Repeated switching between a ustekinumab biosimilar and its reference product showed no loss

Design

Randomised, double-blind interchangeability trial

Population

453 adults with moderate to severe plaque psoriasis randomised after run-in

Primary outcome

AUCtau and Cmax between weeks 52 and 64

Effect

AUCtau ratio 0.93 (90% CI 0.89 to 0.98); Cmax ratio 0.95 (0.90 to 1.00)

In this randomised, double-blind trial, patients with moderate to severe plaque psoriasis received ustekinumab reference product for a run-in. Of 494 enrolled, 453 who responded were randomised to continue the reference product (225) or to switch repeatedly: biosimilar ABP 654, then reference product, then biosimilar, at weeks 28, 40 and 52.

Between weeks 52 and 64, the geometric mean ratios for exposure were 0.93 for AUCtau (90% CI 0.89 to 0.98) and 0.95 for Cmax (0.90 to 1.00). Both intervals fell within the prespecified margin of 0.8 to 1.25. Efficacy, antidrug antibodies and adverse events were similar between the groups.

This supports substitution at the pharmacy or between products when cost or supply requires it. It addresses ustekinumab and this one biosimilar, not other biologics. Where the biosimilar is licensed locally, switching on non-medical grounds is supportable, with records of the product given.

• Consider ustekinumab biosimilar use or switching where cost or supply requires it, if it is licensed locally.
• Record the brand and batch given at each dose.
• Tell patients about a switch beforehand to avoid a nocebo effect.
• Follow your formulary and regulator's rules for interchangeability, which differ by country.
• Do not extend this finding to other biologics.

Why it matters

It removes a common objection to switching patients between products to save cost.

Don't overread it

The trial is specific to one biosimilar and followed patients for about a year, so it does not show equivalence of other products or long-term outcomes.

The statistics, in plain English

Equivalence trials ask whether the 90% interval lies inside a pre-set margin (here 0.8 to 1.25), not whether a difference is significant. The intervals sat well inside, so exposure after switching was essentially the same.

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