Merz Therapeutics will present 11 scientific abstracts at the International Society of Physical and Rehabilitation Medicine 2026 World Congress in Vancouver, with new analyses focused on XEOMIN, or incobotulinumtoxinA, in upper and lower limb spasticity. The presentations place dosing optimization, immunogenicity, long-term treatment response and patient-centered outcomes at the center of a broader clinical debate over how botulinum toxin therapy should be managed in chronic neurorehabilitation.

Why Merz Therapeutics is using ISPRM 2026 to shift the spasticity debate from short-term response to long-term treatment durability

The more important signal from the Merz Therapeutics ISPRM 2026 program is not simply that the neurology-focused specialty pharma group is presenting another batch of congress abstracts. It is that the evidence package appears designed around a specific clinical pressure point: spasticity is not usually a one-cycle therapeutic problem, and real-world treatment success often depends on whether patients can remain responsive, functionally engaged and appropriately dosed over repeated injection cycles.

That distinction matters because botulinum toxin therapy in limb spasticity sits in a practical middle ground between pharmacology and rehabilitation. The injection can reduce abnormal muscle tone, but the value of treatment is judged through function, mobility, care burden, pain, hygiene, positioning and goal attainment. A dose that looks reasonable in isolation may be insufficient if the patient’s spasticity pattern changes, if multiple muscle groups need treatment, or if clinicians are forced to trade coverage for caution. By emphasizing dose optimization and goal attainment, Merz Therapeutics is positioning XEOMIN as a therapy whose value should be assessed across a longer rehabilitation journey rather than a single post-injection measurement window.

The unresolved question is how much of this argument can be translated into everyday practice. Post hoc analyses, pooled analyses and meta-analyses can sharpen confidence around treatment strategy, but they do not remove the complexity of patient selection, injection technique, rehabilitation intensity, payer constraints or local dosing norms. For clinicians, the practical issue is not only whether higher or flexible dosing can work, but whether the evidence is strong enough to support consistent decision-making across diverse spasticity presentations.

How flexible incobotulinumtoxinA dosing could influence goal-based care in upper and lower limb spasticity

The inclusion of an updated analysis on goal attainment and ambulation with increasing doses of incobotulinumtoxinA points to one of the central challenges in spasticity management: standard dosing frameworks can be clinically neat, while patient presentations are rarely neat. Limb spasticity can affect isolated muscle groups or complex upper and lower limb patterns, and treatment goals may range from improving walking to easing caregiver-assisted dressing or reducing painful postures.

This is where flexible dosing becomes strategically relevant. In chronic spasticity care, under-treatment can be as consequential as overtreatment because inadequate muscle selection or insufficient dose may produce a partial response that does not translate into meaningful functional improvement. A treatment approach that supports individualized dosing across cycles could give clinicians more room to align therapy with evolving rehabilitation goals, especially in patients with multi-pattern spasticity after stroke, traumatic brain injury or other cerebral lesions.

However, the clinical bar remains demanding. Goal attainment is highly relevant to patients and clinicians, but it can be harder to compare across studies than standardized tone scales. Ambulation outcomes can also be influenced by physiotherapy access, baseline disability, orthopedic limitations, cognition and caregiver support. That means the next layer of evidence will need to show not only that dose optimization can improve selected outcomes, but that the strategy is reproducible and clinically interpretable across real-world rehabilitation settings.

Why immunogenicity remains a high-stakes issue for botulinum toxin therapy in chronic neurorehabilitation

Merz Therapeutics’ focus on neutralizing antibodies and secondary treatment failure reflects a deeper commercial and clinical issue in the botulinum toxin market. In spasticity, treatment durability is not a theoretical advantage. Many patients require repeated injections over years, and any immune response that reduces efficacy can narrow future therapeutic options in a population that may already have limited functional reserve.

The updated meta-analyses comparing neutralizing antibodies and secondary treatment failure across botulinum toxin type A therapies are therefore important because they speak to persistence of response. If a therapy can maintain efficacy with a low risk of immunogenicity, clinicians may have greater confidence using it over multiple cycles, particularly in patients who need repeated treatment for complex spasticity patterns. For Merz Therapeutics, that is a clinically meaningful positioning angle because durability can matter as much as onset or peak effect in long-term neurological disorders.

The limitation is that immunogenicity data can be difficult to interpret across products, indications and study designs. Differences in assay methods, dosing exposure, patient populations, treatment intervals and definitions of secondary non-response can make cross-product comparisons sensitive. Industry observers are likely to watch whether the updated analyses provide enough methodological clarity to support stronger clinical conclusions, or whether they mainly reinforce a direction of travel already familiar to specialists in neurotoxin therapy.

What the XEOMIN data package reveals about the changing expectations for spasticity endpoints

The Merz Therapeutics congress program also highlights a broader shift in how spasticity therapies are being judged. Traditional measures of tone reduction remain important, but the field is increasingly interested in endpoints that reflect patient priorities, caregiver experience and functional relevance. That is why abstracts on patient and caregiver perspectives, trial endpoint relevance and digital rehabilitation support are notable alongside dosing and immunogenicity analyses.

This matters because spasticity treatment has historically faced a measurement problem. A statistically meaningful reduction in muscle tone does not automatically mean that a patient walks better, uses an affected limb more effectively, sleeps more comfortably or requires less assistance. By exploring which endpoints are most relevant to patients, Merz Therapeutics is aligning its evidence narrative with a more modern view of neurorehabilitation, where clinical success is defined through practical function and lived experience rather than tone control alone.

The challenge is that patient-centered outcomes can be more difficult to standardize for regulators, payers and trial designers. A patient’s goal may be highly meaningful but not easily comparable across populations. Digital tools such as smartphone-supported rehabilitation could help capture continuous or behavior-linked outcomes, but proof-of-concept work must still overcome adherence, validation and integration barriers. The opportunity is real, but the field will need stronger evidence that these tools improve decision-making rather than simply adding another layer of data collection.

How pediatric lower limb spasticity and cerebral palsy data could broaden the relevance of Merz Therapeutics’ neurotoxin strategy

The inclusion of incobotulinumtoxinA data in lower limb spasticity among children and adolescents with cerebral palsy adds another strategic dimension. Pediatric spasticity management carries different stakes because treatment decisions may interact with growth, motor development, orthopedic planning and long-term functional independence. For a neurotoxin manufacturer, pediatric evidence can strengthen the perception that a therapy has relevance across the full lifecycle of spasticity care.

Merz Therapeutics has already been pursuing pediatric spasticity expansion in Europe, which makes the ISPRM 2026 pediatric data especially relevant from a regulatory and commercial standpoint. In children and adolescents with cerebral palsy, clinicians often need therapies that can be integrated with physiotherapy, orthoses, serial casting or surgical planning. Evidence supporting lower limb use could therefore influence how specialists think about treatment sequencing and multidisciplinary care.

Still, pediatric spasticity remains a cautious area. Safety, dose selection, repeat treatment exposure and functional endpoints require careful interpretation, particularly when children have heterogeneous motor patterns and developmental trajectories. The key question is whether the data can support broader confidence among pediatric rehabilitation specialists, or whether additional controlled and long-term evidence will be needed before practice patterns shift materially.

Why Merz Therapeutics’ broader ISPRM agenda points to a platform strategy beyond a single spasticity claim

The ISPRM 2026 program is not limited to adult limb spasticity. It also touches paratonia, peripheral neuropathic pain, digital rehabilitation and patient participation in trials. That breadth suggests Merz Therapeutics is not framing XEOMIN only as an established neurotoxin in mature indications, but as part of a wider specialty neurology strategy built around movement disorders, rehabilitation and long-term neuromuscular management.

This is commercially sensible. Botulinum toxin markets are competitive, and differentiation is increasingly difficult if companies rely only on broad claims around efficacy. More durable positioning may come from evidence around specific patient groups, dosing patterns, immunogenicity, real-world persistence, digital integration and outcome relevance. In that sense, Merz Therapeutics appears to be building a defensible evidence ecosystem around clinical decision-making rather than presenting isolated study updates.

The risk is that breadth can dilute focus if the data are not sufficiently connected. A congress portfolio spanning dose escalation, immunogenicity, pediatric spasticity, paratonia, apps and neuropathic pain can look ambitious, but clinicians will ultimately ask which findings should change behavior on Monday morning. The strongest near-term impact is likely to come from evidence that helps physicians make clearer dosing, retreatment and patient selection decisions in spasticity.

What clinicians, regulators and industry observers will watch after the ISPRM 2026 presentations

The next test for Merz Therapeutics will be whether the ISPRM data strengthen confidence in a long-term, individualized model of botulinum toxin therapy. Clinicians will look for practical clarity on which patients benefit from dose escalation, how treatment goals should be set across cycles, and whether low immunogenicity signals translate into lower secondary non-response in routine care. Rehabilitation specialists will also be watching whether patient-centered outcomes can be incorporated without weakening trial comparability.

Regulators and payers may view the data through a different lens. Flexible dosing and broader treatment patterns can improve clinical fit, but they also raise questions about cost, utilization and evidence thresholds. If Merz Therapeutics wants the long-term durability argument to influence adoption, the most persuasive data will be those that connect sustained response with functional value, reduced care burden or improved rehabilitation efficiency.

For the wider neurotoxin market, the message is clear: differentiation is moving beyond whether a botulinum toxin works. The more competitive question is whether it remains reliable across repeated treatment cycles, supports individualized care and helps clinicians translate tone reduction into outcomes patients can actually feel. That is the harder part of spasticity care, and it is where Merz Therapeutics is trying to move the conversation with XEOMIN.

  botulinum toxin, cerebral palsy, incobotulinumtoxinA, ISPRM 2026, lower limb spasticity, Merz Therapeutics, movement disorders, neurorehabilitation, spasticity, upper limb spasticity, XEOMIN