Despite effective antiretroviral therapy, cellular reservoirs of HIV persist. CD4ζ is a chimeric T cell receptor with the intracellular and transmembrane domain of CD4 linked to the zeta signaling chain of the CD3 T cell receptor. The long term persistence of this CAR-T cell therapy was previously estimated.
Fifteen individuals were randomized to 3 groups (cells, IL-2, cells + IL-2) to receive a single infusion of 5-9 x 109 autologous CD4ζ gene modified T cells ± subcutaneous IL-2 at 1.2 million IU/m2 for 56 days. Inclusion criteria included CD4≥200, viral load<50, stable HAART for ≥8 weeks. Pheresis and rectal biopsy were performed at baseline and at 13-15 years follow up. Real-time PCR was used to detect and measure the CD4ζ transgene and the HIV-1 gag gene in PBMCs and rectal tissues. RNAscope using HIV-1 Clade B probe was performed on formalin fixed rectal tissue at long term follow-up. Total and integrated HIV DNA were measured in PBMCs using a highly sensitive nested PCR assay. Mixed models and ANCOVA were used to assess the effects of treatment arms on CD4, CD4%, CD4:CD8, total and integrated HIV DNA over time.
Fifteen persons enrolled (mean age 38.4 ± 7.9 years) and thirteen individuals,11 males and 2 females, completed the long term follow up (LTFU). Race/ethnicity of the participants included one Asian, four Blacks, two Hispanics and six Caucasians. The median CD4 count on enrollment was 821 (IL-2), 712 (cells) and 822 (cells + IL-2), p=0.468. At LTFU median CD4 counts were 779, 720 and 1047 respectively, p=0.376. HIV viral loads were suppressed except in one nonadherent subject at LTFU. No differences by race or sex were seen. There was persistence of CD4ζ CAR-T cells 13-15 years post infusion in both PBMC and rectal tissues in all recipients. Rare HIV-RNA+ cells can be identified in the majority of rectal biopsies. Total PBMC HIV DNA at long-term follow up, and the change in total and integrated HIV DNA from pre- and post-treatment compared among the treatment arms was not statistically different.
The CD4ζ transgene persisted for 13-15 years in CAR-T cell treated subjects. With the caveat of a trial with a small number of subjects, coupled with intersubject variability, our analysis suggests that there was no statistical difference in baseline to LTFU between arms and that HIV remains present in PBMC and rectal tissue. Furthermore, this is the most mature data set to date to indicate that CAR-T cells are safe for at least 15 years.