Rhythm Expands IMCIVREE to Acquired Obesity in Canada

Health Canada has approved Rhythm Pharmaceuticals' IMCIVREE (setmelanotide) for weight management in adults and children four years and older with acquired hypothalamic obesity, extending a drug first approved in Canada in 2023 for a narrower set of genetic conditions. The 22 September 2026 approval follows FDA's own approval of the same indication in March, and gives setmelanotide its fourth on-label use in Canada.

Restoring a pathway the brain can no longer run itself

Acquired hypothalamic obesity develops after injury to the hypothalamus — most often from a craniopharyngioma or other brain tumor, its surgical removal, radiation, trauma, stroke or infection — that disrupts the leptin-melanocortin-MC4R pathway governing hunger and energy use, driving rapid, severe weight gain that standard weight-loss approaches rarely control. Rhythm Pharmaceuticals' IMCIVREE is a daily injected MC4R agonist designed to restore signalling in that same pathway rather than suppress appetite through a different route, as GLP-1 drugs do.

The approval rests on TRANSCEND, a global, randomized, double-blind, placebo-controlled Phase 3 trial. Its primary-endpoint population of 120 patients, aged four and older and randomized 2:1 to setmelanotide or placebo, showed a mean BMI change of −15.8% with setmelanotide versus +2.6% with placebo at 52 weeks (p<0.0001). A later release covering the trial's fuller 142-patient cohort reported an 18.8% placebo-adjusted BMI reduction, the figure Rhythm has cited in support of both its FDA and Health Canada filings.

Three things this approval adds

01

A fourth Canadian indication for one drug

Health Canada first approved IMCIVREE in 2023 for Bardet-Biedl syndrome and biallelic POMC, PCSK1 or LEPR deficiency; acquired hypothalamic obesity is a new, larger and non-genetic population added to the same label.

02

A trial population defined by injury, not genetics

TRANSCEND enrolled patients by documented hypothalamic damage rather than a genetic test, unlike setmelanotide's original indications — a different diagnostic bar for prescribers to clear.

03

A number regulators keep repeating

The −15.8%-versus-+2.6% BMI comparison at 52 weeks has anchored FDA's March 2026 approval, this Health Canada approval, and Rhythm's own investor materials.

The approval in four figures

120patients in TRANSCEND's primary 52-week analysis, randomized 2:1

-15.8%mean BMI change with setmelanotide vs. +2.6% with placebo at Week 52

2020year IMCIVREE first won FDA approval, for a narrower set of genetic obesity disorders

476Rhythm employees as of March 2026, up from 225 in 2023

Figures from Rhythm Pharmaceuticals' TRANSCEND trial announcements and its public employee-count disclosures.

What Health Canada approved, and what it didn't

The 22 September 2026 approval covers weight management in adults and pediatric patients four years and older with acquired hypothalamic obesity, per Rhythm's announcement. Health Canada's public Drug Product Database still shows only IMCIVREE's original 2023 authorization, for Bardet-Biedl syndrome and biallelic POMC, PCSK1 or LEPR deficiency, under DIN 02537745; the database entry had not yet been updated to reflect the new indication as of this writing, a lag Regulatory News will note when the record catches up.

“Acquired hypothalamic obesity is a rare, complex MC4R pathway disease that develops following injury to the hypothalamus, resulting in accelerated and sustained weight gain, hyperphagia and significant impacts on quality of life.” Jennifer Lee, Executive Vice President, Head of North America, Rhythm Pharmaceuticals — 22 September 2026 announcement

A fourth regulator, a still-tiny patient population

Acquired hypothalamic obesity has no other approved targeted therapy that Rhythm's own materials or independent reviews identify; patients and physicians have instead relied on off-label GLP-1 drugs, whose real-world results in this population are inconsistent, and on bariatric surgery, whose benefit tends to fade because a damaged hypothalamus can no longer help sustain the resulting weight loss.

A market too broad to size a rare subset against

$95B → $105B

Two banks' 2030 forecasts for the overall anti-obesity drug market — a category dominated by GLP-1 drugs, not the rare, injury-driven condition IMCIVREE now treats.

2030 (Goldman Sachs)$95B

2030 (Morgan Stanley)$105B

Sources: Goldman Sachs, anti-obesity drug market outlook · Morgan Stanley, obesity drugs market outlook

Regulatory News outlook

We expect the addressable acquired-hypothalamic-obesity population to remain a rounding error against the broader anti-obesity drug market for years to come; IMCIVREE's value case rests on a small, high-need population willing to pay for a targeted MC4R therapy, not on capturing any meaningful share of the mass-market GLP-1 opportunity.

How we got here: Averaging Goldman Sachs' and Morgan Stanley's 2030 forecasts for the overall anti-obesity drug class gives about $100 billion; neither publisher breaks out acquired hypothalamic obesity specifically, and we found no published incidence estimate precise enough to size it independently, so we describe the segment only in relation to that $100 billion total rather than assign it a number we can't support.

IMCIVREE against what patients use today

Option	Form	Regulatory status	Reported effect
IMCIVREE (Rhythm)	MC4R agonist, daily subcutaneous injection	On-label for acquired hypothalamic obesity (US, EU, Canada)	−15.8% mean BMI change vs. +2.6% placebo at 52 weeks (TRANSCEND)
Off-label semaglutide (Wegovy)	GLP-1 agonist, weekly injection	Not labeled for hypothalamic obesity	Real-world mean −4.6% weight change over 44 months in one hypothalamic-obesity cohort
Off-label liraglutide 3mg	GLP-1 agonist, daily injection	Not labeled for hypothalamic obesity	One published case report: −16% weight over 8 months
Bariatric surgery	Surgical	Not obesity-type-specific	Benefit "often disappointing" per a clinical review; weight regain common as hypothalamic damage limits sustained loss

From each therapy's own trial data or published case reports and reviews; not a head-to-head clinical comparison.

From a 2008 startup to a fourth approved indication

Setmelanotide's road to a fourth Canadian label

1. November 2008

   Rhythm Pharmaceuticals incorporated

   Founded in Delaware to develop therapies targeting the MC4R pathway.

2. October 2017

   Nasdaq listing

   Initial public offering under the ticker RYTM.

3. November 2020

   First FDA approval

   IMCIVREE approved for obesity due to biallelic POMC, PCSK1 or LEPR deficiency — setmelanotide's first regulatory approval anywhere.

4. July 2021

   EU authorization

   European Commission authorizes IMCIVREE for the same genetic indications.

5. 2022-2023

   Bardet-Biedl syndrome added; Health Canada's first approval

   The label expands to Bardet-Biedl syndrome in the US, and Health Canada issues its first IMCIVREE approval covering both genetic indications.

6. 19 March 2026

   FDA approves acquired hypothalamic obesity

   FDA extends IMCIVREE to acquired hypothalamic obesity, the first regulator to approve the indication.

7. 22 September 2026

   Health Canada follows

   Health Canada approves the same acquired-hypothalamic-obesity indication for patients four years and older.

8. Expected in the coming weeks

   Drug Product Database update

   Health Canada's public database had not yet been updated to show the new indication as of this writing.

What a still-unconfirmed DIN update still needs

Rhythm has not disclosed Canadian list pricing, reimbursement timelines with provincial drug plans, or how many Canadian patients with acquired hypothalamic obesity it expects the approval to reach.

• Reimbursement: provincial drug-plan negotiations and Canadian list pricing not yet disclosed.
• Regulatory record: Health Canada's public Drug Product Database has not yet been updated to show the new indication.
• Trial data source: the −15.8% figure comes from TRANSCEND's 120-patient primary analysis; a separate, fuller 142-patient cohort reported an 18.8% placebo-adjusted reduction — Rhythm has used both figures in different releases.
• Global rollout: the same indication has now cleared the US (March 2026) and the EU ahead of this Health Canada approval.

What the record doesn't yet show: how many Canadians live with acquired hypothalamic obesity, what the drug will cost a provincial formulary, and whether data beyond TRANSCEND's 52-week readout holds up as patients stay on setmelanotide for years rather than months.

Frequently asked questions

What did Health Canada approve for Rhythm Pharmaceuticals?

IMCIVREE (setmelanotide) for weight management in adults and children four years and older with acquired hypothalamic obesity, announced 22 September 2026 — the drug's fourth on-label indication in Canada, alongside its original Bardet-Biedl syndrome and POMC/PCSK1/LEPR-deficiency approval.

Is this the first regulator to approve IMCIVREE for acquired hypothalamic obesity?

No. FDA approved the same indication on 19 March 2026, about six months earlier; the EU has also authorized it.

What did the pivotal trial show?

TRANSCEND, a Phase 3 trial, found a mean BMI change of -15.8% with setmelanotide versus +2.6% with placebo at 52 weeks (p<0.0001) in its 120-patient primary analysis; a separate, fuller 142-patient cohort reported an 18.8% placebo-adjusted reduction.

What is acquired hypothalamic obesity?

Rapid, severe weight gain caused by injury to the hypothalamus, most often from a brain tumor (commonly craniopharyngioma), its surgical removal, radiation, trauma, stroke or infection, which disrupts the leptin-melanocortin-MC4R pathway that normally regulates hunger and energy use.