Abstract P6-11-01: A randomized phase II clinical trial of whole-brain radiation therapy plus concomitant temozolomide in treatment of brain metastases from breast cancer: Six-month follow-up results

Abstract

Abstract Background: Despite of therapeutics progress in advanced breast cancer, brain metastases occurrence remain a frequent and delicate situation. The efficacy of whole-brain radiation therapy (WBRT), still considered as the standard local treatment in case of multiple brain metastases, is limited. Recently, several phase II studies have shown some efficacy of the association of WBRT and temozolomide (TMZ), an oral alkylating agent already known as a radiosensitizer, with improved brain control rate (44 to 96%). Patients with breast cancer were underrepresented and none of these trials have studied this combined treatment issue in this specific population. The aim of this study was to assess the efficacy and safety of WBRT combined with temozolomide in the treatment of brain metastases from breast cancer. Materials and Methods: A prospective randomized multicenter phase II study was developed, using a modified two-stage Fleming design. Patients with newly diagnosed intraparenchymal brain metastases from breast cancer, not suitable for surgery nor radiosurgery, were included. All patients received conformational WBRT (3 Gy x 10 to 30 Gy). They were randomized to WBRT plus concomitant TMZ administered 75 mg/m2/day during radiation period versus WBRT alone. The primary endpoint was radiologic objective response at six weeks after the end of treatment, defined as a partial or complete response on systematic brain MRI (WHO modified criteria). We also evaluated neurologic symptoms, tolerance, safety, progression free survival (PFS) and overall survival (OS) as secondary endpoints. A longer clinical-brain MRI follow-up was planned, each three months during a two-year period. All of the patients gave their written informed consent to be part of the study, which was approved by the local committee. Results: One hundred patients were enrolled between February 2008 and December 2010 (50 in the WBRT + TMZ arm, 50 in the WBRT arm). The median age was 55 [29 -79]. Eighty (80) patients had brain metastases as single secondary localization. About one third of patients had a triple negative breast cancer subtype (38,3% in the association arm and 35,71% in the WBRT alone arm). There were 26,7% and 14,6% of HER2 positive subtype respectively. The median follow-up was 30 months [range 6-60]. At six months from brain metastases diagnosis (three months after the end of the treatment), objective response rate seems better in the WBRT + TMZ arm: 52% versus 40% in the arm WBRT alone but was not statistically significant (p = 0,54). No complete response was observed. In the WBRT + TMZ group, median PFS and OS at six-months were respectively 55,6% [range 46-7 – 66,0] and 67,7% [range 59,1 – 77,6]. No improvement in neurologic symptoms was noticed. In multivariate analysis, initial TNM status was significantly correlated with PFS and OS. The concurrent use of TMZ with WBRT was well-tolerated. The most frequent upper grade II acute toxicity was reversible leucopenia in the association arm. Conclusion: The addition of temozolomide to WBRT in patients with brain metastases from breast cancer did not improve local control or survival at six months follow-up. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-11-01.