FDA extends the antifungal rezafungin to children 12 and older, without a paediatric trial
Rezzayo's once-weekly echinocandin can now be used in adolescents with candidaemia who have few other options. The expansion rests on adult data and modelling, not on studies in children.
The Food and Drug Administration has widened the approved use of rezafungin, a once-weekly antifungal sold as Rezzayo, to include children aged 12 and older [s1]. The change was recorded on 16 July 2026 as supplement 7 to new drug application 217417, and the updated label took effect on 1 July 2026 [s2][s1]. The application is held by Mundipharma, and the label lists Melinta Therapeutics as the product's manufacturer [s2][s1].
Rezafungin is an echinocandin — the same class as caspofungin and micafungin — used to treat candidaemia and invasive candidiasis, serious bloodstream and deep-tissue infections caused by Candida yeasts [s1]. Its selling point is convenience: a single 400 mg intravenous loading dose followed by 200 mg once weekly, rather than the daily infusions older echinocandins require [s1]. The label notes its safety has not been established beyond four weekly doses [s1].
The approval is deliberately hedged. The drug is indicated for patients "who have limited or no alternative options," and the label states plainly that approval "is based on limited clinical safety and efficacy data" [s1]. It also carries a limitation of use: rezafungin has not been studied in Candida infections of the heart lining, bone, or the central nervous system [s1].
No trial in children
The most important feature of this expansion is what sits behind it. The label is explicit: "There have been no clinical studies conducted with REZZAYO in pediatric patients" [s1]. Effectiveness in those aged 12 and older was instead inferred from the adult trials, supported by population pharmacokinetic analyses that found age and body weight had no clinically meaningful effect on drug exposure [s1]. The adult studies spanned a weight range of 34 to 154.5 kg, which overlaps with older children and so underpins the extrapolation [s1].
Bridging adult data to adolescents through modelling is an established regulatory path when a disease behaves similarly across ages and the drug's exposure is predictable. It is not the same as showing the drug works in children by testing it in them, and the label's framing invites clinicians to treat the paediatric use cautiously.
What the adult trial showed
The underlying efficacy comes from Trial 1, a randomised, double-blind study that pitted rezafungin against caspofungin in adults with candidaemia or invasive candidiasis [s1]. Of 199 patients randomised, 187 formed the main analysis population — 93 on rezafungin and 94 on caspofungin [s1]. The primary measure was all-cause mortality at day 30: 22 deaths (23.7%) on rezafungin versus 20 (21.3%) on caspofungin, a difference of 2.4 percentage points (95% confidence interval −9.7 to 14.4) [s1]. A composite "global cure" endpoint at day 14 was reached by 59.1% on rezafungin and 60.6% on caspofungin, a difference of −1.5 points (95% CI −15.4 to 12.5) [s1].
Those intervals are wide and straddle zero in both directions — the hallmark of a trial designed to show rough equivalence to an existing drug rather than superiority [s1]. Rezafungin looked comparable to caspofungin, no better and no clearly worse, in a modest number of patients.
The trial population was typical of serious Candida infection. Most patients — 70% — had candidaemia alone, 93% were not neutropenic, and the common risk factors read like an intensive-care roster: recent broad-spectrum antibiotics (71%), a central venous catheter (60%), major surgery (35%), diabetes (29%) and active cancer (25%) [s1]. The most frequent organism was Candida albicans (42%), followed by C. glabrata (26%) [s1]. A second, smaller dose-finding study provided supporting safety and efficacy data but was not the basis for the efficacy claim [s1].
How to read it
For an adolescent with a dangerous Candida infection and few options, a once-weekly infusion that can be given and then sent home on is a practical advantage over daily dosing [s1]. But the evidence base is thin by design, built on an adult equivalence trial and pharmacokinetic modelling rather than paediatric data, and the label says so in as many words [s1]. The "limited alternative options" wording signals this is a drug for a corner of practice, not a front-line change.
What to watch
Real-world use in adolescents, and any post-marketing data the FDA requires, will show whether the modelling holds [s1]. The four-dose ceiling on established safety also matters for the sickest patients, whose treatment may run longer [s1].
This article describes regulatory news and is not medical advice. Treatment of fungal bloodstream infections is for patients and their treating clinicians.
Sources
- REZZAYO (rezafungin for injection) prescribing information — Indications and Usage (1), Pediatric Use (8.4) and Clinical Studies (14) — U.S. Food and Drug Administration, label effective 1 July 2026
- Drugs@FDA: Rezzayo (rezafungin acetate), NDA 217417, supplement 7 — approval record — U.S. Food and Drug Administration, approved 16 July 2026
Sources
- REZZAYO (rezafungin for injection) prescribing information — Indications and Usage (1), Pediatric Use (8.4) and Clinical Studies (14) — U.S. Food and Drug Administration (openFDA drug/label API) , July 1, 2026
- Drugs@FDA: Rezzayo (rezafungin acetate), NDA 217417, supplement 7 — approval record — U.S. Food and Drug Administration (openFDA drug/drugsfda API) , July 16, 2026
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