Understanding the Acceptability of Subdermal Implants as a Possible New HIV Prevention Method: Multi-Stage Mixed Methods Study

Long-acting microneedle formulations

The minimally-invasive and painless nature of microneedle (MN) application has enabled the technology to obviate many issues with injectable drug delivery. MNs not only administer therapeutics directly into the dermal and ocular space, but they can also control the release profile of the active compound over a desired period. To enable prolonged delivery of payloads, various MN types have been proposed and evaluated, including dissolving MNs, polymeric MNs loaded or coated with nanoparticles, fast-separable MNs hollow MNs, and hydrogel MNs. These intricate yet intelligent delivery platforms provide an attractive approach to decrease side effects and administration frequency, thus offer the potential to increase patient compliance. In this review, MN formulations that are loaded with various therapeutics for long-acting delivery to address the clinical needs of a myriad of diseases are discussed. We also highlight the design aspects, such as polymer selection and MN geometry, in addition to computational and mathematical modeling of MNs that are necessary to help streamline and develop MNs with high translational value and clinical impact. Finally, up-scale manufacturing and regulatory hurdles along with potential avenues that require further research to bring MN technology to the market are carefully considered. It is hoped that this review will provide insight to formulators and clinicians that the judicious selection of materials in tandem with refined design may offer an elegant approach to achieve sustained delivery of payloads through the simple and painless application of a MN patch.

Perspectives on long-acting formulations of pre-exposure prophylaxis (PrEP) among men who have sex with men who are non-adherent to daily oral PrEP in the United States

INTRODUCTION

Pre-exposure prophylaxis (PrEP) persistence among men who have sex with men (MSM) in real world clinical settings for HIV prevention is suboptimal. New longer-acting formulations of PrEP are becoming available, including injectables, subdermal implants, and other oral medications. These longer-acting formulations have the potential to improve retention among those who have challenges remaining adherent to daily oral PrEP.

METHODS

We interviewed 49 MSM who had initiated but discontinued oral PrEP at three diverse clinics across the United States. We examined participants' perspectives about long-acting PrEP formulations and how long-acting options could affect PrEP use using thematic analysis.

RESULTS

Participants were not very knowledgeable about long-acting formulations of PrEP but were open to learning about them and considering use. Participants were concerned about safety and efficacy of products given that they were still newer and/or in development. Finally, participants had clear preferences for oral pills, injectables, and then subdermal implants and were most interested in options that reduced the number of visits to the clinic.

CONCLUSION

Long-acting formulations of PrEP are acceptable to MSM with suboptimal PrEP persistence and have the potential to improve PrEP persistence. However, many felt they needed more information on safety, efficacy, and use to consider these options. As these long-acting formulations are implemented, public health campaigns and clinical interventions to encourage may maximize uptake particularly among those who are not currently adherent to daily oral PrEP.

A Randomized, Double-Blind, Placebo-Controlled, Phase 1 Trial of Radiopaque Islatravir-Eluting Subdermal Implants for Pre-exposure Prophylaxis Against HIV-1 Infection

BACKGROUND

Islatravir (MK-8591) is a deoxyadenosine analog in development for the treatment and prevention of HIV-1 infection. An islatravir-eluting implant could provide an additional option for pre-exposure prophylaxis (PrEP).

SETTING

Previous data support a threshold islatravir triphosphate concentration for PrEP of 0.05 pmol/10 6 cells in peripheral blood mononuclear cells. Prototype islatravir-eluting implants were previously studied to establish general tolerability and pharmacokinetics (PKs) of islatravir relative to the threshold level.

METHODS

In this randomized, double-blind, placebo-controlled, phase 1 trial, a next-generation radiopaque islatravir-eluting implant (48 mg, 52 mg, or 56 mg) or placebo implant was placed for a duration of 12 weeks in participants at low risk of HIV infection. Safety and tolerability, as well as PK for islatravir parent and islatravir triphosphate from plasma and peripheral blood mononuclear cells, were assessed throughout placement and 8 weeks after removal.

RESULTS

In total, 36 participants (8 active and 4 placebo per dose arm) were enrolled and completed this study. Implants were generally well tolerated, with no discontinuations due to an adverse event, and no clear dose-dependence in implant-related adverse events. No clinically meaningful relationships were observed for changes in laboratory values, vital signs, or electrocardiogram assessments. Mean islatravir triphosphate levels at day 85 (0.101-0.561 pmol/10 6  cells) were above the PK threshold for all dose levels.

CONCLUSION

Islatravir administered using a subdermal implant has the potential to be an effective and well-tolerated method for administering PrEP to individuals at risk of acquiring HIV-1.

Preferences Among Physicians and Men Who Have Sex with Men (MSM) for a Long-Acting, Removable Implant for HIV Prevention: A Discrete Choice Study

A longer acting, removable implant for HIV prevention has the potential to improve uptake of HIV pre-exposure prophylaxis (PrEP) by removing the need for daily adherence to an oral tablet, reducing potential side effects, and eliminating concerns about residual drug following injections. To end the HIV epidemic, we must understand the needs and preferences of groups most affected by HIV (e.g., men who have sex with men; MSM), and the physicians who prescribe PrEP to them. This article describes a discrete choice experiment to estimate the preference share for the implant within a competitive context of other PrEP products (including the oral tablet, dissolvable implant, and injection) and evaluate the impact of potential implant attributes. Physicians who had prescribed oral PrEP (n = 75) and MSM at risk for HIV (n = 175) completed a web-based survey that prompted decision-making about PrEP product preferences. The findings from both physicians and MSM demonstrated that the removable implant could capture a meaningful portion of the preference share, making it feasible to advance in the development pipeline as an important addition to the biomedical HIV prevention toolkit. Among MSM, specifically, the cost of treatment was the most important attribute impacting product preference. Our findings inform implant developers and future payers (e.g., commercial manufacturers, insurance companies) about specific device attributes that will likely affect MSM's willingness to use and physicians' willingness to prescribe this HIV prevention strategy.

Key population perceptions and opinions about long-acting antiretrovirals for prevention and treatment: a scoping review

PURPOSE OF REVIEW

Key populations are disproportionately affected by human immunodeficiency virus (HIV). Access, retention, and adherence are important barriers for the efficacy of preexposure prophylaxis (PrEP) and HIV treatment among these populations. Long-acting (LA) antiretrovirals hold the promise to solve some of these backdrops. The objective of the current review is to update the perceptions of key populations and PLWH about LA, based on their opinion, acceptability, and willingness to use it.

RECENT FINDINGS

According to the review preferences for LA vary with the population studied. Regarding people living with HIV (PLWH), male having sex with men are interested in having different options, adolescents are interested in LA (strong preference for implants), yet also perceive substantial obstacles to using biomedical prevention; transgender women aimed to nonvisible small implants, with long-lasting effects or LA injections that can be applied in other areas than buttocks, and women who experienced history of medical injections might increase preference for LA (except for history of people who inject drugs [IDU]). Female sex workers and IDU both showed interest in LA-PrEP. Regarding antiretroviral therapy, LA increased treatment satisfaction and acceptance, mainly among those receiving injections every 2 months. LA helped overcome pill fatigue, stigma, and adherence issues.

SUMMARY

Knowing preferences for biomedical interventions will contribute to better understanding and developing effective strategies for these populations.

Preferences for Current and Future PrEP Modalities Among PrEP-Experienced Gay and Bisexual Men in Australia

Alternatives to daily dosing of HIV pre-exposure prophylaxis (PrEP) are continuing to emerge. From October 2019 to March 2020, we conducted an online survey of PrEP-experienced gay and bisexual men in Australia about interest in and preference for four different PrEP modalities: daily dosing, event-driven dosing, long-acting injectable (LAI)-PrEP and subdermal PrEP implants. Using data from 1477 participants, we measured interest and preference of different modalities using multivariate logistic regression. High proportions of participants were interested in LAI-PrEP (59.7%), daily PrEP (52.0%), PrEP implants (45.3%) and event-driven PrEP (42.8%). LAI-PrEP was the most frequently selected preference (30.5%), followed by PrEP implants (26.3%), daily PrEP (21.4%) and event-driven PrEP (21.2%). Higher interest and preference for non-daily PrEP modalities were associated with being concerned about side effects and perceived difficulties with daily adherence. As novel modalities emerge, attitudes to them should be considered in public health messaging to facilitate informed decision-making.

Long-acting antiretrovirals: a new era for the management and prevention of HIV infection

The long-acting antiretroviral cabotegravir and rilpivirine combination has just received FDA, EMA and Health Canada approval. This novel drug delivery approach is about to revolutionize the therapy of people living with HIV, decreasing the 365 daily pill burden to only six intramuscular injections per year. In addition, islatravir, a first-in-class nucleoside reverse transcriptase translocation inhibitor, is intended to be formulated as an implant with a dosing interval of 1 year or more. At present, long-acting antiretroviral therapies (LA-ARTs) are given at fixed standard doses, irrespectively of the patient's weight and BMI, and without consideration for host genetic and non-genetic factors likely influencing their systemic disposition. Despite a few remaining challenges related to administration (e.g. pain, dedicated medical procedure), the development and implementation of LA-ARTs can overcome long-term adherence issues by improving patients' privacy and reducing social stigma associated with the daily oral intake of anti-HIV treatments. Yet, the current 'one-size-fits-all' approach does not account for the recognized significant inter-individual variability in LA-ART pharmacokinetics. Therapeutic drug monitoring (TDM), an important tool for precision medicine, may provide physicians with valuable information on actual drug exposure in patients, contributing to improve their management in real life. The present review aims to update the current state of knowledge on these novel promising LA-ARTs and discusses their implications, particularly from a clinical pharmacokinetics perspective, for the future management and prevention of HIV infection, issues of ongoing importance in the absence of curative treatment or an effective vaccine.