P5-19-12: Integration of Capecitabine Monotherapy with Capecitabine Combination Therapy in Metastatic Breast Cancer Patients: First Report on Safety and Efficacy of Single Agent Capecitabine Maintenance Study.

Abstract

Abstract Background: Giving the high degree of efficacy and safety profile, Docetaxel/Paclitaxel in combination with Capecitabine are indicated as 1st line standard chemotherapy for anthracycline pretreated or resistant metastatic breast cancer (MBC) patients. Maintenance chemotherapy is chemotherapy administered to patients without progression after an initial chemotherapy, generally as 1st line treatment. Unfortunately, no clinical studies has prospectively evaluated the efficacy and safety of capecitabine single agent maintenance in MBC. Methods: Previously untreated patients with metastatic breast cancer (MBC) were randomly assigned to receive Capecitabine 1,000 mg/m2 orally twice daily on day 1–14, Vinorbine 25 mg/m2 on day 1 and 8 (NX) in 21-day cycle or Capecitabine 1,000 mg/m2 orally twice daily on day 1–14, Docetaxel 75 mg/m2 on day 1 (TX), in 21-day cycle. The primary endpoint was to compare progression free survival (PFS), second endpoints were safety profiles (NCI-CTC 3.0), overall survival and response rate. During Initial study treatment, 21 days as one cycle and 6–8 cycles are required; Patients who were responding (complete or partial), or whose diseases were stable followed by Capecitabine: 1,000 mg/m2 PO twice daily (day 1–14) 21 days as one cycle until progression or unacceptable toxicity. This was designed as a non-inferiority study. The efficacy analysis was based on the intent-to-treat population (all patients randomized and received at least one dose of test drug). Safety was assessed on the safety population who received at least one dose of study medication. Results: Ninety one women were enrolled in fourteen months. Fifty six patients were treated with TX and 35 with NX. The median PFS was 7 (NX)versus 9 months(NX) (P=0.1888). According to RECIST criteria, similar objective response rates [19(54.2%) on TX versus 28(50%) on NX, P= 0.158] and similar clinical benefit (CR+PR+SD) [29(82.9%) on TX versus 48(85.7%) on NX, P=0.216] were achieved. The main adverse events included grade 3–4 neutropenia (40.0% versus 30.4%; P=0.115), hand-foot syndrome (2.8% versus 12.5%; P=0.096), grade 2–3 gastrointestinal adverse events (37.2% versus 19.7%; P=0.037), myalgia and arthralgia (2.9% versus 5.4%; P=0.363), with NX and TX, respectively. 2.8% versus 12.5% were discontinued treatment for toxicity with NX and TX(P=0.092)..*** Numbers of patients transferred into maintenance treatment with Capecitabine were 22(70.9%) versus 36(64.3%) in NX and TX arm respectively. 13.6% versus 13.9%(P=0.303) of the patients were discontinued treatment for toxicity with NX and TX respectively. The main toxicity in maintenance phase was grade 2–3 hand-foot syndrome. The median cycles of maintenance treatment was 4 cycles, 4 patients received Capecitabine maintenance treatment for more than 12 cycles. Discussion: There are few clinical study to compare the two regimens, especially with Capecitabine maintenance treatment. Our preliminary study found that NX and TX regimen have similar efficacy but different toxicity. Both regimen can be used as front-line treatment of MBC. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-19-12.