RARE-28. The use of subcutaneous interferon in patients with craniopharyngioma: an institutional retrospective review

Current strategies for managing craniopharyngioma result in significant morbidity. Successful treatment with interferon alfa(INFα) after progression is reported in the literature. This retrospective review details our institutional experience with INFα in craniopharyngioma patients. Method: Between 2000-2021, we treated 81 craniopharyngioma patients. Twenty-two patients received 26 treatment courses of subcutaneous INFα. Twenty-three courses were evaluable for response. Results: Ten patients received upfront INFα after cyst decompression +/- ommaya placement. Progression free survival(PFS) ranged between 7-38mo. Three patients continue on treatment (10+, 12+, 14+mo); seven progressed (four on treatment (7, 9, 25, 38mo), three after treatment (13, 19, 32mo)). At progression, three underwent surgery alone, three underwent surgery and radiation, one resumed INFα. Thirteen patients received INFα after progression. Prior to INFα, eight patients had had surgery, five surgery and radiation. Two in each group had INFα, previously. PFS ranged between 5-82+mo. One patient remains on treatment (5+mo); four continue in follow-up without progression (23+,40+,64+,82+mo) with two patients avoiding radiation to date; eight progressed (three on treatment (6-8mo), five after treatment (16,24,26,46,71mo)). At progression, two underwent surgery alone, three underwent surgery and radiation, one received re-irradiation, two resumed INFα. While receiving INFα, two patients experienced serious adverse events (one intra-tumoral hemorrhage (not attributed to INFα), one suicidal ideation). Both recovered. One tolerated retreatment with INFα. Three additional patients stopped INFα for intolerance, but two received INFα at subsequent progression. No other unanticipated side effects were reported. Conclusion: INFα therapy in patients with both newly diagnosed and progressive craniopharyngioma delayed the need for aggressive surgical resection and/or radiotherapy in some cases. In some patients, INFα resulted in prolonged stabilization of disease delaying or avoiding radiation. Overall, INFα side effects were manageable. These results are encouraging regarding INFα therapy for patients with craniopharyngioma and warrant further evaluation with a clinical trial.