Abscopal absence.

Top Line: Nivolumab is a subsequent-line treatment option for patients with metastatic head and neck squamous cell carcinoma (HNSCC) that progresses through first-line platinum therapy, though response rates leave room for improvement.

The Study: For example, the response rate in CheckMate 141 was just 13%. So can all-powerful ablative radiation improve things? In this intriguing phase 2 trial conducted at MSKCC, patients with metastatic HNSCC and at least two sites of disease were randomized to receive nivolumab with or without stereotactic body radiation (SBRT). The two sites of disease included one that could be safely treated with 9 Gy x 3 fractions and another site that was not treated but that could be easily measured for a potential abscopal effect. SBRT was delivered to the single designated site between nivo doses 1 and 2. Interestingly, the primary outcome was the overall response rate of non-irradiated lesions. It’s important to note again that this trial was looking strictly at abscopal effects; it was not an oligometastatic trial targeting all sites of disease. Also important is the small (n=62) and heterogeneous population. One-third of patients were PD-L1(+), another third had oropharyngeal primaries, and the majority of SBRT targets were in the lung (58%). Unfortunately, adding SBRT to nivo didn’t seem to induce a notable abscopal effect nor did it impact objective response rate (29-35%) and duration of response.

TBL: In an unselected population of patients with metastatic HNSCC, SBRT to a single site of disease sadly did not improve the response rate at non-irradiated sites of disease. | McBride, J Clin Oncol 2020