Intratumoral Delivery of STING Agonist Results in Clinical Responses in Canine Glioblastoma

Clin Cancer Res. 2021 Oct 15;27(20):5528-5535. doi: 10.1158/1078-0432.CCR-21-1914. Epub 2021 Aug 25.


Purpose: Activation of STING (stimulator of interferon genes) can trigger a robust, innate antitumor immune response in immunologically "cold" tumors such as glioblastoma.

Patients and methods: A small-molecule STING agonist, IACS-8779, was stereotactically administered using intraoperative navigation intratumorally in dogs with spontaneously arising glioblastoma. The phase I trial used an escalating dose design, ascending through four dose levels (5-20 μg). Treatment was repeated every 4-6 weeks for a minimum of two cycles. Radiographic response to treatment was determined by response assessment in neuro-oncology (RANO) criteria applied to isovoxel postcontrast T1-weighted MR images obtained on a single 3T magnet.

Results: Six dogs were enrolled and completed ≥1 cycle of treatment. One dog was determined to have an abscess and was removed from further analysis. One procedure-related fatality was observed. Radiographic responses were dose dependent after the first cycle. The first subject had progressive disease, whereas there was 25% volumetric reduction in one subject and greater than 50% in the remaining surviving subjects. The median progression-free survival time was 14 weeks (range: 0-22 weeks), and the median overall survival time was 32 weeks (range: 11-39 weeks).

Conclusions: Intratumoral STING agonist (IACS-8779) administration was well tolerated in dogs with glioblastoma to a dose of 15 μg. Higher doses of IACS-8779 were associated with radiographic responses.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain Neoplasms* / drug therapy
  • Brain Neoplasms* / veterinary
  • Dogs
  • Female
  • Glioblastoma* / drug therapy
  • Glioblastoma* / veterinary
  • Injections, Intralesional
  • Interferons / drug effects
  • Interferons / genetics
  • Treatment Outcome


  • Interferons
  • IACS-8779