Logic-gated CARs to target phenotypic rather than viral features of latent HIV reservoirs

About This Grant

ABSTRACT Antiretroviral therapy (ART) is remarkably successful at preventing AIDS but is unable to cure HIV infection due to a durable pool of latently infected cells carrying integrated HIV provirus. The persistence of this latent reservoir contributes to a growing population of people living with HIV whose lifespans are shortened by non-AIDS co- morbidities of chronic infection and in whom HIV infection can reactivate upon ART interruption. Selective targeting of the latent HIV reservoir is difficult due to the absence of either detectable viral antigens or cell- surface markers that would reveal viral reservoirs to the immune system. Alternative strategies to reactive latent HIV in these cells and promote susceptibility to immune attack are not sufficiently robust to facilitate elimination of an adequate quantity of the reservoir to achieve cure. Latent provirus in ART-treated HIV-1-infected patients highly enriched in a heterogeneous pool of CD4 T cells exhibiting variably elevated expression of sets of cell surface proteins, including programmed cell death-1 (PD-1) and very late antigen-4 (VLA-4). We believe that logic-gated chimeric antigen receptors (CAR) can be developed to facilitate highly selective killing of cells with these combination of markers (AND gate targeting of cells co-expressing PD-1 and VLA-4, for example) while sparing important uninfected immune effector cells with the similar features (NOT gate to prevent killing of CD8+ T cells). This strategy would permit virus-agnostic eradication of sets of cells with defined phenotypic features that encompass most latently infected cells. Such a strategy could be employed in the context of effective ART to shrink the viral reservoir to a level that can be restrained by antiviral immune responses to facilitate drug-free remission. In this proposal, we will build these CAR molecules and test their ability to durably endow human NK cells with highly selective functional activity against discrete subsets of T cells. In addition, we will characterize the expression of the targeted combination of receptors on latently infected tissue T cells. These studies will provide compelling evidence of the feasibility of these logic-controlled CAR regimens and validate a set of target markers in a pre-clinical latency model. These data will facilitate more advanced preclinical testing in non-human primates, humanized mice, and bona fide reservoir cells from people living with HIV.