ASCO-GI 2019—ICI and SBRT combination safe, feasible in aPDAC


  • Melissa Pandika
  • Univadis
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Takeaway

  • Immune checkpoint inhibition (ICI) combined with stereotactic body radiation therapy (SBRT) was safe and well-tolerated in advanced pancreatic adenocarcinoma (aPDAC).

Why this matters

  • Chemotherapy only modestly improves aPDAC outcome.
  • Single-agent ICI has limited effectiveness in PDAC, possibly due to an immunosuppressive tumor microenvironment.
  • Since SBRT boosts antitumor immunity, it may enhance ICI activity, suggesting that combining the 2 therapies may offer more clinical benefit for aPDAC than either alone.

Study design

  • 51 patients who had received prior chemotherapy for aPDAC underwent 1 of 4 treatment regimens until unacceptable toxicity or disease progression:
    • Durvalumab 1500 mg every 4 weeks + SBRT 1 fraction x 8 Gy on day 1.
    • SBRT 5 fractions x 5 Gy, followed by durvalumab.
    • Durvalumab + Tremelimumab 75 mg every 4 weeks + SBRT 1 fraction x 8 Gy on day 1.
    • SBRT 5 fractions x 5 Gy, followed by durvalumab + tremelimumab.
  • Primary objectives were safety and feasibility.

Key results                          

  • 31 patients were evaluable.
  • Median PFS was 2.2 months.
  • Median OS was 4.9 months.
  • 2 patients who received 5 Gy x 5 + durvalumab +tremelimumab had partial responses with a duration longer than 12 months.  

Limitations

  • Small pilot study.