Business Description

ProMIS Neurosciences Inc. (the “Company” or “ProMIS”) is applying its patented technology platform to build a portfolio of antibody therapies, therapeutic vaccines, and other antibody-based therapies in neurodegenerative diseases and other protein-misfolding diseases, with a focus on Alzheimer’s disease (AD), multiple system atrophy (MSA), and amyotrophic lateral sclerosis (ALS). The Company believes these diseases share a common biologic cause — misfolded versions of proteins, that otherwise perform a normal function, become toxic and kill neurons, resulting in disease. ProMIS’ technology platform enables drug discovery through a combination of protein biology, physics and supercomputing. ProMIS believes this platform provides a potential advantage in selectively targeting the toxic misfolded proteins with therapeutics or detecting them with diagnostics.

The Company is developing a pipeline of antibodies aimed at selectively targeting misfolded toxic forms of proteins that drive neurodegenerative diseases without interfering with the essential functions of the same properly folded proteins. The Company's product candidates are PMN310, PMN267, and PMN442. The lead product candidate is PMN310, a monoclonal antibody designed to treat AD by selectively targeting toxic, misfolded oligomers of amyloid-beta. PMN267 is the second lead product candidate targeting ALS. It has been shown in preclinical studies to selectively recognize misfolded, cytoplasmic TDP-43 aggregates without interacting with normal TDP-43. Misfolded TDP-43 is believed to play an important role in the development of ALS. In light of research suggesting that misfolded toxic a-syn is a primary driver of disease in synucleinopathies such as MSA and Parkinson’s disease, the third lead product candidate, PMN442, has shown robust binding to pathogenic a-syn oligomers and seeding fibrils in preclinical studies, with negligible binding to a-syn monomers and physiologic tetramers which are required for normal neuronal function.

The Company was incorporated on January 23, 2004 under the Canada Business Corporations Act (“CBCA”). On July 13, 2023, the Company continued its existence from a corporation incorporated under the CBCA into the Province of Ontario under the Business Corporations Act (Ontario) (“OBCA”) (“Continuance”). The Continuance was approved by the Company’s shareholders at the Company’s 2023 Annual Meeting of Shareholders held on June 29, 2023. The Company is located at 1920 Yonge Street, Toronto, Ontario. The Company’s Common Shares are traded on the Nasdaq Capital Market (“Nasdaq”) under the symbol PMN. The Company has a wholly-owned U.S. subsidiary, ProMIS Neurosciences (U.S.) Inc. (“ProMIS USA”), which was incorporated in January 2016 in the State of Delaware. As of March 31, 2026, ProMIS USA has had no material activity and has no material financial impact on the Company’s consolidated financial statements.

Liquidity Risk

The accompanying unaudited condensed consolidated financial statements were prepared on a going concern basis, which assumes that the Company will continue its operations for the foreseeable future and will be able to realize its assets and discharge its liabilities in the normal course of business. The Company has not generated revenues from its activities. The Company had a net loss of $8.2 million for the three months ended March 31, 2026, an accumulated deficit of $138.7 million as of March 31, 2026, and negative cash flows from operations of $12.4 million. In January 2026, the Company received net proceeds of $70.1 million from the sale of Common Shares, Common Share warrants, and pre-funded warrants to purchase Common Shares to external investors and certain of the Company’s directors and management in a private placement (“January 2026 PIPE”). Refer to additional discussion in Note 6.

Based on the Company’s current operating plan, the Company expects that its existing cash and short-term investments will be sufficient to fund the Company’s operating expenses and capital expenditure requirements through 2027. The Company based this estimate on assumptions that may prove to be wrong, and the Company could exhaust its available capital resources sooner than it expects, including based on its decision to initiate other clinical trials or programs.

Future capital requirements will depend upon many factors, including the timing and extent of spending on research and development and market acceptance of the Company’s products, if approved for commercial sale. The Company will require

additional funding to conduct future clinical activities. The Company expects to seek additional funding through public and private financings, debt financings, collaboration agreements, strategic alliances and licensing agreements. Although the Company has been successful in raising capital in the past, there is no assurance of success in obtaining such additional financing on terms acceptable to us, if at all, and there is no assurance that the Company will be able to enter into collaborations or other arrangements. If the Company is unable to obtain funding or other arrangements, it could force delays, reduce or eliminate research and development programs, and/or reduce product portfolio expansion or commercialization efforts, which could adversely affect future business prospects, and the ability to continue operations.