A phase I trial of sorafenib with whole brain radiotherapy (WBRT) in breast cancer patients with brain metastases and a correlative study of FLT-PET brain imaging to evaluate treatment response after WBRT sorafenib.

TPS2103 Background: WBRT is a standard therapy for metastatic breast cancer (MBC) patients with brain metastases (BM). Despite WBRT, disease progression in the brain is common, and survival is poor. One approach to improve outcome is the use of radiosensitizers. Sorafenib, a multi-kinase TKI with anti-VEGF activity, has demonstrated anti-tumor efficacy in MBC and radiosensitizing activity in preclinical studies. Concurrent use of anti-VEGF drug with radiotherapy (RT) has a potential to confound response assessments due to pseudo-progression and pseudo-response using brain magnetic resonance imaging (MRI). FDG PET is not ideal for brain imaging due to high background glucose uptake. Thus, a newer imaging modality is warranted for accurate response assessment. [18F] 3’deoxy-3’-fluorothymidine (FLT) is a new PET tracer which has shown to correlate with cellular proliferation and may be useful in improving response assessment. Methods: We are conducting a phase I trial of sorafenib with WBRT in MBC patients w...