The present invention provides cyclic-di-nucleotide (CDN) compounds that inhibit signaling at a recently discovered cytoplasmic receptor known as STING (Stimulator of Interferon Genes). In particular, the CDNs of the present invention are provided in the form of a composition comprising one or more cyclic purine dinucleotides which inhibit STING-dependent TBK1 activation and the resulting production of type I interferon.