Passage Bio (NASDAQ: PASG) has released interim data from its upliFT-D Phase 1/2 clinical trial evaluating PBFT02, an investigational gene therapy for frontotemporal dementia (FTD) caused by progranulin (GRN) mutations. The update, announced in early April 2024, indicates that PBFT02 demonstrated a positive effect on reducing brain atrophy and stabilizing plasma neurofilament light chain (NfL) levels in patients with GRN-FTD. These biomarkers are closely tied to neurodegeneration, making the findings potentially significant for a disease with no approved disease-modifying therapies.
The upliFT-D trial is an open-label, dose-escalation study designed to assess the safety, tolerability, and preliminary efficacy of PBFT02 in adult patients with clinically confirmed GRN-FTD. PBFT02 uses an adeno-associated virus (AAV) vector to deliver a functional copy of the GRN gene to the central nervous system, aiming to restore progranulin protein levels deficient in this form of FTD. Progranulin is a protein critical for lysosomal function and neuroinflammation regulation, and its deficiency leads to frontotemporal lobe degeneration.
According to Passage Bio’s press release dated April 8, 2024, the interim analysis included data from the first six patients dosed in the trial. Researchers observed a reduction in the rate of brain volume loss, as measured by magnetic resonance imaging (MRI), compared to natural history data from untreated GRN-FTD patients. Plasma NfL levels — a biomarker of axonal injury — showed stabilization or decline following treatment, suggesting a potential slowing of neuroaxonal damage.
“The early signals from upliFT-D are encouraging,” said Passage Bio’s Chief Medical Officer in the company’s statement. “Seeing effects on both structural brain changes and a key neurodegeneration biomarker supports the biological rationale of PBFT02 and motivates continued development.” The company emphasized that the data remain preliminary and that the trial is ongoing, with further dosing and long-term follow-up planned.
Frontotemporal dementia accounts for approximately 10–20% of all dementia cases and is a leading cause of early-onset dementia, typically presenting between ages 45, and 65. GRN mutations are among the most common genetic causes of familial FTD, yet no therapies currently target the underlying biology. Current management focuses on symptomatic relief and supportive care, underscoring the high unmet need for disease-modifying interventions.
The upliFT-D trial is being conducted at multiple sites across the United States, including academic medical centers with expertise in neurodegenerative disorders. Passage Bio has not disclosed specific enrollment targets but indicated that the study will continue to evaluate multiple dose levels of PBFT02 to determine an optimal balance between biological activity and safety. Adverse events reported to date have been largely mild to moderate and manageable, with no dose-limiting toxicities observed in the initial cohort.
Regulatory engagement remains a key focus for Passage Bio. The company has previously interacted with the U.S. Food and Drug Administration (FDA) regarding PBFT02’s development path, including discussions around biomarker qualification and potential accelerated approval pathways based on surrogate endpoints like NfL and volumetric MRI changes. While no formal breakthrough or orphan drug designation updates were included in the April release, Passage Bio holds orphan drug status for PBFT02 in both the U.S. And European Union for the treatment of GRN-FTD.
Financially, Passage Bio reported cash, cash equivalents, and marketable securities of approximately $215.3 million as of December 31, 2023, according to its latest Form 10-K. The company states that this runway supports operations into the second half of 2025, assuming current spending levels. The upliFT-D trial represents a cornerstone of Passage Bio’s pipeline, which also includes gene therapy programs for other rare neurological disorders such as Krabbe disease (PBKR03) and ALS associated with SOD1 mutations (PBALS-01).
Investor and patient advocacy responses to the interim data have been cautiously optimistic. Organizations such as the Association for Frontotemporal Degeneration (AFTD) have highlighted the importance of advancing genetic therapies for FTD, noting that biomarker-driven trials like upliFT-D offer a path toward meaningful clinical endpoints. However, experts also stress the need for larger, controlled studies to confirm whether biomarker improvements translate to clinical benefits in cognition, behavior, or daily functioning.
Passage Bio plans to provide additional updates on upliFT-D as more patients are enrolled and longer-term data become available. The company anticipates sharing further interim results later in 2024, with a focus on safety, pharmacodynamics, and exploratory efficacy measures. A definitive timeline for trial completion has not been disclosed, but Passage Bio indicated that data readouts will guide decisions on potential Phase 3 development.
For now, the upliFT-D interim update offers a rare glimmer of progress in a therapeutic area long marked by setbacks. While PBFT02 remains investigational and far from approval, its ability to influence core biological markers of neurodegeneration in GRN-FTD suggests that gene therapy may one day play a role in altering the course of this devastating disease. As the trial advances, the neuroscience and patient communities will be watching closely for signs that early biological effects can eventually lead to tangible improvements in patients’ lives.
The next confirmed checkpoint for Passage Bio is the anticipated release of additional upliFT-D interim data later in 2024, pending ongoing patient enrollment and data analysis. Investors, clinicians, and advocacy groups are encouraged to monitor the company’s investor relations portal and official press releases for verified updates. Readers interested in following developments in neurodegenerative disease research can stay informed through trusted sources such as the National Institutes of Health’s ClinicalTrials.gov registry and peer-reviewed journals like Lancet Neurology and JAMA Neurology.
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