Dr. Gail Farfel reports

PROMIS NEUROSCIENCES ANNOUNCES THIRD QUARTER 2023 FINANCIAL RESULTS AND RECENT HIGHLIGHTS

Promis Neurosciences Inc. has released financial results for the third quarter ended Sept. 30, 2023, and provided a corporate update.

"The third quarter was marked by significant progress across both our clinical and corporate initiatives," said Dr. Gail Farfel, PhD, chief executive officer of Promis Neurosciences. "We are excited to begin dosing subjects in our first-in-human trial of PMN310 as a treatment for AD. Our confidence in PMN310 is bolstered by compelling non-clinical data that demonstrate PMN310's greater selectively for toxic amyloid beta oligomers, which indicate its potential for greater therapeutic benefit and an improved safety profile compared with currently available treatments. We look forward to dosing the first subjects in our phase 1a clinical study of PMN310 this month and expect to have early cohort results in the first half of 2024.

"We were encouraged by the recent clinical results presented by Acumen Pharmaceuticals, which showed in a small, three-month study that targeting soluble amyloid beta oligomers in AD patients can improve biomarkers of pTau181 and neurogranin. These results replicated biomarker findings from the Clarity-AD trial of lecanemab, which also predominantly targets soluble amyloid beta oligomers. We are encouraged by these new clinical findings, as we believe PMN310 is the most specific antibody targeting soluble amyloid beta oligomers, and we look forward to demonstrating its effect in the clinic.

"Importantly, we strengthened our balance sheet with an equity financing that raised in excess of $20-million in gross proceeds to support continued development of PMN310 and the ongoing development of our novel antibody therapies for neurodegenerative diseases through a number of potentially value-creating milestones."

Recent highlights

Alzheimer's disease program (PMN310)

PMN310, Promis's lead compound, is a humanized IgG1 antibody directed against toxic amyloid beta oligomers that are believed to be a major driver of AD:

• Promis obtained Investigation review board approval at its clinical site, is currently screening subjects and expects to dose the first participants in a first-in-human phase 1a clinical trial of PMN310 as a potential treatment for AD in November, 2023. The phase 1a clinical trial is a double-blind, placebo-controlled, single-ascending dose study of the safety, tolerability and pharmacokinetics of PMN310 infusions in up to five cohorts of eight healthy volunteers. PMN310 exposure levels in blood and cerebrospinal fluid (CSF) will be evaluated as well as safety. In October, 2023, the PMN310 phase 1a trial was added to the ClinicalTrials database (study NCT06105528).
• In July, 2023, Promis presented preclinical data at Alzheimer's Association International Conference 2023 indicating greater selectivity, compared with approved therapies, of PMN310 for toxic amyloid beta oligomers translating into potentially greater clinical benefit, improved safety profile, reduced incidence of amyloid-beta-oligomer-related imaging abnormalities (ARIA) and preserved memory function.

Discovery programs

Promis continues to advance its amyloid beta vaccine program in AD based on its oligomer target epitope(s):

• In July, 2023, the company presented preclinical data from mouse vaccination studies at AAIC 2023. Immunization with an amyloid beta oligomers epitope-based vaccine was shown to induce robust, long-term antibody responses focused on toxic oligomers without potentially detrimental cross-reactivities. These promising data support further evaluation of this vaccine approach for AD prevention with the potential for sustained anti-disease activity and ease of use with fewer doses compared with chronic antibody treatment.

Corporate:

• In November, 2023, Dr. Farfel was a speaker at the CNS Summit in Boston, Mass., and Dr. Johanne Kaplan, PhD, chief development officer at Promis, participated in a Canadian ITN (Initiative for Translational Neuroscience) event in Montreal in a round table discussion on improving public-private partnerships to advance drug discovery.
• In August, 2023, Promis completed a private placement of 9,945,969 common shares and 954,725 prefinanced warrants, for gross proceeds of $20.4-million. Proceeds from the private placement are expected to be used to advance the clinical development of PMN310, as well as for working capital and other general corporate expenses.
• In July, 2023, Promis consolidated trading of its shares on the Nasdaq Capital Market and completed a voluntary delisting of its common shares from the Toronto Stock Exchange (TSX).

Third quarter 2023 financial highlights:

• Cash and cash equivalents were $16.9-million as of Sept. 30, 2023, compared with $5.9-million as of Dec. 31, 2022. During the quarter, the company raised $20.4-million in gross proceeds from a private investment in public equity financing, less $2.7-million of issuance costs.
• Research and development expenses were $1.1-million for the three-months ended Sept. 30, 2023, compared with $4.6-million for the same period in 2022. The decrease was primarily attributable to a decrease in direct research and development expenses following the submission of the PMN310 investigational new drug application with the U.S. Food and Drug Administration in April, 2023.
• General and administrative expenses modestly decreased to $1.4-million for the quarter ended Sept. 30, 2023, compared with $1.5-million for the same period in 2022, largely the result of a decrease in share-based compensation costs and professional consulting fees.
• Net loss was $2.4-million for the quarter ended Sept. 30, 2023, compared with a net loss of $6-million for the same period in 2022.

About Promis Neurosciences Inc.

Promis Neurosciences is a clinical development-stage biotechnology company focused on generating and developing antibody therapeutics selectively targeting toxic misfolded proteins in neurodegenerative diseases such as Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS) and multiple system atrophy (MSA). 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 MSA. Promis has offices in Toronto, Ont., and Cambridge, Mass.

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