A phase III comparison of radiation therapy with or without recombinant beta-interferon for poor-risk patients with locally advanced non-small-cell lung cancer (RTOG 93-04).

Purpose: The results of Phase I/II data testing beta-interferon with radiation therapy in a non-small-cell lung cancer population were promising. Based on these data, the Radiation Therapy Oncology Group (RTOG) initiated a Phase III trial to test the efficacy of beta-interferon in poor-risk patients with Stages IIIA and IIIB non-small-cell lung carcinoma.

Methods: Between September 1994 and March 1998, 123 patients were accrued to this trial. Enrolled patients were not eligible for other chemoradiation studies within the RTOG. Eligibility criteria included histologically confirmed Stage IIIA or IIIB non-small-cell lung cancer (according to American Joint Committee on Cancer) considered clinically inoperable or unresectable at the time of surgery. Patients were required to have a Karnofsky performance status 50-70 or >70 and at least 5% weight loss over the preceding 3 months. Betaseron (recombinant human interferon beta(ser), rHuIFN-beta(ser),) was the chosen preparation of beta-interferon. The patients randomized to the investigational arm received 16 x 10(6) IU of Betaseron by i.v. bolus given 3 days a week (Monday-Wednesday) on Weeks 1, 3, and 5. The Betaseron was given 30 minutes before radiation therapy for a total of nine doses. Irradiation was delivered at 2 Gy per fraction, 5 days a week, for a total of 60 Gy over 6 weeks and was identical for both arms. The primary end point of the trial was overall survival with local control as a secondary end point. Toxicities occurring within 90 days of therapy completion were defined as acute.

Results: The median follow-up was 4 years (range: 2.5-6 years) for surviving patients. Seventy-six percent of all patients completed beta-interferon. Toxicity was the primary reason for noncompliance. Radiotherapy (RT) compliance was excellent in the RT-alone arm, with 94% completing therapy, compared to 82% in the beta-interferon arm (p = 0.0475). Grade 3 and 4 acute toxicities were higher on the beta-interferon arm (p = 0.0249). Grade 3 and 4 acute toxicities were primarily related to lung (n = 8) and esophagus (n = 7). No Grade 4 or 5 late toxicities were seen for patients in the radiation-alone arm. However, three patients on the beta-interferon arm experienced Grade 4 toxicity, and one patient died. The 1-year survival rate for the RT-alone arm was 44% with a median survival time of 9.5 months. The 1-year survival on the beta-interferon arm was 42% with a median survival of 10.3 months. There was no statistical difference in survival times (p = 0.66).

Conclusions: This multicenter, controlled Phase III trial failed to confirm the efficacy of Betaseron in patients receiving definitive radiotherapy for locally advanced, nonmetastatic non-small-cell lung cancer. The use of beta-interferon led to greater rates of both acute and late treatment-related toxicity. The RTOG continues to investigate other biologic modifiers that may provide a nontoxic alternative for this poor-risk population.