HIV-Specific, Ex Vivo Expanded T Cell Therapy: Feasibility, Safety, and Efficacy in ART-Suppressed HIV-Infected Individuals.

Adoptive T cell therapy has had dramatic successes in the treatment of virus-related malignancies and infections following hematopoietic stem cell transplantation. We adapted this method to produce ex vivo expanded HIV-specific T cells (HXTCs), with the long-term goal of using HXTCs as part of strategies to clear persistent HIV infection. In this phase 1 proof-of-concept study (NCT02208167), we administered HXTCs to antiretroviral therapy (ART)-suppressed, HIV-infected participants. Participants received two infusions of 2 × 107 cells/m2 HXTCs at a 2-week interval. Leukapheresis was performed at baseline and 12 weeks post-infusion to measure the frequency of resting cell infection by the quantitative viral outgrowth assay (QVOA). Overall, participants tolerated HXTCs, with only grade 1 adverse events (AEs) related to HXTCs. Two of six participants exhibited a detectable increase in CD8 T cell-mediated antiviral activity following the two infusions in some, but not all, assays. As expected, however, in the absence of a latency reversing agent, no meaningful decline in the frequency of resting CD4 T cell infection was detected. HXTC therapy in ART-suppressed, HIV-infected individuals appears safe and well tolerated, without any clinical signs of immune activation, likely due to the low residual HIV antigen burden present during ART.

Expansion of T cells targeting multiple antigens of cytomegalovirus, Epstein-Barr virus and adenovirus to provide broad antiviral specificity after stem cell transplantation.

BACKGROUND AIMS: Hematopoietic stem cell transplant (HSCT) is the treatment of choice for a proportion of patients with hematologic malignancies as well as for non-malignant diseases. However, viral infections, particularly Epstein-Barr virus (EBV), cytomegalovirus (CMV) and adenovirus (Ad), remain problematic after transplant despite the use of antiviral drugs. We have shown that cytotoxic T lymphocytes (CTL) generated against CMV-pp65, EBV and Ad antigens in a single culture are capable of controlling infections with all three viruses after HSCT. Although pp65-specific CTL have proved efficacious for the control of CMV infection, several reports highlight the importance of targeting additional CMV antigens. METHODS: To expand multivirus-specific T cells with activity against both CMV-pp65 and CMV-IE-1, peripheral blood mononuclear cells (PBMC) were transduced with the adenoviral vector (Ad5f35-IE-1-I-pp65). After 9-12 days the CTL were restimulated with autologous EBV-transformed B cells transduced with the same Ad vector. RESULTS: After 18 days in culture nine CTL lines expanded from less than 1.5 × 10(7) PBMC to a mean of 6.1 × 10(7) T cells that recognized CMV antigens pp65 [median 273 spot-forming cells (SFC), range 47-995] and IE-1 (median 154 SFC, range 11-505), the Ad antigens hexon (median 153 SFC, range 26-465) and penton (median 37 SFC, range 1-353), as well as EBV lymphoblastoid cell lines (median 55 SFC, range 9-301). Importantly, the T cells recognized at least two antigens per virus and lysed virus peptide-pulsed targets. CONCLUSIONS: CTL that target at least two antigens each of CMV, EBV and Ad should have clinical benefit with broad coverage of all three viruses and enhanced control of CMV infections compared with current protocols.

An inducible caspase 9 suicide gene to improve the safety of mesenchymal stromal cell therapies.

Mesenchymal stromal cells (MSCs) have been infused in hundreds of patients to date, with minimal reported side effects. However, follow-up is limited and long-term side effects are unknown. Because several animal models have raised safety concerns, we sought to develop a system allowing control over the growth and survival of MSCs used therapeutically. We have previously described a suicide system based on an inducible caspase-9 (iCasp9) protein that is activated using a specific chemical inducer of dimerization (CID), analogs of which have been safely tested in a phase I study. Here, we show that MSCs can be easily transduced with this system and selected to high purity (greater than 97%) with clinical grade immunomagnetic procedures. The transduced cells maintain their basic physiology, including expression of surface antigens (such as positivity for CD73, CD90, and CD105, and negativity for hematopoietic markers) and their potential to differentiate into diverse connective tissue lineages (adipocytes, osteoblasts, and chondroblasts). Those cells and their differentiated progeny can be selectively eliminated in vitro or in vivo within 24 hours after exposure to pharmacological levels of CID, with evidence of apoptosis in more than 95% of iCasp9-positive cells. In conclusion, we have developed directed MSC killing to provide a necessary safety mechanism for therapies using progenitor cells. We believe that this approach will become of increasing value as clinical applications for MSCs develop further.