On Sept. 28 the U.S. Food and Drug Administration approved Emcitate (tiratricol) tablets for oral suspension to treat peripheral thyrotoxicosis in patients with MCT8 deficiency, also known as Allan-Herndon-Dudley syndrome. This is the first FDA-approved therapy specifically for symptoms of this rare genetic disorder.
MCT8 deficiency is caused by pathogenic variants in the gene that encodes the MCT8 transporter, a protein required to move thyroid hormone into the brain. Because the transporter is nonfunctional in affected patients, the brain receives insufficient thyroid hormone while hormone levels accumulate in the bloodstream. Clinically, many patients—predominantly males—have severe neurodevelopmental impairment, limited or absent speech, inability to sit or walk independently, feeding difficulties, and chronic metabolic and cardiovascular stress.
The approval rationale emphasized that tiratricol does not rely on the defective MCT8 transporter to enter cells, allowing it to lower elevated circulating thyroid hormone levels. The FDA noted that patients treated with Emcitate in clinical studies experienced reductions in excess blood thyroid hormone and improvements in cardiovascular and metabolic measures such as systolic blood pressure and heart rate.
Emcitate’s efficacy was evaluated in two clinical studies that included patients from infancy through adulthood: an international, multicenter, randomized, placebo-controlled trial (registered as NCT05579327) and a longer-term open-label study. Across both trials, treatment with Emcitate reduced excess circulating thyroid hormone and improved related clinical parameters. The most commonly reported adverse events were diarrhea, vomiting, rash and excessive sweating.
Emcitate is administered once daily as a liquid suspension, by mouth or via feeding tube for patients who cannot swallow. The approval includes warnings about coadministration with other thyroid medications: patients on another thyroid drug should consult their clinician because Emcitate and other thyroid therapies should not be used together. The approval was granted to Egetis Therapeutics US Inc., and Emcitate received multiple regulatory designations during development, including Orphan Drug, Rare Pediatric Disease, Fast Track, Breakthrough Therapy and Priority Review.
On Sept. 28 Bayer announced that the FDA has accepted a supplemental New Drug Application and granted Priority Review for Lynkuet (elinzanetant) for treatment of moderate to severe vasomotor symptoms (VMS) in women receiving endocrine therapy for hormone receptor–positive (HR+) breast cancer. Lynkuet is a dual neurokinin receptor antagonist targeting NK-1 and NK-3 and had previously received FDA approval in October 2025 for menopausal VMS.
Bayer submitted the sNDA based on results from the Phase III OASIS-4 trial. OASIS-4 was a 52-week, double-blind, randomized, placebo-controlled interventional study conducted at 90 sites outside the United States. The trial enrolled 474 women aged 18 to 70 years with moderate to severe VMS associated with endocrine therapy for HR+ breast cancer or as prevention. Participants were randomized 2:1 to elinzanetant (n=316) for 52 weeks or placebo for 12 weeks followed by elinzanetant for 40 weeks (n=158).
Lynkuet met the primary endpoints in OASIS-4, demonstrating reductions in the mean daily frequency of moderate to severe VMS from baseline to weeks 4 and 12 compared with placebo in women on endocrine therapy. Adverse events reported across the trial included headache, fatigue and somnolence; during the 12-week placebo-controlled period somnolence, fatigue and diarrhea were reported more frequently with elinzanetant than with placebo.
Key OASIS-4 findings were presented at ASCO 2025 and published in the New England Journal of Medicine. Bayer and investigators highlighted the unmet need because endocrine therapy—recommended by ASCO guidelines for many women with HR+ breast cancer and typically given for at least five years—commonly causes hot flashes and no FDA-approved treatment for endocrine therapy–related VMS was available in the U.S. at the time of the announcement.
On Sept. 24 Eli Lilly announced FDA approval of Onswik (insulin efsitora alfa-gobe), a once-weekly basal insulin indicated with diet and exercise to improve glycemic control in adults with type 2 diabetes. Onswik is formulated to provide steady basal insulin exposure over seven days and represents an alternative to daily basal insulin injections.
The approval follows regulatory authorizations in other jurisdictions and was based on the QWINT Phase 3 program. The QWINT trials enrolled more than 3,400 adults with type 2 diabetes and evaluated once-weekly Onswik versus standard daily basal insulins. In each trial, Onswik met the primary endpoint of noninferior A1C reduction from baseline compared with insulin glargine U‑100 or insulin degludec U‑100.
Lilly reported that Onswik demonstrated an overall safety profile similar to the daily basal insulins studied. Onswik is contraindicated for use in people with type 1 diabetes because of an increased risk of severe hypoglycemia. Common adverse reactions observed in clinical development include hypoglycemia, allergic reactions, injection-site reactions, lipodystrophy (skin thickening or pits), itching, rash, peripheral swelling and weight gain.
The approved Onswik KwikPen will be available in two concentrations: 500 units/mL (1,500 units total) and 1,000 units/mL (3,000 units total); pens are expected to become available in the U.S. in the coming months. The announcement reiterated the public-health context: a substantial proportion of the U.S. population lives with diabetes—most with type 2—and insulin remains an important treatment for many people who do not achieve glycemic targets with other therapies.
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