To this end, we compared (Supplementary Fig. 6a) efficacy (tumor growth inhibition), serum cytokine induction, and tumor STING activation of a HER2-directed STINGa ADC vs. a systemically administered free STINGa (diABZI IV agonist), which is structurally similar to the ADC payload33. The gene discussed is ERBB2; the disease is neoplasm.