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JCI Insight. 2018 Feb 8;3(3). pii: 98368. doi: 10.1172/jci.insight.98368. eCollection 2018 Feb 8.

Efficacy of intracellular immune checkpoint-silenced DC vaccine.

Author information

1
Department of Hematopoietic Stem Cell Transplantation, Affiliated Hospital of Academy of Military Medical Sciences, Beijing, China.
2
Department of Molecular Microbiology and Immunology and Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California, USA.
3
Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, Texas, USA.
4
Department of Oncology, Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China.

Abstract

BACKGROUND:

DC-based tumor vaccines have had limited clinical success thus far. SOCS1, a key inhibitor of inflammatory cytokine signaling, is an immune checkpoint regulator that limits DC immunopotency.

METHODS:

We generated a genetically modified DC (gmDC) vaccine to perform immunotherapy. The adenovirus (Ad-siSSF) delivers two tumor-associated antigens (TAAs), survivin and MUC1; secretory bacterial flagellin for DC maturation; and an RNA interference moiety to suppress SOCS1. A 2-stage phase I trial was performed for patients with relapsed acute leukemia after allogenic hematopoietic stem cell transplantation: in stage 1, we compared the safety and efficacy between gmDC treatment (23 patients) and standard donor lymphocyte infusion (25 patients); in stage 2, we tested the efficacy of the gmDC vaccine for 12 acute myeloid leukemia (AML) patients with early molecular relapse.

RESULTS:

gmDCs elicited potent TAA-specific CTL responses in vitro, and the immunostimulatory activity of gmDC vaccination was demonstrated in rhesus monkeys. A stage 1 study established that this combinatory gmDC vaccine is safe in acute leukemia patients and yielded improved survival rate. In stage 2, we observed a complete remission rate of 83% in 12 relapsed AML patients. Overall, no grade 3 or grade 4 graft-versus-host disease incidence was detected in any of the 35 patients enrolled.

CONCLUSIONS:

This study, with combinatory modifications in DCs, demonstrates the safety and efficacy of SOCS1-silenced DCs in treating relapsed acute leukemia.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT01956630.

FUNDING:

National Institute of Health (R01CA90427); the Key New Drug Development and Manufacturing Program of the "Twelfth Five-Year Plan" of China (2011ZX09102-001-29); and Clinical Application Research of Beijing (Z131107002213148).

KEYWORDS:

Dendritic cells; Hematology; Immunology; Immunotherapy; Leukemias

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