- Design
- Randomised, multicentre, phase 3 trial
- Population
- 204 patients undergoing haploidentical stem cell transplant
- Primary outcome
- 365-day GVHD-free, relapse-free survival
- Effect
- 66.7% vs 50.0%; HR 0.67 (95% CI 0.45–0.995)
A randomised phase 3 trial in Cancer Letters enrolled 204 patients undergoing haploidentical haematopoietic stem cell transplant in China. Anti-thymocyte globulin for graft-versus-host disease prophylaxis was given either at a fixed 10 mg/kg or at a dose targeted by therapeutic drug monitoring to a defined exposure.
One-year GVHD-free, relapse-free survival was 66.7% with targeted dosing against 50.0% with fixed dosing (HR 0.67). Moderate to severe chronic GVHD fell from 22.5% to 9.8%, and grade 3–5 infections from 70.6% to 44.1%. More patients reached optimal ATG exposure, and CD4 T-cell recovery was better.
ATG pharmacokinetics vary widely between patients, so a weight-based dose over-exposes some, raising infection and relapse risk, and under-exposes others, leaving them open to GVHD. This trial suggests that measuring exposure and adjusting the dose improves the balance.
The primary result only just reached significance and comes from one country's programme. But the direction is consistent across GVHD, infection and immune recovery, which makes it a strong signal for transplant pharmacology.
- Consider exposure-targeted ATG dosing in haploidentical transplant where drug level assays are available
- Recognise that fixed weight-based ATG doses produce widely varying exposure
- Monitor infection risk closely in patients likely to be over-exposed
- Track CD4 T-cell recovery as a marker of the exposure balance
Why it matters
It shows drug monitoring can change hard outcomes, not just levels, for a biologic with variable kinetics.
Don't overread it
The primary result's interval reaches 0.995, just below 1, and needs confirmation in other centres.
The statistics, in plain English
An HR of 0.67 means a third lower rate of the composite of GVHD, relapse or death. The interval from 0.45 to 0.995 only just excludes no effect, so the size of the benefit is uncertain even though the direction is consistent.
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