aibioProthena cuts about 63% of workforce after ending birtamimab, expects $16 to $20 million in charges
Tickers PRTA
Prothena will cut about 63% of its workforce after ending birtamimab, and expects $16 to $20 million in charges, mostly cash. The 8-K gives no headcount, cash balance or savings figure.
Key facts
- Company
- Prothena Corporation plc (NASDAQ: PRTA)
- News type
- Distress
- Primary source
- Prothena Corporation plc 8-K (2025-06-18)
The reduction
Prothena Corporation plc (Nasdaq: PRTA) announced on June 18, 2025 an approximate 63% reduction in its workforce. The company disclosed it in a Form 8-K under Item 2.05, which covers costs of exit or disposal activities. Prothena says the aim is to cut operating costs to those needed for its remaining wholly-owned programs, its obligations to partnered programs and its expected business development work.
The cut follows the company's May 23, 2025 decision to discontinue further development of birtamimab, its wholly-owned program for AL amyloidosis. The 8-K refers back to that decision but does not restate the reasons for it.
The 10-K filed in February 2025, which predates both steps, listed birtamimab first among the wholly-owned programs, followed by two Alzheimer's programs: PRX012, which targets amyloid beta, and PRX123, a dual amyloid beta and tau vaccine. Its partnered programs included prasinezumab with Roche for Parkinson's disease, BMS-986446 and PRX019 with Bristol Myers Squibb, and coramitug, which falls under the share purchase agreement with Novo Nordisk on the ATTR amyloidosis business. The 10-K also reports that in December 2024 Roche announced topline results from the Phase 2b PADOVA trial of prasinezumab in early Parkinson's disease, and that Roche was still evaluating the data. An early Phase 2 trial of coramitug in ATTR cardiomyopathy is being run by Novo Nordisk. The 8-K does not say how the cut affects PRX012, PRX123 or any partnered program.
Charges and timing
Prothena expects approximately $16 to $20 million in total charges. They cover severance and related benefits for employees laid off, plus non-cash share-based compensation tied to accelerated stock options. The 8-K says the charges are "primarily one-time severance payments" and are "primarily cash charges." It also says the company may incur other charges or cash expenditures that are not currently contemplated.
The reduction is expected to be substantially complete by the end of the fourth quarter of 2025. The 8-K says more detail will come in the quarterly reports on Form 10-Q for the periods ending June 30 and September 30, 2025, and in the annual report on Form 10-K for 2025.
Who is leaving
The 8-K names two officers. Carol D. Karp, the Chief Regulatory Officer, and David A. Ford, the Chief People Officer, will leave effective August 1, 2025. Their terminations trigger payments and benefits under the Prothena Biosciences Inc Amended and Restated Severance Plan, plus accelerated vesting of some stock options, as described in the company's proxy statement filed March 28, 2025.
Affected U.S. employees are eligible for severance under that plan. Affected employees outside the United States are eligible for statutory or contractual payments. Certain senior executives will have portions of their options vest early and will get longer post-employment exercise periods.
What the filing leaves out
The 8-K gives no headcount and does not say how many employees are affected, although its forward-looking statements refer to "the number of employees impacted." It gives no cash balance, no savings estimate and no figure for the cash the company expects to keep after the charges.
What comes next
The reduction is due to be substantially complete by the end of 2025, with the charges recorded as the company completes the work. The next detail is due in the June and September 2025 quarterly reports, which will show how much of the $16 to $20 million was recorded and how much of the cost base is gone.