Shares crash as Mainstay back pain device fails clinical trial

Company insists other data support case for its implanted electrical stimulation device

Shares in Mainstay Medical, the Irish medical device company targeting chronic back pain, crashed to record lows after a key clinical trial failed.

Mainstay has spent several years developing an implantable spinal neuromodulator – a device that works by stimulating muscles supporting the lower back with electrical impulses.

The Reactiv8-B trial was designed to demonstrate how patients receiving the treatment fared compared to a control group.

After the 120-day study, 56 per cent of the patients receiving therapy indicated a 30 per cent reduction in chronic lower back pain. However, this was not statistically significant, given that 47 per cent of the control group reported similar improvement.


Shares plunged 45 per cent as the company published topline results from the trial and were at €8.40 in the late afternoon trading. The previous low for the company was €12.90.

Despite its failure to meet its primary goal, the lead investigator in the clinical trial said how he was encouraged by the results.

"The totality of this data is encouraging for this large group of patients with limited treatment alternatives," said Dr Chris Gilligan, chief of the division of pain medicine, at the Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women's Hospital in Boston.


“The data on the patients that have completed one year of therapy are important, particularly because these patients have not experienced meaningful pain relief from existing treatment options,” said Dr Gilligan, who is also assistant professor of anaesthesia at Harvard Medical School.

Sixty per cent of patients have experienced a reduction in pain of 50 per cent or more one year after starting treatment. That, said Dr Gilligan, “surpasses what many implanting physicians expect from implantable neurostimulation devices”.

It also said that 44 per cent of the 50 patients who had completed the one-year assessment and had been on opioids pain relief before the trial started, had voluntarily eliminated or significantly reduced their use of opioids

The company said it intended to push to expand commercialisation of the device under its current European approval.

It also signalled its intention to pursue market approval in the key US market.

"In summary, we believe the evidence of effectiveness and the favourable safety profile of ReActiv8 show considerable promise, particularly when compared to the response rates and safety profiles of alternative treatments," said chief executive Jason Hannon. "We believe that the totality of the data will support the submission of a PMA [pre-market approval] application for ReActiv8 to the FDA.

“We plan to seek a pre-PMA meeting with the FDA in the coming months to obtain guidance on our filing content and strategy.”

Dominic Coyle

Dominic Coyle

Dominic Coyle is Deputy Business Editor of The Irish Times