Now that Ionis Pharmaceuticals Inc. and affiliate Akcea Therapeutics Inc. have gained FDA clearance – albeit delayed and with a black box warning – of antisense oligonucleotide Tegsedi (inotersen) for polyneuropathy of hereditary transthyretin (ATTR)-mediated amyloidosis in adults, speculation has begun about the drug's chances in the marketplace given the double-stranded small interfering RNA drug Onpattro (patisiran) from Alnylam Pharmaceuticals Inc., which won the FDA's go-ahead in August for the same indication.