Low protracted dose of temozolomide (TMZ) and concurrent radiotherapy for brain metastasis of solid tumors
12525 Background. Whole brain radiotherapy (WBRT) remains the mainstay of therapy for brain metastasis of solid tumours not amenable to surgical resection. Chemotherapy with temozolomide (TMZ) has emerged as an alterative approach for recurrent brain metastases. It has been already used alone or in combination with radiotherapy in the treatment of primary brain tumours. Protracted administration of TMZ, even at relatively low daily doses, leads to significant and prolonged depletion of enzyme O6-alkylguaninae-DNA alkyltransferase (AGAT) activity, with may enhance the antitumor activity of the agent. Methods. Patients with histologically or cytologically confirmed breast cancer and NSCLC and inoperable brain metastasis were eligible for the study .We have treated 29 consecutive patients (16 F and 13 M, mean age: 55, range 46–76) affected by brain metastases ( 16 non-small-cell lung cancer and 13 breast cancer) with WBRT at 3 Gy/day administered over a two-week period (on wks 1–2), total dose 30 Gy, and an induction with TMZ 50 mg/m2/day during this period, following TMZ 50mg/m2 fractionated in 21 days every 28 days, for up to 12 cycles. Pts who received at least one cycle of TMZ were assessable for response. Results. Twenty-four patients were subjected to the induction therapy and 124 cycles were performed. TMZ was generally well tolerated, and the main toxicities seen were hematologic. The toxicities were generally between grade 1 or 2 in severity although two patients had grade 3 events. Two CR, in patients with breast cancer and NSCLC. Nine partial responses were recorded in 5/11 patients with breast cancer, 4/13 patients with NSCLC, while a stable disease was achieved in other 5 patients. Eight patients showed progressive BM growth during the treatment. The overall response rate was 45.5% (C.I. 38.7–56.9%), while the disease control rate was 77% (C.I. 61.7–82.4%). At the present, the overall survival at 12 months was 64%. Conclusions. We developed a new regimen based on a different strategy: the utilization of a more intensive TMZ dosing schedule that would permit the concomitant use of a second cytotoxic agent on the primary cancer. Final data analysis will be presented. The schedule was safe and well tolerated and has suggested an encouraging activity in brain metastases. No significant financial relationships to disclose.