HNSCC study repudiates the abscopal effect myth

  • McBride S & al.
  • J Clin Oncol
  • 21 Aug 2020

  • curated by Deepa Koli
  • Univadis Clinical Summaries
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Takeaway

  • In patients with metastatic head and neck squamous cell carcinoma (HNSCC), no abscopal effect was seen with the addition of stereotactic body radiotherapy (SBRT) to nivolumab.

Why this matters

  • The abscopal effect is a hypothetical result of radiation, whereby tumors situated outside the radiation field are reduced or eliminated by an assumed reaction mediated by the immune system.
  • A previous trial in lung cancer also failed to show a significant difference in objective response rate (ORR).

Study design

  • Phase 2 study of 62 patients with metastatic HNSCC including 3 biologic entities (HPV-positive, Epstein-Barr-positive, and tobacco-associated/nonviral head and neck cancer) who were randomly assigned to nivolumab (n=30) or nivolumab plus SBRT (n=32).
  • Only 1 lesion was irradiated and ≥1 other was left nonirradiated to evaluate the abscopal effect.
  • Funding: National Cancer Institute.

Key results

  • No significant difference was seen in the nivolumab vs nivolumab+SBRT groups for:
    • ORR: 34.5% vs 29.0% (P=.86).
    • Median duration of response: not reached vs 9.4 months (P=.26).
  • There was no significant interaction between treatment group and programmed death ligand-1 status (P=.76).
  • No significant difference was seen in grade 3-5 toxicities between the groups (P=.70).
  • Patients with virus-positive vs virus-negative status showed no significant difference in:
    • ORR (P=.14).
    • OS (P=.07).

Limitations

  • Small, single-center study.