Concurrent twice-a-week docetaxel and radiotherapy: A dose escalation trial with immunological toxicity evaluation

Purpose: In vitro studies show that docetaxel (Taxotere) is potent radiosen sitizer, In a previous study we observed a 27% complete response rate after radiotherapy and weekly docetaxel for non-small-cell lung cancer. In this dose escalation study we investigated the feasibility of a twice-a-week doc etaxel regimen together with conventionally fractionated radiotherapy for b rain, chest, and pelvic tumors. Methods and Materials: Nine patients with stage IIIb lung cancer, 9 with st age IVa pelvic tumors, and 9 with brain glioblastoma were recruited. The st arting dose was 15 mg/m(2) (twice a week) and was escalated by 4 mg/m(2) in crements every 3 patients with chest, pelvic, and brain tumors. Results: The maximum tolerated dose of docetaxel was 15 mg/m(2) (twice a we ek) for chest and pelvic cancer patients. The dose-limiting toxicity (DLT) was asthenia and mucosal toxicity (esophagitis or diarrhea in chest and pel vic tumors, respectively). Patients with glioblastomas received 23 mg/m(2) (twice a week) without toxicity. Complete response of the chest disease was observed in 3/9 (33%) patients and partial response in 4/9 (44%). Three pa tients with glioblastoma had a partial response. In pelvic malignancies a h igh complete response rate was observed (4/9; 45%). Severe monocytopenia an d lymphocytopenia were observed during the fourth week of treatment. IgG an d IgA immunoglobulins were also reduced. This coincided with the onset of a sthenia and severe mucosal toxicity. Asthenia was absent in patients treate d for brain tumors, and lymphocyte toxicity was less pronounced. Conclusions: Docetaxel radiochemotherapy is a promising therapeutic approac h for locally advanced cancer. The recommended dose of docetaxel for chest and pelvic cancer patients is 15 mg/m(2) twice a week. Patients with brain tumors can be safely treated with higher doses of docetaxel (23 mg/m(2) twi ce a week) without toxicity. The severe immunologic toxicity observed sugge sts that granulocyte-macrophage colony-stimulating factor (GM-CSF) and immu noglobulin administration may be important in the efficacy and tolerance of taxane-based radiochemotherapy. Randomized trials are required to assess w hether the efficacy of docetaxel radiochemotherapy depends on the frequency of docetaxel administration during radiation treatment. (C) 1998 Elsevier Science Inc.