Nivolumab in combination with radiotherapy for unresectable advanced or recurrent gastric cancer (CIRCUIT trial): A 5-year update of the progression-free survival and local control outcomes.

BACKGROUND AND PURPOSE: We have previously reported a single-arm, phase 1/2 trial against unresectable advanced or recurrent gastric cancer (GC) treated with a combination of radiotherapy and nivolumab (CIRCUIT trial). We present the 5-year updated results of the progression-free survival (PFS) and local control (LC) rates.

MATERIALS AND

METHODS

We enrolled 41 patients with unresectable advanced or recurrent GC who developed progression after the primary and secondary chemotherapies with more than one tumor assessable by diagnostic imaging. Thirty-three patients had five or more tumors and 34 had two or more organs with cancer. The largest or symptomatic tumors were irradiated in 22.5 Gy/5 fractions/5 days. Three patients had multiple sites irradiated. Ten patients underwent irradiation of additional newly appeared tumors after the first irradiation. A total of 65 irradiated fields were evaluated.

RESULTS

The median survival time and time to progression were 7.3 and 3.0 months, respectively. The overall survival and PFS rates were 29.6% and 7.5% at 1 year, 16.2% and 7.5% at 2 years, and 10.8% and 5.0% at 5 years, respectively. Two patients have lived without disease progression for >5 years. The median LC period was 49.8 months. The LC rates at 1, 2, and 5 years for the irradiated tumor were 84.8%, 71.8%, and 57.5%, respectively. Severe adverse events related to radiotherapy were not observed.

CONCLUSION

The addition of radiotherapy to nivolumab therapy was safe and seemed to be beneficial for survival. Furthermore, a good LC rate was observed even with administering a palliative irradiation dose.