Preclinical evaluation of aluminum hydroxide-tethered interleukin-12 (JEN-101) therapy in pet dogs with advanced malignant melanoma

A Phase I study was conducted to determine the tolerability, activity, and immune responses of JEN-101 in dogs with advanced melanoma. A 3+3 dose escalation design was used to evaluate intratumoral injection of JEN-101 at 1, 3, 10, or 20 μg/kg every three weeks for four cycles. A second course was allowable in the absence of disease progression or toxicity. Peripheral blood, serum, and tumor biopsies were collected at baseline and at pre-specified timepoints for pharmacokinetic and immune analyses, which included serum cytokines, immunohistochemistry, and gene expression assessment. JEN-101 was well tolerated with adverse events being fever, lethargy, and isolated elevated liver enzymes. Five dogs experienced grade 3 events and no grade 4 events were observed. Pharmacokinetic analysis showed a trend towards dose-related Cmax within 8 hours of injection. Responding dogs demonstrated increased systemic interferon-γ and IL-10 AUC levels and local recruitment of CD3+ T cells. Increased pro-inflammatory and antigen processing gene expressions were identified in responding lesions. Pet dogs with melanoma were enrolled into four cohorts of 1, 3,10, and 20 µg/kg administered by local injection of aluminum hydroxide-tethered interleukin-12 (JEN-101) every three weeks for four cycles. For dogs without disease progression or clinically significant toxicity, another four cycles of JEN-101 every three weeks were allowable. Dogs were followed for up to one year following completion of treatment. Baseline tumor biopsy was required in all dogs and post-treatment biopsies were collected when clinically feasibility or at the time of death.