Long-Term Results from the IDEAL-CRT Phase 1/2 Trial of Isotoxically Dose-Escalated Radiation Therapy and Concurrent Chemotherapy for Stage II/III Non-small Cell Lung Cancer.

PURPOSE: The IDEAL-CRT phase 1/2 multicenter trial of isotoxically dose-escalated concurrent chemoradiation for stage II/III non-small cell lung cancer investigated two 30-fraction schedules of 5 and 6 weeks' duration. We report toxicity, tumor response, progression-free survival (PFS), and overall survival (OS) for both schedules, with long-term follow-up for the 6-week schedule. METHODS AND MATERIALS: Patients received isotoxically individualized tumor radiation doses of 63 to 71 Gy in 5 weeks or 63 to 73 Gy in 6 weeks, delivered concurrently with 2 cycles of cisplatin and vinorelbine. Eligibility criteria were the same for both schedules. RESULTS: One-hundred twenty patients (6% stage IIB, 68% IIIA, 26% IIIB, 1% IV) were recruited from 9 UK centers, 118 starting treatment. Median prescribed doses were 64.5 and 67.6 Gy for the 36 and 82 patients treated using the 5- and 6-week schedules. Grade ≥3 pneumonitis and early esophagitis rates were 3.4% and 5.9% overall and similar for each schedule individually. Late grade 2 esophageal toxicity occurred in 11.1% and 17.1% of 5- and 6-week patients. Grade ≥4 adverse events occurred in 17 (20.7%) 6-week patients but no 5-week patients. Four adverse events were grade 5, with 2 considered radiation therapy related. After median follow-up of 51.8 and 26.4 months for the 6- and 5-week schedules, median OS was 41.2 and 22.1 months, respectively, and median PFS was 21.1 and 8.0 months. In exploratory analyses, OS was significantly associated with schedule (hazard ratio [HR], 0.56; 95% confidence interval [CI], 0.32-0.98; P = .04) and fractional clinical/internal target volume receiving ≥95% of the prescribed dose (HR, 0.88; 95% CI, 0.77-1.00; P = .05). PFS was also significantly associated with schedule (HR, 0.53; 95% CI, 0.33-0.86; P = .01). CONCLUSIONS: Toxicity in IDEAL-CRT was acceptable. Survival was promising for 6-week patients and significantly longer than for 5-week patients. Survival might be further lengthened by following the 6-week schedule with an immune agent, motivating further study of such combined optimized treatments.

IDEAL-CRT: A Phase 1/2 Trial of Isotoxic Dose-Escalated Radiation Therapy and Concurrent Chemotherapy in Patients With Stage II/III Non-Small Cell Lung Cancer.

PURPOSE: To report toxicity and early survival data for IDEAL-CRT, a trial of dose-escalated concurrent chemoradiotherapy (CRT) for non-small cell lung cancer. PATIENTS AND METHODS: Patients received tumor doses of 63 to 73 Gy in 30 once-daily fractions over 6 weeks with 2 concurrent cycles of cisplatin and vinorelbine. They were assigned to 1 of 2 groups according to esophageal dose. In group 1, tumor doses were determined by an experimental constraint on maximum esophageal dose, which was escalated following a 6 + 6 design from 65 Gy through 68 Gy to 71 Gy, allowing an esophageal maximum tolerated dose to be determined from early and late toxicities. Tumor doses for group 2 patients were determined by other tissue constraints, often lung. Overall survival, progression-free survival, tumor response, and toxicity were evaluated for both groups combined. RESULTS: Eight centers recruited 84 patients: 13, 12, and 10, respectively, in the 65-Gy, 68-Gy, and 71-Gy cohorts of group 1; and 49 in group 2. The mean prescribed tumor dose was 67.7 Gy. Five grade 3 esophagitis and 3 grade 3 pneumonitis events were observed across both groups. After 1 fatal esophageal perforation in the 71-Gy cohort, 68 Gy was declared the esophageal maximum tolerated dose. With a median follow-up of 35 months, median overall survival was 36.9 months, and overall survival and progression-free survival were 87.8% and 72.0%, respectively, at 1 year and 68.0% and 48.5% at 2 years. CONCLUSIONS: IDEAL-CRT achieved significant treatment intensification with acceptable toxicity and promising survival. The isotoxic design allowed the esophageal maximum tolerated dose to be identified from relatively few patients.