PF-06881894, a Proposed Biosimilar to Pegfilgrastim, Versus US-Licensed and EU-Approved Pegfilgrastim Reference Products (Neulasta®): Pharmacodynamics, Pharmacokinetics, Immunogenicity, and Safety of Single or Multiple Subcutaneous Doses in Healthy Volunteers.

INTRODUCTION: PF-06881894 is a proposed biosimilar to pegfilgrastim (Neulasta®). This study evaluated the pharmacodynamic/pharmacokinetic (PD/PK) equivalence, immunogenicity, and safety of PF-06881894 vs pegfilgrastim reference products (US- and EU-Neulasta®) in healthy volunteers. METHODS: A phase 1, open-label, randomized, crossover study was conducted to assess the pharmacologic equivalence and safety of a single 6-mg dose of PF-06881894, pegfilgrastim-US, and pegfilgrastim-EU. The primary PD endpoints were area under the effect-versus-time curve for absolute neutrophil count (ANC) from dose administration to 288 h postdose, and maximum observed ANC value among subjects confirmed negative for anti-pegfilgrastim antibodies. Primary PK variables included area under the serum pegfilgrastim-versus-time curve from the time of dose administration to time infinity and maximum observed serum pegfilgrastim concentration. A second phase 1, open-label, randomized (1:1), parallel-group, non-inferiority study was conducted to assess the immunogenicity and safety of multiple 6-mg doses of PF-06881894 versus pegfilgrastim-US. The primary endpoint for the immunogenicity study was the proportion of subjects with both negative baseline and confirmed positive postdose anti-pegfilgrastim antibodies at any time during the study. RESULTS: Across the single- and multiple-dose studies (N = 153 and N = 420 treated subjects, respectively), demographics for age (18-65 years), male gender (n = 264/573), and white race (n = 423/573) were similar. Three-way PD/PK equivalence of PF-06881894, pegfilgrastim-US, and pegfilgrastim-EU was demonstrated with the primary PD endpoints and primary PK variables being completely contained within the predefined 90% confidence interval acceptance limits (80-125%). The non-inferiority of PF-06881894 versus pegfilgrastim-US in terms of immunogenicity was established according to the prespecified non-inferiority margin (≤10%). Overall, there were no clinically meaningful differences in safety profiles among or between study groups. CONCLUSIONS: Single-dose PF-06881894 demonstrated PD/PK equivalence and comparable safety with US- and EU-pegfilgrastim reference products. Multiple-dose PF-06881894 demonstrated immunogenicity non-inferiority to pegfilgrastim-US with comparable safety. Both studies contributed to the totality of evidence supporting biosimilarity. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT02629289; NCT03273842 (C1221005).

Anti-drug Antibody Assay Validation: Improved Reporting of the Assay Selectivity via Simpler Positive Control Recovery Data Analysis.

Anti-drug antibody (ADA) assay selectivity is evaluated during assay validation to assess the potential for individual matrices to interfere with detection of ADA. While current EMA and FDA guideline documents suggest comparative analysis with and without matrix, they do not provide specific recommendations on the acceptance criteria such as an acceptable percent positive control (PC) recovery range or positive rate. Industry has adopted an approach where recovery of PC spiked sample is expected to fall within ± 20% (80 to 120%) vs. that for the PC material spiked in negative control matrix or assay buffer. Here, it is proposed that ADA assay selectivity evaluated using a qualitative assessment of PC recovery vs. a PK-like quantitative method may be more appropriate. The PC recovery test should focus on the reliability of the method to detect the low PC level in individual samples and avoid false-negative ADA reporting. Therefore, it is proposed that assessment of high PC level as well as the assessment of quantitative percent recovery (within ± 20%) should not be included in the test. The recovery test may be viewed as acceptable should a pre-selected number of individual samples (for example at least 8 or 9 out of 10) prepared at the low PC concentration of the assay score as ADA positive.

Ligand-dependent coactivation of the human bile acid receptor FXR by the peroxisome proliferator-activated receptor gamma coactivator-1alpha.

Peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) has been shown to play an important role in energy metabolism by coordinating transcriptional programs involved in mitochondrial biogenesis, adaptive thermogenesis, gluconeogenesis, and fatty acid oxidation. PGC-1alpha also plays a crucial role in cholesterol metabolism by serving as a coactivator of the liver X receptor-alpha and inducing the expression of cholesterol 7-alpha-hydroxylase. Here, we demonstrate that PGC-1alpha also functions as an effective coactivator of farnesoid X receptor (FXR), the bile acid receptor. Transient cotransfection assays demonstrate that PGC-1alpha enhances ligand-mediated FXR transcription when either full-length FXR or Gal4 DNA binding domain-FXR-ligand binding domain chimeras were analyzed. Mammalian two-hybrid analyses, glutathione S-transferase affinity chromatography and biochemical coactivator recruitment assays demonstrate ligand-dependent interaction between the two proteins both in vivo and in vitro. PGC-1alpha-mediated coactivation of FXR was highly ligand-dependent and absolutely required an intact activation function-2 (AF-2) domain of FXR and the LXXLL motif in PGC-1alpha. The integrity of the charge clamp was required, further illustrating the role of the ligand binding domain of FXR in PGC-1alpha recognition. Together, these results indicate that PGC-1alpha functions as a potent coactivator for FXR and further implicates its role in the regulation of genes that are involved in bile acid and lipid metabolism.

T0901317 is a dual LXR/FXR agonist.

We characterize the ability of the liver X receptor (LXRalpha [NR1H3] and LXRbeta [NR1H2]) agonist, T0901317, to activate the farnesoid X receptor (FXR [NR4H4]). Although T0901317 is a much more potent activator of LXR than FXR, this ligand actually activates FXR more potently than a natural bile acid FXR ligand, chenodeoxycholic acid. Thus, the FXR activity of T0901317 must be considered when utilizing this agonist as a pharmacological tool to investigate LXR function.

A natural product ligand of the oxysterol receptor, liver X receptor.

Natural products have been identified as ligands for a number of members of the nuclear hormone receptor (NHR) superfamily. Often these natural products are used as dietary supplements to treat myriad ailments ranging from perimenopausal hot flashes to hypercholesterolemia and reduced cognitive function. Examples of some natural product ligands for NHRs include genestein (estrogen receptors NR3A1 and NR3A2), guggulsterone (farnesoid X receptor NR1H4), and St. John's wort (pregnane X receptor, NR1I2). In this study, we identified the first nonoxysterol natural product that functions as a ligand for the liver X receptor (LXRalpha and LXRbeta; NR1H3, NR1H2), a NHR that acts as the receptor for oxysterols and plays a key role in regulation of cholesterol metabolism and transport as well as glucose metabolism. We show that paxilline, a fungal metabolite, is an efficacious agonist of both LXRalpha and LXRbeta in biochemical and in vitro cell-based assays. Paxilline binds directly to both receptors and is an activator of LXR-dependent transcription in cell-based reporter assays. We also demonstrate that paxilline binding to the receptors results in efficient activation of transcription of two physiological LXR target genes, ABCA1 and SREBP. The discovery of paxilline, the first reported nonoxysterol natural product ligand of the LXRs, may provide insight into the mechanism of ligand recognition by these receptors and reaffirms the utility of examining natural product libraries for identifying novel NHR ligands.