macrophages accumulate in the gut mucosa of untreated HIV-infected patients.

BACKGROUND: Mucosal macrophages are involved in the maintenance of epithelial barrier integrity and the elimination of invading pathogens. Although an intestinal barrier defect and microbial translocation are hallmarks of human immunodeficiency virus (HIV) infection, recent data on gut mucosal macrophages in HIV infection are sparse. METHODS: Treatment-naive and treated HIV-infected patients and healthy controls were studied for frequencies and functional parameters of blood monocytes and macrophages in duodenal mucosa. RESULTS: We found mucosal enrichment of macrophages in untreated HIV infection associated with reduced monocyte counts in blood and increased monocyte expression of the gut-homing molecule integrin ß7. Increased CCR2 density on integrin ß7-expressing monocytes and mucosal secretion of CCL2 suggest that CCR2/CCL2-chemotaxis is involved in enhanced trafficking of blood monocytes to the gut. Secretion of macrophage-related proinflammatory molecules interleukin 1ß, CCL5, CXCL9, and CXCL10 was increased in the gut mucosa of untreated patients. Moreover, mucosal macrophages of untreated patients showed reduced phagocytic activity. CONCLUSIONS: These data suggest a role for gut mucosal macrophages in HIV immune pathogenesis: infiltrated macrophages in the intestinal mucosa may promote local inflammation and tissue injury, whereas their low phagocytic activity prevents the efficient elimination of luminal antigens that cross the damaged intestinal barrier.

Stage-adapted treatment of HIV-associated Hodgkin lymphoma: Long-term results of a prospective, multicenter study.

Results of a prospective study of stage-adapted treatment of human immunodeficiency virus (HIV)-associated Hodgkin lymphoma (HIV-HL) showed a 2-year overall survival (OS) of 90.7% with no significant difference between early favorable (EF), early unfavorable (EU), and advanced HL. Patients with EF HIV-HL received two to four cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) + 30 Gy involved field (IF) radiation, those with EU HIV-HL received four cycles of ABVD or BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone) baseline + 30 Gy IF, and six to eight cycles of BEACOPP baseline were administered in advanced disease. The objective of the present analysis is to determine long-term outcomes of HIV-HL. Of 108 patients, 23 (21%) had EF HL, 14 (13%) had EU HL, and 71 (66%) had advanced-stage HL. After a median follow-up of 9.14 (range, 0-12.9) years, there were five primary refractory HL patients (5%) and 11 relapses (10%), of which seven were late relapses (>2 years). A second primary malignancy (SPM) occurred in 10 patients after a median of 7.3 years (range, 1.5-10.7) from HL diagnosis. The 10-year OS for patients with EF, EU, and advanced HL was 95.7%, 84.6%, and 76.1%, respectively. By multivariate analysis, Center for Disease Control and Prevention category C (hazard ratio [HR] 3.00, 95% confidence interval [CI]: 1.16-7.74, p = 0.023) and achievement of complete remission were significant for OS (HR 0.03, 95% CI: 0.01-0.08, p = 2.45 × 10-9). In conclusion, a stage-adapted treatment approach for HIV-HL is highly effective with long-term survival rates similar to those reported in HIV-uninfected HL. However, the risk for late relapse and SPM is significant.

Pharmacodynamics, safety, and pharmacokinetics of BMS-663068, an oral HIV-1 attachment inhibitor in HIV-1-infected subjects.

BACKGROUND: BMS-663068 is a prodrug of the small-molecule inhibitor BMS-626529, which inhibits human immunodeficiency virus type 1 (HIV-1) infection by binding to gp120 and interfering with the attachment of virus to CD4+ T-cells. METHODS: Fifty HIV-1-infected subjects were randomized to 1 of 5 regimen groups (600 mg BMS-663068 plus 100 mg ritonavir every 12 hours [Q12H], 1200 mg BMS-663068 plus 100 mg ritonavir every bedtime, 1200 mg BMS-663068 plus 100 mg ritonavir Q12H, 1200 mg BMS-663068 Q12H plus 100 mg ritonavir every morning, or 1200 mg BMS-663068 Q12H) for 8 days in this open-label, multiple-dose, parallel study. The study assessed the pharmacodynamics, pharmacokinetics, and safety of BMS-663068. RESULTS: The maximum median decrease in plasma HIV-1 RNA load from baseline ranged from 1.21 to 1.73 log(10) copies/mL. Plasma concentrations of BMS-626529 were not associated with an antiviral response, while low baseline inhibitory concentrations and the minimum and average steady-state BMS-626529 plasma concentrations, when adjusted by the baseline protein binding-adjusted 90% inhibitory concentration (inhibitory quotient), were linked with antiviral response. BMS-663068 was generally well tolerated. CONCLUSIONS: Administration of BMS-663068 for 8 days with or without ritonavir resulted in substantial declines in plasma HIV-1 RNA levels and was generally well tolerated. Longer-term clinical trials of BMS-663068 as part of combination antiretroviral therapy are warranted. Clinical Trials Registration.NCT01009814.

Uncapped Metered-Dose Inhalers: A Risk for Foreign Body Aspiration. A Case Report and Review of the Literature.

The risk of foreign body aspiration associated with uncapped handheld metered-dose inhalers (MDIs) is underestimated. We report a case in which a plastic cable clip accidentally lodged in the mouthpiece of an uncapped pressurized MDI was aspirated during its use. A literature search revealed 16 other cases of foreign body aspiration associated with uncapped handheld inhalers, all but one of which were pressurized inhalers. Patients should be informed of the risk of foreign body aspiration associated with uncapped pocket inhalers. The use of an uncuffed armoured tracheal tube with a separate oxygen tubing during flexible bronchoscopy for foreign body removal ensures a safe airway. Foreign bodies that exceed the lumen size of the tracheal tube can be pulled to the distal opening with forceps and removed when the tube is withdrawn.

Single Oral Doses of MK-8507, a Novel Non-Nucleoside Reverse Transcriptase Inhibitor, Suppress HIV-1 RNA for a Week.

BACKGROUND: MK-8507 is a novel HIV-1 non-nucleoside reverse transcriptase inhibitor being developed for treatment of HIV-1 infection. MK-8507 has high antiviral potency in vitro and pharmacokinetic (PK) properties that support once-weekly dosing. SETTING: A phase 1, open-label, proof-of-concept study was conducted in treatment-naive adults with HIV-1 infection to assess monotherapy antiviral activity. METHODS: In 3 sequential panels, participants aged 18-60 years with baseline plasma HIV-1 RNA ≥10,000 copies/mL and CD4+ T-cell count >200/mm3 received a single oral dose of 40, 80, or 600 mg MK-8507 in the fasted state. Participants were assessed for HIV-1 RNA for at least 7 days, PKs for 14 days, and safety and tolerability for 21 days postdose. RESULTS: A total of 18 participants were enrolled (6 per panel). The mean 7-day postdose HIV-1 RNA reduction ranged from ∼1.2 to ∼1.5 log10 copies/mL across the doses assessed. One patient had a viral rebound associated with emergence of an F227C reverse transcriptase variant (per chain-termination method sequencing) 14 days postdose; this variant was found in a second participant by ultra-deep sequencing as an emerging minority variant. MK-8507 PKs were generally dose-proportional and similar to observations in participants without HIV-1 infection in prior studies; mean MK-8507 half life was 56-69 hours in this study. MK-8507 was generally well tolerated at all doses. CONCLUSIONS: The robust antiviral activity, PK, and tolerability of MK-8507 support its continued development as part of a complete once weekly oral regimen for HIV-1 treatment; combination therapy could mitigate the emergence of resistance-associated variants.