Rhythm Pharma Sees Strong Growth, Eyes Key 2026 Obesity Drug Approval

BOSTON, MA – January 09, 2026 – Rhythm Pharmaceuticals has capped off a year of robust commercial growth with the announcement of strong preliminary revenues for 2025, setting the stage for a pivotal 2026 that could see the company expand its reach into new, challenging rare disease markets. The Boston-based biopharmaceutical firm reported a significant surge in sales for its flagship drug, IMCIVREE® (setmelanotide), and laid out a series of highly anticipated clinical and regulatory milestones.

The news underscores the company’s successful execution in the niche market of rare neuroendocrine diseases, but also highlights the high-stakes nature of biotech, as its future growth hinges on crucial data readouts and a major regulatory decision expected in the coming months.

A Year of Strong Commercial Growth

Rhythm announced preliminary unaudited net product revenues of approximately $194 million for the full year 2025, marking a roughly 50% increase from the $130 million reported in 2024. The fourth quarter alone generated approximately $57 million, an 11% sequential increase over the third quarter of 2025. This consistent growth is primarily driven by global sales of IMCIVREE, with U.S. sales contributing about 69% of the full-year revenue.

"2025 was a year of strong execution and reflects significant progress toward our mission of transforming the lives of patients with rare neuroendocrine diseases,” said David Meeker, M.D., Chairman, Chief Executive Officer and President of Rhythm, in a statement. He attributed the performance to a "steady increase in patients on reimbursed therapy and continued progress in securing access to IMCIVREE."

While the top-line growth is impressive, some market analysts remain cautious, noting that the company is not yet profitable and trades at a high revenue valuation multiple. Projections for fiscal 2025 still anticipate a net loss, a common scenario for commercial-stage biotech companies investing heavily in research, development, and market expansion. The focus for investors and the medical community alike is now shifting from current sales to the company's rich pipeline and its potential to unlock new, larger markets.

Targeting a Critical Unmet Need: Hypothalamic Obesity

The most significant near-term catalyst for Rhythm is the potential FDA approval of setmelanotide for a new indication: acquired hypothalamic obesity (HO). The U.S. Food and Drug Administration has set a Prescription Drug User Fee Act (PDUFA) goal date of March 20, 2026, to complete its review of the company's supplemental New Drug Application (sNDA).

Acquired HO is a rare, severe, and intractable form of obesity caused by damage to the hypothalamus, the brain's master regulator of hunger and energy expenditure. The condition most often arises as a devastating consequence of treatment for brain tumors like craniopharyngioma, where surgery or radiation therapy damages this critical neural circuitry. Patients experience unrelenting hunger, or hyperphagia, and a slowed metabolism, leading to rapid and extreme weight gain that is notoriously resistant to diet, exercise, and existing medications.

Currently, there are no FDA-approved treatments specifically for HO. The market, valued at over $1.1 billion in 2024 and projected to grow, represents a significant area of unmet medical need for the estimated 5,000 to 10,000 patients living with the condition in the United States. Setmelanotide, a melanocortin-4 receptor (MC4R) agonist, is designed to bypass the damaged hypothalamus and directly activate downstream pathways that regulate appetite and weight, offering a novel therapeutic approach. An approval in March would not only provide a desperately needed option for patients but also significantly expand IMCIVREE's commercial footprint.

Expanding the Frontier for Rare Obesity

Beyond the immediate focus on acquired HO, Rhythm is advancing a broad clinical program aimed at solidifying its leadership in treating rare genetic and neuroendocrine obesity disorders. The first quarter of 2026 is poised to be data-rich, with the company expecting to report topline results from two key Phase 3 trials.

One is the Japanese cohort of its setmelanotide trial in acquired HO, which will provide crucial insights into the drug's efficacy in this patient population ahead of a potential global rollout. The other is the Phase 3 EMANATE trial, which evaluates setmelanotide in a basket of different genetically caused diseases of the MC4R pathway. Positive results from EMANATE could further broaden the label for IMCIVREE, making it a treatment option for a wider range of rare genetic obesities.

The company is also making headway in another challenging condition, Prader-Willi syndrome (PWS), a complex genetic disorder characterized by severe hyperphagia. Following positive preliminary data from a Phase 2 trial announced in December 2025, Rhythm anticipates sharing six-month results from a larger patient group in the first half of 2026. This space is becoming increasingly active, with patient advocacy groups like the Foundation for Prader-Willi Research championing new therapies and other companies advancing their own candidates. Rhythm's progress is a welcome addition to a field desperate for effective treatments to manage the insatiable hunger that defines PWS.

Navigating the High Stakes of Biotech Innovation

Rhythm’s packed 2026 calendar exemplifies the high-risk, high-reward nature of the biopharmaceutical industry. The company’s future valuation and growth trajectory are heavily dependent on the outcomes of its upcoming clinical trials and regulatory decisions. This pathway is supported by an evolving regulatory landscape designed to foster innovation for rare diseases.

The FDA has established multiple programs, such as Orphan Drug Designation and expedited review pathways, to incentivize and accelerate the development of treatments for conditions with small patient populations and significant unmet needs. This framework provides companies like Rhythm with a clearer, albeit still challenging, path to market for drugs targeting conditions that were once considered untreatable.

Looking further ahead, Rhythm is also developing its next generation of MC4R agonists, including an oral candidate, bivamelagon, for which it plans to initiate a pivotal Phase 3 trial in acquired HO this year. This long-term vision, combined with the multiple near-term catalysts, positions the company at a critical juncture. The coming months will determine whether its strong commercial momentum can be amplified by clinical and regulatory success, truly transforming the treatment landscape for thousands of patients living with rare and devastating forms of obesity.