Prothena Stock Price, News & Analysis

Prothena (NASDAQ:PRTA) announced that Paula Cobb will step down from its Board of Directors effective December 12, 2025 to become Chief Operating Officer at Manifold Bio.

Ms. Cobb served on the board for six years after joining in 2019 and was described as providing global development, business strategy and commercial expertise. The board now has 8 directors.

Prothena (NASDAQ:PRTA) will present preclinical data for its TDP-43 CYTOPE® program at Neuroscience 2025 on November 19, 2025 at 1:00 PM PT. The poster (PSTR440.04) reports that systemically administered TDP-43 CYTOPE distributed to the brain and periphery, internalized into the cytosol, colocalized with pTDP-43 pathology, and significantly reduced intracellular pTDP-43 in an rNLS8 mouse model of ALS.

In vitro data in rat and human neuronal lines and human iPSC motor neurons showed cytosolic internalization, clearance of pTDP-43 aggregates, and reduction of RNA dysregulation driven by cryptic exon inclusions. The results highlight CYTOPE as a modality for delivering large molecules into cells to target intracellular disease pathways.

Prothena (NASDAQ:PRTA) announced publication of Phase 2 data for coramitug in the American Heart Association journal Circulation and presentation at AHA Scientific Sessions on November 10, 2025. The Phase 2 trial was randomized, double-blind, and placebo-controlled in patients with ATTR amyloidosis with cardiomyopathy. Novo Nordisk has initiated the Phase 3 CLEOPATTRA outcomes trial (NCT07207811). Under a July 2021 deal, Novo Nordisk acquired Prothena’s ATTR program; Prothena may receive up to $1.2 billion in milestones, with $100 million already earned. Prothena is eligible for an additional clinical milestone tied to CLEOPATTRA enrollment criteria.

Prothena (NASDAQ:PRTA) reported Q3 2025 results and business updates on November 6, 2025, highlighting partnered Phase 3 starts, program milestones, and capital plans.

Key metrics: Q3 net loss $36.5M and YTD net loss $222.5M; Q3 revenue $2.4M and YTD revenue $9.7M; cash $331.7M as of Sept 30, 2025; and guidance for $170–$178M net cash used in operating and investing activities for full-year 2025 with ~$298M year-end cash (midpoint).

Pipeline and milestones: Roche plans a Phase 3 PARAISO start for prasinezumab by end-2025; Novo Nordisk initiated Phase 3 CLEOPATTRA for coramitug and will present Phase 2 data on Nov 10, 2025; BMS received Fast Track for BMS-986446 and continues Phase 2; potential to earn up to $105M in aggregate clinical milestones by end-2026. The board will seek shareholder approval on Nov 19, 2025 for a capital reduction to enable a potential 2026 share redemption program.

Prothena (NASDAQ:PRTA) will report its third quarter and first nine months of 2025 financial results on Thursday, November 6, 2025, after the U.S. market close.

Consistent with prior practice, the company announced it will not hold a conference call with this release. The announcement notes Prothena is a late-stage clinical biotechnology company focused on investigational therapeutics built on protein dysregulation expertise.

Prothena (NASDAQ:PRTA) announced that its partner Bristol Myers Squibb has received Fast Track Designation from the FDA for BMS-986446 (PRX005), an anti-MTBR-tau antibody being developed for Alzheimer's disease treatment.

The Phase 2 study of BMS-986446 is fully enrolled and includes biomarkers to evaluate the drug's impact on disease progression. The antibody demonstrated promising results in preclinical models, showing significant reductions in tau uptake and spread, and was well-tolerated in Phase 1 trials.

Under the global license agreement, Prothena is eligible to receive up to $562.5 million in regulatory and sales milestone payments, plus tiered royalties on net sales. Bristol Myers Squibb maintains responsibility for all development, manufacturing, and commercialization activities.

Prothena (NASDAQ:PRTA), a late-stage clinical biotechnology company specializing in protein dysregulation therapeutics, has announced its participation in the upcoming Cantor Fitzgerald Global Healthcare Conference. The company's senior management team will engage in a fireside chat on September 4, 2025, at 10:55 a.m. ET in New York.

Investors can access the presentation through a live webcast on the investor relations section of Prothena's website. The replay will remain available for 90 days following the presentation.

Prothena (NASDAQ:PRTA) has announced results from its Phase 1 ASCENT clinical program for PRX012, their anti-amyloid beta antibody for early symptomatic Alzheimer's disease. The study demonstrated that PRX012 achieved dose- and time-dependent reductions in amyloid plaque, with the 400mg dose showing mean reduction to 27.47 centiloids at month 12.

While PRX012 showed positive aspects including stable pharmacokinetics, low anti-drug antibodies, and low injection site reactions (4.1%), it demonstrated higher overall ARIA-E rates compared to FDA-approved anti-Aβ antibodies. Due to this non-competitive safety profile, Prothena plans to explore partnership opportunities to advance both PRX012 and its preclinical PRX012-TfR antibody variant.

Prothena (NASDAQ:PRTA) announced that Novo Nordisk will advance coramitug (formerly PRX004) into Phase 3 development for ATTR amyloidosis with cardiomyopathy (ATTR-CM) in 2025. Coramitug, a potential first-in-class amyloid depleter antibody, was initially developed by Prothena and acquired by Novo Nordisk in July 2021.

Under the agreement terms, Prothena is eligible to receive up to $1.2 billion in clinical development and sales milestones, including $100 million earned to date. The company will earn an additional milestone payment when prespecified enrollment criteria are met in the Phase 3 trial.