ProMIS Neurosciences, Inc. Q2 FY2026 earnings call

• PMN310 (Lead Alzheimer's Candidate) Phase 1b Interim Progress • Blinded 6-month interim data from the PRECISE-AD Phase 1b trial showed a favorable safety profile: 0 cases of ARIA-E (the severe symptomatic form of ARIA) across all genotypes, including the high-risk APOE4 homozygote population, which is typically underserved by approved amyloid-directed therapies. Total ARIA (including mild ARIA-H microhemorrhage) was 4.4%, all cases were mild and asymptomatic, with zero treatment-related serious adverse events, zero drug-related discontinuations, and only one mild non-serious infusion reaction. • Blinded pooled exploratory biomarker analysis showed an approximate 15% decline in plasma pTAU217 and 13.3% decline in CSF MTBR TAU243 from baseline, with 62.5% of patients showing a decline. This direction of change (opposite of the expected rise in untreated Alzheimer's patients) is consistent with target engagement and potential drug effect. The trial remains blinded and ongoing, with no efficacy conclusion drawn at this interim stage. • PRECISE-AD completed enrollment of 144 subjects in December 2025; as of the July 22, 2026 data cutoff, 49% of patients have completed the full 12-month dosing regimen.

• Earlier-Stage Pipeline Progress • PMN267 (for ALS, targeting misfolded TDP43) and PMN442 (for dementia with Lewy bodies and Parkinson's disease, targeting pathogenic alpha-synuclein) have both been humanized in a human IgG1 framework and are progressing toward IND-enabling studies. • Therapeutic vaccine programs for Alzheimer's, Parkinson's, and ALS are advancing, and the EpiSelect discovery platform is being updated with machine learning to accelerate identification of new disease-specific epitopes.

• Financial Position • Ended Q2 2026 with $53.4 million in cash and short-term investments, up from $6.1 million at December 31, 2025, driven by $70.1 million in net proceeds from a January 2026 private placement financing. • Q2 2026 net loss was $11.7 million ($1.28 per share), compared to a $10.1 million net loss ($7.26 per share) in Q2 2025. The lower per-share loss reflects the larger share count post-financing. • For the first half of 2026, net loss was $20 million, compared to $17.5 million in the prior year period, driven by increased R&D activity for the PRECISE-AD trial.

ProMIS Neurosciences is a clinical-stage biotechnology company, with all activities focused on pipeline development of neurodegenerative disease therapies; there are no separate reported product segments with commercial revenue. Total operating cash use for the first half of 2026 was $22.8 million, with the vast majority allocated to the PMN310 Alzheimer's disease program and the remainder split between earlier-stage pipeline candidates. Q2 2026 operating expense breakdown: research and development (R&D) expenses were $9.5 million (77.9% of total Q2 expenses), up from $8.7 million in Q2 2025; general and administrative (G&A) expenses were $2.7 million (22.1% of total Q2 expenses), up from $1.4 million in Q2 2025.

• The company expects existing cash and investments to fund operations through 2027, which covers costs through the expected 12-month top-line unblinded data readout for PRECISE-AD in Q1 2027, meeting the previous cash runway guidance.
• All patients are expected to complete 12-month dosing for PRECISE-AD in Q4 2026, with unblinded 12-month top-line data (including full safety, detailed biomarkers, and first clinical cognitive outcome data) expected to be reported in Q1 2027, maintaining the previously communicated timeline.
• Management targets advancing PMN267 and PMN442 to IND-enabling studies within 6 to 9 months, with entry into the clinic within approximately 1 year, assuming ongoing resource allocation aligned with current plans.
• Development of a subcutaneous formulation of PMN310 is prioritized to improve patient compliance, with work ongoing to finalize formulation characteristics and determine how to integrate it into future clinical development.

• All forward-looking statements (including clinical trial timelines, trial outcomes, and regulatory approval) are subject to inherent risks and uncertainties that could cause actual results to differ materially from expectations, as detailed in the company's SEC filings.
• The blinded interim biomarker signals from PRECISE-AD are early exploratory results, not confirmed efficacy outcomes, and there is no guarantee that unblinded 12-month data will confirm the positive safety and biomarker trends observed in the interim analysis.
• Development of the subcutaneous PMN310 formulation faces technical risks related to viscosity, dosing, and delivery device design that could delay timelines or change development plans.
• Advancing earlier-stage pipeline candidates depends on successful preclinical proof-of-concept data and available resource allocation, with no guarantee that candidates will successfully advance to clinical trials or approval.

Q: What has KOL reaction to the PMN310 interim data been, and what are the next steps for PMN310 if 12-month data is positive?

A: KOL and stakeholder reaction has been very positive, with results meeting or exceeding pre-interim expectations, particularly for the clean safety profile and clear target engagement signal. Management is actively preparing PMN310's lifecycle and regulatory path: planning a single potential registration study, scheduling an FDA meeting post-data readout (leveraging PMN310's existing fast track designation), developing a subcutaneous formulation for better patient access, and evaluating expansion to the preclinical asymptomatic Alzheimer's patient population. The company is also holding discussions with potential strategic partners and evaluating options to fund future development.

Q: How should the market interpret the current blinded target engagement signal, and will the zero ARIA-E finding hold beyond the 6-month interim mark?

A: The consistent decline in two complementary biomarkers (one upstream amyloid-linked, one downstream tangle-specific) against expected natural history is a strong encouraging signal of target engagement. For safety, zero ARIA-E was observed across all patients with more than 6 months of dosing, including 49% of patients that already completed the full 12-month regimen. Since over 90% of ARIA-E cases occur within the first 6 months of dosing for this drug class, the zero finding is highly meaningful and expected to persist. The absence of ARIA-E is consistent with PMN310's design as a non-plaque-binding antibody, which avoids the vascular binding that causes ARIA.

Q: Will additional blinded biomarker data be released before the Q1 2027 readout, and what is the status of the novel A-beta oligomer assay presented at AAIC?

A: No additional unblinded or blinded interim data will be released prior to the full 12-month readout. The novel assay developed by ProMIS is the first to directly measure low-concentration toxic A-beta oligomers in CSF, and it demonstrated a dose-dependent reduction in oligomers after a single PMN310 dose in Phase 1a. The assay is still being refined and will be implemented in the Phase 1b dataset to confirm mechanism of action when the study unblinds.

Q: How will existing Phase 3 trial data for approved amyloid therapies inform PMN310's registrational study design?

A: Management will follow FDA guidance to use CDR-SB as the primary endpoint, with secondary cognitive endpoints consistent with current regulatory standards. The main lessons from prior trials relate to patient recruitment timelines and strategies. Due to PMN310's differentiated favorable safety profile, the company expects it will not require as large a safety database as prior approved drugs, potentially allowing for a more streamlined, smaller registrational study. ProMIS plans to run a global trial to support global patient access and commercialization.