TY - JOUR
T1 - Microparticle encapsulation of a prostate-targeted biologic for the treatment of liver metastases in a preclinical model of castration-resistant prostate cancer
AU - Rogers, Oliver C.
AU - Antony, Lizamma
AU - Levy, Oren
AU - Joshi, Nitin
AU - Simons, Brian W.
AU - Dalrymple, Susan L.
AU - Rosen, D. Marc
AU - Pickering, Andrew
AU - Lan, Haoyue
AU - Kuang, Heidi
AU - Ranganath, Sudhir H.
AU - Zheng, Lei
AU - Karp, Jeffrey M.
AU - Howard, S. Peter
AU - Denmeade, Samuel R.
AU - Isaacs, John T.
AU - Brennen, W. Nathaniel
N1 - Funding Information:
The authors would like to acknowledge the expert assistance of the Sidney Kimmel Comprehensive Cancer Center (SKCCC) Cell Imaging Facility, Flow Cytometry Core, Tissue Services, and Immunohistochemistry Cores supported by the SKCCC Cancer Center Support Grant [CCSG, (P30 CA006973)]. This work was supported by a Prostate Cancer Foundation (PCF) Young Investigator Award (to W.N. Brennen), SKCCC CCSG developmental funds (P30 CA006973 to W.N. Brennen), PCF/Move-mber Challenge Award (to J.T. Isaacs, S.R. Denmeade, and J.M. Karp), NIH-Prostate SPORE Grant P50 CA058236 (to S.R. Denmeade and J.T. Isaacs), the Department of Defense (W81XWH-13-1-0304 to J.T. Isaacs, S.R. Denmeade, and J.M. Karp), the NIH grant R01HL095722 (to J.M. Karp), and a Natural Sciences and Engineering Research Council of Canada Discovery grant (to S.P. Howard).
Publisher Copyright:
© 2020 American Association for Cancer Research.
PY - 2020/11/1
Y1 - 2020/11/1
N2 - PRX302 is a highly potent, mutant bacterial pore-forming biologic protoxin engineered for selective activation by PSA, a serine protease expressed by benign and malignant prostate epithelial cells. Although being developed as a local therapy for benign prostatic hyperplasia and localized prostate cancer, PRX302 cannot be administered systemically as a treatment for metastatic disease due to binding to ubiquitously expressed glycosylphosphatidylinositol (GPI)-anchored proteins, which leads to poor accumulation within the tumor microenvironment. To overcome this limitation, poly-lactic-co-glycolic acid (PLGA) microparticles encapsulating the protoxin were developed, which are known to accumulate in the liver, a major site of metastasis for prostate cancer and other solid tumors. A highly sensitive and reproducible sandwich ELISA to quantify PRX302 released from microparticles was developed. Utilizing this assay, PRX302 release from different microparticle formulations was assessed over multiple days. Hemolysis assays documented PSA-dependent pore formation and lytic potential (i.e., function) of the released protoxin. MTT assays demonstrated that conditioned supernatant from PRX302-loaded, but not blank (i.e., unloaded), PLGA microparticles was highly cytotoxic to PC3 and DU145 human prostate cancer cells in the presence of exogenous PSA. Microparticle encapsulation prevented PRX302 from immediately interacting with GPI-anchored proteins as demonstrated in a competition assay, which resulted in an increased therapeutic index and significant antitumor efficacy following a single dose of PRX302-loaded microparticles in a preclinical model of prostate cancer liver metastasis with no obvious toxicity. These results document that PRX302 released from PLGA microparticles demonstrate in vivo antitumor efficacy in a clinically relevant preclinical model of metastatic prostate cancer.
AB - PRX302 is a highly potent, mutant bacterial pore-forming biologic protoxin engineered for selective activation by PSA, a serine protease expressed by benign and malignant prostate epithelial cells. Although being developed as a local therapy for benign prostatic hyperplasia and localized prostate cancer, PRX302 cannot be administered systemically as a treatment for metastatic disease due to binding to ubiquitously expressed glycosylphosphatidylinositol (GPI)-anchored proteins, which leads to poor accumulation within the tumor microenvironment. To overcome this limitation, poly-lactic-co-glycolic acid (PLGA) microparticles encapsulating the protoxin were developed, which are known to accumulate in the liver, a major site of metastasis for prostate cancer and other solid tumors. A highly sensitive and reproducible sandwich ELISA to quantify PRX302 released from microparticles was developed. Utilizing this assay, PRX302 release from different microparticle formulations was assessed over multiple days. Hemolysis assays documented PSA-dependent pore formation and lytic potential (i.e., function) of the released protoxin. MTT assays demonstrated that conditioned supernatant from PRX302-loaded, but not blank (i.e., unloaded), PLGA microparticles was highly cytotoxic to PC3 and DU145 human prostate cancer cells in the presence of exogenous PSA. Microparticle encapsulation prevented PRX302 from immediately interacting with GPI-anchored proteins as demonstrated in a competition assay, which resulted in an increased therapeutic index and significant antitumor efficacy following a single dose of PRX302-loaded microparticles in a preclinical model of prostate cancer liver metastasis with no obvious toxicity. These results document that PRX302 released from PLGA microparticles demonstrate in vivo antitumor efficacy in a clinically relevant preclinical model of metastatic prostate cancer.
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U2 - 10.1158/1535-7163.MCT-20-0227
DO - 10.1158/1535-7163.MCT-20-0227
M3 - Article
C2 - 32943549
AN - SCOPUS:85100451727
SN - 1535-7163
VL - 19
SP - 2353
EP - 2362
JO - Molecular Cancer Therapeutics
JF - Molecular Cancer Therapeutics
IS - 11
ER -