Standing in the GAP : To formulate a novel radioimmunotherapy regime to improve the long-term outcome in breast cancer.

Aim: The new radioimmunotherapeutic regime GAP15R aims to stimulate glucocorticoid-induced TNF-related protein (G) to overcome Treg suppression; add IFN- (A) to promote inflammatory milieu; block PD1 (P) to disinhibit T effector cytotoxicity; add IL-15 (15) to enhance danger signals & T-cell expansion; and apply radiation (R) at critical time point to sustain localized inflammation. Patients & methods/materials & methods: This was tested in a murine 4T1 metastatic breast carcinoma model given GAP15R with regular monitoring of tumor volume and complications. Results: We had demonstrated long-term complete remission up to 50% of treated mice, which is not associated with major treatment-related complication, in cases with specific tumor burden. Conclusion: GAP15R is efficacious with potential to be applicable to other tumors.