A recent flurry of deals highlighted growing industry interest in RNAi-based drugs that can silence disease-causing genes, just months after the FDA approved Alnylam's first-in-modality RNAi drug patisiran for hereditary transthyretin-mediated amyloidosis.

In October, Johnson & Johnson partnered with Arrowhead Pharmaceuticals for rights to develop the phase I/II candidate ARO-HBV for the treatment of chronic hepatitis B viral infection. The deal included an upfront payment of US$175 million to Arrowhead, a $75 million equity investment in the biotech and up to $3.5 billion in potential milestone payments.

Later in the month, Alexion partnered with Dicerna Pharmaceuticals for rights to collaborate on the discovery and development of RNAi-based therapies for complement-mediated diseases. This included rights to two preclinical RNAi molecules and exclusive options to two additional targets in the complement pathway. Alexion made an upfront payment of $22 million, a $15 million equity investment in Dicerna and committed to approval-related milestone payments of up to $105 million per target.

Eli Lilly is also getting into the RNAi space, partnering with Dicerna to collaborate on cardiometabolic, neurodegeneration and pain targets. Eli Lilly made an upfront payment of $100 million and an equity investment of $100 million to collaborate on more than ten targets. Dicerna will also be eligible for up to $350 million in milestones per target.

The enthusiasm for RNAi-based drugs is driven by hopes that these gene-silencing oligonucleotides can open up targets that have eluded other drug modalities. At least six RNAi-based products are currently in phase III development, and next-generation candidates stand to offer better access to targets beyond the liver, better therapeutic indices and better delivery options.