Prothena reports Q2 2026 results, updates year-end cash guidance to $259 million

Prothena Corporation reported second quarter and first-half 2026 results on August 6, 2026, alongside several pipeline updates. During the quarter, Roche published results in The Lancet from the Phase 2b PADOVA trial evaluating prasinezumab in patients with early Parkinson's disease, which the company said further supported prasinezumab's potential as a disease-modifying therapy.¹ The PADOVA results highlighted exploratory signals of clinical and biological activity in early-stage Parkinson's disease, with findings consistent across clinical and biomarker endpoints.¹

Roche's follow-on Phase 3 study is underway. Roche is conducting the Phase 3 PARAISO trial in approximately 900 participants with early-stage Parkinson's disease, with primary completion expected in 2029 (NCT07174310).¹

On the ATTR amyloidosis program, Novo Nordisk is conducting the Phase 3 CLEOPATTRA trial in approximately 1,280 participants with ATTR-CM, with primary completion expected in 2029 (NCT07207811).¹ A related imaging study is also ongoing, with an open-label study evaluating the biodistribution of 89Zr-coramitug and its effects on depleting TTR amyloid deposits, with primary completion expected in 2027 (NCT07448623).¹

For the Alzheimer's program with Bristol Myers Squibb, the Phase 2 TargetTau-1 trial of moponetug in about 310 patients with early Alzheimer's disease has a primary completion expected in the first half of 2027 (NCT06268886).¹ Separately, Prothena said it could earn a $55 million clinical milestone payment if Bristol Myers Squibb decides to advance the PRX019 program, with a BMS decision expected by year-end 2026.¹

On finances, Prothena had $289.1 million in cash, cash equivalents and restricted cash as of June 30, 2026, and no debt.¹ The company updated its projected year-end cash balance to approximately $259 million at the midpoint, a decrease of $14 million from prior guidance of $273 million, driven primarily by about $12 million in share repurchases between May 1 and July 30, 2026.¹ This guidance excludes the potential $55 million PRX019 milestone or any further share repurchases.¹