Purpose: Imexon is an iminopyrrolidone that induces apoptosis and has synergistic activity with docetaxel in preclinical models. This trial was designed to establish the maximum tolerated dose (MTD) of imexon given with docetaxel in breast, prostate and non-small cell lung cancer (NSCLC).
Patients and methods: 34 patients received protocol therapy. 26 patients received escalating doses of imexon given intravenously over 60 min on days 1-5 every 21 days. Docetaxel was administered intravenously at a fixed dose of 75 mg/m(2) immediately following imexon on day 1 every 21 days. A 3+3 design was used with eight additional patients treated at MTD. Response was measured using RECIST.
Results: Seven dose levels of imexon were evaluated (390 mg/m(2) to 1,700 mg/m(2)). The MTD was imexon 1,300 mg/m(2) IV on days 1-5 in combination with docetaxel. Dose limiting toxicities were grade 3 non-cardiac chest pain and grade 3 diarrhea. Activity was seen in 4 patients [2 partial responses (NSCLC (PR=1), prostate cancer (PR=1)), 2 minor responses (MR=breast, NSCLC)]. Eleven patients had stable disease by RECIST (including the patients with MR; prostate cancer=6, NSCLC=3). Six (one with breast cancer, two with prostate cancer and three with NSCLC) demonstrated stable disease (SD) for > or = 3 months.
Conclusion: The MTD of combination therapy is imexon 1,300 mg/m(2) IV on days 1-5 with docetaxel 75 mg/m(2) IV on day 1 of a 21 day treatment cycle. Demonstrated responses warrant further investigation in phase II trials of which a phase II trial in NSCLC is planned.