Translational Development of A Tumor Junction Opening Technology

Abstract

Our goal is to overcome treatment resistance in ovarian cancer patients, which occurs in most cases after an initial positive response to chemotherapy. A central resistance mechanism is the maintenance of desmoglein-2 (DSG2)-positive tight junctions between malignant cells, which prevents drug penetration into the tumor. We generated JO4, a recombinant protein that binds to DSG2, resulting in the transient opening of junctions in epithelial tumors. Here, we present studies on the clinical translation of JO4 in combination with PEGylated liposomal doxorubicin/Doxil® for ovarian cancer therapy. A manufacturing process for cGMP-compliant production of JO4 was developed. GLP toxicology studies using material from this process in DSG2 transgenic mice and cynomolgus macaques showed no treatment-related toxicities after intravenous injection at doses reaching 24 mg/kg. Multiple cycles of intravenous JO4 plus Doxil® (4 cycles, 4 weeks apart, simulating the treatment regimen in the clinical trial) elicited antibodies against JO4 that increased with each cycle and were accompanied by elevation of pro-inflammatory cytokines IL6 and TNF. Pretreatment with steroids and cyclophosphamide reduced the anti-JO4 antibody response and blunted cytokine release. Our data indicate acceptable safety of our new treatment approach if immune reactions are monitored and counteracted with appropriate immune suppression.