Zeidan1, G Lee2, R Fromentin3, M Aid1, J Lalezari4, R Mitsuyasu5, S Wang2, W
Tang2, S Deeks6, D Ando2, RP Sekaly1
1Case Western Reserve University, Cleveland, OH; 2Sangamo Biosciences Inc. Richmond, CA, 3Centre
hospitalier de l’Université de Montréal, Montreal, CA; 4Quest Clinical Research, San Francisco, CA;
5University of California Los Angeles, Los Angeles, CA; 6University of California San Francisco, San
Francisco, CA.
Background: Nine aviremic HIV+ subjects on ART received 10-30 billion
SB-728-T cells. CCR5-modified cells expanded and persisted in PB up to 3.5
yrs post infusion (median = 2.1%), suggesting the presence of long lived CD4
populations, such as T memory stem cells (TSCM), within the product.
Methods: TSCM phenotyping was performed on PBMCs pre- and postinfusion.
Total HIV-DNA was measured using ddPCR. CD4 T-cell subsets were
sorted in the product and post-infusion and the levels of CCR5 modification
and integrated HIV-DNA were determined by qPCR. Gene array analysis was
performed to determine pathways involved in long-term persistence.
Results: We have previously identified a novel TSCM–like CD4 subset,
characterized by co-expression of intermediate levels of CD45RA and
CD45RO and high levels of CD95 and CD58, that expanded post-infusion and
correlated with long-term CD4 reconstitution (p=0.0279). Gene array analysis
suggested that persistence of this novel TSCM subset could be mediated by
up-regulation of genes involved in self-renewal (Notch pathway) and metabolic
pathways associated with cellular longevity (Fatty Acid Oxidation, OXPHOS,
etc...). These cells originated from the product, as they were highly enriched in
CCR5 modification (23.2% ± 17.6 modified alleles at 3yrs). Six out of 9 subjects
displayed a significant decrease in levels of total HIV-DNA over time (range
of decay from 0.5 to 3.6 log). Expansion of TSCM-like CD4 T-cells at month
6 correlated with the long-term decay of the HIV reservoir, which may be
explained by their lower levels of integrated HIV-DNA (mean of 172 copies/1e6
cells vs 1133 and 2415 copies/1e6 for central (TCM) and effector (TEM) memory
cells). Detection of up to 3% CCR5-modified TEM at 3yrs suggests that TSCM
have the capacity to differentiate into other memory populations over time.
Conclusions: A single infusion of CCR5-modified SB-728-T led to significant
decay in the HIV reservoir. An HIV-resistant CD4 TSCM–like population
can reduce the latent reservoir by selection and/or dilution, as well as by
differentiating into effector memory cells and limiting reservoir replenishment.
Our results suggest that targeting TSCM as a source of cells for genetic
manipulation of lymphocytes can enhance efficacy of adoptive T-cell therapy.
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