Prothena Corporation PLC

Latest Results (04.03.2026):

Prothena Corporation PLC — Fourth quarter and full year 2025: Prothena reported a Q4 2025 net loss of $21.6 million and a full-year 2025 net loss of $244.1 million, with Q4 revenue of $21 thousand and full-year revenue of $9.7 million. Quarter-end cash and restricted cash totaled $308.4 million. Net cash used in operating and investing activities was $23.3 million in Q4 and $163.7 million for full-year 2025. The company provided 2026 guidance calling for $50–$55 million of net cash used in operating and investing activities and expects to end 2026 with approximately $255 million in cash (midpoint); this guidance excludes up to $105 million of potential 2026 clinical milestones from partners.

Key financials

Net loss: Q4 2025 −$21.6M; FY 2025 −$244.1M (includes $30.1M restructuring charges and a $43.2M net non‑cash income tax expense). Net loss per share: Q4 $0.40; FY $4.53. Total revenue: Q4 $21k; FY $9.7M (primarily collaboration revenue from BMS).

Cash, run-rate and guidance

Cash + restricted cash at 12/31/2025: $308.4M; no debt. Net cash used (operating & investing): Q4 $23.3M; FY $163.7M. 2026 guidance: expected net cash used $50–$55M and year-end cash ~ $255M (midpoint). Guidance assumes an estimated 2026 net loss of $67–$72M (includes ~$24M non‑cash share‑based comp) and excludes up to $105M potential partner milestones.

Expense trends

R&D expenses declined year-over-year: Q4 2025 $14.6M vs Q4 2024 $50.2M; FY 2025 $134.9M vs FY 2024 $222.5M (lower clinical, personnel, manufacturing and consulting costs). G&A also declined: Q4 2025 $12.6M vs Q4 2024 $16.8M; FY 2025 $59.4M vs FY 2024 $67.2M. Total non-cash share‑based comp: Q4 2025 $7.1M; FY 2025 $37.6M.

Partnerships, milestones and upside

Major partnered programs advanced in Q4 2025: Roche initiated Phase 3 PARAISO (prasinezumab) and Novo Nordisk initiated Phase 3 CLEOPATTRA (coramitug) — both with primary completions expected in 2029. Bristol Myers Squibb fully enrolled Phase 2 TargetTau‑1 (BMS‑986446) with primary completion expected 1H 2027. Prothena cites potential for up to ~ $3 billion in future aggregate milestones from partnered programs and up to $105M of potential clinical milestones in 2026.

Corporate actions and programs

Shareholder-approved reduction in share capital (Nov 19, 2025) created distributable reserves to allow a potential 2026 share redemption program (subject to Board discretion and financial condition). Preclinical and pipeline notes: CYTOPE® TDP‑43 data presented at scientific meetings; PRX012‑TfR and other preclinical efforts ongoing; PRX012 plaque clearance associated with ARIA‑E concerns and is being developed with transferrin receptor approach.

Other capitalization and governance items

As of Feb 12, 2026, ~53.8 million ordinary shares outstanding. Balance sheet highlights: cash and equivalents $307.5M, restricted cash $0.86M, total assets $326.8M, total shareholders’ equity $280.5M, and no debt.