Results of a trial with topotecan dose escalation and concurrent thoracic radiation therapy for locally advanced, inoperable nonsmall cell lung cancer

Purpose: To conduct a dose escalation clinical study with topotecan and concurrent standard dose thoracic irradiation to assess its feasibility and toxicity in the treatment of patients with locally advanced, inoperable nonsmall cell lung cancer (NSCLCA). Methods and Materials: Between April 1993 and August 1994, 12 patients with inoperable, loco-regionally advanced NSCLCA were entered in a prospective dose escalation trial and assigned to receive concurrent thoracic radiotherapy and topotecan. Patients received thoracic irradiation to a total tumor dose of 60 Gy in 30 fractions. Initial fields were to encompass the gross disease plus the mediastinum. Topotecan was delivered by bolus injection days 1 through 5, and days 22 through 26, beginning on the same day as the radiation therapy. The initial dose level was 0.5 mg/m². Two additional dose levels of 0.75 mg/m² and 1.0 mg/m² were tested. Results: Six patients were accessioned to the 0.5 mg/m² dose level, three patients to the 0.75 mg/m² dose level, and three patients to the 1.0 mg/m² dose level. At the 0.5 mg/m² dose level, zero of six patients had ≤Grade 4 hematologic toxicity. One of the six had Grade 3 esophagitis. At the 0.75 mg/m² dose level, two of three patients had ≤Grade 3 nonhematologic toxicity including anorexia, fatigue, nausea, vomiting, and weakness; zero patients experienced ≤Grade 4 hematologic toxicity. At the 1.0 mg/m² dose level one of three patients had ≤Grade 3 esophagitis, and two of three patients experienced Grade 4 neutropenia. With a follow-up of 12 to 24 months, two patients are alive and free of disease, three patients are alive with disease (two with distant metastasis, one with local disease and distant metastasis), and the remaining seven patients are dead of disease. Conclusions: The combination of topotecan and thoracic radiotherapy for nonsmall lung cancer, in the manner given by this protocol, could be safely given at a dose level of only 0.5 mg/m² days 1 to 5 and 22 to 26 with 60 Gy of external beam radiotherapy. Higher doses of topotecan were associated with high hematologic and gastrointestinal toxicity. Distant metastasis was the primary pattern of failure.