Release of HMGB1 in response to proapoptotic glioma killing strategies: efficacy and neurotoxicity.
OBJECTIVE
In preparation for a phase I clinical trial using a combined cytotoxic/immunotherapeutic strategy with adenoviruses (Ad) expressing Flt3L (Ad-Flt3L) and thymidine kinase (Ad-TK) to treat glioblastoma (GBM), we tested the hypothesis that Ad-TK+GCV would be the optimal tumor-killing agent in relation to efficacy and safety when compared with other proapoptotic approaches.


METHODS
The efficacy and neurotoxicity of Ad-TK+GCV was compared with Ads encoding the proapoptotic cytokines [tumor necrosis factor-alpha, tumor necrosis factor-related apoptosis-inducing factor (TRAIL), and Fas ligand (FasL)], alone or in combination with Ad-Flt3L. In rats bearing small GBMs (day 4), only Ad-TK+GCV or Ad-FasL improved survival.


RESULTS
In rats bearing large GBMs (day 9), the combination of Ad-Flt3L with Ad-FasL did not improve survival over FasL alone, whereas Ad-Flt3L combined with Ad-TK+GCV led to 70% long-term survival. Expression of FasL and TRAIL caused severe neuropathology, which was not encountered when we used Ad-TK+/-Ad-Flt3L. In vitro, all treatments elicited release of high mobility group box 1 protein (HMGB1) from dying tumor cells. In vivo, the highest levels of circulating HMGB1 were observed after treatment with Ad-TK+GCV+Ad-Flt3L; HMGB1 was necessary for the therapeutic efficacy of AdTK+GCV+Ad-Flt3L because its blockade with glycyrrhizin completely blocked tumor regression. We also showed the killing efficacy of Ad-TK+GCV in human GBM cell lines and GBM primary cultures, which also elicited release of HMGB1.


CONCLUSIONS
Our results indicate that Ad-TK+GCV+Ad-Flt3L exhibit the highest efficacy and safety profile among the several proapoptotic approaches tested. The results reported further support the implementation of this combined approach in a phase I clinical trial for GBM.
Candolfi
Marianela
M
Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Department of Medicine and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA.
Yagiz
Kader
K
Foulad
David
D
Alzadeh
Gabrielle E
GE
Tesarfreund
Matthew
M
Muhammad
A K M Ghulam
AK
Puntel
Mariana
M
Kroeger
Kurt M
KM
Liu
Chunyan
C
Lee
Sharon
S
Curtin
James F
JF
King
Gwendalyn D
GD
Lerner
Jonathan
J
Sato
Katsuaki
K
Mineharu
Yohei
Y
Xiong
Weidong
W
Lowenstein
Pedro R
PR
Castro
Maria G
MG
D000256:Adenoviridae / Q000235:genetics / Q000502:physiology; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D017209:Apoptosis / Q000502:physiology*; D001932:Brain Neoplasms / Q000097:blood* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D003131:Combined Modality Therapy; D005910:Glioma / Q000097:blood* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D024243:HMGB1 Protein / Q000097:blood* / Q000378:metabolism; D009368:Neoplasm Transplantation; D009474:Neurons / Q000473:pathology* / Q000821:virology; D050130:Oncolytic Virotherapy / Q000009:adverse effects; D051381:Rats; D011917:Rats, Inbred Lew; D013937:Thymidine Kinase / Q000235:genetics; D014185:Transplantation, Isogeneic; D016896:Treatment Outcome; D014407:Tumor Cells, Cultured; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics
D024243:HMGB1 Protein; D013937:Thymidine Kinase; C527539:FLT3 protein, rat; D051941:fms-Like Tyrosine Kinase 3