# The effect of combining HIV latency reversal with inhibition of phosphoinositide-3 kinases or B-cell lymphoma-2 on the HIV reservoir

## TL;DR

This study explores combining HIV latency reversal with drugs that promote cell death to reduce the HIV reservoir, finding only modest additional benefits.

## Contribution

The study evaluates the combined effect of latency reversal agents and pro-apoptotic drugs on HIV-infected cells, revealing model-dependent outcomes.

## Key findings

- Combining LRAs with PI3K inhibitors or venetoclax increased cell death in J-Lat10.6 cells.
- Pro-apoptotic drugs alone reduced HIV DNA in CD4+ T-cells from PWH on ART.
- The additional benefit of combining LRAs with pro-apoptotic drugs was minimal and model-dependent.

## Abstract

The persistence of latently infected CD4 + T-cells in people with HIV (PWH) on suppressive antiretroviral therapy (ART) is the major barrier to an HIV cure. We investigated the impact of two classes of pro-apoptotic drugs, phosphoinositide-3 kinases (PI3K) inhibitors or the B cell lymphoma 2 (Bcl-2) inhibitor venetoclax on depletion of latently infected CD4 + T-cells when administered ex vivo either alone or in combination with a latency reversing agents (LRA) to induce expression of pro-apoptotic viral proteins. We quantified cell death in three latently infected cell lines (J-Lat clones) and the parental cell line (Jurkat) using a live dead stain and flow cytometry. Using CD4 + T-cells isolated from blood from PWH on ART, we quantified intracellular HIV RNA, integrated HIV DNA and intact proviral DNA using quantitative PCR. In the Jat10.6 latently infected cell line, the combination of an LRA with either a PI3K inhibitor or venetoclax, compared to an LRA alone resulted in higher levels of cell death. Using CD4 + T-cells from PWH on ART, there was a significant decrease in HIV DNA following administration of wortmannin (a pan-PI3K inhibitor), venetoclax (a Bcl2 inhibitor) and JQ1 (an LRA) when administered alone. There was minimal additional effect on reservoir reduction following the addition of an LRA with a pro-apoptotic drug, compared to either an LRA or pro-apoptotic drug alone. However, when CD4 + T-cells from PWH on ART were treated with LRAs combined with a PI3K inhibitor, the fold increase in cell associated unspliced HIV RNA correlated with the decline in HIV DNA. Overall, reduction in the HIV reservoir by LRAs could be further enhanced in the presence of pro-apoptotic drugs, but the magnitude of the effect was modest, was dependent on the in vitro model used and for PI3K inhibitors, depended on the potency of latency reversal. These results are consistent with minimal additional efficacy in reservoir reduction when combining currently available LRAs and either PI3K inhibitors or venetoclax.

The persistence of long-lived HIV-infected cells in people with HIV (PWH) on antiretroviral therapy (ART) is a major obstacle to finding a cure. We hypothesised that clearance of infected cells could be enhanced by combining pro-apoptotic drugs with latency reversing agents (LRAs) which will increase expression of pro-apoptotic viral proteins. We combined a range of LRAs with two different classes of drugs that promote cell death, inhibitors of PI3K and inhibitors of B-cell lymphoma-2, and tested the effects alone and in combination on the HIV reservoir in latently infected cell lines and cells from PWH on ART. Compared to an LRA alone, the combination of an LRA with either a PI3K inhibitor or venetoclax resulted in higher levels of cell death in the J-Lat10.6 latently infected cell line. Using CD4 + T-cells from PWH on ART, both classes of pro-apoptotic drugs reduced the HIV reservoir when used alone. There was minimal additional effect on reservoir reduction following the addition of an LRA with a pro-apoptotic drug, compared to either an LRA or pro-apoptotic drug alone. Overall, reduction in the HIV reservoir by LRAs could be further enhanced only modestly in the presence of pro-apoptotic drugs, but the magnitude of the effect was dependent on the in vitro model used and for PI3K inhibitors, on the potency of latency reversal. These results are consistent with minimal additional efficacy in reservoir reduction when combining currently available LRAs and either PI3K inhibitors or venetoclax.