Simian Immunodeficiency Virus (SIV)-Specific Chimeric Antigen Receptor-T Cells Engineered to Target B Cell Follicles and Suppress SIV Replication

Abstract

There is a need to develop improved methods to treat and potentially cure HIV infection. During chronic HIV infection, replication is concentrated within T follicular helper cells (Tfh) located within B cell follicles, where low levels of virus-specific CTL permit ongoing viral replication. We previously showed that elevated levels of simian immunodeficiency virus (SIV)-specific CTL in B cell follicles are linked to both decreased levels of viral replication in follicles and decreased plasma viral loads. These findings provide the rationale to develop a strategy for targeting follicular viral-producing (Tfh) cells using antiviral chimeric antigen receptor (CAR) T cells co-expressing the follicular homing chemokine receptor CXCR5. We hypothesize that antiviral CAR/CXCR5-expressing T cells, when infused into an SIV-infected animal or an HIV-infected individual, will home to B cell follicles, suppress viral replication, and lead to long-term durable remission of SIV and HIV. To begin to test this hypothesis, we engineered gammaretroviral transduction vectors for co-expression of a bispecific anti-SIV CAR and rhesus macaque CXCR5. Viral suppression by CAR/CXCR5-transduced T cells was measured in vitro, and CXCR5-mediated migration was evaluated using both an in vitro transwell migration assay, as well as a novel ex vivo tissue migration assay. The functionality of the CAR/CXCR5 T cells was demonstrated through their potent suppression of SIVmac239 and SIVE660 replication in in vitro and migration to the ligand CXCL13 in vitro, and concentration in B cell follicles in tissues ex vivo. These novel antiviral immunotherapy products have the potential to provide long-term durable remission (functional cure) of HIV and SIV infections.

Transduction and Expansion of Primary T Cells in Nine Days with Maintenance of Central Memory Phenotype

“…Results presented in this publication are similar to those in our previously published work 9,20 . Utilizing the protocol presented here, we expect at least an 8-fold expansion of cells between days 5 and 9 (median 11.1 fold, range 8.7-13 fold).…”

“…B cell follicles are somewhat immune privileged sites in which low levels of virus-specific CTL permit ongoing viral replication 7,8 . For these reasons, targeting HIV/SIV-specific T cells into the follicle through expression of CXCR5 is a strategy for elimination of the follicular reservoir of virally infected cells 9,10 . Specifically, we are targeting SIV-specific CAR T cells to B cell follicles via CXCR5 co-expression.…”

Targeting reservoirs of HIV replication in lymphoid follicles with cellular therapies to cure HIV

“…In support of this approach, a recent study demonstrated that CXCR5 transduction of CD8 T cells led to the preferential accumulation of CXCR5 transduced cells in follicles of lymph nodes and spleen in rhesus macaques . In further support of this approach, we have engineered HIV‐ and SIV‐specific CAR‐T cells that co‐express the lymphoid follicle homing molecule CXCR5 . The CARs in our studies (developed by Dr. Edward Berger) include bispecific CD4 and MBL protein motifs that bind HIV or SIV .…”

Adaptive NK cell responses in HIV/SIV infections: A roadmap to cell-based therapeutics?

“…Much of the focus revolves around the development of CARs target gp120 and/or gp41 via expression of CD4 (described below), bNAbs and bi-specific antibodies. [83][84][85] These developments, and in particular CAR NK cells derived from induced pluripotent stem cells (iPSC) 78 have the potential to be clinically scalable in order to provide "off-the-shelf" treatment for cancer patients. 86 Because the targets for CAR NK cells are customizable, it is quite probable that this technology will be highly relevant to developing targeted NK cell therapy to eliminate SIV/HIV-virally infected cells.…”

“…Several studies suggest that using CAR‐T cells could be an asset in HIV therapy and cure work. Much of the focus revolves around the development of CARs target gp120 and/or gp41 via expression of CD4ζ (described below), bNAbs and bi‐specific antibodies . These developments, and in particular CAR NK cells derived from induced pluripotent stem cells (iPSC) have the potential to be clinically scalable in order to provide “off‐the‐shelf” treatment for cancer patients .…”