Effects of oral sepiapterin on blood Phe concentration in a broad range of patients with phenylketonuria (APHENITY): results of an international, phase 3, randomised, double-blind, placebo-controlled trial.

BACKGROUND: Phenylketonuria is an inherited condition characterised by neurotoxic accumulation of phenylalanine (Phe). APHENITY assessed the efficacy and safety of orally administered synthetic sepiapterin in children and adults with phenylketonuria. METHODS: APHENITY was a phase 3, randomised, double-blind, placebo-controlled study performed at 34 clinics, hospitals, and university sites in 13 countries. Individuals of all ages with a clinical diagnosis of phenylketonuria were eligible for inclusion if they had a blood Phe concentration of 360 µmol/L or higher at study entry, whereas individuals with hyperphenylalaninaemia due to pathogenic variants in GCH1, PTS, QDPR, SPR, and PCBD1, consistent with a diagnosis of primary BH4 deficiency, were excluded. Part 1 was a 14-day open-label assessment of blood Phe concentration response to sepiapterin. In part 2, sepiapterin-responsive participants were randomly assigned (1:1) by a web-response system based on a block randomisation schedule (permuted block size of 2 and 4) to 6 weeks of sepiapterin (forced-dose escalation: 20, 40, and 60 mg/kg per day per consecutive 2-week period) or placebo. The investigational drug and placebo were identical in their appearance and delivery. Dried blood samples were collected for analysis of Phe concentration on days -1, 1 (before dose was administered), 5, 10, 14, 19, 24, 28, 33, 38, and 42 in part 2, either in-clinic or at home. The primary endpoint for part 2, mean change from baseline in blood Phe after 6 weeks, was assessed in the primary analysis set of participants with at least a 30% reduction in blood Phe concentration in part 1, who took at least one dose in part 2. Safety was evaluated in all participants receiving at least one dose of treatment. The completed study is registered at EudraCT (2021-000474-29) and ClinicalTrials.gov (NCT05099640). FINDINGS: APHENITY was conducted between Sept 30, 2021, and April 3, 2023. 187 people were assessed for eligibility, of whom 157 were enrolled. In part 1, 156 participants were assessed or evaluated, of whom 114 (73%) were sepiapterin-responsive (ie, ≥15% reduction in blood Phe from baseline). In part 2, 98 participants (49 in the placebo group and 49 in the sepiapterin group) were in the primary analysis set. There was a significant reduction of blood Phe concentration after 6 weeks of sepiapterin (-63%, SD 20) compared with placebo (1%, 29; least squares mean change -395·9 µmol/L, SE 33·8; p<0·0001). Treatment-emergent adverse events were reported in 33 (59%) of 56 participants who received sepiapterin and 18 (33%) of 54 participants who received placebo. Most treatment-emergent adverse events were mild gastrointestinal events (11 [20%] of 56 participants who received sepiapterin and ten [19%] of 54 participants who received placebo) that resolved quickly. There were no deaths and no serious or severe adverse events. INTERPRETATION: Sepiapterin is a promising oral therapy for individuals with phenylketonuria, was well tolerated, and resulted in significant and clinically meaningful reductions in blood Phe concentration in participants with varying disease severity. FUNDING: PTC Therapeutics.

Clinical Assessment of Breast Cancer Resistance Protein (BCRP)-Mediated Drug-Drug Interactions of Sepiapterin with Curcumin and Rosuvastatin in Healthy Volunteers.

BACKGROUND AND OBJECTIVE: Sepiapterin, also known as PTC923 and CNSA-001, is a synthetic form of endogenous sepiapterin being developed as a novel oral treatment for phenylketonuria. Sepiapterin is a natural precursor of tetrahydrobiopterin (BH4) and, when orally administered, is converted to BH4 via the pterin salvage pathway. In vitro studies have demonstrated that both sepiapterin and BH4 are both substrates and inhibitors of the breast cancer resistance protein (BCRP) transporter. This phase I study investigated BCRP-mediated drug-drug interactions of sepiapterin as a victim and as a perpetrator. METHODS: An open-label, fixed-sequence, four-period, crossover, single-dose study was conducted in adult male and female healthy volunteers (18-55 years of age). In a given treatment period, subjects received a single oral dose of sepiapterin (20 mg/kg), sepiapterin (20 mg/kg) plus curcumin (2 g), rosuvastatin (10 mg), or rosuvastatin (10 mg) plus sepiapterin (60 mg/kg). The pharmacokinetics of sepiapterin, its metabolite BH4, and rosuvastatin were studied, and geometric mean ratios of exposures in the presence and absence of the BCRP inhibitor curcumin or sepiapterin were estimated. The presence of the BCRP c.421C>A polymorphism was evaluated in all subjects. RESULTS: A total of 29 subjects were enrolled and included in the safety analysis. Among them, 26 subjects were included in the pharmacokinetic and drug-drug interaction analyses. Following oral administration 20 mg/kg sepiapterin, sepiapterin was rapidly and extensively converted to BH4, and BH4 maximum observed concentration (415.0 ng/mL) was observed 4.95 h (time to maximum observed concentration) post-dose. Sepiapterin maximum observed concentration and area under the concentration-time curve from time 0 to time of the last quantifiable measurement or the last sample collection time (AUClast) were <1% of BH4 values. Coadministration of the BCRP inhibitor curcumin (2 g) increased BH4 maximum observed concentration, AUClast, and area under the concentration-time curve from time 0 extrapolated to infinity by 24%, 21%, and 20%, respectively. When sepiapterin was coadministered with the BCRP substrate rosuvastatin, there was no effect on the pharmacokinetics of rosuvastatin. BCRP c.421C/A carriers (n = 4) had higher plasma exposures of BH4 (1.39 × for AUClast) and rosuvastatin (1.61 × for AUClast) than c.421C/C carriers (n = 22). Greater increases in BH4 exposures (1.33 vs 1.18 for AUClast) were observed in c.421C/A carriers compared with c.421C/C carriers when sepiapterin was coadministered with curcumin. All treatments were well tolerated during the study. CONCLUSIONS: Oral coadministration of the BCRP inhibitor curcumin slightly increased the plasma exposure of sepiapterin and its metabolite BH4 in healthy volunteers. This modest increase was deemed not clinically meaningful. Sepiapterin did not alter the pharmacokinetics of the BCRP substrate rosuvastatin.

Relative Oral Bioavailability and Food Effects of Two Sepiapterin Formulations in Healthy Participants.

Sepiapterin is an orally administered drug in development for the treatment of phenylketonuria, an inborn error of metabolism characterized by the deficiency of the phenylalanine-metabolizing enzyme phenylalanine hydroxylase. This study characterized the pharmacokinetics, safety, and tolerability of 2 clinical sepiapterin formulations (Phase 1/2, Phase 3) and the effects of food on the pharmacokinetics of the Phase 3 formulation in healthy participants. In Part A, 18 participants were randomized to one of 2 treatment sequences, each with 4 dosing periods comprising a single dose (20 or 60 mg/kg) of the Phase 1/2 or the Phase 3 formulation with a low-fat diet. In Part B, 14 participants were randomized to one of 2 sequences, each comprising 4 dosing periods of a single dose (20 or 60 mg/kg) of the Phase 3 formulation under fed (high-fat) or fasted conditions. Following oral administration, sepiapterin was quickly absorbed and rapidly and extensively converted to tetrahydrobiopterin (BH4). BH4 was the major circulating active moiety. Under low-fat conditions, the Phase 3 formulation was bioequivalent to the Phase 1/2 formulation at 20 mg/kg, while slightly lower BH4 exposure (approximately 0.81×) for the Phase 3 formulation was observed at 60 mg/kg. BH4 exposure increased to approximately 1.7× under the low-fat condition and approximately 2.8× under the high-fat condition at a dose of either 20 or 60 mg/kg for the Phase 3 formulation, compared with the fasted condition. Both sepiapterin formulations were well tolerated, with no serious or severe adverse events reported. All treatment-emergent adverse events were mild or moderate in severity.

Utilizing Nottingham Prognostic Index in microarray gene expression profiling of breast carcinomas.

We report a novel approach to gene expression profiling using the Nottingham Prognostic Index (NPI) to stratify 26 patients with invasive breast carcinoma. As an aggregate index of parameters reflecting metastatic potential, growth rate, and genetic instability the NPI has distinct advantages over other clinicopathologic features used to segregate breast cancer patients. As a continuous variable it offers a responsive and sensitive means of modeling a continuum of clinical aggressiveness. Using RNA extracted from 26 tumors and cDNA microarrays with 23 343 unique genetic elements, 84 genes and expressed sequence tags were identified whose expression patterns correlated with NPI. Differential expression by immunohistochemistry (IHC) was also observed for two of three genes evaluated by this method. Correlation was determined by the Spearman rank correlation method with null distribution analysis. Among the 84 genetic elements were seven previously implicated in neoplastic progression (including the two demonstrating differential expression by IHC), 11 without specific cancer association but localized to chromosomal sites whose loss or gain has been identified in cytogenetic studies of breast carcinoma, and 73 not previously associated with breast carcinoma. Collectively, the expression patterns of these 84 elements have potential to distinguish high and low NPI patient samples. These data add support to the assertion that prognostic groups of breast carcinoma are reflected in distinguishable expression profiles of a limited set of genes.