Docetaxel rechallenge after a first response in non-resistant metastatic breast cancer: significant activity with manageable toxicity.

Docetaxel is a major drug in metastatic breast cancer (MBC) treatment. At progression, rechallenge with docetaxel can be discussed, according to previous efficacy and tolerance, as long as it was stopped for reasons other than progression. Currently, no data are available outlining outcomes after this pragmatic approach in MBC. We retrospectively identified 72 patients with the following criteria: (i) objective response or stable disease with a previous line of treatment with docetaxel in the metastatic setting, (ii) discontinuation for a reason other than progression, (iii) rechallenge with docetaxel after a minimal docetaxel-free interval of 3 months. The main objectives were to evaluate overall response (ORR), time to progression (TTP), overall survival (OS) and toxicity at reintroduction of docetaxel. Median patient age was 57 years (range: 34-84). Docetaxel was reintroduced as a 2nd, 3rd, or ≥4th line of chemotherapy in the metastatic setting in 21, 46 and 33% of cases, respectively. Previous agents used included capecitabine, anthracycline, and vinorelbine in 54, 40 and 21% of cases, respectively. The median number of docetaxel cycles was 6 (range: 1-18). Among the 33 patients with disease assessed according to RECIST criteria, 14 (42.5%) had a partial response and 11 (33.5%) a stable disease>6 weeks. Among the 46 patients with an initial CA 15-3 increase, 34 (74%) had a ≥50% decrease of the value. Globally, 55 patients (76%) obtained a benefit from the treatment. The median TTP and OS were 5.7 months (95% CI: 5.0-6.3) and 10.2 months (95% CI: 8.6-11.8), respectively. Forty-six patients (64%) reported grade 1/2 toxicity, 23 patients (32%) experienced grade 3/4 toxicity, mostly neutropenia (17%) and fluid retention (10%). There was no difference in median TTP after subsequent docetaxel in subgroup analyses. This retrospective analysis supports the pragmatic strategy to retreat patients with MBC with docetaxel when this drug has shown previous activity and was stopped for other causes than progression.