Rhythm Pharmaceuticals Reports Third Quarter 2022 Financial Results and Business Update -- U.S. launch of IMCIVREE (setmelanotide) for Bardet-Biedl Syndrome progresses with strong demand with more than 120 prescriptions

Rhythm Pharmaceuticals Reports Third Quarter

2022 Financial Results and Business Update

-- U.S. launch of IMCIVREE

(setmelanotide) for Bardet-Biedl Syndrome progresses with strong demand with more than 120 prescriptions since FDA approval -

-- EC authorization for IMCIVREE expanded to

include BBS; UK launch in POMC and LEPR deficiencies underway -

-- Setmelanotide received FDA Breakthrough

Therapy Designation for hypothalamic obesity; Phase 3 trial expected to be initiated in early 2023 --

-- Successfully completed $140 million public

offering with exercise of underwriters' option, extending cash runway into 2025 --

-- Management to host conference call today

BOSTON, November 8, 2022 -

Rhythm Pharmaceuticals, Inc. (Nasdaq: RYTM) today reported financial results and provided a business update for the third

quarter ended September 30, 2022.

"The third quarter of 2022 was transformative for Rhythm and

our global strategy to deliver IMCIVREE (setmelanotide) as the first precision medicine to address the needs of patients

and families living with hyperphagia and severe obesity caused by rare melanocortin-4 receptor (MC4R) pathway diseases," said David

Meeker, M.D., Chair, President and Chief Executive Officer of Rhythm. "We are pleased with our U.S. commercial launch and the initial

reception of IMCIVREE for Bardet-Biedl syndrome (BBS), and we look forward to continuing to build on early market access successes in

Dr. Meeker continued, "We also are excited by the potential

of setmelanotide to achieve a profound, consistent and sustained reduction in body weight in patients with hypothalamic obesity as demonstrated

in our Phase 2 and long-term-extension trials. Following recent feedback from the U.S. Food and Drug Administration (FDA), we look forward

to initiating our pivotal Phase 3 trial early in 2023."

Third Quarter and Recent Business Highlights:

Development, Regulatory and Commercial Updates:

Hypothalamic Obesity

Bardet-Biedl Syndrome

POMC and LEPR Deficiency Obesities

Clinical Development Updates:

Key Upcoming Milestones:

Rhythm expects to achieve the following near-term milestones:

Third Quarter 2022 Financial Results:

Year to Date 2022 Financial Results:

Financial Guidance: Based

on its current operating plans, Rhythm expects that its existing cash and cash equivalents and short-term investments as of September 30,

2022 will be sufficient to fund operations into 2025.

Conference Call Information

Rhythm Pharmaceuticals will host a live

conference call and webcast at 8:00 a.m. ET today to review its third quarter 2022 financial results and recent business activities.

Participants may register for the conference call here. While not required, it is recommended that participants join the

call ten minutes prior to the scheduled start.

A live webcast of the call will also 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 call.

About Rhythm Pharmaceuticals

Rhythm is a commercial-stage biopharmaceutical company committed

to transforming the lives of patients and their families living with hyperphagia and severe obesity caused by rare melanocortin-4

receptor (MC4R) pathway diseases. Rhythm's precision medicine, setmelanotide, is approved 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 monogenic or

syndromic obesity due to pro-opiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1) or leptin receptor

(LEPR) deficiency confirmed by genetic testing, or patients with a clinical diagnosis of Bardet-Biedl syndrome (BBS).

The European Commission (EC) has authorized setmelanotide for the treatment of obesity and the control of hunger

associated with genetically confirmed BBS or genetically confirmed loss-of-function biallelic POMC, including PCSK1, deficiency or

biallelic LEPR deficiency in adults and children 6 years of age and above. The UK's Medicines & Healthcare

Products Regulatory Agency (MHRA) authorized setmelanotide 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. Additionally, Rhythm is advancing a broad clinical development program for setmelanotide in other

rare MC4R pathway diseases, including acquired hypothalamic 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, MA.

Setmelanotide Indication

States, setmelanotide is indicated for chronic weight management in adult and pediatric patients 6 years of age and older with monogenic

or syndromic obesity due to POMC, PCSK1 or LEPR deficiency as determined by an FDA-approved test demonstrating variants in POMC, PCSK1

or LEPR genes that are interpreted as pathogenic, likely pathogenic, or of uncertain significance (VUS) or BBS.

In the European Union, setmelanotide is indicated for the treatment

of obesity and the control of hunger associated with genetically confirmed Bardet-Biedl syndrome (BBS) or genetically confirmed loss-of-function

biallelic pro-opiomelanocortin (POMC), including PCSK1, deficiency or biallelic leptin receptor (LEPR) deficiency in adults and children

6 years of age and above.

United States and Europe, Setmelanotide should be prescribed and supervised by a physician with expertise in obesity with underlying

Setmelanotide is not indicated for the treatment of patients with

the following conditions as setmelanotide would not be expected to be effective:

WARNINGS AND PRECAUTIONS

Skin Monitoring: Setmelanotide

may lead to generalized increased skin pigmentation and darkening of pre-existing naevi because of its pharmacologic effect. Full body

skin examinations should be conducted annually to monitor pre-existing and new skin pigmentary lesions before and during treatment with

Heart rate and blood pressure monitoring: Heart

rate and blood pressure should be monitored as part of standard clinical practice at each medical visit (at least every 6 months) for

patients treated with setmelanotide.

Prolonged penile erection: Spontaneous

penile erections have been reported in clinical trials with setmelanotide. Patients who have a penile erection lasting longer than 4

hours should be instructed to seek emergency medical attention for potential treatment of priapism.

Depression: In clinical

trials, depression has been reported in patients treated with setmelanotide. Patients with depression should be monitored at each medical

visit during treatment with setmelanotide. Consideration should be given to discontinuing setmelanotide if patients experience suicidal

thoughts or behaviors.

Pediatric Population: The

prescribing physician should periodically assess response to setmelanotide therapy. In growing children, the impact of weight loss on

growth and maturation should be evaluated. The prescribing physician should monitor growth (height and weight) using age- and sex-appropriate

medicinal product contains 10 mg benzyl alcohol in each ml. Benzyl alcohol may cause allergic reactions. Patients who are pregnant or

breastfeeding should be advised of the potential risk from the excipient benzyl alcohol, which might accumulate over time and cause metabolic

acidosis. This medicinal product should be used with caution in patients with hepatic or renal impairment, because of the potential risk

from the excipient benzyl alcohol which might accumulate over time and cause metabolic acidosis.

Sodium: This medicinal

product contains less than 1 mmol sodium (23 mg) per dose, that is to say essentially "sodium-free."

The most frequent adverse reactions are hyperpigmentation (51%), injection

site reaction (39%), nausea (33%), and headache (26%).

USE IN SPECIFIC POPULATIONS

data from the use of setmelanotide in pregnant women. Animal studies do not indicate direct harmful effects with respect to reproductive

toxicity. However, administration of setmelanotide to pregnant rabbits resulted in decreased maternal food consumption leading to embryo-foetal