Rhythm Pharmaceuticals, Inc. filed a Current Report on Form 8-K on August 4, 2026, disclosing preliminary Phase 2 trial data for RM-718 in patients with acquired hypothalamic obesity and announcing its financial results for the second quarter ended June 30, 2026.

Key Highlights

  • BMI reduction: A mean BMI reduction of -11.6% from baseline was reported at 16 weeks of RM-718 treatment (n=7).
  • Comparator context: The 16-week RM-718 result was described as comparable to a -10.1% mean BMI reduction with bivamelagon (600 mg dose; n=7) at 14 weeks and a -10.1% BMI reduction with setmelanotide at 16 weeks (n=64 patients in Phase 2 and 3 trials).
  • Enrollment: Eleven patients with acquired hypothalamic obesity were enrolled in the ongoing, open-label trial.
  • Active treatment: Eight patients remained on active treatment as of July 16, 2026, including two who had not yet reached 16 weeks on therapy.
  • Discontinuations: Two participants discontinued due to adverse events (injection site induration and nausea); one patient withdrew from the extension portion of the trial.
  • Hyperpigmentation: Two mild instances of hyperpigmentation were reported, limited to the injection site, with no generalized hyperpigmentation observed.

Rhythm Pharmaceuticals Releases Preliminary RM-718 Findings in Acquired Hypothalamic Obesity

According to the filing, Rhythm Pharmaceuticals (NASDAQ: RYTM) disclosed preliminary data from an ongoing Phase 2 trial evaluating RM-718, an investigational therapy being studied in patients with acquired hypothalamic obesity (HO). The trial is described as open-label, with eleven patients enrolled. At 16 weeks, the filing reported a mean BMI reduction of -11.6% from baseline among seven evaluable patients.

The company disclosed that the RM-718 efficacy result at 16 weeks was described as "comparable" to a -10.1% mean BMI reduction observed with bivamelagon at a 600 mg dose at 14 weeks (n=7), and a -10.1% BMI reduction with setmelanotide at 16 weeks across 64 patients in Phase 2 and 3 trials. The filing noted that RM-718 "was generally well tolerated," with the most common adverse events being injection site reactions, nausea, and vomiting. Two mild cases of hyperpigmentation were reported and were confined to the injection site.

As of July 16, 2026, eight patients remained on active treatment. Two participants discontinued due to adverse events - specifically injection site induration and nausea - and one patient withdrew from the extension portion of the trial. The filing also stated that the company announced its financial results for the second quarter ended June 30, 2026, with the full press release furnished as Exhibit 99.1. A presentation related to the RM-718 data was made available on the company's investor relations website at ir.rhythmtx.com. The filing was signed by Hunter C. Smith, Chief Financial Officer. Forward-looking statements contained in the filing are the company's own and are subject to its cautionary language and numerous risks and uncertainties as described therein.

What Was Disclosed

The August 4, 2026 filing covered preliminary Phase 2 data for RM-718 in acquired hypothalamic obesity, including BMI reduction results, tolerability findings, and patient status as of July 16, 2026, alongside a reference to second-quarter 2026 financial results.