Mr. Roberto Bellini reports

BELLUS HEALTH REPORTS FIRST QUARTER 2023 FINANCIAL RESULTS AND BUSINESS HIGHLIGHTS

Bellus Health Inc. has released its financial and operating results for the quarter ended March 31, 2023.

"Our merger agreement with GSK [PLC] underscores our corporate and clinical achievements to date and marks the start of a new chapter for our potentially best-in-class P2X3 receptor antagonist, camlipixant," commented Roberto Bellini, president and chief executive officer of Bellus Health. "We are confident that GSK's resources and focused expertise in the development and commercialization of respiratory therapies will help us to achieve our mission of bettering the lives of patients suffering from persistent cough. As we work to close this transaction with GSK, we remain committed to advancing our Calm phase 3 program and are on track to report top-line data from Calm-1 in the second half of 2024 and Calm-2 in 2025."

Program and corporate highlights

GSK to acquire Bellus Health:

• On April 18, 2023, GSK and Bellus Health announced that they have entered into an agreement under which GSK will acquire Bellus Health for $14.75 (U.S.) per share of common stock in cash representing an approximate total equity value of $2.0-billion (U.S.). The per-share price represents a premium of approximately 103 per cent to Bellus Health's closing stock price on April 17, 2023, and a premium of approximately 101 per cent to Bellus Health's volume-weighted average price (VWAP) over the prior 30 trading days. The transaction remains subject to shareholder and regulatory approvals, and is expected to close in the third quarter of 2023 or earlier.

Actively advancing the Calm phase 3 clinical program (Calm-1 and Calm-2 trials) for camlipixant (BLU-5937) in RCC, with patient enrolment continuing:

• The Calm phase 3 clinical program was initiated by the company in the fourth quarter of 2022, with patient enrolment continuing. The Calm program consists of two pivotal trials, Calm-1 and Calm-2, with the primary end point of 24-hour cough frequency measured at 12 and 24 weeks, respectively, using the VitaloJAK cough monitoring system.
• Top-line results from Calm-1 are expected in the second half of 2024, and top-line results from Calm-2 are expected in 2025.

Pursuing development of its P2X3 receptor pipeline:

• Bellus Health reported positive results from its phase 1 clinical trial investigating the safety, tolerability and pharmacokinetic profile of a once-daily, extended-release (ER) formulation of camlipixant. The ER formulation demonstrated equivalent bioavailability to the twice-daily immediate release (IR) formulation. In addition, the ER formulation was well tolerated, with safety data observed to be consistent with previous camlipixant trials and no taste-related adverse events reported.

Presenting at the coming American Thoracic Society (ATS) 2023 International Conference, being held in Washington, D.C., from May 19 to May 24, 2023:

• The company will be presenting an oral abstract entitled "Response in Patient-reported Cough Severity in Soothe, a Phase 2b Trial of Camlipixant in Refractory Chronic Cough" on Sunday, May 21, 2023, at 3:15 p.m. to 3:27 p.m. ET, and a poster presentation entitled "Model-based Dose Selection for Phase 3 Trials of the Selective P2X3 Antagonist Camlipixant in Refractory Chronic Cough" will be presented on Monday, May 22, 2023, at 11:30 a.m. to 1:15 p.m. ET. Following the ATS 2023 International Conference, the presentation materials will be available in the scientific publications section of Bellus Health's website.
• Additionally, conference participants are invited to attend two Bellus Health-sponsored guru bars on Tuesday, May 23, 2023. Booth No. 1100 entitled "Refractory Chronic Cough: Is it All in Our Head?" will be available at 1 p.m. to 1:20 p.m. ET, and Booth No. 1200 entitled "Understanding the Roadmap to Diagnosing Refractory Chronic Cough" will be available at 1:30 p.m. to 1:50 p.m. ET.

Presented at the American Academy of Allergy, Asthma & Immunology (AAAAI) annual meeting and at the American Society of Clinical Pharmacology & Therapeutics (ASCPT) 2023 annual meeting:

• The company presented clinical data from the phase 2b Soothe trial at the AAAAI annual meeting, held in San Antonio, Tex., from Feb. 24 to Feb. 27, 2023. The company also presented results from phase 1 drug to drug interactions studies of camlipixant at the ASCPT 2023 annual meeting, held in Atlanta, Ga., from March 22 to March 24, 2023. The presentation materials are available in the scientific publications section of Bellus Health's website.

Financial results

Cash position: As of March 31, 2023, the company had available cash, cash equivalents and short-term investments totalling $313.0-million, compared with $337.1-million (U.S.L) as of Dec. 31, 2022. The net decrease for the three-month period ended March 31, 2023, is primarily attributable to funds used to finance the company's operating activities, mainly the research and development activities associated with its product candidate camlipixant (BLU-5937).

Net loss: For the quarter ended March 31, 2023, net loss amounted to $25.1-million (U.S.) (20 U.S. cents per share), compared with $14.4-million (U.S.) (13 U.S. cents per share) for the same period in 2022.

Research and development expenses: Research and development expenses, net of research tax credits, amounted to $22.3-million (U.S.) for the quarter ended March 31, 2023, compared with $11.3-million (U.S.) for the same period in 2022, a $11.0-million (U.S.) or 98-per-cent year-over-year increase. The increase is primarily attributable to higher external R&D spend incurred for the development of camlipixant, mainly for activities in relation to the company's Calm phase 3 clinical program, which was initiated in the fourth quarter of 2022. The increase is also due to higher stock-based compensation expense in relation to the company's stock option plan and higher work force expenses due to an increase in head count to support the development of camlipixant.

General and administrative (G&A) expenses: General and administrative expenses amounted to $5.4-million (U.S.) for the quarter ended March 31, 2023, compared with $4.1-million (U.S.) for the same period in 2022, a $1.3-million (U.S.) or 33-per-cent year-over-year increase. The increase is mainly attributable to higher external G&A expenses, as well as to higher stock-based compensation expense in relation to the company's stock option plan.

Net finance income: Net finance income amounted to $2.7-million (U.S.) for the quarter ended March 31, 2023, compared with $1.0-million (U.S.) for the same period in 2022. The increase in net finance income is mainly attributable to higher interest income due to the increased cash, cash equivalents and short-term investments position following the July, 2022, offering and the increase in interest rates, offset in part by a lower foreign exchange gain in the current period resulting from the conversion in U.S. dollars of the company's net monetary assets denominated in Canadian dollars.

The company's full unaudited consolidated interim financial statements and accompanying management's discussion and analysis for the quarter ended March 31, 2023, will be available shortly on SEDAR and on EDGAR.

About Bellus Health Inc.

Bellus Health is a clinical-stage biopharmaceutical company working to better the lives of patients suffering from persistent cough, starting with the development of camlipixant (BLU-5937) for the treatment of refractory chronic cough (RCC). Camlipixant, the company's lead asset, is an investigational P2X3 receptor antagonist for the treatment of refractory chronic cough (RCC), which is currently being evaluated in the Calm phase 3 clinical program. With no approved treatments in the United States, camlipixant has the potential to be a breakthrough in the RCC treatment landscape.

Chronic cough is deined as a cough lasting longer than eight weeks. When the cause of chronic cough cannot be identified or the cough persists despite treatment of any associated condition, the condition is referred to as RCC. RCC is a frequent, yet often underrecognized, medical condition that has significant physical, social and psychological consequences on one's quality of life. There are currently no approved treatments for this condition in the United States, European Union or the United Kingdom.

We seek Safe Harbor.