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SWOG S1801

Simply moving three doses of the same drug to before surgery improved outcomes, a result that changed how the field thinks about timing.

2-year EFS 72% vs 49% (HR 0.58), NEJM 2023. Same total drug exposure in both arms; the difference is attributed to priming the immune response while the tumour and its draining nodes are still present. Three-year follow-up presented at ESMO 2025 sustained the benefit. Together with NADINA it established neoadjuvant immunotherapy as standard for resectable stage III disease.

Setting
Resectable stage IIIB-IV melanoma: three doses of pembrolizumab before surgery then 15 after, vs 18 doses after surgery
Phase
Phase 2
Sponsor
SWOG / NCI
Registry
Headline result
2-year EFS 72% vs 49%; HR 0.58.
Reported
2022
Enrolled
313
Replication
Replicated in principle by NADINA with a different regimen.

Outcomes

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In plain words
What these results mean for people, not percentages
313 people took part
Event-free survival at 2 yearsprimarysurrogate endpoint
  • 72 vs 49 out of 100 free of a major event at 2 years with Neoadjuvant + adjuvant pembrolizumab compared with Adjuvant pembrolizumab; 23 more per 100.
  • Roughly one extra person helped for every 4 treated. That is a rough figure taken from the two percentages, not a guarantee for any one person.
  • Put another way, the treated group had about 42 percent lower chance of the event at any given time (hazard ratio 0.58).
  • This is a surrogate endpoint: it measures the cancer being controlled or absent on scans and tests, which often, but not always, translates into living longer.
  • These results apply to the people the trial enrolled: Resectable stage IIIB-IV melanoma: three doses of pembrolizumab before surgery then 15 after, vs 18 doses after surgery. People in a different situation may not see the same effect.

Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.

313 participants enrolled.

Event-free survival at 2 yearsprimary
HR 0.58
Neoadjuvant + adjuvant pembrolizumab72 of 100
Adjuvant pembrolizumab49 of 100
Source
EndpointArmnValueHR (95% CI)pSource
Event-free survival at 2 yearsprimaryNeoadjuvant + adjuvant pembrolizumab72%0.58link
Adjuvant pembrolizumab49%
Replication
Replicated in principle by NADINA with a different regimen.

Connected

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