Differences in the efficacies of pazopanib and gemcitabine/docetaxel as second-line treatments for metastatic soft tissue sarcoma

Background: We retrospectively investigated the treatment outcomes of second-line treatment with pazopanib or gemcitabine/docetaxel in patients with advanced soft tissue sarcoma (STS). Methods: Ninety-one patients who were treated with pazopanib or gemcitabine/docetaxel for advanced STS between 1995 and 2015 were analyzed. Results: Forty-six and 45 patients received pazopanib and gemcitabine/docetaxel, respectively. The median progression-free survival for the group treated with pazopanib was 4.5 months compared with 3.0 months for the gemcitabine/docetaxel group (p = 0.593). The median overall survival for the group treated with pazopanib was 12.6 months compared with 14.2 months for the gemcitabine/docetaxel group (p = 0.362). The overall response rates (ORRs) were 6.5 and 26.7% in the pazopanib and gemcitabine/docetaxel groups, respectively. The following parameters had ORRs favoring gemcitabine/docetaxel: age ≥50 years (31.6 vs. 2.9%, p = 0.006), histologic grade 1-2 (40.9 vs. 0%, p = 0.001), and poor first-line treatment response (23.3 vs. 3.0%, p = 0.022). Gemcitabine/docetaxel was associated with better ORRs for the following histologic subtypes: leiomyosarcoma (p = 0.624), malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma (p = 0.055), and angiosarcoma (p = 0.182). However, the ORR of synovial sarcoma favored pazopanib (p = 0.99). Conclusions: The efficacies of pazopanib and gemcitabine/docetaxel as second-line treatments after doxorubicin or ifosfamide failure differed among clinical and histologic subgroups and appeared to facilitate a more personalized treatment approach for advanced STS.