Concurrent liposomal doxorubicin with dual HER2 blockade raised pCR without added cardiac harm

Design

Randomised phase 2 trial

Population

156 patients with stage II–III HER2-positive breast cancer

Primary outcome

Pathological complete response

Effect

67.5% vs 48.7% (difference 18.8, 95% CI 3.6–34.0); EFS HR 0.35 (0.09–1.32)

The phase 2 METIS trial randomised 156 patients with stage II–III HER2-positive breast cancer to neoadjuvant pegylated liposomal doxorubicin (PLD)-based chemotherapy given concurrently with trastuzumab and pertuzumab, or to sequential epirubicin-cyclophosphamide followed by HER2-targeted therapy.

Pathological complete response was 67.5% with the concurrent PLD regimen versus 48.7% (difference 18.8 points, 95% CI 3.6–34.0). The gain was larger in hormone receptor-positive disease (58.7% vs 36.7%). At a median 37.5 months there were 3 versus 8 event-free survival events (HR 0.35, 95% CI 0.09–1.32), not statistically significant. There was no symptomatic cardiac dysfunction in either arm.

Anthracyclines have mostly been kept apart from HER2 blockade because of cardiotoxicity; liposomal doxorubicin is less cardiotoxic. This phase 2 result is promising but not yet a reason to change standard regimens — pCR is a surrogate and the survival data are immature. In India, where PLD is available and biosimilar trastuzumab is widely used, a phase 3 confirmation would be directly relevant.

• Concurrent PLD with trastuzumab and pertuzumab raised pCR by about 19 points in a phase 2 trial
• No symptomatic cardiac dysfunction was seen with the concurrent regimen
• Event-free survival was not significantly different — data are immature
• Keep standard neoadjuvant regimens outside trials until phase 3 data

Why it matters

It reopens the question of combining anthracyclines with HER2 blockade, using a less cardiotoxic formulation.

Don't overread it

This is a phase 2 trial with a surrogate primary end point; the survival difference was not significant.

The statistics, in plain English

The 95% confidence interval for the pCR difference, 3.6 to 34.0 points, excludes zero but is wide. The event-free survival hazard ratio's interval, 0.09 to 1.32, includes 1, so no survival benefit is shown yet.

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