PROTHENA CORP PUBLIC LTD CO
PRTA evidence brief
What we can confirm
What it means
What to watch
Prepared research question
What matters most for PRTA—catalysts, financial risk and supporting evidence?
Traceable citations · Unknowns marked
BioSniper AI · PRTA
Prothena Corp PLC is a late-stage clinical biotechnology company focused on developing therapies for neurodegenerative and rare peripheral amyloid diseases, with a pipeline that includes wholly-owned and partnered programs.
Key risk: Clinical trial failure risk
BioSniper Score
Based on 6 of 6 signals
Market Cap
$479.0M
Cash Runway
34.7 moLead Asset
Birtamimab (Phase 3)
Next Catalyst
Phase3_Topline · Aug 31, 2029Financial data as of Jun 30, 2026.
Tracking 4 pipeline candidates · 8 clinical trials · 2 catalysts for PROTHENA CORP PUBLIC LTD CO.
Similar companies
Prothena Corp PLC is a late-stage clinical biotechnology company focused on developing therapies for neurodegenerative and rare peripheral amyloid diseases, with a pipeline that includes wholly-owned and partnered programs.
- Prothena is a late-stage clinical company with a pipeline of investigational therapeutics for neurodegenerative and rare peripheral amyloid diseases [sec · filed 2026-03-27].
- In May 2025, the Phase 3 AFFIRM-AL trial evaluating birtamimab in Mayo Stage IV AL amyloidosis did not meet its primary or secondary endpoints, leading to discontinuation of the program and a corporate restructuring with a ~63% workforce reduction [sec · filed 2026-03-27].
- In 2025, the Phase 1 ASCENT clinical program evaluating PRX012 was completed [sec · filed 2026-03-27].
- As of June 30, 2026, the company reported cash & equivalents of $289.1M, total revenue of $1.0M, and a net loss of -$18.6M [sec].
- The company is advancing discovery and preclinical-stage programs for neurological diseases with significant unmet medical needs [sec_mda · as of 2025-08-04].
What works
- Prothena has a robust pipeline of investigational therapeutics targeting neurodegenerative and rare peripheral amyloid diseases, with potential to change the course of these diseases [sec · filed 2026-03-27].
- The company has a partnered program with an option exercise fee of $80.0 million and is eligible for up to $617.5 million in development, regulatory, and sales milestone payments plus tiered royalties [sec_mda · as of 2025-08-04].
- Prothena is advancing multiple discovery and preclinical-stage programs for neurological diseases with significant unmet medical needs [sec_mda · as of 2025-08-04].
What to weigh
- The Phase 3 AFFIRM-AL trial for birtamimab failed to meet its primary or secondary endpoints, leading to program discontinuation and a 63% workforce reduction [sec · filed 2026-03-27].
- The company's cash resources are subject to numerous assumptions and risks, and it may use available capital sooner than expected due to uncertainties in clinical development [sec_mda · as of 2026-08-06].
- Prothena reported a net loss of -$18.6M for the quarter ended June 30, 2026, with limited revenue of $1.0M [sec].
From the filings
Quoted directly from source documents.
Prothena is a late-stage clinical company with a robust pipeline for neurodegenerative and rare peripheral amyloid diseases.
“stage clinical company with a robust pipeline of investigational therapeutics with the potential to change the course of devastating neurodegenerative and rare peripheral amyloid diseases.”
SEC filings · March 27, 2026
The Phase 3 AFFIRM-AL trial for birtamimab failed to meet endpoints, leading to program discontinuation and workforce reduction.
“the trial did not meet its primary or secondary endpoints and, as such, we subsequently discontinued the development of birtamimab and in June we commenced a corporate restructuring, including an approximate 63% reduction in workforce”
SEC filings · March 27, 2026
Prothena received an $80 million option exercise fee and is eligible for up to $617.5 million in milestones plus royalties.
“we received an associated option exercise fee of $80.0 million. We are eligible to receive development, regulatory, and sales milestone payments of up to $617.5 million as well as tiered royalties on annual, worldwide net sales.”
SEC MD&A · August 4, 2025
The company's cash resources depend on many assumptions and may be used sooner than expected.
“The adequacy of our cash resources depends on many assumptions, including assumptions with respect to our expenses. These assumptions may prove to be wrong, and we could use our available capital resources sooner than we currently expect.”
SEC MD&A · August 6, 2026
Catalyst timeline
- 2029-08-31 · Phase3_Topline — Phase 3 Topline: Optimizing Pain Treatment in Children On Mechanical Ventilation — Topline data readout from a Phase 3 trial evaluating pain treatment optimization in children on mechanical ventilation.
- 2031-06-30 · Phase3_Topline — Phase 3 Topline: A Phase III, Randomized, Double-Blind, Placebo-Controlled, Multicenter Study to Evaluate the Efficac — Topline data readout from a Phase 3 randomized, double-blind, placebo-controlled multicenter efficacy study.
Risks & what to watch (3)›
Key risks
- Clinical trial failure risk — The Phase 3 AFFIRM-AL trial failed to meet endpoints, leading to program discontinuation and restructuring [sec · filed 2026-03-27].
- Cash burn and runway uncertainty — Cash resources depend on many assumptions; company may use capital sooner than expected [sec_mda · as of 2026-08-06].
- Limited revenue and net losses — As of June 30, 2026, revenue was $1.0M with a net loss of -$18.6M [sec].
What to watch
- Progress of the Phase 1 first-in-human clinical trial for the partnered program initiated in November 2024 [sec_mda · as of 2025-08-04].
- Advancement of discovery and preclinical-stage programs for neurological diseases [sec_mda · as of 2025-08-04].
- Any updates on the corporate restructuring and workforce reduction impact on operations [sec · filed 2026-03-27].
Sources: SEC filings · SEC MD&A · Generated August 29, 2026 · How we verify sources →
Run PROTHENA CORP PUBLIC LTD CO through your own thesis
Use the pipeline, catalyst, financial, FDA, and market facts on this page as inputs to a protocol you control.
Your protocol can:
- Turn available PROTHENA CORP PUBLIC LTD CO facts into screen rules or deeper checks
- Show cited findings, blockers, and unresolved evidence together
- Save the logic and rerun it as the company evidence changes
Evidence & data
Score breakdownBased on 6 of 6 signals · derived from public data
34.7 months
D/E 0.05 · 0% dilution
Lead: Phase 3
4 candidates
2 upcoming, next in ~1097d
8 buys · 2 sells (180d)
Runway
Catalysts
Pipeline
Regulatory
Financials
Institutional Holdings
Source: SEC Form 13F · as of Mar 2026Institutional holders
184
Total value held
$406.3M
| Holder | Shares | Value |
|---|---|---|
| fmr llc | 7,551,218 | $73.4M |
| blackrock, inc. | 4,644,160 | $45.1M |
| state street corp | 1,938,498 | $18.8M |
| d. e. shaw & co., inc. | 1,763,347 | $17.1M |
| adar1 capital management, llc | 1,581,443 | $15.4M |
| vanguard portfolio management llc | 1,445,979 | $14.1M |
| morgan stanley | 1,230,448 | $12.0M |
| palo alto investors lp | 1,208,568 | $11.7M |
| two sigma investments, lp | 1,205,978 | $11.7M |
| geode capital management, llc | 1,098,166 | $10.7M |
Showing top 10 of 184 institutional holders of PROTHENA CORP PUBLIC LTD CO. Open the full 13F history after sign-in.
Short Interest
as of Apr 28, 2026- % of float
- 15.7%
- Days to cover
- 13.5
- Shares short
- 7,076,832
- Daily short volume
- -
Short percent of float and days-to-cover reflect reported short positioning. Daily short volume is the exchange-reported short share of a single day's trading volume and is noisier. See the most-shorted biotech ranking →
PRTA short interestGovernance
Frequently asked questions
What is the AI investment thesis for PROTHENA CORP PUBLIC LTD CO?
Prothena Corp PLC is a late-stage clinical biotechnology company focused on developing therapies for neurodegenerative and rare peripheral amyloid diseases, with a pipeline that includes wholly-owned and partnered programs.
What is PROTHENA CORP PUBLIC LTD CO's lead drug candidate?
PROTHENA CORP PUBLIC LTD CO's most advanced tracked candidate is Birtamimab (Phase 3) for Light Chain (AL) Amyloidosis.
What is PROTHENA CORP PUBLIC LTD CO's next catalyst?
PROTHENA CORP PUBLIC LTD CO's next tracked catalyst is a Phase3_Topline event — "Phase 3 Topline: Optimizing Pain Treatment in Children On Mechanical Ventilation" — expected August 31, 2029.
Who is the CEO of PROTHENA CORP PUBLIC LTD CO?
Dr. Gene G. Kinney Ph.D. is the chief executive officer of PROTHENA CORP PUBLIC LTD CO (PRTA).
Where is PROTHENA CORP PUBLIC LTD CO headquartered?
PROTHENA CORP PUBLIC LTD CO (PRTA) is headquartered in Dublin, Ireland.
The AI overview and BioSniper Score are neutral, data-derived signals built from public SEC filings, ClinicalTrials.gov and FDA records — not investment advice.