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.