Collagen-Anchored Interleukin-2 and Interleukin-12 Safely Reprogram the Tumor Microenvironment in Canine Soft-Tissue Sarcomas

Abstract

Purpose: Cytokine therapies such as IL2 and IL12 suffer from impractically small therapeutic windows driven by their on-target, off-tumor activity, limiting their clinical potential despite potent antitumor effects. We previously engineered cytokines that bind and anchor to tumor collagen following intratumoral injection, and sought to test their safety and biomarker activity in spontaneous canine soft-tissue sarcomas (STS).

Experimental Design: Collagen-binding cytokines were canine-ized to minimize immunogenicity and were used in a rapid dose-escalation study in healthy beagles to identify a maximum tolerated dose. Ten client-owned pet dogs with STS were then enrolled into trial, receiving cytokines at different intervals prior to surgical tumor excision. Tumor tissue was analyzed through IHC and NanoString RNA profiling for dynamic changes within treated tumors. Archived, untreated STS samples were analyzed in parallel as controls.

Results: Intratumorally administered collagen-binding IL2 and IL12 were well tolerated by STS-bearing dogs, with only Grade 1/2 adverse events observed (mild fever, thrombocytopenia, neutropenia). IHC revealed enhanced T-cell infiltrates, corroborated by an enhancement in gene expression associated with cytotoxic immune function. We found concordant increases in expression of counter-regulatory genes that we hypothesize would contribute to a transient antitumor effect, and confirmed in mouse models that combination therapy to inhibit this counter-regulation can improve responses to cytokine therapy.

Conclusions: These results support the safety and activity of intratumorally delivered, collagen-anchoring cytokines for inflammatory polarization of the canine STS tumor microenvironment. We are further evaluating the efficacy of this approach in additional canine cancers, including oral malignant melanoma.

Translational Relevance Successful translation of novel cancer therapies could be accelerated through the inclusion of tumor models that accurately recapitulate natural evolution and malignant transformation processes operative in human tumor development. Spontaneous cancer in pet dogs provides an underutilized opportunity to assess the safety and activity of investigational cancer therapies in tumors that arise following years of immunoediting. Particularly for the evaluation of immunotherapies, canine tumors enable the assessment of clinical potential in the context of an experienced, and often senescent, immune background. Beyond efficacy, such evaluation provides meaningful insight into tumor resistance mechanisms that could influence eventual human clinical success. Herein, we characterize immune activities generated by intratumoral injections of engineered collagen-binding cytokines IL2 and IL12 into naturally occurring canine soft-tissue sarcomas, and demonstrate through comparative assessment in mouse tumors the differential learnings from each model and their combined role in guiding rational design of treatment combinations with greater expected efficacy.