ProMIS Neurosciences Announces Second Quarter

ProMIS Neurosciences Announces Second Quarter

2022 Financial and Operating Results

Ontario and CAMBRIDGE, Massachusetts - August 15, 2022 - ProMIS Neurosciences, Inc. (TSX: PMN) (Nasdaq:

PMN) ("ProMIS" or the "Company"), a biotechnology company focused on the discovery and development of antibody

therapeutics targeting misfolded proteins such as toxic oligomers, implicated in the development of neurodegenerative diseases, today

announced its operational and financial results for the three months ended June 30, 2022.

"Q2 was another quarter of strong progress

for ProMIS Neurosciences," according to Gene Williams, Chairman and CEO. "We completed the work necessary to list on Nasdaq,

effective July 7. We want to thank our shareholders for their strong support during this process. Our lead program for Alzheimer's

disease, PMN310, remains on track for an investigational new drug application, or IND, filing by the end of this year, following valuable

written feedback from the FDA on our pre-IND submission. In addition, two other candidate antibodies are undergoing "humanization",

a process required for use in humans and the first step to support future IND filings, subject to discussions with the FDA. Those are

PMN267, targeting misfolded TDP-43 in ALS, and PMN442, targeting misfolded alpha-synuclein in MSA (multiple system atrophy). We believe

our unique discovery platform will also allow us to make "vaccine versions" of our antibody targets. We previously reported

that a vaccine version of PMN310's target showed positive initial results, eliciting strong antibody responses with selectivity

for toxic amyloid-beta oligomers in preclinical testing. A second proprietary ProMIS therapeutic vaccine program has been initiated.

Dr. Neil Cashman's lab at UBC received a Weston Family Foundation Grant to conduct early work on an alpha synuclein therapeutic

vaccine. Our discovery lab continues to address new disease-causing misfolded proteins with our unique discovery engine, as we seek to

rapidly expand our IP and product candidate portfolio. To support our progress, we will continue to add to our strong and experienced

management team. Later this year, we and many others are looking forward to the readout of the Eisai lecanemab pivotal trial which, if

positive, could be a strong catalyst for the Alzheimer's field. We believe that that fact, combined with our planned PMN310 IND

filing, the progress of our other programs, and early signs of a biotech market strengthening, could lead to a positive second half of

ProMIS lead program PMN310: Potential Next

Generation Therapy for AD

PMN310, an antibody therapy selective for toxic

amyloid-beta oligomers in AD, is our lead product candidate. In the second quarter of 2022, the Company made significant progress on

the program elements.

Producer cell line development has been completed.

We have manufactured material to be used in Good Laboratory Practice ("GLP") toxicology studies and are on track for producing

current Good Manufacturing Practice ("cGMP") material for use in the initial clinical trials of PMN310, if allowed to proceed.

We have completed pilot toxicology, pharmacokinetics and tissue cross reactivity ("TCR") studies and secured slots for the

formal GLP studies that are required for an IND. Development of assays to measure drug levels in nonhuman primates and in human studies

was completed in the second quarter of 2022. Vendors have been contracted to perform these assays in support of our GLP studies.

In addition, we have initiated formulation development

with two vendors, with the goal of developing a high concentration formulation that can support subcutaneous dosing as a future step

to improve overall convenience and patient compliance. We expect completion of formulation work in the third quarter of 2022.

Dr. Neil Cashman gave a presentation on

the ProMIS discovery platform and PMN310 antibody program entitled "Selective antibody targeting of pathogenic proteins: Maximizing

target engagement, minimizing target distraction" at the Neuro4D conference in Mainz, Germany.

Expenditures for PMN310 in the three months ended

June 30, 2022 were approximately $1.8 million, not including allocations of senior management time.

ALS Portfolio, including TAR-DNA binding

The top priority for our scientific

validation efforts, largely centered in Dr. Neil Cashman's laboratory at UBC, is currently the Company's amyotrophic

lateral sclerosis ("ALS") portfolio. This portfolio includes antibodies targeting misfolded

forms of TDP-43, receptor of activated protein C kinase 1 ("RACK1"), and superoxide dismutase 1 ("SOD1"). Based

on the binding profile and activity of selected antibodies/intrabodies against misfolded TDP-43, we have declared PMN267 as our lead

candidate for the treatment of ALS. The evidence to date supports potential use of PMN267 both as an intrabody or as a conventional antibody

acting inside neurons as well as outside neurons to stop the cell-to-cell propagation of toxic TDP-43 aggregates. PMN267 is currently

being humanized in a human IgG1 framework for future clinical testing.

ProMIS' capability to create highly selective

antibodies is most critical for intracellular activity since physiologically important TDP 43 is active inside the neuron and should

be avoided by the intrabodies to reduce the possibility of harmful side effects. In addition, with world expert RNA scientist, Dr. Michelle

Hastings, ProMIS is exploring antisense oligonucleotide ("ASO") therapeutic approaches, and with Dr. Justin Yerbury,

is exploring protein degradation ("PROTACS") approaches in ALS.

While targeting TDP-43 has promising therapeutic

potential, we believe an optimal disease modifying therapeutic approach to ALS may require addressing multiple misfolded protein targets

(TDP-43, RACK1, and SOD1), with different modalities (antibody, gene therapy vectorized antibody, ASO, PROTACS). ProMIS' preclinical

data in the ALS space were shared in May 2022 at the ALS Drug Development Summit in Boston, in platform presentations entitled "Antibody

vectorization for selective targeting of intracellular aggregates of misfolded TDP-43" and "Gene therapies for sporadic ALS:

An emerging concept". In addition to pursuing development of PMN267, we are exploring the scientific interaction between therapies

addressing these various targets, and our goal is to identify and develop a portfolio of complementary therapies that alone and/or together

may play a significant role in effectively treating disease.

In the three months ending June 30, 2022,

our total expenditure for the ALS portfolio was $0.3 million, not including allocations of senior management time.

We continue to make considerable progress on

other key projects, in addition to our top priorities PMN310 and PMN267. Based on the characterization of selected antibodies to date,

we have declared PMN442 as our lead alpha-synuclein product candidate. In vivo testing in mouse disease models is ongoing and results

are expected in the second half of 2022. PMN442 is currently being humanized in a human IgG1 framework for future clinical testing

the amyloid vaccine program, the results of our initial studies with the University of Saskatchewan Vaccine and Infectious Disease Organization

("VIDO") were presented at the T21 Research Society Conference in Long Beach, CA in June 2022 in a talk entitled: "Vaccination

approach for prevention and early intervention in Alzheimer's disease: Selective targeting of computationally-derived conformational

B cell epitopes of soluble amyloid-beta toxic oligomers". Building on the data obtained with VIDO,

additional mouse studies are ongoing with VIDO with the goal of developing an optimized AD vaccine, conjugating our peptide antigens

to a carrier protein in formulation with an adjuvant. A vaccination study in a mouse model of AD is ongoing.

David Wishart, our Chief Physics Officer, and

his team are pursuing multiple novel targets including DISC1 involved in the pathogenesis of schizophrenia. ASO approaches to target

pathogenic DISC1 are also being explored with Dr. Michelle Hastings.

Recent Corporate Highlights

In April 2022, the Company announced the

appointment of Dr. Larry Altstiel M.D., Ph.D. to the role of Chief Medical Officer. Dr. Altstiel brings decades of medical

expertise in neurodegenerative diseases and experience in the pharmaceutical industry, formerly serving as vice president and head of

neuroscience and clinical research at Pfizer, Inc. (NYSE: PFE), where he led the selection of drug candidates, development and oversight

of multiple preclinical studies and clinical studies from Phase 1 through Phase 3. He is currently part time Chief Medical Officer at

Pinteon Therapeutics.

In April 2022, the Company announced that

it nominated monoclonal antibody PMN267 as the lead candidate for its ALS program based on its binding profile and activity in cell systems.

Using ProMIS's discovery platform, ProMIS generated high-affinity monoclonal antibodies that are selective for the misfolded toxic

form of TDP-43 and recent data generated by two independent sources have now provided additional support for the therapeutic potential

In May 2022, the Company announced its participation

at the Neuro4D International Conference, held at the Atrium Hotel in Mainz, Germany on May 16-17, 2022. In the conference session

"From Disease Insights to Therapeutic Options," Dr. Neil Cashman, ProMIS's Chief Scientific Officer and a member

of the Conference Advisory Committee, delivered an oral presentation, entitled: "Abeta oligomers in Alzheimer's disease:

target engagement and target distraction." A large body of scientific data has implicated misfolded oligomers as the toxic molecular

species of amyloid-beta ("Abeta") relevant to Alzheimer's disease. In his presentation, Dr. Cashman discussed

the importance of selectivity for toxic Abeta oligomers in order to avoid "target distraction", namely the absorption of

antibodies by monomers which can reduce effective targeting of oligomers, and binding to plaque and vascular deposits which has been

associated with adverse events such as brain edema.

The Company filed a registration statement on

Form 10 filed with the U.S. Securities and Exchange Commission on June 22, 2022, as amended June 30, 2022 and July 1,