- 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).
- 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.
- 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).
- Small, single-center study.