Long-term Outcomes of Chemoradiation for Muscle-invasive Bladder Cancer in Noncystectomy Candidates. Final Results of NRG Oncology RTOG 0524-A Phase 1/2 Trial of Paclitaxel + Trastuzumab with Daily Radiation or Paclitaxel Alone with Daily Irradiation

Abstract

Background: Chemo-radiation is a well-established alternative to radical cystectomy in patients with muscle-invasive bladder cancer. Many patients due to age or medical comorbidity are unfit for either radical cystectomy, or standard cisplatin- or 5-fluorouracil-based chemoradiation, and do not receive appropriate treatment with curative intent. We treated patients with a less aggressive protocol employing seven weekly doses of paclitaxel and daily irradiation. In those whose tumors showed overexpression of her2/neu, seven weekly doses of trastuzumab were also administered.

Objective: To report the long-term survival outcomes and toxicity results of the of NRG Oncology RTOG 0524 study.

Design, setting, and participants: Seventy patients were enrolled and 65 (median age: 76 yr) were deemed eligible. Patients were assigned to daily radiation and weekly paclitaxel + trastuzumab (group 1, 20 patients) or to daily radiation plus weekly paclitaxel (group 2, 45 patients) based on tumor her2/neu overexpression. Radiation was delivered in 1.8 Gy fractions to a total dose of 64.8 Gy.

Outcome measurements and statistical analysis: The primary endpoint was unresolved treatment-related toxicity. The secondary endpoints were complete response rate, protocol completion rate, and disease-free and overall survival.

Results and limitations: Protocol therapy was completed by 60% (group 1) and 76% (group 2); complete response rates at 12 wk were 62% in each group. Acute treatment-related adverse events (AEs) of grade ≥3 were observed in 80% in group 1 and 58% in group 2. There was one treatment-related grade 5 AE in group 1. Unresolved acute treatment-related toxicity was 35% in group 1 and 31% in group 2. The median follow-up was 2.3 yr in all patients and 7.2 yr in surviving patients. Overall survival at 5 yr was 25.0% in group 1 and 37.8% in group 2 (33.8% overall). At 5 yr, disease-free survival was 15.0% in group 1 and 31.1% in group 2.

Conclusions: In a cohort of patients with muscle-invasive bladder cancer who are not candidates for cystectomy or cisplatin chemotherapy, chemoradiation therapy offers a treatment with a significant response rate and 34% 5-yr overall survival. While there were many AEs in this medically fragile group, there were few grade 4 events and one grade 5 event attributable to therapy.

Patient summary: Patients with invasive bladder cancer who cannot tolerate surgery were treated with radiation and systemic therapy without surgically removing their bladders. Most patients tolerated the treatment, were able to keep their bladders, and showed a significant treatment response rate.

Keywords: Bladder cancer; Chemotherapy; Radiation therapy; Targeted therapy.