Small molecules, mainly tyrosine kinase inhibitors, are currently used in various malignancies. Lapatinib, a dual inhibitor of EGFR/HER2 tyrosine kinases, has demonstrated effectiveness in brain metastases from HER2-overexpressing breast cancer. It also appears to sensitize EGFR-expressing cell lines to radiation. To evaluate the efficacy of lapatinib in combination with whole brain radiotherapy (WBRT) in patients with brain metastases from non-small cell lung cancer (NSCLC) and breast cancer, as assessed by volumetric analysis by MRI. 81 patients were treated with WBRT (30 Gy in ten fractions) in combination with lapatinib 1250 mg once daily, followed by lapatinib 1500 mg once daily for a total 6 weeks. 21 patients had primary breast cancer and 60 patients NSCLC. Pre- and post-treatment MRI scans in a compact disk for central volumetric assessment were available for 43 patients. 27 patients (62.8%) achieved partial response, 15 patients (34.9%) had stable disease and only one patient (2.3%) had disease progression. Response was not associated to EGFR protein expression. All 81 patients were assessed for safety. The large majority of the adverse events were mild. Eight deaths occurred, four of which were considered related to the study drugs but there were also other contributing factors. Nine cases of serious infections were observed in eight patients, but they were also receiving dexamethasone. Lapatinib in combination with WBRT in patients with brain metastases from breast cancer and NSCLC is a feasible approach that can be further studied in larger clinical trials.
Keywords: Brain metastases; Breast cancer; Lapatinib; Non-small cell lung cancer; Whole brain radiotherapy.