Effect of Daridorexant on the Pharmacokinetics of Midazolam, and on the Pharmacokinetics and Pharmacodynamics of Warfarin in Healthy Male Subjects.

BACKGROUND AND OBJECTIVES: Daridorexant, a dual orexin receptor antagonist was recently approved for the treatment of insomnia at doses up to 50 mg once per night. This study investigated the effect of single-dose and multiple-dose daridorexant 50 mg at steady state on the pharmacokinetics (PK) of the cytochrome P450 (CYP) 3A4-sensitive substrate midazolam, and the effect of single-dose daridorexant 50 mg on the PK and pharmacodynamics (PD) of the CYP2C9-sensitive substrate warfarin. METHODS: In this prospective, single-center, open-label, fixed-sequence, phase I, drug-drug interaction study, 18 healthy male subjects sequentially received Treatment A, B, and C in three periods. Treatment A consisted of a single oral concomitant administration of midazolam 2 mg and warfarin 25 mg on day 1 of the first period. Treatment B consisted of one oral administration of daridorexant 50 mg followed 1 h later by a single oral dose of midazolam 2 mg concomitantly with a single oral dose of warfarin 25 mg on day 1 and a once-daily oral administration of daridorexant 50 mg for 6 days of the second period. Treatment C consisted of a single oral administration of daridorexant 50 mg at steady state followed 1 h later by a single oral administration of midazolam 2 mg on day 1 of the third period. Blood samples were assessed for midazolam and S-warfarin PK, and PD (international normalized ratio and factor VII). Noncompartmental  PK parameters and PD variables were evaluated with geometric mean ratios and 90% confidence intervals of Treatment B/A versus C/A for midazolam, and treatment B/A for warfarin. Safety and tolerability of each treatment were also assessed. RESULTS: Midazolam maximum plasma concentration (Cmax) and area under the plasma concentration-time curve from 0 to 24 h (AUC0-24) were 1.13- and 1.42-fold higher, respectively, after single-dose administration of daridorexant 50 mg compared to administration of midazolam alone, while Cmax and AUC0-24 were 1.12- and 1.35-fold higher, respectively, after administration of daridorexant 50 mg once daily at steady state. Terminal half-life and time to maximum plasma concentration were comparable between treatments. Daridorexant had no influence on the PK and PD of warfarin. All treatments were safe and well tolerated. CONCLUSIONS: Daridorexant at 50 mg is classified as a weak CYP3A4 inhibitor after single- and multiple-dose administration once daily at steady state. Daridorexant 50 mg did not induce CYP3A4 activity or inhibit CYP2C9 activity. CLINICAL TRIAL REGISTRATION: This trial (NCT05480488) was registered on 29 July, 2022.

Transition from Syringe to Autoinjector Based on Bridging Pharmacokinetics and Pharmacodynamics of the P2Y12 Receptor Antagonist Selatogrel in Healthy Subjects.

BACKGROUND AND OBJECTIVES: Selatogrel is a potent, reversible, and selective antagonist of the platelet P2Y12 receptor currently developed for the treatment of acute myocardial infarction (AMI). In the completed Phase I/II studies, selatogrel was subcutaneously (s.c.) administered as a lyophilizate-based formulation by syringe by a healthcare professional. In the Phase III study, selatogrel will be self-administered s.c. as a liquid formulation with an autoinjector at the onset of AMI symptoms to shorten treatment delay. This clinical bridging study compared the pharmacokinetics (PK) of selatogrel between the different formulations. METHODS: This was a single-center, randomized, open-label, three-period, cross-over Phase I study in 24 healthy subjects. In each period, a single subcutaneous dose of 16 mg selatogrel was administered as (1) a Phase III liquid formulation by autoinjector (Treatment A), (2) a Phase III liquid formulation by prefilled syringe (Treatment B), or (3) a Phase I/II reconstituted lyophilizate-based formulation by syringe (Treatment C). PK parameters including area under the plasma concentration-time curve from zero to infinity (AUC0-∞), maximum plasma concentration (Cmax), time to reach Cmax(tmax), and terminal half-life (t1/2) were determined using noncompartmental analysis. Pharmacodynamic (PD) parameters were estimated using PK/PD modeling, including the time of first occurrence of inhibition of platelet aggregation (IPA) ≥ 80% (tonset), duration of IPA above 80% (tduration), and responder rate defined as the percentage of subjects with tonset ≤ 30 min and tduration ≥ 3 h. Safety and tolerability were also assessed. RESULTS: Comparing Treatment A to Treatment C, the exposure (AUC0-∞) was bioequivalent with a geometric mean ratio (GMR) (90% confidence interval) of 0.95 (0.92-0.97) within the bioequivalence range (0.80-1.25). Absorption following Treatment A was slightly slower with a tmax occurring approximately 30 min later and a 20% lower Cmax. The autoinjector itself had no impact on the PK of selatogrel, as similar values of Cmax and AUC0-∞ were determined after administration as a Phase III liquid formulation by autoinjector or by prefilled syringe (i.e., GMR [90% confidence interval] of 1.06 [0.97-1.15] and 0.99 [0.96-1.03] for Cmax and AUC0-∞, respectively). PK/PD modeling predicted that the median tonset will occur slightly later for Treatment A (7.2 min) compared to Treatment C (4.2  min), while no relevant differences in tduration and responder rate were estimated between the two treatments. Selatogrel was safe and well tolerated following all three treatments. CONCLUSIONS: PK and simulated PD effects of selatogrel were similar across treatments. CLINICAL TRIAL REGISTRATION: NCT04557280.

Clinical pharmacology, efficacy, and safety of orexin receptor antagonists for the treatment of insomnia disorders.

INTRODUCTION: The last two decades have witnessed a rapid increase in the knowledge about the role of the orexin system, particularly in the regulation of wakefulness and arousal. Dual orexin receptor antagonists (DORAs) have been approved for the treatment of insomnia disorders (suvorexant, lemborexant) and drugs with a distinctive profile (daridorexant) or orexin-2 receptor selectivity (seltorexant) are in development. AREAS COVERED: This review discusses pharmacokinetics (PK), pharmacodynamics (PD), efficacy, and safety properties of orexin receptor antagonists (ORAs). EXPERT OPINION: In general, the drugs described have a similar effect on sleep characteristics although their pharmacokinetic variables differ. ORAs have the potential to revolutionize the pharmacological treatment of insomnia because they not only improve sleep, but, in addition, appear to have no dependence - and tolerance-inducing effects, which makes them suitable for long-term-treatment. The safety and tolerability profile of ORAs clearly differ from those of more traditional sleep-promoting drugs. Further research is needed to demonstrate benefits to patients suffering from insomnia disorder, e.g., with respect to improving not only sleep but also daytime functioning. In addition, ongoing and future research will show whether ORAs may have beneficial effects in patients with various psychiatric and neurodegenerative disorders, including Alzheimer's disease.

The dual orexin receptor antagonist daridorexant does not affect the pharmacokinetics of the BCRP substrate rosuvastatin.

Daridorexant is a dual orexin receptor antagonist in clinical development for the treatment of insomnia. Breast-cancer resistant protein (BCRP) is an efflux pump expressed in intestinal epithelium and hepatocytes, contributing to the absorption, distribution, and elimination of drugs and endogenous compounds. In vitro, daridorexant inhibits BCRP with an IC50 of 3.0 µmol/L. The BCRP substrate rosuvastatin is a cholesterol-lowering drug, recommended for clinical drug-drug interaction (DDI) studies. In order to exclude an inhibitory effect of daridorexant on BCRP, this single-centre, open-label, two-treatment Phase 1 study investigated the effect of daridorexant at steady state on the pharmacokinetics (PK) of single-dose rosuvastatin in 20 healthy male subjects. In addition, safety and tolerability were assessed. A single oral dose of 10 mg rosuvastatin on Day 1 was followed by 96 hours observation. Thereafter, 25 mg daridorexant was administered once daily (o.d.) on Days 5-8 and in combination with 10 mg rosuvastatin on Day 8. On Days 9-12, subjects received 25 mg daridorexant alone. PK sampling was performed up to 120 hours after treatment administration. The results showed that concomitant administration of 25 mg daridorexant o.d. at steady state did not affect the exposure parameters of rosuvastatin in a relevant way, as indicated by the ratios of geometric means (GMRs) ([rosuvastatin + daridorexant]/[rosuvastatin alone]) of 0.93 for both Cmax and AUC0-∞ . Administration of a single dose of 10 mg rosuvastatin, multiple doses of 25 mg daridorexant alone or in combination were well tolerated. Taken together, daridorexant and BCRP substrates can be safely co-administered.

Safety, Immunogenicity, and Protective Efficacy against Controlled Human Malaria Infection of Plasmodium falciparum Sporozoite Vaccine in Tanzanian Adults.

We are using controlled human malaria infection (CHMI) by direct venous inoculation (DVI) of cryopreserved, infectious Plasmodium falciparum (Pf) sporozoites (SPZ) (PfSPZ Challenge) to try to reduce time and costs of developing PfSPZ Vaccine to prevent malaria in Africa. Immunization with five doses at 0, 4, 8, 12, and 20 weeks of 2.7 × 105 PfSPZ of PfSPZ Vaccine gave 65% vaccine efficacy (VE) at 24 weeks against mosquito bite CHMI in U.S. adults and 52% (time to event) or 29% (proportional) VE over 24 weeks against naturally transmitted Pf in Malian adults. We assessed the identical regimen in Tanzanians for VE against PfSPZ Challenge. Twenty- to thirty-year-old men were randomized to receive five doses normal saline or PfSPZ Vaccine in a double-blind trial. Vaccine efficacy was assessed 3 and 24 weeks later. Adverse events were similar in vaccinees and controls. Antibody responses to Pf circumsporozoite protein were significantly lower than in malaria-naïve Americans, but significantly higher than in Malians. All 18 controls developed Pf parasitemia after CHMI. Four of 20 (20%) vaccinees remained uninfected after 3 week CHMI (P = 0.015 by time to event, P = 0.543 by proportional analysis) and all four (100%) were uninfected after repeat 24 week CHMI (P = 0.005 by proportional, P = 0.004 by time to event analysis). Plasmodium falciparum SPZ Vaccine was safe, well tolerated, and induced durable VE in four subjects. Controlled human malaria infection by DVI of PfSPZ Challenge appeared more stringent over 24 weeks than mosquito bite CHMI in United States or natural exposure in Malian adults, thereby providing a rigorous test of VE in Africa.

A public antibody lineage that potently inhibits malaria infection through dual binding to the circumsporozoite protein.

Immunization with attenuated Plasmodium falciparum sporozoites (PfSPZs) has been shown to be protective against malaria, but the features of the antibody response induced by this treatment remain unclear. To investigate this response in detail, we isolated IgM and IgG monoclonal antibodies from Tanzanian volunteers who were immunized with repeated injection of Sanaria PfSPZ Vaccine and who were found to be protected from controlled human malaria infection with infectious homologous PfSPZs. All isolated IgG monoclonal antibodies bound to P. falciparum circumsporozoite protein (PfCSP) and recognized distinct epitopes in its N terminus, NANP-repeat region, and C terminus. Strikingly, the most effective antibodies, as determined in a humanized mouse model, bound not only to the repeat region, but also to a minimal peptide at the PfCSP N-terminal junction that is not in the RTS,S vaccine. These dual-specific antibodies were isolated from different donors and were encoded by VH3-30 or VH3-33 alleles that encode tryptophan or arginine at position 52. Using structural and mutational data, we describe the elements required for germline recognition and affinity maturation. Our study provides potent neutralizing antibodies and relevant information for lineage-targeted vaccine design and immunization strategies.

Immunization of Malaria-Preexposed Volunteers With PfSPZ Vaccine Elicits Long-Lived IgM Invasion-Inhibitory and Complement-Fixing Antibodies.

Background: The assessment of antibody responses after immunization with radiation-attenuated, aseptic, purified, cryopreserved Plasmodium falciparum sporozoites (Sanaria PfSPZ Vaccine) has focused on IgG isotype antibodies. Here, we aimed to investigate if P. falciparum sporozoite binding and invasion-inhibitory IgM antibodies are induced following immunization of malaria-preexposed volunteers with PfSPZ Vaccine. Methods: Using serum from volunteers immunized with PfSPZ, we measured vaccine-induced IgG and IgM antibodies to P. falciparum circumsporozoite protein (PfCSP) via ELISA. Function of this serum as well as IgM antibody fractions was measured via in vitro in an inhibition of sporozoite invasion assay. These IgM antibody fractions were also measured for binding to sporozoites by immunofluorescence assay and complement fixation on whole sporozoites. Results: We found that in addition to anti-PfCSP IgG, malaria-preexposed volunteers developed anti-PfCSP IgM antibodies after immunization with PfSPZ Vaccine and that these IgM antibodies inhibited P. falciparum sporozoite invasion of hepatocytes in vitro. These IgM plasma fractions also fixed complement to whole P. falciparum sporozoites. Conclusions: This is the first finding that PfCSP and P. falciparum sporozoite-binding IgM antibodies are induced following immunization of PfSPZ Vaccine in malaria-preexposed individuals and that IgM antibodies can inhibit P. falciparum sporozoite invasion into hepatocytes in vitro and fix complement on sporozoites. These findings indicate that the immunological assessment of PfSPZ Vaccine-induced antibody responses could be more sensitive if they include parasite-specific IgM in addition to IgG antibodies. Clinical Trials Registration: NCT02132299.

Public antibodies to malaria antigens generated by two LAIR1 insertion modalities.

In two previously described donors, the extracellular domain of LAIR1, a collagen-binding inhibitory receptor encoded on chromosome 19 (ref. 1), was inserted between the V and DJ segments of an antibody. This insertion generated, through somatic mutations, broadly reactive antibodies against RIFINs, a type of variant antigen expressed on the surface of Plasmodium falciparum-infected erythrocytes. To investigate how frequently such antibodies are produced in response to malaria infection, we screened plasma from two large cohorts of individuals living in malaria-endemic regions. Here we report that 5-10% of malaria-exposed individuals, but none of the European blood donors tested, have high levels of LAIR1-containing antibodies that dominate the response to infected erythrocytes without conferring enhanced protection against febrile malaria. By analysing the antibody-producing B cell clones at the protein, cDNA and gDNA levels, we characterized additional LAIR1 insertions between the V and DJ segments and discovered a second insertion modality whereby the LAIR1 exon encoding the extracellular domain and flanking intronic sequences are inserted into the switch region. By exon shuffling, this mechanism leads to the production of bispecific antibodies in which the LAIR1 domain is precisely positioned at the elbow between the VH and CH1 domains. Additionally, in one donor the genomic DNA encoding the VH and CH1 domains was deleted, leading to the production of a camel-like LAIR1-containing antibody. Sequencing of the switch regions of memory B cells from European blood donors revealed frequent templated inserts originating from transcribed genes that, in rare cases, comprised exons with orientations and frames compatible with expression. These results reveal different modalities of LAIR1 insertion that lead to public and dominant antibodies against infected erythrocytes and suggest that insertion of templated DNA represents an additional mechanism of antibody diversification that can be selected in the immune response against pathogens and exploited for B cell engineering.