AskBio Publishes Complete Phase 1b Trial Results of AB-1005 Gene Therapy for Parkinson’s Disease in Leading Neurology Journal
Asklepios BioPharmaceutical, Inc. (AskBio), a pioneering gene therapy company that operates as a wholly owned, independent subsidiary of the global pharmaceutical giant Bayer AG, has announced the publication of comprehensive results from its Phase 1b clinical trial investigating AB-1005, an innovative gene therapy candidate designed for the treatment of Parkinson’s disease (PD). The results were published in Movement Disorders, a respected peer-reviewed journal affiliated with the International Parkinson and Movement Disorder Society, providing critical insights into the safety, tolerability, and potential efficacy of AB-1005 in a clinical setting.
Parkinson’s Disease and the Need for New Therapies
Parkinson’s disease is a progressive neurodegenerative disorder characterized primarily by the loss of dopaminergic neurons in the substantia nigra region of the brain, leading to motor symptoms such as tremor, rigidity, bradykinesia (slowness of movement), and postural instability. Beyond these motor impairments, PD patients often suffer from a variety of non-motor symptoms including cognitive decline, sleep disturbances, autonomic dysfunction, and mood disorders, which collectively degrade quality of life.
Current therapies for PD predominantly focus on symptomatic relief, typically involving dopamine replacement strategies such as levodopa or dopamine agonists. However, these treatments do not alter the underlying neurodegenerative process and often lose effectiveness over time. Consequently, there is a critical unmet need for therapies that can slow, halt, or potentially reverse the progression of Parkinson’s disease.
AB-1005: A Novel Gene Therapy Approach
AB-1005 is a gene therapy candidate that delivers the gene encoding glial cell line-derived neurotrophic factor (GDNF) directly into the brain. GDNF is a potent neurotrophic factor known for its ability to promote the survival and function of dopaminergic neurons, the cells most affected in PD. By delivering GDNF via gene therapy, AB-1005 aims to provide a sustained source of this neuroprotective protein within the brain, potentially enabling not only symptom improvement but also neurorestoration and slowing of disease progression.
The Phase 1b trial was designed to evaluate the safety, tolerability, and preliminary efficacy of AB-1005 in people living with Parkinson’s disease, focusing on two cohorts stratified by disease severity: a mild cohort and a moderate cohort.
Key Findings from the Phase 1b Trial
The recently published data reinforce the potential of AB-1005 as a promising gene therapy candidate for PD. The trial enrolled 11 participants, all of whom received a single administration of AB-1005 via intracerebral delivery.
The most critical safety outcome was that AB-1005 was well tolerated across all participants, with no serious adverse events attributed to the gene therapy or the GDNF transgene. This favorable safety profile is encouraging given the invasive nature of intracerebral gene delivery and the potential risks associated with gene therapies.
Clinically, the study reported two key trends in motor function assessments at 18 months post-treatment:
- In the mild PD cohort, clinical motor function assessments demonstrated numerical stability, suggesting that participants maintained their motor abilities without significant decline during the follow-up period.
- In the moderate PD cohort, participants exhibited numerical improvement in motor function measures, indicating a possible positive therapeutic effect of AB-1005.
In addition to motor function, the study also monitored non-motor symptoms, which are increasingly recognized as critical contributors to PD morbidity. Non-motor clinical assessments remained numerically stable over the 18-month follow-up in both cohorts, potentially signifying that AB-1005 might have a broader protective effect beyond motor symptoms.
Importantly, these clinical observations align with the hypothesis that GDNF gene therapy could help stabilize or even improve neurological function in PD patients, thereby potentially slowing disease progression rather than merely treating symptoms.
Expert Perspectives and Future Directions
Dr. Chad Christine, Professor of Neurology at the University of California, San Francisco, and one of the lead authors of the publication, commented on the significance of the findings: “The exploration of the neurorestorative and neuroprotective potential of GDNF gene transfer is critical to advancing our understanding of AB-1005, which may one day be a groundbreaking treatment to slow the progression of Parkinson’s disease. These encouraging results support further evaluation of this therapy in a randomized trial.”
Dr. Christine’s remarks highlight the translational importance of the trial findings and underscore the need for larger, controlled studies to definitively assess efficacy and long-term benefits.
Lila Collins, PhD, Associate Director of Portfolio Development & Review at the California Institute for Regenerative Medicine (CIRM), also weighed in, reflecting on the trial’s importance and the institution’s support for regenerative medicine initiatives. “These results support the continued study of AB-1005 as a potential gene therapy to slow the progression of Parkinson’s disease. We are pleased to have supported this important trial and look forward to AskBio’s Phase 2 REGENERATE-PD results, which will provide additional insights into the durability of the clinical response and potential disease-modifying effect of AB-1005.”
CIRM’s backing signals strong institutional confidence in AB-1005’s potential and the broader regenerative medicine approach to neurodegenerative diseases.
Regulatory Milestone: RMAT Designation
Further validating AB-1005’s potential, the therapy was granted Regenerative Medicine Advanced Therapy (RMAT) designation by the U.S. Food and Drug Administration (FDA) in February 2025. This designation is intended to expedite the development and review process for regenerative medicine therapies that demonstrate preliminary clinical evidence of addressing serious conditions with unmet medical needs.
RMAT designation facilitates increased FDA engagement, priority review, and other regulatory benefits that could accelerate the path to potential approval, offering hope for more rapid patient access if subsequent trial phases confirm efficacy and safety.
The Road Ahead: Phase 2 REGENERATE-PD Trial
Building on the encouraging Phase 1b findings, AskBio is now conducting the Phase 2 REGENERATE-PD trial. This pivotal study is designed as a randomized, controlled trial to evaluate the safety, tolerability, and efficacy of AB-1005 in a larger cohort of Parkinson’s disease patients.
Key objectives of the REGENERATE-PD trial include:
- Assessing the durability of the clinical response observed in the Phase 1b trial.
- Determining whether AB-1005 can demonstrate a disease-modifying effect by slowing or halting the progression of PD.
- Monitoring a broader range of motor and non-motor symptoms using standardized clinical rating scales.
- Evaluating long-term safety with an extended follow-up period.
The results of this trial will be critical in defining the therapeutic potential of AB-1005 and informing subsequent regulatory submissions.AskBio is a leader in gene therapy development with a focus on transforming treatments for serious and rare diseases through advanced genetic medicine. The company’s collaboration with Bayer AG provides it with robust resources, strategic support, and access to cutting-edge technology platforms aimed at accelerating gene therapy research and commercialization.
Important Considerations
AB-1005 remains an investigational gene therapy and has not yet received approval from any regulatory authority worldwide. Its safety and efficacy profile continues to be studied, and patients and clinicians should be aware that gene therapies, while promising, involve complex delivery methods and require careful monitoring.
The publication of the full Phase 1b clinical trial results in Movement Disorders represents a significant milestone for AskBio’s AB-1005 gene therapy program. The demonstrated safety, tolerability, and promising clinical findings offer hope for a new approach to treating Parkinson’s disease—one that goes beyond symptom management to potentially modify the disease course.
As Parkinson’s disease continues to impose a heavy burden on patients, families, and healthcare systems globally, innovations such as AB-1005 represent critical advances in neurotherapeutics. The upcoming results from the Phase 2 REGENERATE-PD trial will be eagerly awaited by the medical and patient communities as a potential beacon of progress in the quest for more effective and durable treatments for Parkinson’s disease.
