TreatHSP Platform: Adaptive Natural History Platform for Ataxias, HSPs, and Spastic Ataxias

Condition(s) studied

Study summary

Ataxias, hereditary spastic paraplegias (HSP), and spastic ataxias (collectively referred to as SPAX diseases) are rare neurological conditions that cause progressive problems with walking, balance, coordination, and daily activities. Although many SPAX diseases are caused by specific genetic changes, there is still limited knowledge about how symptoms develop over time, how fast the diseases progress, and which clinical or biological measures best reflect meaningful changes for patients.

The TreatHSP Master Protocol establishes an adaptive natural history study platform designed to improve the understanding of SPAX diseases across all ages and disease stages. Within this platform, the TreatHSP/SPAX study serves as the core natural history study, providing a shared framework for long-term clinical follow-up, standardized outcome assessments, and biosample collection.

Participants enrolled in TreatHSP/SPAX are followed over time to document disease progression using clinical examinations, patient- and caregiver-reported outcomes, digital movement measures, imaging, and biological samples. In addition to this core dataset, the TreatHSP Platform allows optional, disease- or hypothesis-specific substudies to be added over time in selected participant groups. These additional assessments are introduced under the same master protocol, without creating separate stand-alone studies.

The overall goal of the TreatHSP Master Protocol is to generate high-quality natural history data, identify sensitive and patient-relevant outcome measures, and support the development of future therapies for ataxias, hereditary spastic paraplegias, and spastic ataxias.

Eligibility

Primary outcome measure(s)

• Modified Spastic Paraplegia Rating Scale — Through study completion, an average of 5 years, measured annually
  The modified Spastic Paraplegia Rating Scale (mSPRS) is a clinician-reported outcome measure assessing disease severity in hereditary spastic paraplegia and related spastic movement disorders. It evaluates functional mobility, spasticity, muscle strength, pain and bladder function. The mSPRS is adapted from the original Spastic Paraplegia Rating Scale to improve feasibility and sensitivity to change in longitudinal studies. It can be applied in individuals aged 5 years and older, with higher scores indicating greater disease severity. The mSPRS serves as the primary outcome measure for the assessment of disease severity in all participants with hereditary spastic paraplegia.
• Scale for the Assessment and Rating of Ataxia (SARA) — Through study completion, an average of 5 years, measured annually
  The Scale for the Assessment and Rating of Ataxia (SARA) is a standardized clinician-reported outcome measure used to quantify the severity of ataxia. It assesses key domains including gait, stance, sitting, speech disturbance, limb coordination, and fine motor control. The SARA provides a global measure of ataxia-related motor impairment and is widely used in both clinical practice and longitudinal research studies. The SARA is applied in study participants aged 8 years and older, with higher scores indicating greater ataxia severity. The SARA serves as the primary outcome measure for the assessment of disease severity in all participants with ataxia.
• SPAX Composite Scale (SPAXCOM) — Through study completion, an average of 5 years, measured annually
  SPAXCOM is a clinician-reported composite outcome measure developed to assess disease severity in individuals with spastic ataxia. It integrates key motor and functional domains relevant to spastic-ataxic phenotypes, including gait and balance, coordination, spasticity, and functional mobility. SPAXCOM is designed to capture the combined contribution of pyramidal and cerebellar dysfunction and to provide a sensitive measure of disease severity and progression in spastic ataxia. Higher scores indicate greater disease severity. SPAXCOM serves as the primary outcome measure for participants with spastic ataxia.

Trial sites (30)