Mainstay Medical Announces Two-Year Outcomes from RESTORE Clinical Trial of ReActiv8®

Mainstay Medical Holdings plc today announced the publication of the two-year assessment results from the RESTORE randomized clinical trial of ReActiv8 for the treatment of intractable chronic low back pain. The data show continued improvements in back pain-related disability, pain and quality of life in the ReActiv8 treatment group, and improvements after one year of ReActiv8 therapy in the crossover group that were indistinguishable from the improvements shown by the treatment group at their one-year assessment. The results were published in The Spine Journal, and the article is available free of charge here: https://doi.org/10.1016/j.spinee.2026.07.006.

The study included 203 patients, with 99 randomized into the treatment arm and 104 randomized into the control arm. Patient-reported outcomes were collected at regular intervals to the one-year primary endpoint assessment, at which time the patients in the control arm were offered implantation with the ReActiv8 system. Eighty-three percent of the patients in the control arm elected to cross over to ReActiv8 therapy, and both groups were followed for an additional year. Key results from the study after two years include:

	Treatment Group		OMM Group	Cross-Over Group
	1 Year (n=94)	2 Years (n=80)	1 Year (n=94)	1 Year After Cross-Over (n=77)
Mean improvement in Oswestry Disability Index (ODI) score	-20.0 ± 17.7	−24.6 ± 17.1	-3.0 ± 12.9	−21.1 ± 14.8
Mean improvement in back pain measured using Numeric Rating Scale (NRS)	-3.6 ± 2.5	−4.2 ± 2.4	-0.6 ± 1.7	−3.8 ± 2.2
Mean improvement in healthcare related quality of life measured using the EQ-5D-5L	+0.157 ± 0.165	+0.189 ± 0.163	+0.011 ± 0.148	+0.191 ± 0.144
Proportion of patients who reached the composite endpoint of ≥15-point ODI improvement and/or ≥50% NRS improvement and no worsening in either measure	72%	76%	12%	73%
Proportion of patients reporting pain remission, defined as NRS of ≤3 at one year	52%	60%	6%	60%

The profile of related adverse events was similar to previously reported ReActiv8 studies and favourable to other neuromodulation treatment procedures.

“These long-term data should compel clinicians to challenge their thinking on how they treat axial low back pain. Not only do these data add to the large and growing body of clinical evidence showing durable improvements in disability, pain and quality of life provided by ReActiv8 therapy, but the improvements shown by the crossover group after one year of ReActiv8 therapy reinforce that ReActiv8 is a compelling option for patients who have exhausted conservative therapies,” said Jason Hannon, CEO of Mainstay Medical. “The fact that 83% of participants in the control group elected to cross over underscores the limitations of the current standard of care therapies. We look forward to further engaging payers in the United States to expand commercial insurance access to ReActiv8 to improve health outcomes and mitigate costs.”

About the RESTORE Clinical Study

The RESTORE (ReActiv8 Stimulation Therapy vs Optimal Medical Management: A Randomized Evaluation) clinical study is a multi-center, prospective, randomized trial with one-way cross-over. A total of 203 patients were randomized and followed in the study at 23 leading centers in the U.S. Eligible patients were randomized to either optimized medical management (OMM) or ReActiv8 Restorative Neurostimulation therapy plus OMM. OMM was an individualized treatment plan tailored to each patient’s specific clinical needs and reflected multimodal, guideline-concordant care including physical rehabilitation (e.g., physiotherapy, exercise, spinal manipulation, massage, and TENS), pharmacologic therapies, psychosocial interventions, injections and nerve blocks, and radiofrequency ablation. Patient-reported outcomes were collected at regular intervals out to the one-year primary endpoint assessment, at which time the patients in the control arm were offered implantation with the ReActiv8 system. Assessment of the patients continued for an additional year.

About ReActiv8®

ReActiv8 is an implantable medical device designed to treat adults with intractable chronic low back pain (CLBP) associated with multifidus muscle dysfunction, which may be evidenced by imaging or physiological testing. Candidates for ReActiv8 are patients with multifidus muscle dysfunction who have failed other forms of therapy (including pain medication and physical therapy) and are not candidates for spine surgery. ReActiv8 has received regulatory approval in several geographic areas, and is commercially available in the European Economic Area, Australia, the UK, and the US.

About Mainstay Medical

Mainstay Medical is a medical device company focused on commercializing its innovative implantable Restorative Neurostimulation^™ system, ReActiv8^®, for people with disabling mechanical CLBP. Mainstay Medical is headquartered in Dublin, Ireland and has subsidiaries operating in Ireland, the United States, Australia, Germany, and the Netherlands.

Further information can be found at www.mainstaymedical.com.

Forward-Looking Statements

All statements in this announcement other than statements of historical fact are, or may be deemed to be, forward-looking statements. These forward-looking statements may include, without limitation, statements regarding the company’s intentions, beliefs or current expectations concerning, among other things, the company’s research studies and results, commercial efforts and performance, financial position, financing strategies, product design and development, regulatory applications and approvals, and reimbursement arrangements.

Forward-looking statements involve risk and uncertainty and are not guarantees of future performance. Actual results may differ materially from those described in, or suggested by, the forward-looking statements. A number of factors could cause results and developments to differ materially from those expressed or implied by the forward-looking statements herein, including, without limitation, the risks and uncertainties included in the company’s Annual Report for the year ended 31 December 2025, which should be read in conjunction with the company’s public disclosures (available on the company’s website (www.mainstaymedical.com)). The forward-looking statements herein speak only as of the date of this announcement.

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