Phase II Radiation Therapy Oncology Group trial of conventional radiation therapy followed by treatment with recombinant interferon-beta for supratentorial glioblastoma: results of RTOG 9710.

PURPOSE: The aim of this study was to determine whether recombinant human interferon beta-1a (rhIFN-beta), when given after radiation therapy, improves survival in glioblastoma.

METHODS AND MATERIALS: After surgery, 109 patients with newly diagnosed supratentorial glioblastoma were enrolled and treated with radiation therapy (60 Gy). A total of 55 patients remained stable after radiation and were treated with rhIFN-beta (6 MU/day i.m., 3 times/week). Outcomes were compared with the Radiation Therapy Oncology Group glioma historical database.

RESULTS

RhIFN-beta was well tolerated, with 1 Grade 4 toxicity and 8 other patients experiencing Grade 3 toxicity. Median survival time (MST) of the 55 rhIFN-beta-treated patients was 13.4 months. MST for the 34 rhIFN-beta-treated in RPA Classes III and IV was 16.9 vs. 12.4 months for historical controls (hazard ratio [HR] = 1.27, 95% confidence interval [CI] = 0.89-1.81). There was also a trend toward improved survival across all RPA Classes comparing the 55 rhIFN-beta treated patients and 1,658 historical controls (HR = 1.24, 95% CI = 0.94-1.63). The high rate of early failures (54/109) after radiation and before initiation of rhIFN-beta was likely caused by stricter interpretation of early radiographic changes in the current study. Matched-pair and intent-to-treat analyses performed to try to address this bias showed no difference in survival between study patients and controls.

CONCLUSION

RhIFN-beta given after conventional radiation therapy was well tolerated, with a trend toward survival benefit in patients who remained stable after radiation therapy. These data suggest that rhIFN-beta warrants further evaluation in additional studies, possibly in combination with current temozolomide-based regimens.