ABSTRACT
Toll-like receptor 5 (TLR5) controls endogenous immune responses to pathogens and is a promising target for pharmacological stimulation of anti-tumor immunity. Mobilan is an innovative gene therapy agent consisting of a non-replicating bicistronic adenovirus directing constitutive expression of human Toll-like receptor 5 (TLR5) and the secreted flagellin-based TLR5 agonist, 502s. In mice, Mobilan injection into prostate tumors resulted in autocrine TLR5 signaling, immune system activation, and suppression of tumor growth and metastasis. Here we report a first-in-human placebo-controlled clinical study of Mobilan aimed at evaluating safety, tolerability, pharmacokinetics and pharmacodynamics of a single intra-prostate injection of Mobilan in early stage prostate cancer patients. Mobilan was safe and well-tolerated at all tested doses; thus, the maximum tolerated dose was not identified. Injection of Mobilan induced signs of self-resolving inflammation not present in placebo-injected patients, including transient elevation of PSA and cytokine (G-CSF, IL-6) levels, and increased lymphoid infiltration in prostate tissue. The highest dose of Mobilan (1011 viral particles) produced the best combination of safety and pharmacodynamic effects. Therefore, Mobilan is well-tolerated and induces the expected pharmacodynamic response in humans. These results support further clinical development of Mobilan as a novel immunotherapy for prostate cancer.
ABSTRACT
BACKGROUND: Targeted therapy with axitinib resulted in a greater objective response rate and prolonged progression-free survival (PFS) compared to sorafenib in patients with previously treated metastatic renal cell carcinoma (mRCC) in the phase 3 AXIS study, where 75% of patients had intermediate and poor International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk. OBJECTIVE: In this phase 2 study (FavorAx), we assessed the activity of axitinib in mRCC patients with a favorable risk and history of prior vascular endothelial growth factor receptor (VEGFR)-directed therapy. PATIENTS AND METHODS: Patients were required to have clear-cell mRCC, favorable risk according to IMDC criteria, and to have received first-line treatment with sunitinib or pazopanib. Prior treatment with other agents was not permitted. The primary endpoint of the study was 5 months PFS. Additional endpoints included response rate, safety, PFS, and overall survival (OS). RESULTS: A total of 21 patients were enrolled, 62% of whom were male. The mean age was 60 years. Eleven (52%) patients had two or more metastatic sites. 67% and 33% of patients received first-line sunitinib or pazopanib, respectively, with a median PFS of 17 months [95% confidence interval (CI), 14-20]. After a median follow-up of 25 months, the median PFS was 19 months (95% CI, 15-23). The current study did achieve its primary endpoint based on the 5-month PFS of 100%. The median OS was not yet reached. The 18 months OS rate was 85.7%. The objective response rate was 33% and one patient achieved a complete response. Seven patients had dose escalation of axitinib and four patients had dose reduction. Grade 3 adverse events were observed in 19% of cases. There was no discontinuation of therapy due to toxicity. CONCLUSIONS: The encouraging PFS and favorable safety profile observed in the FavorAx study support the administration of axitinib in mRCC patients with favorable IMDC risk and a history of prior sunitinib or pazopanib.
