ProMIS Neurosciences Announces US$15 Million Offering of Units

ProMIS Neurosciences Inc. ("ProMIS" or the "Company") (TSX: PMN), a biotechnology company focused on the discovery and development of antibody therapeutics targeting toxic oligomers implicated in the development of neurodegenerative diseases, has filed today a preliminary prospectus supplement (the "Supplement") to its final short form base shelf prospectus dated June 30, 2021 (the "Base Prospectus") in connection with a proposed commercially reasonable efforts public offering of units (the "Units") for gross proceeds to the Company of up to US$15,000,000, exclusive of the Agent's Option (as defined herein) (the "Offering"). 

Each Unit consists of one common share of the Company (a "Common Share") and one quarter of one Common Share purchase warrant (each whole purchase warrant, a "Warrant"). Each Warrant will entitle the holder thereof to purchase one Common Share (each, a "Warrant Share") at any time up to 60 months following Closing (as defined below), subject to an acceleration provision such that in the event that following the Closing the Common Shares have a volume weighted average price on the Toronto Stock Exchange ("TSX") greater than three (3) times the Warrant exercise price for each of ten (10) consecutive trading days (based on the Bank of Canada noon exchange rate on the applicable trading day), then the Company may accelerate the expiry date of the Warrants to a date that is 30 days after the date on which the Company gives notice of the acceleration to the holders of Warrants. The Units offered under the Offering will be priced in the context of the market and pricing will be reflected in a final prospectus supplement.

The Supplement was filed with the securities regulatory authorities in each of the province and territories of Canada (other than Québec). Additionally, the Offering is expected to be conducted by way of private placement other jurisdictions where the Offering can lawfully be made.

In connection with the Offering, the Company intends to enter into an agency agreement with Leede Jones Gable Inc. (the "Agent") and certain other agents to be added to the syndicate. The Company expects to close the Offering on or about August 24, 2021, or other such date as may be mutually agreed to by the Company and the Agent (the "Closing"), subject to satisfaction of customary closing conditions, including the approval of the listing of the Common Shares and the Warrant Shares on the TSX.

The Company has agreed to grant to the Agent an option (the "Agent's Option"), exercisable, in whole or in part, at the sole discretion of the Agent, to increase the size of the Offering by up to 15%. The Agent's Option is exercisable, in whole or in part, at any time until the date that is two (2) business days prior to the date of Closing.

The Company intends to use the net proceeds from the Offering to advance its lead Alzheimer's therapy PMN310 to the filing of an Investigational New Drug ("IND") application to enable a first clinical trial, including working with a qualified vendor to manufacture drug product to GMP (Good Manufacturing Practice) standards, developing manufacturing assays as necessary for regulatory approvals, conducting animal toxicology studies to GLP (Good Laboratory Practice) standards at a qualified vendor, conducting additional in vivo testing of PMN310, and conducting formulation work with a qualified vendor to support potential development of a subcutaneous delivery form of PMN310, expanding the ProMIS portfolio of antibodies and patents, including further development of targets that have been disclosed (such as tau in Alzheimer's disease, or RACK1 in amyotrophic lateral sclerosis (ALS), as well as addressing novel mis-folded protein targets implicated in disease with the ProMIS technology platform and general corporate purposes. Any additional proceeds from the Offering, such as those from the possible exercise of the Agent's Option will be used to: (a) conduct activities that might speed the progress to file an IND and, subject to the U.S. Federal Drug Administration's approval, to commence a clinical trial for PMN310; (b) accelerate other research and development programs with additional in vitro and in vivo work; (c) increase the rate of hiring additional key personnel in critical areas such as Clinical Operations and Discovery Operations; and/or (d) increase expenditures on shareholder and investor relations.

The securities referred to in this news release have not been, nor will they be, registered under the United States Securities Act of 1933, as amended (the "U.S. Securities Act"), or applicable state securities laws, and such securities may not be offered or sold to, or for the account or benefit of, persons in the United States or U.S. persons (as such terms are defined in Regulation S under the U.S. Securities Act) absent registration or an applicable exemption from such registration requirements. This press release does not constitute an offer for sale of securities nor a solicitation for offers to buy any securities in any jurisdiction in which such offer, solicitation or sale would be unlawful.

ABOUT PROMIS

ProMIS is a development stage biotechnology company focused on discovering and developing antibody therapeutics selectively targeting toxic oligomers implicated in the development and progression of neurodegenerative diseases, in particular Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD). The Company's proprietary target discovery engine is based on the use of two complementary techniques. The Company applies its thermodynamic, computational discovery platform - ProMIS™ and Collective Coordinates - to predict novel targets known as Disease Specific Epitopes on the molecular surface of misfolded proteins. Using this unique approach, the Company is developing novel antibody therapeutics for AD, ALS and PD. ProMIS is headquartered in Toronto, Ontario, with offices in Cambridge, Massachusetts. ProMIS' common shares are listed and posted for trading on the Toronto Stock Exchange under the symbol PMN.