Channeling effects in the prescription of new therapies: the case of emicizumab for hemophilia A.

Aim: To determine if emicizumab was channeled to clinically complex people with hemophilia A upon approval. Methods: Claims data (16 November 2017, through 31 December 2019) from US-based insurance databases were analyzed to compare the clinical complexity of people with hemophilia A initiating emicizumab with matched individuals receiving factor VIII (FVIII) episodically or prophylactically. People with hemophilia A with evidence of previous bypassing agent use (indicating FVIII inhibitors) were excluded. Outcomes included bleeding events, arthropathy, pain, comorbidities and healthcare costs. Results: A larger proportion of emicizumab users had bleeding events, comorbidities and arthropathy and greater healthcare costs in the year prior to starting emicizumab compared with FVIII users. Conclusion: Claims-based data limitations prevent an absolute conclusion. Nevertheless, emicizumab users appear more clinically complex than FVIII users, suggesting post-approval channeling.

Estimating the risk of thrombotic events in people with congenital hemophilia A using US claims data.

Aim: Compare thrombotic risk in people with congenital hemophilia A (PwcHA) to the general non-hemophilia A (HA) population. Patients & methods: US claims databases were analyzed to identify PwcHA. Incidence rates of myocardial infarction, pulmonary embolism, ischemic stroke, deep vein thrombosis and device-related thrombosis were compared with a matched cohort without HA. Results: Over 3490 PwcHA were identified and 16,380 individuals matched. PwcHA had a similar incidence of myocardial infarction and pulmonary embolism compared with the non-HA population, but a slightly higher incidence of ischemic stroke and deep vein thrombosis. The incidence of device-related thrombosis was significantly higher in PwcHA. Conclusion: This analysis suggests that PwcHA are not protected against thrombosis, and provides context to evaluate thrombotic risk of HA treatments.

Application of a hemophilia mortality framework to the Emicizumab Global Safety Database.

BACKGROUND: As the first non-factor replacement therapy for persons with congenital hemophilia A (PwcHA), emicizumab's safety profile is of particular interest to the community. OBJECTIVES: We applied an algorithm for categorization of fatal events contemporaneous to emicizumab using reporter-assessed causality documented in the Roche Emicizumab Global Safety Database. PATIENTS/METHODS: All fatalities in PwcHA reported to the database (from clinical trials, pre-market access, and spontaneous post-marketing reports) were categorized into: associated with hemophilia A-hemorrhagic, thrombotic, human immunodeficiency virus (HIV)/hepatitis C virus (HCV), hepatic (non-HCV); associated with general population-trauma/suicide, non-HA-associated conditions; or, unspecified. Reported cause of death was not reassessed. RESULTS: As of cut-off May 15, 2020, 31 fatalities in PwcHA taking emicizumab were reported. Median age at death was 58 years; 51% had factor VIII inhibitors. Fifteen fatalities were considered associated with HA; overall, the most frequent category was hemorrhage (11/31). Of these, six had a history of life-threatening bleeds, and four had a history of intracranial hemorrhage. The remaining HA-associated fatalities were related to HIV/HCV (3/31) and other hepatic causes (1/31). No cases were categorized as thrombotic. Of 10 cases considered not associated with HA, two were categorized as cardiovascular (non-thrombotic), five as infection/sepsis, and one each of trauma/suicide, pulmonary, and malignancy. Six cases were unspecified. CONCLUSIONS: No unique risk of death was associated with emicizumab prophylaxis in PwcHA. The data reveal that mortality in PwcHA receiving emicizumab was primarily associated with hemorrhage or non-HA-associated conditions, and was not reported by treaters to be related to emicizumab treatment.

Establishment of a framework for assessing mortality in persons with congenital hemophilia A and its application to an adverse event reporting database.

BACKGROUND: Despite recent therapeutic advances, life expectancy in persons with congenital hemophilia A (PwcHA) remains below that of the non-HA population. As new therapies are introduced, a uniform approach to the assessment of mortality is required for comprehensive evaluation of risk-benefit profiles, timely identification of emerging safety signals, and comparisons between treatments. OBJECTIVES: Develop and test a framework for consistent reporting and analysis of mortality across past, current, and future therapies. PATIENTS/METHODS: We identified known causes of mortality in PwcHA through literature review, analysis of the US Food and Drug Administration Adverse Event Reporting System (FAERS) database, and expert insights. Leading causes of death in general populations are those recognized by the Centers for Disease Control and Prevention and the World Health Organization. We developed an algorithm for assessing fatalities in PwcHA and used this to categorize FAERS data as a proof of concept. RESULTS: PwcHA share mortality causes with the non-HA population including cardiovascular disease, malignancy, infections, pulmonary disease, dementias, and trauma/suicide. Causes associated with HA include hemorrhage, thrombosis, human immunodeficiency virus, hepatitis C virus, and liver dysfunction. We propose an algorithm employing these classes to categorize fatalities and use it to classify FAERS fatality data between 01/01/2000 and 03/31/2020; the most common causes were hemorrhage (22.2%) and thrombosis (10.4%). CONCLUSIONS: A conceptual framework for examining mortality in PwcHA receiving any hemophilia therapy is proposed to analyze and interpret fatalities, enabling consistent and objective assessment. Application of the framework using FAERS data suggests a generally consistent pattern of reported mortality across HA treatments, supporting the utility of this unified approach.

Safety analysis of rFVIIa with emicizumab dosing in congenital hemophilia A with inhibitors: Experience from the HAVEN clinical program.

BACKGROUND: Recombinant activated factor VII (rFVIIa; eptacog alfa activated, NovoSeven® , Novo Nordisk A/S) is a bypassing agent used in congenital hemophilia A patients with inhibitors. Emicizumab (Hemlibra® ; F Hoffmann-La Roche Ltd) is a recombinant, humanized, bispecific monoclonal antibody used for routine prophylaxis in patients with congenital hemophilia A with inhibitors. Concomitant use of the hemostatic agents rFVIIa and emicizumab carries a theoretical increased risk of thrombotic complications. Roche and Novo Nordisk collaboratively analyzed all available data on the use of rFVIIa in patients receiving emicizumab prophylaxis in the Study to Evaluate the Efficacy, Safety, and Pharmacokinetics of Prophylactic Emicizumab Versus no Prophylaxis in Hemophilia A Participants With Inhibitors (HAVEN) clinical development program. OBJECTIVE: Obtain further insights into the concomitant clinical use and safety of rFVIIa and emicizumab. METHODS: The initial individual rFVIIa dose, dosing intervals and cumulative dosing were evaluated in the HAVEN 1, HAVEN 2, and HAVEN 4 trials. All adverse events reported in each of the three trials in patients treated with rFVIIa, including available narratives, were assessed. RESULTS: The vast majority of bleeds occurred in HAVEN 1. When rFVIIa was used to treat a bleeding episode, a 100 ± 20 µg/kg dose was used to initiate treatment in the majority of cases. The dosing interval, as well as cumulative dosing were consistent with prescribing information and current practice. No serious adverse events, no thrombotic microangiopathy cases, or thromboembolic events were assessed to be associated with rFVIIa when used in conjunction with emicizumab prophylaxis in the HAVEN trials. CONCLUSION: rFVIIa use in the context of emicizumab prophylaxis does not change the rFVIIa safety profile as described in the product information.

Persistent HIV Type 1 Seronegative Status Is Associated With Lower CD8+ T-Cell Activation.

We leveraged data from the Preexposure Prophylaxis Initiative (iPrEx), a global trial of preexposure chemoprophylaxis against human immunodeficiency virus type 1 (HIV-1) infection, to compare T-cell activation between those who remained negative for HIV-1 and those who became infected during the trial. The frequency of CD38(+)HLA-DR(+) CD8(+) T cells was greater in those who seroconverted, relative to the frequency in those who remained uninfected (1.30% vs 0.82%, respectively; P = .005). This translated to an odds ratio of 4.26 (95% confidence interval, 1.54-11.78) for the association between CD8(+) T-cell activation and infection with HIV-1. T-cell activation may be a biomarker for elevated HIV-1 infection risk.

Brief Report: HIV-1 gp120 T-Cell Responses Correspond to Infection Outcomes in the Global iPrEx Chemoprophylaxis Trial.

Association of HIV-1-specific T-cell responses to infection risk in seronegative individuals is controversial. We quantified and phenotypically characterized gp120-specific T-cell responses in HIV-1 exposed, but uninfected subjects enrolled in the global Pre-exposure Prophylaxis Initiative (iPrEx) chemoprophylaxis trial. IFNγ ELISpot responses were detected in 24% of subjects irrespective of infection outcome. HIV-1 gp120 envelope-specific T-cell responses were more uniformly IFN-γ+TNF-α+Mip-1ß+ in persistently seronegative subjects relative to subjects who later seroconverted (median frequency of 76.5% and 66.5%, respectively). IFNγ responses targeted the V2 loop for subjects who remained seronegative. HIV-1 gp120 envelope V2 loop-specific CD8 T-cell responses may help to protect against HIV-1 acquisition.

Cellular immune correlates analysis of an HIV-1 preexposure prophylaxis trial.

HIV-1-specific T-cell responses in exposed seronegative subjects suggest that a viral breach of the exposure site is more common than current transmission rates would suggest and that host immunity can extinguish subsequent infection foci. The Preexposure Prophylaxis Initiative (iPrEx) chemoprophylaxis trial provided an opportunity to rigorously investigate these responses in a case-control immunology study; 84 preinfection peripheral blood mononuclear cell samples from individuals enrolled in the iPrEx trial who later seroconverted were matched with 480 samples from enrolled subjects who remained seronegative from both the placebo and active treatment arms. T-cell responses to HIV-1 Gag, Protease, Integrase, Reverse Transcriptase, Vif, and Nef antigens were quantified for all subjects in an IFN-γ enzyme-linked immunospot (ELISpot) assay. IFN-γ responses varied in magnitude and frequency across subjects. A positive response was more prevalent in those who remained persistently HIV-1-negative for Gag (P = 0.007), Integrase (P < 0.001), Vif (P < 0.001), and Nef (P < 0.001). When correlated with outcomes in the iPrEx trial, Vif- and Integrase-specific T-cell responses were associated with reduced HIV-1 infection risk [hazard ratio (HR) = 0.36, 95% confidence interval (95% CI) = 0.19-0.66 and HR = 0.52, 95% CI = 0.28-0.96, respectively]. Antigen-specific responses were independent of emtricitabine/tenofovir disoproxil fumarate use. IFN-γ secretion in the ELISpot was confirmed using multiparametric flow cytometry and largely attributed to effector memory CD4+ or CD8+ T cells. Our results show that HIV-1-specific T-cell immunity can be detected in exposed but uninfected individuals and that these T-cell responses can differentiate individuals according to infection outcomes.

Pharmacokinetics of ranibizumab after intravitreal administration in patients with retinal vein occlusion or diabetic macular edema.

OBJECTIVE: To describe the systemic pharmacokinetics of ranibizumab after intravitreal administration in patients with retinal vein occlusion (RVO) or diabetic macular edema (DME). DESIGN: A population approach of nonlinear mixed-effect pharmacokinetics modeling based on serum concentrations of ranibizumab measured at various times after intravitreal administration. PARTICIPANTS: Patients with RVO (n = 441) and DME (n = 435) from 4 large, randomized, phase 3 clinical trials of monthly ranibizumab intravitreal administration. METHODS: A 1-compartment pharmacokinetics model with first-order absorption and elimination rate constants previously developed in patients with age-related macular degeneration (AMD) was fitted separately to RVO and DME data. Population pharmacokinetic parameters and interindividual variability were estimated for each model. Baseline covariates were evaluated for potential effects on systemic pharmacokinetics. Model performance was validated using general diagnostic plots and a visual predictive check. MAIN OUTCOME MEASURES: Ranibizumab disposition was determined in RVO and DME patients and compared with that previously seen in AMD patients. RESULTS: The AMD pharmacokinetics model correctly predicted the measured serum ranibizumab concentration data for RVO and DME patients. Most observed data points were within the simulated 90% confidence interval, indicating that systemic ranibizumab concentrations were comparable among AMD, RVO, and DME patients. No disease-related covariates were identified by the population pharmacokinetics analysis. CONCLUSIONS: The systemic pharmacokinetics of ranibizumab were similar among patients with AMD, RVO, or DME. Disease-related differences and patient demographics, measured in this study, did not lead to variability in ocular elimination or in systemic exposure of ranibizumab after intravitreal administration. In all disease processes tested, ranibizumab exits the eye slowly and then is eliminated rapidly from the circulation, thus minimizing systemic exposure.

Increased expression of intrinsic antiviral genes in HLA-B*57-positive individuals.

The genetic background of HIV-1-infected subjects, particularly the HLA class I haplotype, appears to be critical in determining disease progression rates, thought to be a result of the role of HIV-1-specific CD8(+) T cell responses. The HLA-B*57 allele is strongly associated with viremic suppression and slower disease progression. However, there is considerable heterogeneity in HIV-1 disease progression rates among HLA-B*57-positive subjects, suggesting that additional factors may help to contain viral replication. In this report, we investigated the association between host restriction factors, other established immunological parameters, and HLA type in HIV-1-seronegative individuals. Our results demonstrate that healthy, uninfected HLA-B*57-positive individuals exhibit significantly higher gene-expression levels of host restriction factors, such as APOBEC3A, APOBEC3B, BST-2/tetherin, and ISG15. Interestingly, HLA-B*57 individuals have significantly lower CD4(+) T cell frequencies but harbor slightly more activated CD4(+) T cells compared with their HLA-B*35 counterparts. We detected significant correlations between CD4(+) T cell activation and expression of several APOBEC3 family members, BST-2/tetherin, SAMHD1, and TRIM5α in HLA-B*57-positive individuals. To our knowledge, this is the first report showing distinct associations between host restriction factors and HLA class I genotype. Our results provide insights into natural protection mechanisms and immunity against HIV-1 that fall outside of classical HLA-mediated effects.

Pharmacokinetics of ranibizumab in patients with neovascular age-related macular degeneration: a population approach.

PURPOSE: To characterize ranibizumab pharmacokinetics in patients with AMD. METHODS: A population approach of nonlinear mixed-effect pharmacokinetic modeling based on concentration-time data from 2993 serum samples from 674 AMD patients enrolled in 5 phase 1 to 3 clinical trials of single or multiple intravitreal (ITV) doses of ranibizumab (0.3-2.0 mg/eye) administered biweekly or monthly for up to 24 months. RESULTS: A TOTAL OF 696 CONCENTRATION-TIME RECORDS FROM 229 SUBJECTS WITH ONE OR MORE MEASURABLE TOTAL SERUM RANIBIZUMAB CONCENTRATIONS WERE ANALYZED. THE SYSTEMIC CONCENTRATION-TIME DATA FOR RANIBIZUMAB WERE BEST DESCRIBED BY A ONE-COMPARTMENT MODEL WITH FIRST-ORDER ABSORPTION INTO AND FIRST-ORDER ELIMINATION FROM THE SYSTEMIC CIRCULATION. VITREOUS ELIMINATION HALF-LIFE (T1/2) WAS CALCULATED TO BE 9 DAYS AND THE INTRINSIC SYSTEMIC ELIMINATION T1/2 WAS CALCULATED TO BE APPROXIMATELY 2 HOURS. FOLLOWING ITV ADMINISTRATION, RANIBIZUMAB EGRESSES SLOWLY INTO THE SYSTEMIC CIRCULATION, RESULTING IN AN APPARENT SERUM T1/2 OF 9 DAYS. SYSTEMIC-TO-VITREOUS EXPOSURE RATIO WAS ESTIMATED TO BE 1: 90,000. With monthly and quarterly ITV regimens, the serum concentrations of ranibizumab at steady-state for both the 0.3 and 0.5 mg/eye dose levels were estimated to be below the range needed to inhibit VEGF-A-induced endothelial cell proliferation in vitro by 50% at all times. CONCLUSIONS: Systemic exposure to ranibizumab after ITV injection was very low due to elimination on reaching systemic circulation from the vitreous. Population pharmacokinetic analysis of data from a representative sample of AMD patients did not identify clinically significant sources or correlates of variability in ranibizumab exposure. (ClinicalTrials.gov numbers, NCT00056836, NCT00056823.).

Skewed distribution of natural killer cells in psoriasis skin lesions.

Psoriasis is a hyper-proliferative disease of the skin in which immunological mechanisms play a direct pathogenetic role. There have been limited studies of natural killer (NK) cells in psoriasis. The aim of this study was to examine the phenotype of NK cells in skin biopsies and peripheral blood mononuclear cells from patients with psoriasis and healthy controls. CD56(+) CD16(-) and CD56(+) CD16(+) NK cells were isolated from lesional skin, unaffected skin and PBMC of psoriasis patients, and normal skin and PBMC from healthy controls. The expression of CD57, NKG2A and NKG2C was assessed by flow cytometry. NK cells in psoriasis skin lesions were skewed in their expression of CD57, a marker of NK cell maturity, with CD57 expression significantly reduced and NKG2A expression increased on NK cells in lesional and unaffected skin compared to controls. These data suggest that in this patient cohort, NK cells could be isolated from psoriasis lesions and exhibit an immature phenotype.

Psoriasis patients are enriched for genetic variants that protect against HIV-1 disease.

An important paradigm in evolutionary genetics is that of a delicate balance between genetic variants that favorably boost host control of infection but which may unfavorably increase susceptibility to autoimmune disease. Here, we investigated whether patients with psoriasis, a common immune-mediated disease of the skin, are enriched for genetic variants that limit the ability of HIV-1 virus to replicate after infection. We analyzed the HLA class I and class II alleles of 1,727 Caucasian psoriasis cases and 3,581 controls and found that psoriasis patients are significantly more likely than controls to have gene variants that are protective against HIV-1 disease. This includes several HLA class I alleles associated with HIV-1 control; amino acid residues at HLA-B positions 67, 70, and 97 that mediate HIV-1 peptide binding; and the deletion polymorphism rs67384697 associated with high surface expression of HLA-C. We also found that the compound genotype KIR3DS1 plus HLA-B Bw4-80I, which respectively encode a natural killer cell activating receptor and its putative ligand, significantly increased psoriasis susceptibility. This compound genotype has also been associated with delay of progression to AIDS. Together, our results suggest that genetic variants that contribute to anti-viral immunity may predispose to the development of psoriasis.

Protective effect of human endogenous retrovirus K dUTPase variants on psoriasis susceptibility.

Previous genetic and functional studies have implicated the human endogenous retrovirus K (HERV-K) dUTPase located within the PSORS1 locus in the major histocompatibility complex region as a candidate psoriasis gene. Here, we describe a variant discovery and case-control association study of HERV-K dUTPase variants in 708 psoriasis cases and 349 healthy controls. Five common HERV-K dUTPase variants were found to be highly associated with psoriasis, with the strongest association occurring at the missense single-nucleotide polymorphism (SNP) rs3134774 (K158R, P=3.28 × 10(-15), odds ratio =2.36 (95% confidence interval: 1.91-2.92)). After adjusting the association of the HERV-K dUTPase variants for the potential confounding effects of HLA alleles associated with psoriasis, the HERV-K SNPs rs9264082 and rs3134774 remained significantly associated. Haplotype analysis revealed that HERV-K haplotypes containing the non-risk alleles for rs3134774 and rs9264082 significantly reduced the risk of psoriasis. Functional testing showed higher antibody responses against recombinant HERV-K dUTPase in psoriasis patients compared with controls (P<0.05), as well as higher T-cell responses against a single HERV-K dUTPase peptide (P<0.05). Our data support an independent role for the HERV-K dUTPase on psoriasis susceptibility, and suggest the need for additional studies to clarify the role of this dUTPase in the pathogenesis of psoriasis.

Association of differentiation state of CD4+ T cells and disease progression in HIV-1 perinatally infected children.

BACKGROUND: In the USA, most HIV-1 infected children are on antiretroviral drug regimens, with many individuals surviving through adolescence and into adulthood. The course of HIV-1 infection in these children is variable, and understudied. METHODOLOGY/PRINCIPAL FINDINGS: We determined whether qualitative differences in immune cell subsets could explain a slower disease course in long term survivors with no evidence of immune suppression (LTS-NS; CD4%≥25%) compared to those with severe immune suppression (LTS-SS; CD4%≤15%). Subjects in the LTS-NS group had significantly higher frequencies of naïve (CCR7+CD45RA+) and central memory (CCR7+CD45RA-) CD4+ T cells compared to LTS-SS subjects (p = 0.0005 and <0.0001, respectively). Subjects in the rapid progressing group had significantly higher levels of CD4+ T(EMRA) (CCR7-CD45RA+) cells compared to slow progressing subjects (p<0.0001). CONCLUSIONS/SIGNIFICANCE: Rapid disease progression in vertical infection is associated with significantly higher levels of CD4+ T(EMRA) (CCR7-CD45RA+) cells.

Immunodominance of HIV-1 specific CD8+ T-cell responses is related to disease progression rate in vertically infected adolescents.

BACKGROUND: HIV-1 vertically infected children in the USA are living into adolescence and beyond with the widespread use of antiretroviral drugs. These patients exhibit striking differences in the rate of HIV-1 disease progression which could provide insights into mechanisms of control. We hypothesized that differences in the pattern of immunodomination including breadth, magnitude and polyfunctionality of HIV-1 specific CD8+ T cell response could partially explain differences in progression rate. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we mapped, quantified, and assessed the functionality of these responses against individual HIV-1 Gag peptides in 58 HIV-1 vertically infected adolescents. Subjects were divided into two groups depending upon the rate of disease progression: adolescents with a sustained CD4%≥25 were categorized as having no immune suppression (NS), and those with CD4%≤15 categorized as having severe immune suppression (SS). We observed differences in the area of HIV-1-Gag to which the two groups made responses. In addition, subjects who expressed the HLA- B*57 or B*42 alleles were highly likely to restrict their immunodominant response through these alleles. There was a significantly higher frequency of naïve CD8+ T cells in the NS subjects (p = 0.0066) compared to the SS subjects. In contrast, there were no statistically significant differences in any other CD8+ T cell subsets. The differentiation profiles and multifunctionality of Gag-specific CD8+ T cells, regardless of immunodominance, also failed to demonstrate meaningful differences between the two groups. CONCLUSIONS/SIGNIFICANCE: Together, these data suggest that, at least in vertically infected adolescents, the region of HIV-1-Gag targeted by CD8+ T cells and the magnitude of that response relative to other responses may have more importance on the rate of disease progression than their qualitative effector functions.

Significant species difference in amide hydrolysis of GDC-0834, a novel potent and selective Bruton's tyrosine kinase inhibitor.

(R)-N-(3-(6-(4-(1,4-dimethyl-3-oxopiperazin-2-yl)phenylamino)-4-methyl-5-oxo-4,5-dihydropyrazin-2-yl)-2-methylphenyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxamide (GDC-0834) is a potent and selective inhibitor of Bruton's tyrosine kinase (BTK), investigated as a potential treatment for rheumatoid arthritis. In vitro metabolite identification studies in hepatocytes revealed predominant formation of an inactive metabolite (M1) via amide hydrolysis in human. The formation of M1 appeared to be NADPH-independent in human liver microsomes. M1 was found in only minor to moderate quantities in plasma from preclinical species dosed with GDC-0834. Human clearance predictions using various methodologies resulted in estimates ranging from low to high. In addition, GDC-0834 exhibited low clearance in PXB chimeric mice with humanized liver. Uncertainty in human pharmacokinetic prediction and high interest in a BTK inhibitor for clinical evaluation prompted an investigational new drug strategy, in which GDC-0834 was rapidly advanced to a single-dose human clinical trial. GDC-0834 plasma concentrations in humans were below the limit of quantitation (<1 ng/ml) in most samples from the cohorts dosed orally at 35 and 105 mg. In contrast, substantial plasma concentrations of M1 were observed. In human plasma and urine, only M1 and its sequential metabolites were identified. The formation kinetics of M1 was evaluated in rat, dog, monkey, and human liver microsomes in the absence of NADPH. The maximum rate of M1 formation (V(max)) was substantially higher in human compared with that in other species. In contrast, the Michaelis-Menten constant (K(m)) was comparable among species. Intrinsic clearance (V(max)/K(m)) of GDC-0834 from M1 formation in human was 23- to 169-fold higher than observed in rat, dog, and monkey.

Decay kinetics of HIV-1 specific T cell responses in vertically HIV-1 exposed seronegative infants.

OBJECTIVE: The majority of infants born, in developed countries, to HIV-1 positive women are exposed to the HIV-1 virus in utero or peri/post-partum, but are born uninfected. We, and others, have previously shown HIV-1 specific T cell responses in HIV-1 exposed seronegative (HESN) neonates/infants. Our objective in this study was to examine the rate of decay in their HIV-1 specific T cell response over time from birth. DESIGN: Cross-sectional and longitudinal studies of HIV-1 specific T cell responses in HESN infants were performed. METHODS: Peripheral blood mononuclear cells (PBMC) were isolated from 18 HIV-1 DNA PCR negative infants born to HIV-1 infected mothers receiving care at the Jacobi Medical Center, Bronx, NY, USA. PBMC were examined for T cell responses to HIV-1 antigens by interferon-gamma (IFN-γ) ELISPOT. RESULTS: PBMC from 15 HESN neonates/infants were analyzed. We observed a decay of HIV-1 specific T cell responses from birth at a rate of -0.599 spot forming unit/106 cells per day, with a median half-life decay rate of 21.38 weeks (13.39-115.8). CONCLUSION: Our results support the dynamic nature of T cell immunity in the context of a developing immune system. The disparate rate of decay with studies of adults placed on antiretroviral drugs suggests that antigen specific T cell responses are driven by the natural rate of decay of the T cell sub-populations themselves.

Bioequivalence studies for three formulations of a recombinant human growth hormone: challenges and lessons learned.

Two bioequivalence (BE) studies in healthy volunteers comparing new formulations of the recombinant human growth hormone (rhGH) Nutropin AQ (somatropin [rDNA origin] injection; Genentech, Inc., South San Francisco, CA) with the currently marketed formulation (5 mg/mL) were conducted to extend available dosing options. All formulations were administered by subcutaneous (SC) injection ranging in volume from 0.25 to 1.0 mL depending on the formulation concentration. Study A was a 2-period crossover design to assess the BE of 5 and 10 mg/mL. The estimate for relative bioavailability (AUC(0-24 h)) was within the prespecified BE interval (0.80-1.25). However, while the C(max) estimate (1.17) was contained within the range for BE, the 90% CI (0.986-1.38) extended beyond the prespecified BE interval. As a result, Study A failed to show BE between the 5 and 10mg/mL formulations. Review of the data showed unexpected increased variability in the observed C(max). Further review of individual data suggested that in 4 subjects, the GH concentration profile of 1 of the 2 injections closely resembled the absorption kinetics of an intramuscular injection rather than an SC injection. Because study conduct may have contributed to these results, we performed a second study, Study B. This study incorporated injection technique training, a defined injection site, and a larger sample size to accommodate variability. It also included a third formulation, creating a 3-period crossover design to assess the BE of 2.5, 5, and 10 mg/mL. Study B results demonstrated BE of the new 2.5- and 10-mg/mL formulations to the reference 5-mg/mL formulation, and BE to each other, with all 90% CIs within the BE range of 0.80 to 1.25. Thus the challenge of recognizing that design issues could affect outcomes gave us the tools to perform a second study, and the positive results taught us that demonstrating BE is an issue not only of pharmacology, but also of study methodology and execution.

An overview of the pharmacokinetics and pharmacodynamics of efalizumab: a monoclonal antibody approved for use in psoriasis.

Efalizumab is a recombinant humanized monoclonal IgG(1) antibody shown to be efficacious for the treatment of moderate to severe chronic plaque psoriasis. Efalizumab, a targeted inhibitor of T cell interactions, binds to the CD11a subunit of lymphocyte function-associated antigen 1 (LFA-1), thereby preventing LFA-1 binding to intercellular adhesion molecule 1 (ICAM-1). The authors review the pharmacokinetic and pharmacodynamic data from the efalizumab clinical development program and discuss how these data led to selection of the optimal weekly subcutaneous (SC) dose of efalizumab (1.0 mg/kg) in adults. Efalizumab SC dosages of 1.0 mg/kg/wk or greater exerted maximal pharmacodynamic effects for CD11a expression and available CD11a binding sites on T lymphocytes. Dosages greater than 1.0 mg/kg/wk SC did not provide additional benefits; moreover, higher doses did not alter the safety profile. During long-term administration of efalizumab, serum levels were generally stable and pharmacodynamic markers remained maximally affected.