Prothena Provides Update on PRX012 and Announces Results from the Phase 1 ASCENT Clinical Program
MWN-AI** Summary
Prothena Corporation plc (NASDAQ:PRTA) recently provided an update on its Phase 1 ASCENT clinical program, focusing on PRX012, an anti-amyloid beta (A?) antibody aimed at treating early symptomatic Alzheimer's disease (AD). Results confirmed PRX012’s efficacy as a once-monthly, subcutaneous treatment, demonstrating a dose- and time-dependent reduction in amyloid plaque levels, achieving a mean reduction to 27.47 centiloids (CL) at the 400 mg dose at the 12-month mark. However, the program also revealed higher rates of aria-related imaging abnormalities (ARIA-E) compared to FDA-approved A? antibodies, limiting its suitability for the patient demographic studied.
The ASCENT program, which includes randomized and open-label trials, showcased PRX012's stable pharmacokinetics and minimal injection site reactions, with low incidences of anti-drug antibodies. Among the 228 participants across various cohorts, safety data indicated that PRX012 was generally well-tolerated, despite an observed increase in ARIA rates at higher dosages. Notably, adverse events included treatment-emergent serious adverse events and a single death deemed unrelated to the drug.
Prothena’s Chief Development Officer, Chad Swanson, expressed gratitude to all stakeholders involved in the clinical program and announced intentions to seek potential partnership opportunities to advance both PRX012 and a related preclinical candidate, PRX012-TfR, which may further mitigate ARIA risks. The company aims to leverage their findings to potentially secure collaborations that further these promising therapeutic avenues. For now, Prothena has chosen not to release additional data publicly while it continues its exploration of partnership options.
MWN-AI** Analysis
Prothena Corporation's recent update regarding PRX012 and the Phase 1 ASCENT clinical program provides valuable insights for investors in the biopharmaceutical sector, particularly those interested in Alzheimer’s disease therapies. The trial results indicated that PRX012 has notable therapeutic potential, demonstrating a significant reduction in amyloid plaque in patients with early symptomatic Alzheimer's disease, despite a higher rate of ARIA-E compared to FDA-approved alternatives.
The recent partnership exploration signals Prothena’s strategic intent to leverage its advancements in anti-amyloid beta antibodies, which may attract interest from larger pharmaceutical companies. This could provide Prothena with the necessary capital and resources to accelerate development. Investors should consider that partnership opportunities can mitigate financial risks while enhancing credibility as they progress through clinical trials.
However, the profile of PRX012 raises caution. The elevated ARIA-E rates observed could pose challenges for widespread acceptance and regulatory approval, potentially limiting the market size for this therapy. Prothena's response to these challenges through its emphasis on the preclinical PRX012-TfR program suggests a commitment to addressing safety concerns. Should this program demonstrate superior safety while maintaining efficacy, it could significantly bolster market confidence.
Moreover, investors should monitor upcoming developments closely. The absence of further public data on ASCENT could indicate a strategic choice by Prothena to optimize partnership discussions rather than bolster current stock prices through premature releases. Thus, maintaining a balanced perspective on potential risks versus the opportunity presented by partnership developments is crucial.
In summary, investors focusing on Prothena should adopt a wait-and-see approach, keeping an eye on potential partnerships and further data releases. While the pipeline shows promise, the elevated safety concerns warrant careful evaluation before committing significantly to positions in the company.
**MWN-AI Summary and Analysis is based on asking OpenAI to summarize and analyze this news release.
- As previously communicated, Prothena plans to explore potential partnership interest to advance PRX012 and its preclinical PRX012-TfR (transferrin receptor) antibody
- Phase 1 ASCENT clinical program established proof-of-mechanism for PRX012 as a once-monthly, subcutaneous anti-amyloid beta antibody with high binding potency, dose- and time-dependent reduction of amyloid plaque, although with a non-competitive ARIA-E profile in patients with early symptomatic Alzheimer’s disease
Prothena Corporation plc (NASDAQ:PRTA), today announced results from the Phase 1 ASCENT clinical program in participants with early symptomatic Alzheimer’s disease (AD). As previously communicated, Prothena plans to explore potential partnership interest to advance PRX012 and its preclinical PRX012-TfR (transferrin receptor) antibody.
The Phase 1 ASCENT clinical program results demonstrated PRX012 as a potential once-monthly, subcutaneous anti-amyloid beta (A?) antibody with stable pharmacokinetics, low anti-drug antibodies, low injection site reactions, and dose- and time-dependent reductions in amyloid plaque. At the 400 mg dose level, PRX012 demonstrated a mean reduction in amyloid PET to 27.47 centiloids (CL) at month 12; FDA approved anti-A? antibodies have defined amyloid negativity thresholds of ?30 CL or ?24.1 CL. However, PRX012 was associated with higher overall ARIA-E rates relative to FDA approved anti-A? antibodies, making PRX012 less appropriate for the patients studied in the ASCENT clinical program. When ARIA-E did occur, the characteristics were similar to those reported following treatment with other anti-A? antibodies.
Based on the profile observed in the ASCENT clinical program and feasibility work already completed on its preclinical A?-transferrin receptor antibody surrogate, Prothena believes this approach may represent an opportunity to significantly lower the risk of ARIA and quickly reduce amyloid plaque with a once-monthly subcutaneous administration. Initial preclinical studies have demonstrated substantially increased brain exposure and facilitated rapid targeting of A? plaques in an APP/PS1 transgenic mouse model.
“On behalf of our entire team, we extend our continued appreciation to the patients, families, investigators, and staff whose dedication and collaboration enabled the Phase 1 ASCENT clinical program to achieve its objectives," said Chad Swanson, Ph.D., Chief Development Officer, Prothena. “We plan to explore potential partnership interest to further develop PRX012 and PRX012-TfR.”
Prothena does not plan to publicly share additional data from the ASCENT clinical program while it expects to explore potential partnership interest to advance PRX012 and PRX012-TfR.
Phase 1 ASCENT Clinical Program
The Phase 1 ASCENT clinical program includes ASCENT-1: a randomized, double-blind, placebo-controlled single-ascending-dose trial; ASCENT-2: a randomized, double-blind, placebo-controlled six-month multiple-dose trial; and ASCENT-3: a twelve-month open-label extension trial. The objectives of the ASCENT clinical program were to determine the safety, tolerability, immunogenicity, and pharmacokinetics of PRX012. The ASCENT-2 and ASCENT-3 trials also evaluated the pharmacodynamics of PRX012, including amyloid plaque deposition as measured by positron emission tomography (PET), in participants with early symptomatic AD.
The results include data from the five ASCENT-2 Group A cohorts in 228 participants with early symptomatic AD who are either APO?4 non-carriers or heterozygous carriers ranging in doses of PRX012 from 45 mg to 400 mg, randomized to PRX012 or placebo in a 3:1 ratio. Additional amyloid plaque reduction data from an interim read-out of ASCENT-3, the open-label extension (OLE) trial, was included.
ASCENT-2 Group A: Adverse Events 1
Placebo | 45 mg | 70 mg | 200 mg 2 | 400 mg | |
Treatment Emergent | 33 (57.9%) | 10 (40.0%) | 13 (54.2%) | 66 (68.0%) | 18 (75.0%) |
Treatment Emergent Serious Adverse Event (TESAE) | 5 (8.8%) | 2 (8.0%) | 1 (4.2%) | 7 (7.2%) | 1 (4.2%) |
Study drug related TESAE | 0 | 0 | 1 (4.2%) | 5 (5.2%) | 1 (4.2%) |
TEAE Leading to Withdrawal of Study Drug | 0 | 0 | 1 (4.2%) | 4 (4.1%) | 0 |
TEAE Leading to Withdrawal from the Study | 0 | 0 | 1 (4.2%) | 1 (1.0%) | 0 |
Death | 0 | 1 (4.0%) | 0 | 0 | 0 |
Death due to Study Drug | 0 | 0 | 0 | 0 | 0 |
Overall ARIA | 4 (7.0%) | 4 (16.0%) | 5 (20.8%) | 41 (42.3%) | 10 (41.7%) |
ARIA-E | 1 (1.8%) 3 | 3 (12.0%) | 2 (8.3%) | 37 (38.1%) | 10 (41.7%) |
ARIA-H | 4 (7.0%) | 3 (12.0%) | 4 (16.7%) | 29 (29.9%) | 8 (33.3%) |
Concurrent | 0 | 2 (8.0%) | 1 (4.2%) | 24 (24.7%) | 8 (33.3%) |
1 Safety population includes all randomized participants who received at least one dose of study drug |
PRX012 was generally well-tolerated across all dose cohorts of the trial. Injection site reactions in participants treated with PRX012 were low (4.1%). Treatment emergent anti-drug antibodies were low and generally transient with titer values close to the assay’s detection threshold. There was one death in the study in the 45 mg dose cohort, which was determined by the investigator to be not related to study drug.
Group A: Amyloid PET Centiloid (CL) Values
ASCENT-2 and ASCENT-3 Interim Data
Placebo | 45 mg | 70 mg | 200 mg 1 | 400 mg | |
Baseline Mean CL | 77.74 (n=49) | 75.64 (n=22) | 75.62 (n=19) | 75.47 (n=86) | 70.95 (n=23) |
6 Months Mean CL (double-blind placebo controlled) | 77.84 (n=49) | 77.39 (n=22) | 67.44 (n=19) | 68.83 (n=85) | 58.66 (n=23) |
12 Months Mean CL 2 (OLE) | n/a | 78.86 (n=18) | 61.60 (n=13) | 52.88 (n=57) | 27.47 (n=13) |
1 Participants received 200 mg dose level in two separate cohorts (a core and an expansion cohort) |
About Prothena
Prothena Corporation plc is a late-stage clinical biotechnology company with expertise in protein dysregulation and a pipeline of investigational therapeutics with the potential to change the course of devastating neurodegenerative and rare peripheral amyloid diseases. Fueled by its deep scientific expertise built over decades of research, Prothena is advancing a pipeline of therapeutic candidates for a number of indications and novel targets for which its ability to integrate scientific insights around neurological dysfunction and the biology of misfolded proteins can be leveraged. Prothena’s pipeline includes both wholly-owned and partnered programs being developed for the potential treatment of diseases including ATTR amyloidosis with cardiomyopathy, Alzheimer’s disease, Parkinson’s disease and a number of other neurodegenerative diseases. For more information, please visit the Company’s website at www.prothena.com and follow the Company on X (formerly Twitter) @ProthenaCorp.
Forward-Looking Statements
This press release contains forward-looking statements. These statements relate to, among other things, the treatment potential, design, and proposed mechanism of action of our A?-transferrin receptor antibody program; and our exploration of potential partnership interest to advance our PRX012 and PRX012-TfR programs. These statements are based on estimates, projections and assumptions that may prove not to be accurate, and actual results could differ materially from those anticipated due to known and unknown risks, uncertainties and other factors, including but not limited to uncertainties related to the completion of operational and financial closing procedures, audit adjustments and other developments that may arise that would require adjustments to the preliminary financial results included in this press release, as well as those described in the “Risk Factors” sections of our Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (SEC) on August 4, 2025, and discussions of potential risks, uncertainties, and other important factors in our subsequent filings with the SEC. We undertake no obligation to update publicly any forward-looking statements contained in this press release as a result of new information, future events, or changes in our expectations.
View source version on businesswire.com: https://www.businesswire.com/news/home/20250827764180/en/
Mark Johnson, CFA, Vice President, Investor Relations
650-837-8550
IR@prothena.com
Media@prothena.com
FAQ**
How might the partnership interest exploration impact Prothena Corporation plc (NASDAQ: PRTA) in advancing its PRX0and PRX012-TfR programs, especially given the promising results from the ASCENT clinical program?
What strategies is Prothena Corporation plc (NASDAQ: PRTA) considering to address the higher ARIA-E rates associated with PRX012 in comparison to FDA-approved anti-A? antibodies?
Can Prothena Corporation plc (NASDAQ: PRTA) provide more context on the implications of the ASCENT clinical program's results for future studies targeting amyloid plaque in Alzheimer's disease?
What specific opportunities does Prothena Corporation plc (NASDAQ: PRTA) see in the feasibility work completed for the PRX012-TfR antibody, and how might this inform their partnership discussions?
**MWN-AI FAQ is based on asking OpenAI questions about Prothena Corporation plc (NASDAQ: PRTA).
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