Clinical hold weakens investors’ bond with Avidity

A clinical hold is not an ideal setup for first-in-patient data with a novel technology, but this is exactly what Avidity unveiled this morning. Enrolment has been halted into the phase 1/2 Marina trial of AOC 1001, the company’s lead antibody-targeted oligonucleotide for myotonic dystrophy type 1, after a single serious event. Avidity said the event was seen with 4mg/kg – the highest dose tested so far – and that the patient was at home undergoing further tests. The event is not thought to be related to the technology or DMPK knockdown, the target of AOC 1001. The company is focusing on finding the cause of the event, though its nature, timing and severity remain under wraps to "protect privacy". Lack of detail probably contributed to Avidity’s 23% share price plunge this morning, though executives also ducked questions about plans to escalate to an 8mg/kg dose. Investors also shrugged off the news that the FDA had cleared the start of clinical trials of two follow-on projects, which use the same technology as AOC 1001; under normal circumstances this could have provided a boost. Much now rests on disclosure of preliminary data from Marina's 1 and 2mg/kg dose cohorts, due in the coming weeks.