[Effect of interferon inducer (poly ICLC) in the treatment of malignant brain tumor (author's transl)]

Interferon inducing activity, antitumor activity and toxicity of poly ICLC (poly IC stabilized with poly L-Lysine and carboxymethyl cellulose) in rodents were studied. SD strain rats were injected intravenously with poly IC or poly ICLC. Interferon in rat plasma was assayed by a plaque reduction method using stomatitis virus. The peak level of plasma interferon of the poly ICLC injection rat was as high as that of poly IC injection rat, and in the former, high level of plasma interferon persisted for 4-12 hours. Next, brain tumor-bearing rats were treated intravenously with poly ICLC and observed for death daily. Weekly treatment with 1 mg/kg of poly ICLC increased the mean survival time although no antitumor effect was observed with poly IC. The LD 50 value of poly IC was 33.5 mg/kg, and that of poly ICLC was 18.6 mg/kg and as to poly ICLC administration, no remarkable side effect was recognized below the dose of 1.5 mg/kg. In clinical trials, poly ICLC was given intravenously at the dose of 0.05-0.2 mg/kg to 9 patients with malignant brain tumor. (6 patients were glioblastoma, 1 was astrocytoma, and 2 were ependymoma.) In 2 patients, poly ICLC was administered once, in 2 patients twice, in 2 patients 3 times, and in 3 patients more than 5 times. The interval of each administration was 7 days. Poly ICLC induced high level of serum interferon (more than 100 reference unit/ml) in all patients and over 100 unit/ml of interferon was maintained for 24 hours. The highest interferon titer induced was 875 unit/ml. The most frequently encountered toxic reaction was fever, which occurred in all cases. The mean peak temperature elevation was 1.9 degrees C, which usually occurred 4-8 hours after drug administration. Modest hypotention was detected in one case. Leucopenia was detected in 3 cases. These abnormalities were all modest, and improved in a few days. As to the effect of poly ICLC, neurological improvement was recognized in 3 cases, and in one of them, remission on CT scan was also recognized.