Dr. Gail Farfel reports

PROMIS NEUROSCIENCES ANNOUNCES FIRST QUARTER 2023 FINANCIAL RESULTS AND RECENT HIGHLIGHTS

Promis Neurosciences Inc. has released its first quarter 2023 financial results and recent highlights.

"In the first quarter, we completed the required steps that enabled us to file our PMN310 [investigational new drug] in April in order to advance PMN310 toward the clinic. Last week, we announced that the [Food and Drug Administration] cleared our IND for PMN310 in Alzheimer's disease, which is an exciting milestone for Promis," said Dr. Gail Farfel, PhD, chief executive officer of Promis. "Additionally, we presented key data on PMN310, as well as data supporting an amyloid-beta vaccine candidate in Alzheimer's and a new target for ALS treatment, at neurology conferences in March. We look forward to progressing our programs through the rest of 2023."

Recent highlights

Alzheimer's disease program (PMN310)

PMN310, Promis's lead compound, is a novel monoclonal antibody, which is highly selective for toxic oligomers of amyloid beta that are believed to be a major driver of AD. The company has the following updates:

• Received clearance from the U.S. Food and Drug Administration for its investigational new drug application for PMN310 for the treatment of AD;
• Presented in vitro preclinical data in which PMN310 demonstrated greater selectivity for target toxic oligomers compared with other amyloid beta (Abeta)-directed antibodies at the International Conference on Alzheimer's and Parkinson's Disease and Related Neurological Disorders (AD/PD 2023);
• Presented PMN310 preclinical data set including data showing PMN310 protected memory function in two rodent models of AD at the 75th American Academy of Neurology (AAN) annual meeting.

Discovery programs:

• Promis continues to advance its amyloid beta vaccine program in AD based on its oligomer target epitope(s) and gave a platform presentation on results from mouse vaccination studies at the AAN annual meeting.
• The company presented preclinical data supporting the receptor of activated C-kinase 1 (Rack1) as a potential target in ALS and frontotemporal lobar degeneration with TDP-43-immunoreactive pathology (FTLD-TDP) at the AAN annual meeting.
• Johanne Kaplan, PhD, Promis's chief development officer, will chair the coming ALS Drug Development Summit taking place on May 16 to May 18 in Boston.

First quarter 2023 financial highlights:

• Cash and cash equivalents were $3.3-million as of March 31, 2023, compared with $5.9-million as of Dec. 31, 2022.
• Research and development expenses were $3.5-million for the quarter ended March 31, 2023, compared with $1.9-million for the same period in 2022. The increase was primarily attributable to increased spending on PMN310 to finalize drug product manufacturing and costs to complete the IND filing.
• General and administrative expenses were $1.4-million as of March 31, 2023, compared with $2.0-million for the same period in 2022.
• Net loss was $5.0-million for the quarter ended March 31, 2023, compared with $2.1-million for the same period in 2022.

About Promis Neurosciences Inc.

Promis is a development-stage biotechnology company focused on generating and developing antibody therapeutics selectively targeting toxic misfolded proteins in neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral sclerosis and multiple system atrophy, an alpha-synucleinopathy. The company's proprietary target discovery engine applies a thermodynamic, computational discovery platform -- Promis and collective co-ordinates -- 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 MSA. Promis has offices in Toronto, Ont., and Cambridge, Mass. Promis is listed on the Nasdaq and the Toronto Stock Exchange under the symbol PMN.

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