RESUMEN
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.
RESUMEN
Radiation treatment of head and neck cancer frequently causes severe collateral damage to normal tissues including mouth mucosa, salivary glands and skin. This toxicity limits the radiation dose that can be delivered and affects the patient's quality of life. Previous studies in mice and nonhuman primates showed that entolimod, a toll-like receptor 5 (TLR5) agonist derived from bacterial flagellin, effectively reduced radiation damage to hematopoietic and gastrointestinal tissues in both total-body and local irradiation scenarios, with no protection of tumors. Here, using a mouse model, we analyzed the efficacy of entolimod administered before or after irradiation in reducing damage to normal tissues. Animals received local fractionated radiation to the head and neck area, thus modeling radiotherapy of head and neck cancer. Tissue damage was evaluated through histomorphological examination of samples collected at different time points up to four weeks, mice were exposed locally to five daily fractions of 5, 6 or 7 Gy. A semiquantitative scoring system was used to assess the severity of observed pathomorphological changes. In this model, radiation damage was most severe in the lips, tongue and skin, moderate in the upper esophagus and minor in salivary glands. The kinetics of injury appearance and recovery of normal morphology varied among tissues, with maximal damage to the tongue, esophagus and salivary glands developing at earlier times (days 8-11 postirradiation) relative to that of lip and skin mucosa (days 11-15 postirradiation). While both tested regimens of entolimod significantly reduced the extent of radiation damage and accelerated restoration of normal structure in all tissues analyzed, administration of entolimod 1 h after each irradiation was more effective than treatment 30 min before irradiation. These results support the potential clinical use of entolimod as an adjuvant for improving the therapeutic index of head and neck cancer radiotherapy by reducing the radiation toxicity in normal tissues.