A tolerability and safety analysis of adding granulocyte-macrophage colony-stimulating factor to local radiotherapy in a case series of seven patients with thoracic cancer.

Background: Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been demonstrated to improve the anti-cancer effects in combination with radiotherapy. However, the tolerability and safety of adding GM-CSF to radiotherapy in thoracic cancer patients need to be further explored.

Methods: Between June 2020 and Sep 2020, seven patients with thoracic cancer were treated with concurrent radiotherapy and GM-CSF (200 µg subcutaneously injected q.o.d during the radiotherapy). The primary endpoint was adverse event.

Results: Of seven enrolled patients, four were non-small cell lung cancer, two were small cell lung cancer, and the other one patient was thymic carcinoma. The total dose of GM-CSF that each patient received was at least 3000 µg. All patients had finished the radiotherapy and GM-CSF injection and suffered one or more any grade adverse events. Only one patient had a grade ≥3 hematological adverse event (lymphocytopenia). Grade ≥3 non-hematological toxicities were not observed during the combination treatment. The highest cell counts of white blood cell, neutrophile granulocyte, and monocyte across the treatment were 22.38×109/L,18.65×109/L, and 1.28×109/L respectively.

Conclusions: The combination therapy of radiotherapy and GM-CSF (200 µg subcutaneously q.o.d) is tolerable and safe. Further studies are warranted to confirm the effects and optimal total GM-CSF injection doses in the combination of radiotherapy in thoracic cancer patients.