Recombinant human interferon-beta (rHuIFN-beta) and radiation therapy for inoperable non-small cell lung cancer

Abstract

Fifteen patients with stage II, IIIA, and IIIB non-small cell lung cancer (NSCLC) received subcutaneous (s.c.) recombinant, glycosylated, human interferon-beta 1a (Rebif; rHuIFN-beta 1a) on each day of conventionally fractionated radiation therapy (RT) given in 2.0 Gy fractions to 60 Gy in 6 weeks. The rHuIFN-beta 1a was generated in CHO cells by recombinant DNA technology and is identical to natural IFN-beta produced by fibroblasts in primary sequence and glycosylation. Cohorts of three patients each were treated with escalating doses of rHuIFN-beta 1a: 1.5, 3, 6, 12, and 24 MIU/m2 per treatment day. Acute toxicity was assessed according to modified WHO criteria; late toxicity was graded using RTOG late toxicity criteria. The maximum tolerated dose (MTD) of rHuIFN-beta 1a was defined as the dose level immediately below that in which dose-limiting toxicity occurred in > or = two of six patients. Immunomodulatory effects and antigenicity of rHuIFN-beta 1a were assessed by 2-5A synthetase, beta 2-microglobulin, and neopterin levels and by measurement of anti-rHuIFN-beta antibodies, respectively. Fourteen of fifteen patients experienced grades 1-3 acute (early) toxicity (< or = 90 days), which was primarily gastrointestinal: dysphagia/esophagitis (14/15), nausea/vomiting (12/15), anorexia (7/15), and liver transaminasemia (6/15). One of three patients treated with 24 MIU/m2 per treatment day (total rHuIFN-beta 1a dose 672 MIU) died of complications secondary to pneumonia, sepsis, adult respiratory distress syndrome (ARDS), and radiation pneumonitis. Twelve patients were evaluable for late toxicity (> 90 days). Maximum toxicity was grade 0 in five patients, grade 1 in four patients, and grade 5 in one patient (radiation pneumonitis). Clinical responses from the combination were 1/15 CR, 6/15 PR, 6/15 stable disease, and 1/15 progressive disease. The MTD of rHuIFN-beta 1a has been estimated at 12 MIU/m2 per treatment day when given daily during conventional RT to 60 Gy in 6 weeks. Biologic response by rHuIFN-beta 1a alone was reflected by significant and dose-related increases in 2-5A synthetase, beta 2-microglobulin, and neopterin. Radiation therapy alone had no effect on these immune response parameters and did not diminish their augmentation by rHuIFN-beta 1a. There was no association of biologic modulation with clinical response or survival.