A curative regimen would decrease HIV prevalence but not HIV incidence unless targeted to an ART-naïve population

Model-based evaluation of the impact of a potential HIV cure on HIV transmission dynamics

The development of an HIV cure is a global health priority, with the target product profile (TPP) for an HIV cure guiding research efforts. Using a mathematical model calibrated to data from men who have sex with men (MSM) in the Netherlands, we assessed whether an effective cure could help end the HIV epidemic. Following the TPP, we evaluated two scenarios: (i) HIV remission, where the virus is suppressed in an individual without ongoing antiretroviral therapy (ART) but may rebound, and (ii) HIV eradication, which aims to completely remove the virus from the individual. Here, we show that sustained HIV remission (without rebound) or HIV eradication could reduce new HIV infections compared to a scenario without a cure. In contrast, transient HIV remission with a risk of rebound could increase new infections if rebounds are not closely monitored, potentially undermining HIV control efforts. Our findings emphasize the critical role of cure characteristics in maximizing cure benefits for public health and highlight the need to align HIV cure research with public health objectives to end the HIV epidemic.

The long-term impact and value of curative therapy for HIV: a modelling analysis

INTRODUCTION

Curative therapies (CTx) to achieve durable remission of HIV disease without the need for antiretroviral therapy (ART) are currently being explored. Our objective was to model the long-term health and cost outcomes of HIV in various countries, the impact of future CTx on those outcomes and the country-specific value-based prices (VBPs) of CTx.

METHODS

We developed a decision-analytic model to estimate the future health economic impacts of a hypothetical CTx for HIV in countries with pre-existing access to ART (CTx+ART), compared to ART alone. We modelled populations in seven low-and-middle-income countries and five high-income countries, accounting for localized ART and other HIV-related costs, and calibrating variables for HIV epidemiology and ART uptake to reproduce historical HIV outcomes before projecting future outcomes to year 2100. Health was quantified using disability-adjusted life-years (DALYs). Base case, pessimistic and optimistic scenarios were modelled for CTx+ART and ART alone. Based on long-term outcomes and each country's estimated health opportunity cost, we calculated the country-specific VBP of CTx.

RESULTS

The introduction of a hypothetical CTx lowered HIV prevalence and prevented future infections over time, which increased life-years, reduced the number of individuals on ART, reduced AIDS-related deaths, and ultimately led to fewer DALYs versus ART-alone. Our base case estimates for the VBP of CTx ranged from $5400 (Kenya) up to $812,300 (United States). Within each country, the VBP was driven to be greater primarily by lower ART coverage, lower HIV incidence and prevalence, and higher CTx cure probability. The VBP estimates were found to be greater in countries where HIV prevalence was higher, ART coverage was lower and the health opportunity cost was greater.

CONCLUSIONS

Our results quantify the VBP for future curative CTx that may apply in different countries and under different circumstances. With greater CTx cure probability, durability and scale up, CTx commands a higher VBP, while improvements in ART coverage may mitigate its value. Our framework can be utilized for estimating this cost given a wide range of scenarios related to the attributes of a given CTx as well as various parameters of the HIV epidemic within a given country.

The potential impact of a "curative intervention" for HIV: a modelling study

BACKGROUND

Efforts to develop an HIV "cure" (i.e., an intervention leading to durable ART-free remission or eradication of HIV infection) have become better resourced and coordinated in recent years. Given, however, the availability of other interventions for prevention and treatment of HIV disease, it is unclear whether, to what extent, and under which circumstances a curative intervention would have an impact in ending the AIDS epidemic and which characteristics of its implementation would be most important. We designed a range of analyses to investigate these unknowns.

METHODS

We used a deterministic, compartmental model of HIV infection in South Africa to estimate the impact of a curative intervention. We first examined how its impact would be affected by the state of the epidemic at the time that it is introduced, by the timing and pace of scale-up, and by various targeting strategies. We then investigated the impact of a curative intervention relative to its ability to maintain viral suppression.

FINDINGS

To the extent that other interventions have failed to control the epidemic, i.e., if incidence and AIDS deaths remain high, a curative intervention would result in a larger reduction in incidence. Earlier and faster scale-up allows for greater impact. We also found that a curative intervention would more efficiently reduce transmission if it is prioritised to those not able to obtain or remain on ART and to those aged 15-25 rather than older persons. On the other hand, an intervention that does not maintain viral suppression if the individual is exposed to re-infection could lead to an increase in HIV incidence.

CONCLUSIONS

Our findings suggest that a curative intervention for HIV would have the greatest impact if the epidemic is not under control by 2030, particularly if the intervention is targeted to those who are more likely to transmit virus, and if it maintained durable viral suppression, even upon exposure to re-infection. These considerations underscore the need to carefully consider the "target product profiles" for an HIV cure in the context of how and where it would be used, and suggest that such profiles may require revision as the epidemic evolves in the coming years.

Adherence to antiretroviral therapy and factors affecting low medication adherence among incident HIV-infected individuals during 2009-2016: A nationwide study

For ideal clinical benefit, human immunodeficiency virus (HIV)-infected individuals should receive continuous medication. This is the first nationwide antiretroviral therapy (ART) adherence study in Asia, where medication monitoring at national level is systemically available. We estimated the ART adherence of incident HIV-infected individuals and investigated factors affecting low medication adherence using the national health insurance (NHI) claims data from 2007 to 2016. Medication possession ratio (MPR) was used to measure medication adherence and risk factors were identified by multivariable logistic regression analysis. Of the 8,501 newly diagnosed HIV-infected individuals during 2009–2016 with at least one ART prescription, 70.4% of HIV patients had adequate adherence to ART defined as MPR ≥95%. Requiring prophylactic antibiotics, female gender, age of 0–19 and same or over 50 s compared to 30–39, and having a history of malignancy, lower socioeconomic status, not visiting tertiary hospital, and being diagnosed in the earlier years were risk factors for lower adherence (Odds ratio 1.7, 1.6, 1.6, 1.4, 1.6, 2.1, 1.2, and 1.6 to 3.8 respectively). Health authority should take into consideration of these modifiable and unmodifiable barriers to establish sustainable monitoring system at national level and to improve adherence.

Use of 'eradication' in HIV cure-related research: a public health debate

BACKGROUND

The landscape of Human Immunodeficiency Virus (HIV) research has changed drastically over the past three decades. With the remarkable success of antiretroviral treatment (ART) in decreasing AIDS-related mortality, some researchers have shifted their HIV research focus from treatment to cure research. The HIV cure research community often uses the term eradication to describe the science, and talks about eradicating the virus from the body. In public discourse, the term eradication could be conflated with disease eradication at the population level. In this paper, we call for a reframing of HIV cure research as control, as it is a more accurate descriptor and achievable goal in the foreseeable future.

DISCUSSION

The properties of HIV are discordant with eradicability standards at both the individual level (as a clinical concept), and at the population level (as a public health concept). At the individual level, true eradication would necessitate absolute elimination of all latent HIV reservoirs from the body. Current HIV cure-related research strategies have proven unsuccessful at accurately quantifying, let alone eliminating these reservoirs. At the population level, eradication implies the permanent global reduction of HIV to zero new cases and to zero risk for future cases. Given the absence of an efficacious HIV vaccine and the impracticality and unethicality of eliminating animal reservoirs, global eradication of HIV is highly implausible. From a public health perspective, HIV eradication remains an elusive goal.

CONCLUSION

The term 'eradication' is a misleading description of current HIV cure-related research. Instead, we call for the use of more realistic expressions such as 'sustained virologic HIV suppression (or control)' or 'management of HIV persistence' to describe HIV cure-related research. Using these terms reorients what HIV cure science can potentially achieve in the near future and avoids creating unrealistic expectations, particularly among the millions of people globally who live with HIV.