A chemically copied semaglutide matched Wegovy for weight loss in China

Semaglutide, the peptide behind Wegovy and Ozempic, is one of the hardest drugs in the world to manufacture at scale, and that bottleneck is a large part of why it is expensive and, in many countries, rationed. So a trial testing whether a chemically synthesised copy of the molecule works as well as the original is less a scientific surprise than a supply-and-price story. One such trial has now been published [s1].

What the trial tested

HD1916 is a chemically synthesised version of semaglutide — the same peptide, made by a different route. The phase 3 trial, run at 30 centres in China, enrolled adults aged 18 to 75 with obesity (a body-mass index of 28 kg/m² or higher) and without diabetes [s1]. A total of 462 participants were randomly assigned 1:1 to once-weekly subcutaneous HD1916 or to the reference product, branded semaglutide, for 44 weeks — 231 people in each group [s1].

The design matters. This was an open-label, active-controlled equivalence trial, not a placebo comparison [s1]. The question it set out to answer was narrow: does the copy behave like the original? The primary endpoint was the percentage change in body weight from baseline to week 44, and equivalence was to be declared only if the 95% confidence interval for the difference between the two groups stayed inside a prespecified margin of plus or minus 4.16 percentage points [s1].

The numbers

At week 44, mean body weight fell by 13.1% on HD1916 and by 14.4% on the reference semaglutide [s1]. The estimated treatment difference was 1.35 percentage points, with a 95% confidence interval of −0.02 to 2.72 — comfortably inside the equivalence margin, which is the result the trial was built to produce [s1].

The secondary endpoints tracked the same pattern. The share of participants losing at least 5% of body weight was 87.8% on the copy and 90.5% on the original; for at least 10%, the figures were 68.7% and 73.6% [s1]. Reductions in waist circumference were described as comparable between the groups [s1].

On tolerability, any-grade treatment-emergent adverse events occurred in 86.5% of the HD1916 group and 89.2% of the reference group, most of them grade 1 to 2 — the mild-to-moderate band that, for this drug class, is overwhelmingly gastrointestinal [s1].

How to read "equivalent"

Two cautions are worth stating plainly. First, the point estimates were not identical: the copy came in 1.3 percentage points lower on the primary measure, and on both the 5% and 10% weight-loss thresholds a slightly larger share of the reference group hit the mark [s1]. "Equivalent" here is a statistical verdict — the difference sat inside a predefined margin — not a claim that the two products performed the same to the decimal. The upper edge of the confidence interval reached 2.72 percentage points, so a modest real difference in either direction is not excluded [s1].

Second, this was an open-label trial, meaning participants and investigators knew which product each person received [s1]. For a weight outcome driven partly by adherence and diet, blinding matters, and its absence is a limit the result carries.

What the trial does establish is that the branded drug's weight-loss effect is reproducible: the reference arm's 14.4% loss over 44 weeks is in the same territory as the efficacy that made once-weekly semaglutide a standard obesity therapy in the first place, a role established in the placebo-controlled STEP 1 trial [s2]. The two studies are not comparable head to head — STEP 1 ran longer, against placebo, in a different population — but the reference arm here behaves as the drug is known to behave.

Why it matters, and what it does not settle

The practical significance is about access, not pharmacology. If a synthesised copy can be made to perform within a tight margin of the original, the ceiling on who can be treated is set by manufacturing capacity and price rather than by the chemistry of the molecule. That is the lever that moves when patents lapse and when more makers can produce the peptide.

It does not follow that HD1916 is interchangeable in any regulatory sense, or available anywhere. This was a single trial in Chinese adults without diabetes, over 44 weeks, judging one manufacturer's product against the brand [s1]. It says nothing about how the copy performs in people with type 2 diabetes, about cardiovascular outcomes — which it was not designed to measure — or about durability beyond 44 weeks. Approval pathways for copies of complex peptide drugs differ by country and are their own hurdle.

The headline, then, is modest and real: a copy of semaglutide hit its weight-loss target within the margin set for calling it equivalent to the brand, with a similar early safety profile [s1]. Whether that translates into cheaper, more widely available treatment is a regulatory and commercial question this trial cannot answer.

This article is informational and does not constitute medical advice.

Sources

• [s1] Efficacy and Safety of Chemically Synthesized Semaglutide Injection (HD1916) for the Treatment of Obesity: A Multicenter, Randomized, Phase III Trial. Diabetes, Obesity and Metabolism, 7 October 2026. https://doi.org/10.1111/dom.71354
• [s2] Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine, 18 March 2021. https://doi.org/10.1056/NEJMoa2032183