A multicenter phase II study of TSU-68, an oral multiple tyrosine kinase inhibitor, in combination with docetaxel in metastatic breast cancer patients with anthracycline resistance.

BACKGROUND: TSU-68 is a novel multiple tyrosine kinase inhibitor that inhibits vascular endothelial growth factor receptor-2, platelet-derived growth factor receptor, and fibroblast growth factor receptor. This open-label, non-comparative, multicenter phase II study evaluated TSU-68 in combination with docetaxel in patients with metastatic breast cancer that had relapsed within 1 year despite prior treatment with an anthracycline-containing regimen.

METHODS: TSU-68 was orally administered on days 1-21, and docetaxel was intravenously delivered on day 1. The regimen was repeated every 21 days. Primary endpoint was objective response rate according to the RECIST guidelines version 1.0.

RESULTS: TSU-68 in combination with docetaxel produced objective responses in 21.1% and clinical benefits in 42.1% of the patients, respectively (1 complete response, 3 partial response, and 4 stable disease for at least 24 weeks, n = 19). Median time to progression was 148 days, and median overall survival was 579 days. The common adverse drug reactions were leukopenia, neutropenia, nail disorder, malaise, dysgeusia, alopecia, and edema.

CONCLUSIONS: TSU-68 in combination with docetaxel showed a promising antitumor response with manageable toxicity in patients with anthracycline-resistant metastatic breast cancer. Further studies are warranted in a different population of breast cancer or other solid cancers.