PRINCETON, NJ--Direct intratumor radioimmunotherapy (RAIT), with multiple courses delivered via indwelling or removable catheters, resulted in prolonged survival in patients with malignant glioma. Observations in newly diagnosed patients suggests that this treatment may have its greatest benefits as an adjuvant to primary surgical excision, Dr. Agostino Arista said at the Fifth Conference on Radioimmunodetection and Radioimmunotherapy of Cancer.
Patients with recurrent malignant glioma had improved survival with the treatment, and those with minimal residual disease following conventional primary therapy showed improved response rates. The treatment was associated with no significant local or systemic side effects, said Dr. Arista, of M. Buffalini Hospital, Cesena, Italy, who presented the report for principal investigator P. Riva.
The investigators used two different iodine(Drug information on iodine) 131-labeled murine monoclonal antibodies, BC-2 and BC-4, which react with tenascin, an extracellular antigen associated exclusively with malignant gliomas, Dr. Arista said.
Treatment was carried out in 38 patients after surgery for recurrent glioma and in 14 patients following surgery and other conventional treatments for newly diagnosed brain tumors. 131I was delivered at doses escalating from 5 up to 69 mCi per cycle, and patients received up to six treatments.
Of 48 evaluable patients, 12 experienced complete remissions. Six patients had a partial remission, while nine had stable disease and 21 progressed. The study did not include a randomized control group, but median survival in the treated patients was considerably longer than that reported for comparable patients who received conventional therapy (18 months versus 12 months), Dr. Arista said.
The likelihood of a response was determined primarily by tumor size, Dr. Arista continued. The response rate was about 40% in the group as a whole, 54% in those with small or minimal lesions following other therapy, and only 23% in those with bulky lesions. Patients with newly diagnosed tumors had a somewhat greater rate of response than those with recurrent disease.
Headaches, the only clinically apparent treatment side effect, occurred in 13 patients and were transient in all cases. There was no systemic, hematologic, hepatic, or renal toxicity.