ASCO-GI 2019—NACT tops upfront surgery for PDAC in phase 2/3 trial

  • Melissa Pandika
  • Univadis
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  • Neoadjuvant chemotherapy with gemcitabine and S-1 (NACT-GS) led to longer OS than did upfront surgery (Up-S) for resectable pancreatic adenocarcinoma (PDAC).

Why this matters

  • In resectable PDAC, the standard of care is upfront surgery followed by adjuvant chemotherapy but it has limited survival benefit.
  • This is the first study to show the value of NACT in resectable PDAC.

Study design

  • Phase 2/3 randomized, multicenter Prep-02/JSAP-05 trial.
  • Phase 2:
    • 364 patients with resectable PDAC randomly assigned 1:1 to NACT-GS (1 g/m2 gemcitabine on days 1 and 8, 40 mg/m2 of  S-1 twice daily on days 1 to 14) or Up-S.
    • Both arms received S-1 for 6 months for patients with curative resection and full recovery within 10 weeks postsurgery.
    • Primary endpoint was resection rate.
  • Phase 3:
    • If sufficient resection rate, evaluate OS as primary endpoint.

Key results

  • 362 evaluable patients (182 in NACT-GS, 180 in Up-S).
  • Phase 2:
    • Resection rate was 93% in NACT-GS, 82% in Up-S.
  • Phase 3:
    • Median OS was 36.72 months in NACT-GS, 26.65 months in Up-S (HR, 0.72, P=.015).


  • NACT-GS regimen used only in Japan, other parts of Asia, so unlikely to change practice in U.S., Europe.
  • Clarification on some data should perhaps be provided, e.g., DFS, dose intensity of chemotherapy, and how many patients received additional chemotherapy at time of recurrence. 

Expert comment

  • “I think this result definitely provides another viable option in Japan for patients with pancreatic cancer.  However, the results should also be interpreted cautiously,” said Andrew X. Zhu, MD, PhD, professor of medicine at Harvard Medical School and director of liver cancer research at Massachusetts General Hospital Cancer Center, who was not involved in the trial.