Mr. Neil Warma reports

PROMIS NEUROSCIENCES ISSUES LETTER TO SHAREHOLDERS

Promis Neurosciences Inc.'s chief executive officer, Neil Warma, issued the following letter to the company's shareholders.

Dear Promis shareholders,

On behalf of the board of directors, I am honoured to have recently joined the Promis management team as the interim CEO to steer the company through what we believe will be an exciting and informative clinical development path that could demonstrate the potential of Promis in the treatment of multiple dementias. Your steadfast support has been instrumental in our progress thus far, and I am excited to share some pivotal developments that will shape the future of our company.

As part of our commitment to becoming a leader in the treatment of dementias, we are intensifying our focus on advancing our drug candidates into and through clinical development. Our ultimate goal is to get these potential new drugs to patients who are in desperate need of safe and effective treatment options.

Promis's scientific platform is truly unique. Designed and developed by our chief scientific officer, Dr. Neil Cashman, MD, it leverages artificial intelligence (AI) to identify novel epitopes on toxic misfolded proteins, which have been shown to be an underlying cause of multiple diseases. Using a complex and proprietary algorithm, Dr. Cashman and the team at Promis are able to identify novel epitopes on misfolded proteins and design antibodies (drug candidates) that we believe will bind with high affinity to these targets, resulting in the elimination of these toxic and harmful proteins from the brain to prevent or slow disease progression. It is an elegant, yet complex, solution that we believe is clearly differentiated among neurology-focused companies. The deliberate specificity of our antibodies is one unique aspect of our approach and we have been aggressive with our intellectual property strategy and have built a robust patent portfolio. Our belief is that if you can specifically target only the harmful or pathogenic proteins (that is, misfolded proteins), this should result in a beneficial outcome to the patient and with fewer side effects. Our wealth of preclinical data demonstrates this, and we are hopeful the clinical data will continue to support this belief.

I am pleased to share that our lead clinical drug candidate, PMN310, is progressing well through phase 1a clinical development for the treatment of Alzheimer's disease (AD). We recently received clearance from the independent data and safety monitoring board to advance PMN310 to the second dose level in this single ascending dose (SAD) trial in healthy volunteers. This milestone is a testament to the dedication and hard work of our clinical development team. We believe PMN310 holds immense promise to address the urgent need for effective treatments in AD and remains unique in its ability to specifically target only misfolded forms (that is, toxic oligomers) of amyloid-beta (Abeta), which are believed to drive disease progression in AD. This specificity is expected to improve efficacy outcomes and prevent any off-target safety issues, which are common with other AD therapies currently marketed or in development.

We remain committed to advancing PMN310 through the rigorous clinical development process. Over the coming months, we will be laser-focused on completing the SAD clinical study with PMN310 and, subsequently, rolling into the phase 1b multiple ascending dose (MAD) study, subject to the availability of sufficient capital. As the phase 1b MAD study will be conducted in AD patients, this could provide the first signal demonstrating that PMN310 positively benefits patients with AD. We expect to report data on the phase 1a study around mid-2024. This is our first drug candidate to advance into the clinic based on our novel and differentiated platform and should lead the way for others to follow. Beyond AD, we have our targets set on the treatment of amyotrophic lateral sclerosis (ALS), multiple system atrophy (MSA) and Parkinson's disease.

In line with our commitment to collaboration and growth, we are aggressively pursuing partnering discussions to leverage synergies and enhance our capabilities. We believe that strategic partnerships will not only accelerate our progress but also enable us to bring innovative treatments to patients more efficiently and could provide significant validation to the platform.

We truly believe that we have a powerful technology platform from which multiple drug candidates could be developed and we are diligent in identifying ways to untap this potential while not distracting our focus from the lead development program with PMN310 and our tight control on cash management. Specific to our pipeline candidates, earlier this year, we presented data at key scientific conferences including validation of RACK1 as a potentially novel target for the treatment of ALS and frontotemporal lobar degeneration (FTLD-TDP). We remain excited about the early data generated for these debilitating diseases.

In summary, I am honoured to be representing you as Promis's interim CEO. Our priorities are clear: to advance PMN310 through clinical development; to increase the company's visibility to better highlight the significant value of Promis; to advance strategic partnering discussions; and to effectively allocate and manage cash. We remain committed to our goal of generating shareholder value and improving the lives of patients worldwide.

Finally, I want to express my deepest gratitude for your ongoing support as shareholders. Your belief in our mission and commitment to making a meaningful impact on the lives of those affected by neurodegenerative diseases drive us every day. Together, we are building a company that has the potential to treat multiple dementias and revolutionize the field in order to bring hope to millions of individuals and their families.

As we navigate this transformative period, I am confident that Promis will emerge stronger, more resilient and better positioned to make significant contributions to health care. We are on an exciting journey, and I look forward to sharing more successes with you in the future.

Thank you for your continued trust and support.

Sincerely,

Mr. Warma

Chief executive officer

Promis Neurosciences

About Promis Neurosciences Inc.

Promis Neurosciences is a clinical-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 applies a 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.

We seek Safe Harbor.