Durable Suppression Research Articles

HIGH-FREQUENCY failure of combination antiretroviral therapy in paediatric HIV infection is associated with unmet maternal needs causing maternal NON-ADHERENCE

BackgroundEarly combination antiretroviral therapy (cART) reduces the size of the viral reservoir in paediatric and adult HIV infection. Very early-treated children may have higher cure/remission potential. MethodsIn an observational study of 151 in utero (IU)-infected infants in KwaZulu-Natal, South Africa, whose treatment adhered strictly to national guidelines, 76 infants diagnosed via point-of-care (PoC) testing initiated cART at a median of 26 h (IQR 18–38) and 75 infants diagnosed via standard-of-care (SoC) laboratory-based testing initiated cART at 10 days (IQR 8–13). We analysed mortality, time to suppression of viraemia, and maintenance of aviraemia over the first 2 years of life. FindingsBaseline plasma viral loads were low (median 8000 copies per mL), with 12% of infants having undetectable viraemia pre-cART initiation. However, barely one-third (37%) of children achieved suppression of viraemia by 6 months that was maintained to >12 months. 24% had died or were lost to follow up by 6 months. Infant mortality was 9.3%. The high-frequency virological failure in IU-infected infants was associated not with transmitted or acquired drug-resistant mutations but with cART non-adherence (plasma cART undetectable/subtherapeutic, p<0.0001) and with concurrent maternal cART failure (OR 15.0, 95%CI 5.6–39.6; p<0.0001). High-frequency virological failure was observed in PoC- and SoC-tested groups of children. InterpretationThe success of early infant testing and cART initiation strategies is severely limited by subsequent cART non-adherence in HIV-infected children. Although there are practical challenges to administering paediatric cART formulations, these are overcome by mothers who themselves are cART-adherent. These findings point to the ongoing obligation to address the unmet needs of the mothers. Eliminating the particular barriers preventing adequate treatment for these vulnerable women and infants need to be prioritised in order to achieve durable suppression of viraemia on cART, let alone HIV cure/remission, in HIV-infected children. FundingWellcome Trust, National Institutes of Health.

Despite early Medicaid expansion, decreased durable virologic suppression among publicly insured people with HIV in Washington, DC: a retrospective analysis

BackgroundDespite widely available access to HIV care in Washington, DC, inequities in HIV outcomes persist. We hypothesized that laboratory monitoring and virologic outcomes would not differ significantly based on insurance type.MethodsWe compared HIV monitoring with outcomes among people with HIV (PWH) with private (commercial payer) versus public (Medicare, Medicaid) insurance receiving care at community and hospital clinics. The DC Cohort follows over 8000 PWH from 14 clinics. We included those ≥18 years old enrolled between 2011 and 2015 with stable insurance. Outcomes included frequency of CD4 count and HIV RNA monitoring (> 2 lab measures/year, > 30 days apart) and durable viral suppression (VS; HIV RNA < 50 copies/mL at last visit and receiving antiretroviral therapy (ART) for ≥12 months). Multivariable logistic regression models examined impact of demographic and clinical factors.ResultsAmong 3908 PWH, 67.9% were publicly-insured and 58.9% attended community clinics. Compared with privately insured participants, a higher proportion of publicly insured participants had the following characteristics: female sex, Black race, heterosexual, unemployed, and attending community clinics. Despite less lab monitoring, privately-insured PWH had greater durable VS than publicly-insured PWH (ART-naïve: private 70.0% vs public 53.1%, p = 0.03; ART-experienced: private 80.2% vs public 69.4%, p < 0.0001). Privately-insured PWH had greater durable VS than publicly-insured PWH at hospital clinics (AOR = 1.59, 95% CI: 1.20, 2.12; p = 0.001).ConclusionsParadoxical differences between HIV monitoring and durable VS exist among publicly and privately-insured PWH in Washington, DC. Programs serving PWH must improve efforts to address barriers creating inequity in HIV outcomes.

The role of drug resistance in poor viral suppression in rural South Africa: findings from a population-based study

BackgroundUnderstanding factors driving virological failure, including the contribution of HIV drug resistance mutations (DRM), is critical to ensuring HIV treatment remains effective. We examine the contribution of drug resistance mutations for low viral suppression in HIV-positive participants in a population-based sero-prevalence survey in rural South Africa.MethodsWe conducted HIV drug resistance genotyping and ART analyte testing on dried blood spots (DBS) from HIV-positive adults participating in a 2014 survey in North West Province. Among those with virologic failure (> 5000 copies/mL), we describe frequency of DRM to protease inhibitors (PI), nucleoside reverse transcriptase inhibitors (NRTI), and non-nucleoside reverse transcriptase inhibitors (NNRTI), report association of resistance with antiretroviral therapy (ART) status, and assess resistance to first and second line therapy. Analyses are weighted to account for sampling design.ResultsOverall 170 DBS samples were assayed for viral load and ART analytes; 78.4% of men and 50.0% of women had evidence of virologic failure and were assessed for drug resistance, with successful sequencing of 76/107 samples. We found ≥1 DRM in 22% of participants; 47% were from samples with detectable analyte (efavirenz, nevirapine or lopinavir). Of those with DRM and detectable analyte, 60% showed high–level resistance and reduced predicted virologic response to ≥1 NRTI/NNRTI typically used in first and second-line regimens.ConclusionsDRM and predicted reduced susceptibility to first and second-line regimens were common among adults with ART exposure in a rural South African population-based sample. Results underscore the importance of ongoing virologic monitoring, regimen optimization and adherence counseling to optimize durable virologic suppression.

90-90-90 cascade analysis on reported CLHIV infected by mother-to-child transmission in Guangxi, China: a modeling study

The prevalence of HIV in Guangxi was very high, and there were many children living with HIV (CLHIV) because of larger baseline of pregnant women infected by HIV. It is necessary for children to explore the status of antiretroviral therapy (ART) on different initial CD4 counts in children with HIV infected by mother-to-child transmission (MTCT) in Guangxi and to evaluate the progress towards the 90-90-90 targets proposed by UNAIDS/WHO. Based on a retrospective observational cohort of children with HIV infected from the Guangxi Center for Disease Prevention and Control (CDC), the variables of all patients included viral loads, CD4 counts, laboratory results and WHO clinical staging of HIV/AIDS were collected. Several indicators were defined before analyzed: (1) diagnosis of MTCT: infants born to HIV-positive mothers who tested positive for HIV twice before 18 months; (2) ART initiation: the children who were enrolled in the treatment cohort and were still having HIV monitoring as of 6 months before date censored and (3) viral suppression: a recently viral load measurement that was less than 1000 copies per milliliter. The number of CLHIV in Guangxi was projected by using the estimates of the national HIV/AIDS prevalence from China CDC. An Autoregressive Integrated Moving Average (ARIMA) model and the Holt Exponential Smoothing (ES) model were used to predict the number of CLHIV, the diagnosed CLHIV, the diagnosed CLHIV receiving ART and the number of them achieving viral suppression, in 2019 and 2021, respectively. In this 14-year HIV/AIDS treatment cohort, 807 children who were HIV infected by MTCT were enrolled. The ARIMA and Holt ES models showed that by the end of 2019, 82.71% of all CLHIV in Guangxi knew their HIV status, 84.50% of those diagnosed had initiated ART, and 85.68% of those on ART had durable viral suppression. By the end of 2021, 93.51% of all CLHIV in Guangxi will know their HIV status, 84.28% of those diagnosed will have initiated antiretroviral therapy, and 85.83% of those on ART will have durable viral suppression. Therefore, in 2021, Guangxi fails to achieve the WHO/UNAIDS 90-90-90 targets for CLHIV, and there is still a wide time interval between the first HIV-positive diagnosis and ART initiation. National free antiretroviral treatment program (NFATP) requires strong enforcement to reduce the prevalence of later chronic diseases and complications.

The proprotein convertase furin is a pro-oncogenic driver in KRAS and BRAF driven colorectal cancer.

Mutations in KRAS and/or BRAF that activate the ERK kinase are frequently found in colorectal cancer (CRC) and drive resistance to targeted therapies. Therefore, the identification of therapeutic targets that affect multiple signaling pathways simultaneously is crucial for improving the treatment of patients with KRAS or BRAF mutations. The proprotein convertase furin activates several oncogenic protein precursors involved in the ERK-MAPK pathway by endoproteolytic cleavage. Here we show that genetic inactivation of furin suppresses tumorigenic growth, proliferation, and migration in KRAS or BRAF mutant CRC cell lines but not in wild-type KRAS and BRAF cells. In a mouse xenograft model, these KRAS or BRAF mutant cells lacking furin displayed reduced growth and angiogenesis, and increased apoptosis. Mechanistically, furin inactivation prevents the processing of various protein pecursors including proIGF1R, proIR, proc-MET, proTGF-β1 and NOTCH1 leading to potent and durable ERK-MAPK pathway suppression in KRAS or BRAF mutant cells. Furthermore, we identified genes involved in activating the ERK-MAPK pathway, such as PTGS2, which are downregulated in the KRAS or BRAF mutant cells after furin inactivation but upregulated in wild-type KRAS and BRAF cells. Analysis of human colorectal tumor samples reveals a positive correlation between enhanced furin expression and KRAS or BRAF expression. These results indicate that furin plays an important role in KRAS or BRAF-associated ERK-MAPK pathway activation and tumorigenesis, providing a potential target for personalized treatment.

Left sinus of Valsalva-Electroanatomic basis and outcomes with ablation for outflow tract arrhythmias.

The ablation of outflow tract premature ventricular contractions (PVCs) is generally safe and effective. In some patients, successful ablation sites may not correlate with the earliest activation. We sought to evaluate mechanistic and anatomic relevance of the region below the left sinus of Valsalva in variable morphology outflow tract ventricular arrhythmias. PVC cases where ablation was in the region inferior to the left sinus of Valsalva were identified. Procedural and demographic information and long-term outcomes were obtained. Cadaver dissections to evaluate regional anatomy were done as well. A total of 51 cases were included (age 53 ± 10; 37 [73%] males). Ablation was done for high PVC burden (>20%; mean 27% ± 8%) and presence of symptoms (73%) or ejection fraction less than 50% (78%). QRS morphology included either R wave (8; 16%), Rs (9; 18%), or rS (67%) in lead I, no precordial transition (40; 78%), V2 transition, (7; 14%), or V3 transition (4; 8%). In 31 (61%), the site just below the left coronary cusp was the earliest site, while the remainder had another site earlier. Ablation was acutely successful in 50 of 51 (98%). After 3 months, success was noted in 48 of 51 (94%). In two patients, repeat ablation in the same region resulted in durable suppression. The cases presented emphasize the importance of a region centered below the left sinus of Valsalva, where multivariable morphology QRS may be successfully ablated. Consideration of mapping and ablation even when signals are late in this region may be warranted in previously failed ablation attempts or first-line evaluation.

T cells with high PD-1 expression are associated with lower HIV-specific immune responses despite long-term antiretroviral therapy.

We evaluated frequencies of T cells with high PD-1 expression (PD-1) before and after long-term effective antiretroviral therapy (ART), and determined if frequencies on-ART correlated positively with measures of HIV persistence and negatively with HIV-specific responses. We enrolled individuals who started ART during chronic infection and had durable suppression of viremia for at least 4 years (N = 99). We assessed PD-1 T-cell frequencies at timepoints pre-ART and on-ART using flow cytometry, and evaluated how frequencies on-ART are associated with measures of HIV persistence, HIV-specific immune responses, and immune activation levels. Pre-ART, PD-1 CD4 T cells correlated positively with viremia and negatively with CD4 T-cell count. At year 1 on-ART, %PD-1 CD4 T cells decreased but then remained stable at 4 and 6-15 years on-ART, whereas %PD-1 CD8 T cells on-ART remained similar to pre-ART. PD-1 CD4 T cells correlated positively with HIV DNA pre-ART and on-ART, and with CD4 T-cell activation on-ART. PD-1 CD4 T cells negatively correlated with HIV Gag-specific and Env-specific T-cell responses but not with CMV-specific or EBV-specific responses. PD-1 CD8 T cells trended towards a negative correlation with responses to Gag and Env, but not to CMV and EBV. PD-1 T cells persist in blood despite prolonged suppression on ART, correlate with HIV DNA levels, and are associated with lower HIV-specific T-cell responses but not CMV-specific or EBV-specific responses, suggesting that these cells are HIV-specific. The findings support evaluating PD-1 blockade strategies for their effect on HIV persistence and HIV-specific immunity.

Proteasomal and lysosomal degradation for specific and durable suppression of immunotherapeutic targets

Cancer immunotherapy harness the body’s immune system to eliminate cancer, by using a broad panel of soluble and membrane proteins as therapeutic targets. Immunosuppression signaling mediated by ligand-receptor interaction may be blocked by monoclonal antibodies, but because of repopulation of the membrane via intracellular organelles, targets must be eliminated in whole cells. Targeted protein degradation, as exemplified in proteolysis targeting chimera (PROTAC) studies, is a promising strategy for selective inhibition of target proteins. The recently reported use of lysosomal targeting molecules to eliminate immune checkpoint proteins has paved the way for targeted degradation of membrane proteins as crucial anti-cancer targets. Further studies on these molecules’ modes of action, target-binding “warheads”, lysosomal sorting signals, and linker design should facilitate their rational design. Modifications and derivatives may improve their cell-penetrating ability and the in vivo stability of these pro-drugs. These studies suggest the promise of alternative strategies for cancer immunotherapy, with the aim of achieving more potent and durable suppression of tumor growth. Here, the successes and limitations of antibody inhibitors in cancer immunotherapy, as well as research progress on PROTAC- and lysosomal-dependent degradation of target proteins, are reviewed.

HI-511 overcomes melanoma drug resistance via targeting AURKB and BRAF V600E.

Rationale: Melanoma is an aggressive tumor of the skin and drug resistance is still a major problem in melanoma therapy. Novel targets and effective agents to overcome drug resistant melanoma are urgently needed in clinical therapy.Methods: Gene Expression Omnibus (GEO) database analysis, pathway enrichment analysis, and survival rate analysis were utilized to identify a candidate target. An anchorage-independent cell growth assay, flow cytometry, Western blot, and a xenograft mouse model were used to study the function of Aurora kinase B (AURKB) in both drug-sensitive and drug-resistant melanoma. Next, HI-511, a novel dual-target inhibitor targeting both AURKB and BRAF V600E, was designed and examined by an in vitro kinase assay. Methods as indicated above in addition to a BRAF V600E/PTEN-loss melanoma mouse model were used to demonstrate the effect of HI-511 on melanoma development in vitro and in vivo.Results: AURKB is highly expressed in melanoma and especially in vemurafenib-resistant melanoma and the expression was correlated with patient survival rate. Knocking down AURKB inhibited cell growth and induced apoptosis in melanoma, which was associated with the BRAF/MEK/ERKs and PI3-K/AKT signaling pathways. Importantly, we found that HI-511, a novel dual-target inhibitor against AURKB and BRAF V600E, suppresses both vemurafenib-sensitive and vemurafenib-resistant melanoma growth in vitro and in vivo by inducing apoptosis and mediating the inhibition of the BRAF/MEK/ERKs and PI3K/AKT signaling pathways.Conclusion: AURKB is a potential target for melanoma treatment. HI-511, a novel dual-target inhibitor against both AURKB and BRAF V600E, could achieve durable suppression of melanoma growth, even drug-resistant melanoma growth.

Abstract C043: Targeting TXNRD1 with a competitive inhibitor exposes an Achilles heel of SCLC

Abstract Targeting TXNRD1 to kill cancer cells has long been discussed as a promising strategy for the following reasons: 1) TXNRD1 over-expression was repeatedly identified as having a statistically significant association with poor prognosis. 2) It is suggested to be a key player in redox regulation, with a lower dependency in most normal adult cells and tissues than in cancer cells. Last but not least, potent inhibitors of TXNRD1 activity cause cytotoxicity in cancer cells. Despite this highly plausible and promising target profile, the success rate of TXNRD1 inhibitors has been disappointing in preclinical and clinical studies. One reason for this lack of success might be the physicochemical shortcomings of lead compounds, which pose liabilities in the area of bioavailability, stability, and dose limiting side effects. Auranofin, so far the most studied inhibitor of TXNRD1, is a prominent example for these kind of problems, but there are also more recent reports which show that it is demanding to improve the balance between cytotoxicity and selectivity in order to achieve more efficacious and durable tumor suppression. In addition, it is possible that TXNRD1 is not a critical target for all cancer entities, but rather plays critical roles only in a limited set of cancer entities or subtypes thereof. We have identified a class of dinuclear dithiocarbamate gold complexes, with superior efficacy and selectivity for TrxR1, which bind in competition with the TrxR1 substrate thioredoxin-1 (Trx1). Consequently, cells which express higher levels of Trx1, like most cancer and normal cells, are resistant while cells expressing low levels of Trx1, like SCLC, are hypersensitive to the drug. Our data show that all tested SCLC-derived cell lines and primary isolates are hypersensitive to the drug, independent of their resistance status to cisplatin. Unlike most other gold complexes, our drug is devoid of activity on the glutathione system and the proteasome at concentrations cytotoxic to cells. Most importantly, we observe oxidative stress only in the cytoplasm, but not in mitochondria, contributing to a low general toxicity profile. Finally, in SCLC animal models, the inhibitor eradicates residual tumor cells surviving first line therapy and completely prevents tumor recurrence. The safety profile in mouse is favorable for long term treatment and is compatible with first line therapy (cisplatin/etoposide). We present data describing the discovery of the lead compound and its optimization towards improved formulation and on-target activity as well as enhanced cytotoxicity on large 3-D aggregates of tumor cells. We also present a biomarker concept which explains the susceptibility of SCLC but also shows a rational to extend the use of our drug for other cancer (sub-) entities. Citation Format: Nikolas Peter Gunkel, Eberhard Amtmann, Pjotr Fabrowski, Sanaz Taromi, Tobias Dick. Targeting TXNRD1 with a competitive inhibitor exposes an Achilles heel of SCLC [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C043. doi:10.1158/1535-7163.TARG-19-C043

Time to viral load suppression and its associated factors in cohort of patients taking antiretroviral treatment in East Shewa zone, Oromiya, Ethiopia, 2018

BackgroundA key goal of Antiretroviral Treatment (ART) is to achieve and maintain durable viral suppression. Thus, the most important use of viral load measurement is to monitor the effectiveness of therapy after initiation of ART. The main objective of the study was to determine the time for virological suppression and its associated factors among people living with HIV taking antiretroviral treatments in East Shewa Zone, Oromiya, Ethiopia.MethodsPatients diagnosed with Human Immunodeficiency Virus presenting to the study health centers between October 3, 2011 and March 1, 2013 were included in the study given the following criteria: age 18 years or greater, eligible to start ART. All patients with baseline viral load measurements were included in the study. Interaction between explanatory variables with the response variable was analyzed by using cross tab features of (Statistical Package for the Social Sciences) SPSS, International Business Machines (IBM) Inc. Significance group comparison was done by Kaplan Meier log-rank test. Cox proportional hazard model was used to select significant factors to the variability between groups.ResultPlasma viral load was suppressed below the detection level in 72% of individuals taking a different regimen of ART. The median Human Immunodeficiency virus (HIV)-1 plasma viral load in the cohort was estimated to be log 5.3111 copies/ml. The study observed Survival curve difference in the category of marital status (p-value 0.023) and baseline cluster of differentiation 4 (CD4) value (p-value 0.023). The estimated median time to Plasma Viral Load (PVL) suppression was 181 days (CI: 140.5–221.4) with the age group of 30–39 years having minimum time to achieve suppression with 92 days (CI: 60.1–123.8) and the maximum time required to reach the level was found among the age group between 50 and 59 years.ConclusionThe study found that the estimated time to achieve PVL after taking ART to be 181 days. Factors affecting time to suppression level were marital status and baseline CD4.

Abstract B073: Development of combination therapies to potentiate the impact of KRAS-G12C inhibitors in lung cancer

Abstract Oncogenic mutations in KRAS are frequent in non-small cell lung cancer (NSCLC) and have been associated with poor prognosis and resistance to existing therapies. We have previously shown that NSCLC cells harboring KRAS mutations are selectively sensitive to inhibition of MEK and IGF1R signaling. Using a whole-genome shRNA screen, we shown that this effect is markedly enhanced by simultaneous inhibition of mTOR, while maintaining selectivity for the KRAS mutant genotype. Mechanistic investigations demonstrated that IGF1R inhibitors block the reactivation of the PI3K pathway induced by mTOR inhibition, resulting in a robust suppression of PI3K and mTORC1 signalling. Addition of a MEK inhibitor to the combination results in simultaneous inhibition of the main nodes downstream of RAS. Notably, the inhibition of these signalling pathways is stronger in KRAS-mutant cells than in their wild-type counterparts. Combining MEK, IGF1R and mTOR inhibitors produces a profound and durable suppression of cell proliferation and a stronger induction of apoptosis, resulting in marked tumor regression in three different Kras-driven lung cancer mouse models. In order to achieve strong downstream pathway inhibition even more specifically in KRAS-mutant cells and reduce potential unwanted toxicities, we used KRAS-G12C mutant inhibitors. We show that the triple combination of mTOR, IGF1R and KRAS-G12C inhibitors causes a profound and durable inhibition of the main pathways downstream RAS and greatly improves the effectiveness of ARS-1620 on KRAS-G12C mutant lung cancer cells in vitro and in mouse models. This provides a clear rationale for the design of combination treatments to enhance and extend the response to KRAS-G12C inhibitors. Citation Format: Miriam Molina-Arcas, Christopher Moore, Sareena Rana, Febe Van Maldegem, Edurne Mugarza, Pablo Romero-Clavijo, Stuart Horswell, David Hancock, Julian Downward. Development of combination therapies to potentiate the impact of KRAS-G12C inhibitors in lung cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B073. doi:10.1158/1535-7163.TARG-19-B073

Durable HIV Suppression Among People Who Inject Drugs From a Community-Based Cohort Study in Baltimore, Maryland, 1997-2017.

People who inject drugs (PWID) face disparities in human immunodeficiency virus (HIV) treatment outcomes and may be less likely to achieve durable viral suppression. We characterized transitions into and out of viral suppression from 1997 to 2017 in a long-standing community-based cohort study of PWID, the AIDS Link to Intravenous Experience (ALIVE) Study, analyzing HIV-positive participants who had made a study visit in or after 1997. We defined the probabilities of transitioning between 4 states: 1) suppressed, 2) detectable, 3) lost to follow-up, and 4) deceased. We used multinomial logistic regression analysis to examine factors associated with transition probabilities, with a focus on transitions from suppression to other states. Among 1,061 participants, the median age was 44 years, 32% were female, 93% were African-American, 59% had recently injected drugs, and 28% were virologically suppressed at baseline. Significant improvements in durable viral suppression were observed over time; however, death rates remained relatively stable. In adjusted analysis, injection drug use and homelessness were associated with increased virological rebound in earlier time periods, while only age and race were associated with virological rebound in 2012-2017. Opioid use was associated with an increased risk of death following suppression in 2012-2017. Despite significant improvements in durable viral suppression, subgroups of PWID may need additional efforts to maintain viral suppression and prevent premature mortality.

Combining CDK2/9 Inhibitor CYC065 with Venetoclax, a BCL2 Inhibitor, to Treat Patients with Relapsed or Refractory AML or MDS

Cyclin dependent kinases (CDKs) are critical for cell cycle regulation and transcriptional elongation. Dysregulated CDKs have been linked to the cancer hallmarks of uncontrolled proliferation and increased survival. CYC065 is a potent and orally‐available inhibitor of CDK2 and CDK9. CDK9 regulates transcription of genes through phosphorylation of RNA polymerase II (RNAP II) C-terminal domain (CTD). Through inhibition of CDK9, CYC065 suppresses CDK9-dependent gene expression and reduces the level of MCL1, a key anti-apoptotic protein. In the first-in-human study, CYC065 was administered by 4-hour infusion every 3 weeks in patients with advanced cancers. Biomarkers related to CYC065 target inhibition, e.g. phosphorylation of RNAP II CTD Ser2, a direct substrate of CDK9, and protein levels of downstream targets, such as MCL1, were determined in patient's peripheral blood mononuclear cells (PBMCs). Durable MCL1 suppression was observed after a single dose in 11 out of 13 patients treated at the recommended phase 2 dose (RP2D) of 192 mg/m2. Five of these 13 patients achieved stable disease lasting ≥ 6 cycles (Do, KT et al, AACR Annual Meeting 2018 Abs CT037). Acute myeloid leukemia (AML) frequently relapses after initial treatment by intensive or low-intensive therapy. Drug resistance has been attributed to dysregulation in apoptotic pathways. AML cells often upregulate pro-survival members of the BCL2 family, such as BCL2 and MCL1, to avoid apoptosis (Grundy M et al, Oncotarget, 2018). Suppression of MCL1 triggered rapid apoptosis in AML, and cured AML-afflicted mice (Glaser SP et al, Genes Dev. 2012). Preclinically, CYC065 has demonstrated potent anti-tumor effect in various AML cell lines, including those with MLL rearrangements, and xenograft models (Frame S et al, AACR, 2010 Abs 3886; Frame S et al, SOHO, 2014 Abs 209). Venetoclax has modest single agent activity in AML. MCL1 dependence appeared to correlate with resistance to venetoclax (Konopleva M et al, Cancer Discovery, 2016). Preclinical study confirmed synergy of CYC065 and venetoclax, suggesting that the suppression of both BCL2 and MCL1 may be more beneficial than inhibiting either one alone (MacKay C et al. AACR-NCI-EORTC 2015 Abs B182). Based on the above rationale, a clinical study (NCT04017546) has been initiated to evaluate a combination of CYC065 with venetoclax in relapsed/refractory AML and MDS. CYC065 will be administered intravenously via 4-hour infusion on Day 1 and Day 15 in combination with daily venetoclax every 4 weeks. Initial dose escalation is 33% and then 25% upon occurrence of the first dose limiting toxicity (DLT). RP2D is the highest dose level at which less than one-third of at least 6 patients experience a DLT during the first treatment cycle. Eligible patients are ≥18 years with previously treated AML or MDS and ≥10% blasts in bone marrow or peripheral blood; adequate bone marrow, renal and liver functions are required. All patients will be asked to participate in the pharmacokinetic and pharmacodynamic studies. Plasma levels of CYC065 and its metabolites as well as venetoclax will be determined. PBMCs will be collected to assess MCL1 levels and the phosphorylation and protein levels of other downstream targets of CDK9 inhibition. Treatment will continue until progression of disease, unacceptable toxicity or changes in patient condition that renders patients ineligible for further treatment. Laboratory tests and bone marrow aspirate/biopsy will be performed to assess response according to standard criteria. Disclosures Borthakur: AbbVie: Research Funding; BioLine Rx: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; GSK: Research Funding; Polaris: Research Funding; Tetralogic Pharmaceuticals: Research Funding; Incyte: Research Funding; Cyclacel: Research Funding; Janssen: Research Funding; Bayer Healthcare AG: Research Funding; BioTheryX: Membership on an entity's Board of Directors or advisory committees; Merck: Research Funding; Oncoceutics, Inc.: Research Funding; Strategia Therapeutics: Research Funding; PTC Therapeutics: Consultancy; BMS: Research Funding; Oncoceutics: Research Funding; Eisai: Research Funding; NKarta: Consultancy; Xbiotech USA: Research Funding; Cantargia AB: Research Funding; FTC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Eli Lilly and Co.: Research Funding; Agensys: Research Funding; Argenx: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Research Funding; Arvinas: Research Funding. Kadia:BMS: Research Funding; Bioline RX: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Research Funding; Jazz: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees. Al Azzawi:Cyclacel LTD: Research Funding. Zheleva:Cyclacel Ltd: Employment, Equity Ownership, Patents &amp; Royalties. Blake:Cyclacel Ltd: Employment, Equity Ownership, Patents &amp; Royalties. Chiao:Cyclacel Ltd: Employment, Equity Ownership, Patents &amp; Royalties.

A Phase I Study Combining CDK2/9 Inhibitor CYC065 with Venetoclax, a BCL2 Inhibitor, to Treat Relapsed or Refractory Chronic Lymphocytic Leukemia (CLL)

Cyclin dependent kinases (CDKs) are critical for cell cycle regulation and transcriptional elongation. Dysregulated CDKs have been linked to the cancer hallmarks of uncontrolled proliferation and increased survival. CYC065 is a potent and orally‐available inhibitor of CDK2 and CDK9. CDK9 regulates transcription of genes through phosphorylation of RNA polymerase II (RNAP II) C-terminal domain (CTD). Through inhibition of CDK9, CYC065 suppresses CDK9-dependent gene expression and reduces the level of MCL1, a key anti-apoptotic protein. In the first-in-human study, CYC065 was administered by 4-hour infusion every 3 weeks in patients with advanced solid cancers. Biomarkers related to CYC065 target inhibition, e.g. phosphorylation of RNAP II CTD Ser2, a direct substrate of CDK9, and protein levels of downstream targets, such as MCL1, were determined in patient peripheral blood mononuclear cells (PBMCs). Durable MCL1 suppression was observed after a single dose in 11 out of 13 patients treated at the recommended phase 2 dose (RP2D) of 192 mg/m2. Five of these 13 patients achieved stable disease lasting ≥6 cycles (Do, KT et al, AACR Annual Meeting 2018 Abs CT037). Chronic lymphocytic leukemia (CLL) is a disease that depends upon the overexpression of anti-apoptotic proteins (MCL1, BCL2) for survival. Venetoclax, a BCL2 inhibitor, is one of the most active agents against CLL. However upregulation of MCL1 is associated with resistance to venetoclax (Oppermann S et al., Blood, 2016). Preclinical studies have demonstrated that CYC065 and venetoclax are synergistic in primary CLL cells, inducing apoptosis (Chen R et al, AACR Annual Meeting 2018 Abs 3905). This synergy may arise from targeting parallel anti-apoptotic mechanisms in the intrinsic apoptotic pathway that promote survival in CLL cells. The above findings support the conduct of an ongoing clinical study (NCT03739554) investigating a combination of CYC065 with venetoclax in CLL. CYC065 will be administered intravenously via 4-hour infusion on Day 1 and Day 15 in combination with daily venetoclax. One cycle is 28 days. Initial dose escalation is 33% and then 25% upon occurrence of the first dose limiting toxicity (DLT). RP2D is the highest dose level at which less than one-third of at least 6 patients experience a DLT during the first treatment cycle. Eligible patients are ≥18 years with CLL relapsed or refractory to standard treatment(s) including those with Richter transformation; adequate bone marrow, renal and liver functions are required. All patients will be asked to participate in the pharmacokinetic and pharmacodynamic studies. Plasma levels of CYC065 and its metabolites as well as venetoclax will be determined. PBMCs will be collected to assess MCL1 levels and phosphorylation and protein levels of other downstream targets of CDK9 inhibition. Treatment will continue until progression of disease, unacceptable toxicity or changes in patient condition that renders patients ineligible for further treatment. Laboratory tests and CT scans will be performed regularly to assess response according to standard criteria. Disclosures Wierda: Pharmacyclics LLC: Research Funding; AbbVie: Research Funding; GSK/Novartis: Research Funding; Gilead Sciences: Research Funding; KITE pharma: Research Funding; Sunesis: Research Funding; Genentech: Research Funding; Xencor: Research Funding; Janssen: Research Funding; Loxo Oncology Inc.: Research Funding; Cyclcel: Research Funding; Oncternal Therapeutics Inc.: Research Funding; Miragen: Research Funding; Juno Therapeutics: Research Funding; Acerta Pharma Inc: Research Funding. Chen:Cyclacel Ltd: Research Funding. Zheleva:Cyclacel Ltd: Employment, Equity Ownership, Patents &amp; Royalties. Blake:Cyclacel Ltd: Employment, Equity Ownership, Patents &amp; Royalties. Chiao:Cyclacel Ltd: Employment, Equity Ownership, Patents &amp; Royalties. Plunkett:Cyclacel Ltd: Research Funding.

No Evidence for Hematopoietic Stem Cell Self-Renewal in-Vivo Following Inflammatory Challenge

Elevated levels of inflammation have been previously linked to both inherited and acquired bone marrow failure (BMF) syndromes, as well as to normal aging, suggesting a role in the etiology of these conditions. One potential explanation for this phenomenon is that repeated inflammation can promote the suppression of hematopoietic stem cell (HSC) function.We have previously demonstrated that interferon-α can accelerate HSC attrition by driving HSCs out of quiescence, leading to the development of BMF in a mouse model of Fanconi anemia (Walter et al. Nature, 2015). To more broadly address the impact of repetitive inflammatory challenge on HSC regeneration, we challenged C57BL6 wild type (WT) mice with polyinosinic:polycytidylic acid (pI:C), a TLR3 agonist that mimics viral infection. Injection with 1-3 rounds of pI:C (8 injections per round) in WT mice had no sustained impact on hematopoiesis, since peripheral blood (PB) and bone marrow (BM) counts were within normal ranges at 5 weeks (5wk) post-treatment. However, in vitro analysis of the clonal proliferation potential of 411 individual sorted long-term (LT)-HSCs revealed a 2-fold reduction (p&amp;lt;0.0001) in the total number of progeny produced per HSC. Additionally, cell fate tracking experiments showed accelerated entry into first division and differentiation following treatment. In line with this data, competitive repopulation assays demonstrated a progressive depletion of functional HSC numbers, with an approximate 2-fold decrease in multi-lineage competitive repopulating activity with each additional round of inflammatory challenge (p&amp;lt;0.01). In order to assess in vivo recovery of HSCs following inflammatory challenge, competitive and limiting dilution transplantation assays were used to quantify HSC frequencies using BM harvested from mice at 5, 10 or 20wk after 3 rounds of pI:C treatment. In both assays we observed a sustained ~18 fold decrease in functional HSCs, with no evidence of recovery within the 20wk window. To exclude microenvironment effects on HSC function, we performed reverse transplantation experiments in which pI.C challenged WT mice were injected with saturating doses of LT-HSCs from non-treated WT donors, in the absence of additional irradiation conditioning. We observed a durable suppression of endogenous HSCs that was sufficient to facilitate robust engraftment of donor LT-HSCs up to 20wk post-treatment. We next used the inducible transgenic Scl-tTA;H2B-GFP mouse model (Wilson et al., Cell, 2008) in order to prospectively segregate quiescent label retaining LT-HSCs (LRCs) from LT-HSCs that proliferate in vivo in response to pI:C (nonLRCs). Following a single round of pI:C challenge, label retention was reduced as a result of LT-HSC proliferation (Table 1). Importantly, the clonal proliferative potential of individual LRCs was preserved upon pI:C challenge while that of nonLRCs was more than halved. This suggests that LT-HSCs fail to undergo self-renewal divisions in vivo under these conditions but rather are functionally compromised in line with increasing proliferative history. We hypothesized that this apparent progressive irreversible depletion of functional HSCs may eventually lead to compromised hematopoiesis. We therefore assessed the hematologic parameters of aged mice that had been exposed to repetitive pI:C treatment in early to mid-life. While these mice had normal PB counts at 5wk post-treatment, upon reaching 2 years of age, treated mice demonstrated mild PB cytopenias, BM hypocellularity and a relative expansion of BM adipocytes (Table 2). Taken together, our data contradict the canonical view that HSCs demonstrate extensive self-regenerative capacity following injury. Rather, in the context of inflammatory challenge, HSCs are progressively and irreversibly depleted as they are driven out of their quiescent state. These findings have broad implications regarding the role of inflammation in the suppression of hematopoiesis that are likely relevant to BMF and also normal aging. Disclosures Lipka: InfectoPharm GmbH: Employment. Frenette:Pfizer: Consultancy; Cygnal Therapeutics: Equity Ownership; Ironwood Pharmaceuticals: Research Funding; Albert Einstein College of Medicine, Inc: Patents &amp; Royalties.

Genotypic Methods for HIV Drug Resistance Monitoring: The Opportunities and Challenges Faced by China.

AIDS is a globalized infectious disease. In 2014, UNAIDS launched a global project of "90-90-90" to end the HIV epidemic by 2030. The second and third 90 require 90% of HIV-1 infected individuals receiving antiretroviral therapy (ART) and durable virological suppression. However, wide use of ART will greatly increase the emergence and spreading of HIV drug resistance and current HIV drug resistance test (DRT) assays in China are seriously lagging behind, hindering to achieve virological suppression. Therefore, recommending an appropriate HIV DRT method is critical for HIV routine surveillance and prevention in China. In this review, we summarized the current existing HIV drug resistance genotypic testing methods around the world and discussed the advantages and disadvantages of these methods.

1321. Trans Females Receiving Gender-Affirming Surgical Referrals are More Likely to Have Durable Virologic Suppression at Whitman-Walker Health, 2008–2017

BackgroundTrans females bear a disproportionate burden of HIV infection yet little is known about their HIV care continuum participation. We characterized the care continuum among trans female people with HIV (PWH) at Whitman-Walker Health (WWH) in Washington, DC and explored the impact of gender-affirming care on continuum participation.MethodsThis IRB-approved review from 2008 to 2017 analyzed trans female and nontrans PWH cohorts. Trans females were selected via self-identification and chart review, based on hormone prescription or narrative charting. Chi-square analysis was performed to examine associations between gender identity and demographic factors, comorbidities, and achieving steps in the care continuum. Bivariate analysis using chi-square test of independence and point-biserial correlation was performed between predictor and outcome variables in the care continuum. Multivariate logistic regression analysis was performed to identify predictors of poor outcomes in the care continuum.ResultsWe analyzed 219 trans female and 456 nontrans PWH (Figure 1). Trans female PWH were more likely to be Black and/or Hispanic, have unstable housing, and be publically insured when compared with nontrans PWH (Table 1). There was no difference in ART initiation, retention in care (RiC), or durable virologic suppression (DVS) <200 copies/mL based on gender identity (Figure 2). Nontrans PWH had a higher odds of DVS at lower limits of detection (LLOD) than trans female PWH (OR 1.59, 95% CI 1.15–2.20). Hormone prescription did not impact trans female PWH continuum participation (Table 2). Surgical referral was found to impact DVS < 200 (P = 0.036) and DVS < LLOD (P = 0.021), but multivariate modeling could not be performed. Trans female PWH with surgical referrals were more likely to achieve DVS < 200 (OR 3.57, 95% CI 1.02–12.23) and DVS < LLOD (OR 2.85, 95% CI 1.14–7.12).ConclusionThis novel analysis of gender-affirming care and the HIV care continuum shows trans female PWH were less likely than nontrans to achieve durable VS < LLOD. Trans female PWH who received surgical referrals were 3.5 times more likely to achieve durable VS < 200 and almost three times more likely to achieve durable VS < LLOD. Further research is needed to explore this association between surgical referrals and DVS among trans female PWH. Disclosures All authors: No reported disclosures.

380. Characterizing Host Factors, Treatment Strategy, and Clinical Outcomes of Group A Streptococcus Orthopedic Infections

BackgroundThe annual incidence of invasive β-hemolytic group A streptococcus (GAS) infections in the United States is approximately 3.8 cases per 100,000 patients with 10–30% mortality. But data in GAS orthopedic infections is limited. We sought to characterize patient factors, medical and surgical management, and clinical outcomes from GAS orthopedic infections at our medical center.MethodsA total of 12 patients with GAS orthopedic infections (necrotizing fasciitis, osteomyelitis, prosthetic joint infection, septic arthritis, or tenosynovitis) from July 2017 and March 2019 were included. Medical records were reviewed for site of positive GAS culture (blood, wound, joint fluid, or tissue cultures), demographics, comorbidities, surgical management, and antibiotic regimen and duration. The primary outcome was cure at 90 days defined as clinical improvement without recurrent or new infection, or further surgical or medical management at 90 days after treatment completion. The secondary outcome was erythrocyte sedimentation rates (ESR) before and after treatment.ResultsThe median age of the 12 patients was 56 years (range 3–75); 58% were female and 58% had a body mass index ≥30 kg/m2. The median Charlson comorbidity index score was 3 (range 0–7) with 58% having diabetes mellitus. Two patients had either rheumatoid arthritis or monoclonal gammopathy (Table 1). Most patients had severe infections; 33% with necrotizing fasciitis and 25% with orthopedic implants. All patients had an elevated initial ESR, including 75% with ESR >40 mm/h. 92% required surgery, including 42% amputations and 17% prosthesis removals. Patients were mostly treated with β-lactams and vancomycin (92%); only 50% received clindamycin or linezolid. Most patients (75%) required at least 2 weeks of antibiotics. Five patients (42%) were not cured at 90 days, and 1 died of infectious complications (Table 2).ConclusionSevere GAS orthopedic infections necessitate both surgical management and prolonged antibiotics. 42% of our patients were not cured at 90 days and most eventually required amputation. Toxin mediators, clindamycin and linezolid, were underutilized. Chronic suppressive antibiotics should be considered for patients with orthopedic implants, especially those with durable immune suppression. Disclosures All authors: No reported disclosures.

2840. Long-term Efficacy, Safety, and Durability of CAB and RPV as Two Drug Oral Maintenance Therapy: LATTE Week 312 Results

BackgroundCabotegravir (CAB), an INI, is under development in both oral and long-acting (LA) injectable formulations. LATTE (NCT01641809) was designed to select a daily oral dose of CAB and evaluate a two-drug ART regimen with rilpivirine (RPV), as suppressive maintenance therapy. Results enabled the LATTE-2 (NCT02120352) study to evaluate CAB LA + RPV LA dosed once every 1 or 2 months.MethodsPhase 2b, multicentre, partially blinded dose-ranging study in ART-naïve HIV infected adults, randomized 1:1:1:1 to the induction regimen of once-daily oral CAB 10, 30, or 60 mg or efavirenz (EFV) 600 mg with TDF/FTC or ABC/3TC through W24. CAB patients with VL <50 c/mL immediately prior to W24 discontinued NRTIs and began RPV 25 mg as a two-drug oral maintenance regimen through W96. No change was made to the EFV arm. After W96, at the start of the open-label (OL) phase, all patients randomized to CAB were given the option to continue and switch to the sponsor-selected dose of oral CAB 30 mg. EFV patients completed the study at W96. The OL phase was completed at W312 (288 weeks on CAB + RPV). Successful CAB + RPV patients transitioned to the POLAR study (NCT03639311).ResultsA total of 243 patients were randomized and initiated treatment (ITT-E). Of those randomized to CAB (n = 181), 160 patients began CAB + RPV (W24) and 138 continued into OL phase (W96). One hundred and ten patients successfully completed the study (W312). Among patients who began CAB + RPV at W24, 66% maintained <50 c/mL, 9% had HIV-1 RNA ≥ 50 c/mL, and 25% were categorized as “No Virologic Data” by Snapshot at W312 (ITT-ME). There were 11 protocol-defined virologic failures (PDVF) on CAB; only 2 occurring after W144. Six patients developed treatment emergent (TE) resistance to one or both agents during the study; of which 4 patients developed TE major INI resistance mutations, 3 after W96. The median increase in CD4+ cell count from Baseline was 393 cells/mm3 (−174 to 1118). During the maintenance and OL phases, 4% of CAB patients reported drug-related AEs ≥ Grade 2; SAEs occurred in 9% of CAB patients (none drug related); 3% of CAB patients withdrew due to AEs. 43% of CAB patients who entered maintenance phase reported TE lab abnormalities ≥ Grade 3.ConclusionAs maintenance therapy in virologically suppressed patients, the 2DR CAB + RPV provided durable viral suppression through W312. Through 7 years of study, CAB + RPV continues to be generally safe and well tolerated. Disclosures All Authors: No reported Disclosures.