Pharmacokinetics, Disposition, and Biotransformation of [14C]Lenacapavir, a Novel, First-in-Class, Selective Inhibitor of HIV-1 Capsid Function, in Healthy Participants Following a Single Intravenous Infusion

The development and evolution of biological AMS at Livermore: a perspective

Biological accelerator mass spectrometry (AMS) provides ultrasensitive carbon-14 isotopic analysis enabling a deeper understanding of human health concerns by enabling quantification of pharmacokinetics and other molecular endpoints directly in humans. It enables environmentally and human relevant studies of metabolic pathways through the use of very low concentrations of labeled metabolic substrates in cells and organisms. Here, we discuss why AMS is an important tool for the biosciences, the development and evolution of biological AMS at Livermore and discuss technical refinements that will improve the efficiency of operation for the measurement of ultra-trace levels of 14C, which, long term, will enable greater ease of use and sample throughput.

Lenacapavir: Playing the Long Game in the New Era of Antiretrovirals

The mainstay of antiretroviral therapy (ART) has been combination oral therapy. While oral ART is highly effective, nonadherence remains a chief concern. Addressing this concern in recent years is the emergence of long-acting antiretrovirals for the treatment and prevention of HIV-1 infection. The most recently approved long-acting antiretroviral is the first-in-class capsid inhibitor lenacapavir (LEN) for heavily treatment-experienced adults with multidrug-resistant HIV-1 infection. Due to its biannual subcutaneous dosing scheme to inhibit the HIV-1 capsid, LEN exhibits unique pharmacokinetics and reinforces an evolving era of ART. In this review, we evaluate published and accepted research articles, conference proceedings, and clinical trial records to provide a comprehensive overview of LEN for treatment and preliminary data for the prevention of HIV-1 infection. These data include clinical trials outcomes, in vitro and in vivo resistance profiles, and preclinical data supporting downstream indications. We also discuss the unique clinical pharmacology of LEN with the goal of serving as a resource toward subsequent physiologically based, population-based, and other miscellaneous pharmacometric-focused analyses. Given the dynamic nature of the HIV treatment and prevention research fields, we also discuss ongoing studies related to LEN for treatment-naïve adults and for prevention. Lastly, we discuss important pharmacologic gaps in special populations, drug-drug interactions, and at the sites of action germane to HIV treatment and prevention. The information discussed in this review will provide knowledge and understanding of the unique pharmacologic properties of LEN to assist clinicians and researchers as they navigate the dynamic HIV research landscape.

Effect of Food Intake or Coadministration With an Acid-Reducing Agent on Lenacapavir Pharmacokinetics Following Oral Administration

Lenacapavir is a potent, long-acting HIV-1 capsid inhibitor used in combination with other antiretrovirals to treat HIV-1 infection. The pharmacokinetics of orally administered drugs may be affected by food intake or coadministration of acid-reducing agents (ARA). Two Phase 1 studies were conducted on healthy participants to evaluate the effect of food and the impact of the histamine H2-receptor antagonist famotidine in parallel cohorts. In Study 1, oral lenacapavir (300 mg) was administered under fasting conditions, after a standardized high-fat meal, and after a low-fat meal (n = 8/cohort). In Study 2, lenacapavir 300 mg was administered alone (n = 27) and 2 hours after famotidine (40 mg; n = 25), each under fasting conditions. For the high-fat meal versus fasted comparison, the percentage geometric least-squares mean (%GLSM) ratios for the lenacapavir area under the curve to infinity (AUCinf) and maximum concentration (Cmax) were 115.2 and 145.2, respectively. For the low-fat meal, the %GLSM ratios for lenacapavir AUCinf and Cmax were 98.6 and 115.8, respectively, versus the fasted state. In the famotidine study, the %GLSM ratio for lenacapavir AUC from time zero to the last quantifiable concentration was 137.4, and for Cmax was 100.6. Based on available clinical safety data, the exposure increases observed in these studies were not expected to be clinically relevant. Overall, these data support the dosing of oral lenacapavir without regard to food intake or coadministration with ARAs.

Drug-drug interactions potential with the HIV-1 capsid inhibitor lenacapavir

INTRODUCTION

Lenacapavir is the first HIV-1 capsid inhibitor administered subcutaneously twice yearly. While lenacapavir is currently only indicated as salvage therapy, it has the potential to become a foundation of future treatments and to revolutionize HIV prevention.

AREAS COVERED

This review summarizes the pharmacology of lenacapavir with particular emphasis placed on its drug-drug interaction (DDI) potential as it is used in treatment-experienced individuals who often present multiple comorbidities and polypharmacy. The effect of lenacapavir on drug metabolizing enzymes and transporters as well as findings of DDI studies are summarized. These data were used to predict DDIs with 1073 comedications. Finally, the management of selected DDIs is discussed. Conferences/workshops abstracts (i.e. CROI, IAS, EACS, HIV Glasgow, PK workshop) were screened using the terms: 'lenacapavir,' 'capsid inhibitor,' 'GS-6207,' and a PubMed search was used to compile data until September 2024.

EXPERT OPINION

Lenacapavir has a favorable DDI profile with 80% of evaluated comedications estimated to have no clinically significant DDIs. More studies are needed to address pharmacological gaps including the pharmacokinetics of lenacapavir in special populations, its transfer across the blood-brain barrier or the placenta as well as the possibility to manage DDIs with moderate/strong inducers by reducing lenacapavir dosing interval.

Lenacapavir Exhibits Atropisomerism-Mechanistic Pharmacokinetics and Disposition Studies of Lenacapavir Reveal Intestinal Excretion as a Major Clearance Pathway

Lenacapavir (LEN), a long-acting injectable, is the first approved human immunodeficiency virus type 1 capsid inhibitor and one of a few Food and Drug Administration-approved drugs that exhibit atropisomerism. LEN exists as a mixture of two class 2 atropisomers that interconvert at a fast rate (half-life < 2 hours) with a ratio that is stable over time and unaffected by enzymes or binding to proteins in plasma. LEN exhibits low systemic clearance (CL) in nonclinical species and humans; however, in all species, the observed CL was higher than the in vitro predicted CL. The volume of distribution was moderate in nonclinical species and consistent with the tissue distribution observed by whole-body autoradiography in rats. LEN does not distribute to brain, consistent with being a P-glycoprotein (P-gp) substrate. Mechanistic drug disposition studies with [14C]LEN in intravenously dosed bile duct-cannulated rats and dogs showed a substantial amount of unchanged LEN (31%-60% of dose) excreted in feces, indicating that intestinal excretion (IE) was a major clearance pathway for LEN in both species. Coadministration of oral elacridar, a P-gp inhibitor, in rats decreased CL and IE of LEN. Renal excretion was < 1% of dose in both species. In plasma, almost all radioactivity was unchanged LEN. Low levels of metabolites in excreta included LEN conjugates with glutathione, pentose, and glucuronic acid, which were consistent with metabolites formed in vitro in Hμrel hepatocyte cocultures and those observed in human. Our studies highlight the importance of IE for efflux substrates that are highly metabolically stable compounds with slow elimination rates. SIGNIFICANCE STATEMENT: LEN is a long-acting injectable that exists as conformationally stable atropisomers. Due to an atropisomeric interconversion rate that significantly exceeds the in vivo elimination rate, the atropisomer ratio of LEN remains constant in circulation. The disposition of LEN highlights that intestinal excretion has a substantial part in the elimination of compounds that are metabolically highly stable and efflux transporter substrates.

Pharmacokinetics of long-acting lenacapavir in participants with hepatic or renal impairment

Lenacapavir is a novel, first-in-class, multistage inhibitor of HIV-1 capsid function approved for the treatment of multidrug-resistant HIV-1 infection in combination with other antiretrovirals for heavily treatment-experienced people with HIV. Two Phase 1, open-label, parallel-group, single-dose studies assessed the pharmacokinetics (PK) of lenacapavir in participants with moderate hepatic impairment [Child-Pugh-Turcotte (CPT) Class B: score 7-9] or severe renal impairment [15 ≤ creatinine clearance (CLcr) ≤29 mL/min] to inform lenacapavir dosing in HIV-1-infected individuals with organ impairment. In both studies, a single oral dose of 300 mg lenacapavir was administered to participants with normal (n = 10) or impaired (n = 10) hepatic/renal function who were matched for age (±10 years), sex, and body mass index (±20%). Lenacapavir exposures [area under the plasma concentration-time curve from time 0 to infinity (AUCinf) and maximum concentration (Cmax)] were approximately 1.47- and 2.61-fold higher, respectively, in participants with moderate hepatic impairment compared to those with normal hepatic function, whereas lenacapavir AUCinf and Cmax were approximately 1.84- and 2.62-fold higher, respectively, in participants with severe renal impairment compared to those with normal renal function. Increased lenacapavir exposures with moderate hepatic or severe renal impairment were not considered clinically meaningful. Lenacapavir was considered generally safe and well tolerated in both studies. These results support the use of approved lenacapavir dosing regimen in patients with mild (CPT Class A: score 5-6) or moderate hepatic impairment as well as in patients with mild (60 ≤ CLcr ≤ 89 mL/min), moderate (30 ≤ CLcr ≤ 59 mL/min), and severe renal impairment.