Treating metastatic solid tumors with bortezomib and a tumor necrosis factor-related apoptosis-inducing ligand receptor agonist antibody.
BACKGROUND
Resistance of tumors to cell death signals poses a complex clinical problem. We explored the therapeutic potential and in vivo toxicity of a combination of bortezomib, a proteasome inhibitor, and MD5-1, a tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor (DR5) agonist monoclonal antibody, in mouse carcinomas. METHODS; Mice bearing Renca-FLAG (renal) or 4T1 (mammary) tumors were treated with bortezomib and/or MD5-1 and examined for lung metastases (Renca-FLAG: n = 93; 4T1: n = 40) or monitored for survival (Renca-FLAG: n = 143). Toxicity was assessed by histopathology and hematology. Viability and apoptotic signaling in Renca-FLAG and 4T1 cells treated with bortezomib alone or in combination with TRAIL were analyzed using 3-[4,5-dimethyiazol-2-yl-5]-[3-carboxymethyloxyphenyl]-2-[4-sulfophenyl]-2H tetrazolium assay and by measuring mitochondrial membrane depolarization and caspase-8 and caspase-3 activation. All statistical tests were two-sided.


RESULTS
Bortezomib (20 nM) sensitized Renca-FLAG and 4T1 cells to TRAIL-mediated apoptosis (mean percent decrease in numbers of viable cells, bortezomib + TRAIL vs TRAIL: Renca-FLAG, 95% vs 34%, difference = 61%, 95% confidence interval [CI] = 52% to 69%, P < .001; 4T1, 85% vs 20%, difference = 65%, 95% CI = 62% to 69%, P < .001). Sensitization involved activation of caspase-8 and caspase-3 but not mitochondrial membrane depolarization, suggesting an amplified signaling of the extrinsic cell death pathway. Treatment with bortezomib and MD5-1 reduced lung metastases in mice carrying Renca and 4T1 tumors (mean number of metastases, bortezomib + MD5-1 vs MD5-1: Renca-FLAG, 1 vs 8, difference = 7, 95% CI = 5 to 9, P < .001; 4T1, 1 vs 12, difference = 11, 95% CI = 9 to 12, P < .001) and increased median survival of mice bearing Renca-FLAG tumors (bortezomib + MD5-1 vs bortezomib + control isotype antibody: 22 of 30 [73%] were still alive at day 180 vs median survival of 42 days [95% CI = 41 to 44 days, P < .001]) in the absence of obvious toxicity.


CONCLUSIONS
Bortezomib combined with DR5 agonist monoclonal antibody may be a useful treatment for metastatic solid tumors.
Shanker
Anil
A
Laboratory of Experimental Immunology, Cancer and Inflammation Program, SAIC-Frederick, Inc, National Cancer Institute-Frederick, Frederick, MD 21702, USA.
Brooks
Alan David
AD
Tristan
Carlos Alberto
CA
Wine
John William
JW
Elliott
Peter John
PJ
Yagita
Hideo
H
Takeda
Kazuyoshi
K
Smyth
Mark John
MJ
Murphy
William Joseph
WJ
Sayers
Thomas Joseph
TJ
D000230:Adenocarcinoma / Q000188:drug therapy* / Q000556:secondary; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007680:Kidney Neoplasms / Q000188:drug therapy* / Q000473:pathology; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000556:secondary; D015674:Mammary Neoplasms, Animal / Q000188:drug therapy* / Q000556:secondary; D051379:Mice; D008807:Mice, Inbred BALB C; D051336:Mitochondrial Membranes / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011719:Pyrazines / Q000494:pharmacology*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000819:agonists*; D015398:Signal Transduction / Q000187:drug effects; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D001897:Boronic Acids; D011480:Protease Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D011719:Pyrazines; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; D000069286:Bortezomib; D053148:Caspase 3; D053181:Caspase 8