Key Highlights

  • PMN shares trading down 42.60% to $6.36, implying a prior close near $11.08.
  • Acumen reported a failed Phase 2 trial for an Alzheimer's antibody targeting amyloid Beta oligomers on the same day.
  • PMN held $53.4 million in cash and short-term investments as of June 30, 2026.
  • The PRECISE-AD Phase 1b trial enrolled 144 patients, with topline data expected in the first quarter of 2027.
  • Q2 2026 net loss was $11.7 million, or $1.28 per share.

ProMIS Slides as Acumen's Oligomer Antibody Misses in Phase 2

ProMIS Neurosciences (NASDAQ:PMN) shares are trading down 42.60% at $6.36 today. No ProMIS-specific announcement was identified for the decline, and the company's latest update was the appointment of a chief commercial officer earlier this month.

On the same day, Acumen Pharmaceuticals (NASDAQ:ABOS) reported that its Phase 2 ALTITUDE-AD study of sabirnetug, an antibody aimed at toxic amyloid beta oligomers, missed its primary endpoint at both doses. ProMIS's lead candidate also targets toxic amyloid beta oligomers, though any link between the two moves has not been confirmed.

PMN310 and the PRECISE-AD Phase 1b Trial Timeline

ProMIS is a clinical-stage biotechnology company developing antibodies against toxic misfolded proteins in neurodegenerative disease. Its lead candidate, PMN310, is a humanized antibody designed to target toxic amyloid beta oligomers while avoiding plaque. The pipeline also includes programs for ALS and frontotemporal dementia and for Parkinson's-related disorders.

PRECISE-AD is a randomized, double-blind, placebo-controlled Phase 1b study that enrolled 144 patients across 5, 10 and 20 mg/kg cohorts with monthly dosing for 12 months. Blinded six-month interim data in July showed no ARIA-E cases among 136 evaluable patients and a 4.4% rate of mild, asymptomatic ARIA-H. The company noted that interim blinded results may not predict final outcomes.

Cash Position, Private Placement and Market Value After the Drop

ProMIS reported $53.4 million in cash and short-term investments at the end of June, up from $6.1 million at the end of 2025, following $70.1 million in net proceeds from a January private placement. The second-quarter net loss was $11.7 million, or $1.28 per share. Management expects the cash to fund operations through 2027. The January financing was structured as a private placement of up to $175 million, with directors and management participating alongside outside investors.

With roughly 9 million shares outstanding, today's price implies a market value near $57 million, based on a share count from a data provider. Before the drop, the stock's 52-week range ran from $6.27 to $27.40, and the average analyst price target listed by a data provider was $43.40. Those levels were set before today's decline.

Several research firms had raised targets over the summer. Guggenheim moved its price target to $100 from $69, Chardan to $33 from $20, while Roth Capital trimmed its target to $29 from $30. These figures are data points and predate today's move.

Unblinded PRECISE-AD Data in First Quarter 2027 Is the Next Defined Catalyst

All patients are expected to complete 12 months of dosing by the fourth quarter of 2026, with unblinded topline data, including cognitive outcomes, due in the first quarter of 2027. Until then, investors will watch for any company commentary on the Acumen result and for how oligomer-targeting programs are assessed after the failed Phase 2 readout. The chief commercial officer hire, a former Biogen and Roche executive, signals preparation for later stages of development, although the company has not outlined a commercialization timeline. Fourth-quarter results should also update the cash balance.