Rhythm Pharmaceuticals Reports First Quarter 2022 Financial Results and Business Update -- Patient identification and physician engagement ongoing in preparation for U.S. commercial launch in June 2022 in BBS and Alstr m

Rhythm Pharmaceuticals Reports First Quarter

2022 Financial Results and Business Update

-- Patient identification and physician engagement

ongoing in preparation for U.S. commercial launch in June 2022 in BBS and Alstr m syndrome, pending FDA approval --

-- First commercial patients treated with IMCIVREE

(setmelanotide) in France under paid early access program --

-- First patients enrolled in Phase 3 EMANATE

trial and Phase 2 DAYBREAK trial --

-- Multiple abstracts accepted for presentation

-- Management to host conference call today

BOSTON, May 3, 2022 - Rhythm

Pharmaceuticals, Inc. (Nasdaq: RYTM), a commercial-stage biopharmaceutical company committed to transforming the care of people living

with rare genetic diseases of obesity, today reported financial results and provided a business update for the first quarter ended March

"We are excited by the progress we are making towards our long-term

vision of transforming the care of individuals living with rare genetic diseases of obesity," said David Meeker, M.D., Chair, President

and Chief Executive Officer of Rhythm. "We continue to build out our U.S. and international commercial organizations while advancing

patient identification efforts to support a successful U.S. launch for setmelanotide in Bardet-Biedl and Alstr m syndromes in June,

pending U.S. Food and Drug Administration (FDA) approval. We achieved our first European sales in France during the quarter and continue

to have constructive market access discussions with authorities in several key European markets."

Dr. Meeker continued, "Additionally, our robust clinical

development program is advancing with patients enrolled in multiple phase 2 and 3 clinical trials. We have optimized our ongoing Phase

3 EMANATE trial to focus exclusively on patient populations with the highest probability of responding to setmelanotide and narrowed our

Phase 2 DAYBREAK trial to more efficiently evaluate rare variants associated with ten prioritized genes. In the months ahead, we look

forward to reporting interim data from our Phase 2 trial in hypothalamic obesity and our Phase 2 Basket Study in obesity due to a variant

in the melanocortin-4 receptor (MC4R)."

First Quarter and Recent Business Highlights:

Update on Bardet-Biedl and Alstr m Syndromes:

International Updates:

Clinical Development Updates:

Key Upcoming Milestones:

First Quarter 2022 Financial Results:

Financial Guidance: Based on its current operating plans,

Rhythm expects that its existing cash, cash equivalents and short-term investments as of March 31, 2022 will be sufficient to fund

its operating expenses and capital expenditure requirements into at least the fourth quarter of 2023.

Conference Call Information

Rhythm Pharmaceuticals will host a live conference call and webcast

at 8:30 a.m. ET today to discuss this update, as well as review its first quarter 2022 financial results and recent business

activities. The conference call may be accessed by dialing (866) 374-5140 (domestic) or (404) 400 0571 (international) and referring to

conference ID 79122322. A webcast of the call will be available under "Events and Presentations" in the Investor Relations section

of the Rhythm Pharmaceuticals website at http://ir.rhythmtx.com/. The archived webcast will be available on Rhythm

Pharmaceuticals' website approximately two hours after the conference call and will be available for 30 days following the

About Rhythm Pharmaceuticals

Rhythm is a commercial-stage

biopharmaceutical company committed to transforming the treatment paradigm for people living with rare genetic diseases of obesity. Rhythm's

precision medicine, IMCIVREE (setmelanotide), was approved in November 2020 by the U.S. Food and Drug Administration (FDA)

for chronic weight management in adult and pediatric patients 6 years of age and older with obesity due to POMC, PCSK1 or LEPR deficiency

confirmed by genetic testing and in July and September 2021, respectively, by the European Commission (EC) and Great Britain's Medicines

& Healthcare Products Regulatory Agency (MHRA) for the treatment of obesity and the control of hunger associated with genetically

confirmed loss-of-function biallelic POMC, including PCSK1, deficiency or biallelic LEPR deficiency in adults and children 6 years of

age and above. IMCIVREE is the first-ever FDA-approved and EC- and MHRA-authorized therapy for patients with these rare genetic diseases

of obesity. The Company submitted a supplemental New Drug Application (sNDA) to the FDA, which was accepted for filing in November

2021 and is currently assigned a Prescription Drug User Fee Act (PDUFA) goal date of June 16, 2022, for the treatment of obesity

and control of hunger in adult and pediatric patients six years of age and older with Bardet-Biedl Syndrome (BBS) or Alstr m syndrome.

A Type II variation application to the European Medicines Agency seeking regulatory approval and authorization for setmelanotide

to treat obesity and control of hunger in adult and pediatric patients 6 years of age and older with BBS also is under review. Additionally,

Rhythm is advancing a broad clinical development program for setmelanotide in other rare genetic diseases of obesity and is leveraging

the Rhythm Engine and the largest known obesity DNA database -- now with approximately 45,000 sequencing samples -- to improve the understanding,

diagnosis and care of people living with severe obesity due to certain genetic deficiencies. Rhythm's headquarters is in Boston,

IMCIVREE (setmelanotide) Indication

United States, IMCIVREE is indicated for chronic weight management in adult and pediatric patients 6 years of age and older with obesity

due to proopiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1), or leptin receptor (LEPR) deficiency. The condition

must be confirmed by genetic testing demonstrating variants in POMC, PCSK1, or LEPR genes that

are interpreted as pathogenic, likely pathogenic, or of uncertain significance (VUS).

In the EU and Great Britain, IMCIVREE is indicated for the treatment

of obesity and the control of hunger associated with genetically confirmed loss-of-function biallelic POMC, including PCSK1, deficiency

or biallelic LEPR deficiency in adults and children 6 years of age and above. IMCIVREE should be prescribed and supervised by a physician

with expertise in obesity with underlying genetic etiology.

IMCIVREE is not indicated for the treatment of patients with the following

conditions as IMCIVREE would not be expected to be effective:

Important Safety Information

WARNINGS AND PRECAUTIONS

Disturbance in Sexual Arousal: Sexual adverse reactions

may occur in patients treated with IMCIVREE. Spontaneous penile erections in males and sexual adverse reactions in females occurred in

clinical studies with IMCIVREE. Instruct patients who have an erection lasting longer than 4 hours to seek emergency medical attention.

Depression and Suicidal Ideation: Some drugs that target

the central nervous system, such as IMCIVREE, may cause depression or suicidal ideation. Monitor patients for new onset or worsening of

depression. Consider discontinuing IMCIVREE if patients experience suicidal thoughts or behaviors.

Skin Pigmentation and Darkening of Pre-Existing Nevi: IMCIVREE

may cause generalized increased skin pigmentation and darkening of pre-existing nevi due to its pharmacologic effect. This effect is reversible

upon discontinuation of the drug. Perform a full body skin examination prior to initiation and periodically during treatment with IMCIVREE

to monitor pre-existing and new skin pigmentary lesions.

Risk of Serious Adverse Reactions Due to Benzyl Alcohol Preservative

in Neonates and Low Birth Weight Infants: IMCIVREE is not approved for use in neonates or infants.

USE IN SPECIFIC POPULATIONS

Discontinue IMCIVREE when pregnancy is recognized unless the benefits

of therapy outweigh the potential risks to the fetus.

Treatment with IMCIVREE is not recommended for use while breastfeeding.

To report SUSPECTED ADVERSE REACTIONS, contact Rhythm Pharmaceuticals at

+1 (833) 789-6337 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

See Full Prescribing Information, EU SmPC

and MHRA SmPC for IMCIVREE.

Forward-Looking Statements

This press release contains forward-looking

statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release

that do not relate to matters of historical fact should be considered forward-looking statements, including without limitation statements

regarding the potential, safety, efficacy, and regulatory and clinical progress of setmelanotide, including the anticipated timing for

initiation of clinical trials and release of clinical trial data and our expectations surrounding potential regulatory submissions, approvals

and timing thereof, our business strategy and plans, including regarding commercialization of setmelanotide, sales of our lead product

candidate IMCIVREE, our participation in upcoming events and presentations, and the sufficiency of our cash, cash equivalents and short-term

investments to fund our operations. Statements using word such as "expect", "anticipate", "believe",