Preclinical evaluation of an anchored immunotherapy strategy with aluminum hydroxide-tethered interleukin-12 in dogs with advanced malignant melanoma.

Melanoma is an aggressive cancer in dogs involving skin and mucosa similar to people. Anchored immunotherapeutics offer a novel approach to increase intratumoral retention of therapeutic payloads while decreasing systemic exposure, and this strategy can be critically evaluated through a comparative oncology approach. JEN-101 is an anchored canine interleukin-12 (IL-12) tethered to aluminum hydroxide administered by local injection. 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. JEN-101 was well tolerated with evidence of biologic and therapeutic activities. Anchored IL-12 immunotherapy merits further investigation in dogs with melanoma and our approach represents an immune competent model to inform human clinical trials.