Eribulin on par with dacarbazine in patients with leiomyosarcoma
Eribulin is as effective as dacarbazine in patients with leiomyosarcoma (LMS), with both agents showing manageable safety profiles, results of a subgroup analysis from a phase III, open-label, randomized study have shown.
Of the 309 LMS patients (median age, 57 years; 42 percent had uterine disease; 57 percent had nonuterine disease) included, 157 were on eribulin and 152 on dacarbazine.
Median overall survival (OS) was comparable between eribulin- and dacarbazine-treated patients (12.7 vs 13.0 months; hazard ratio [HR], 0.93; 95 percent CI, 0.71–1.20; p=0.57). Median progression-free survival (PFS; 2.2 vs 2.6 months; HR, 1.07; 0.84–1.38; p=0.58) and objective response rate (ORR; 5 percent vs 7 percent) were also similar between the two groups. [Br J Cancer 2019;doi:10.1038/s41416-019-0462-1]
Treatment-emergent adverse events with a grade of 3 or above occurred in 69 percent of patients on eribulin and 59 percent of those receiving dacarbazine. There were no new safety signals found, and AEs associated with eribulin were similar to previous findings. [Lancet Oncol 2011;12:1045-1052]
“Historical data suggest that dacarbazine is more active in LMS than in other sarcomas,” according to researchers.
A randomized trial of doxorubicin every 3 weeks vs weekly doxorubicin vs doxorubicin plus dacarbazine for metastatic soft tissue sarcoma (STS) showed a significant improvement in response rates among LMS patients on combination therapy compared with those on doxorubicin alone (44 percent vs 17 percent [weekly] vs 20 percent [every 3 weeks], respectively). [J Clin Oncol 1987;5:840-850]
“That trial included 99 of 275 (36 percent) evaluable patients with LMS. By comparison, this phase III trial enrolled 309 of 452 (68 percent) patients with LMS,” researcher said.
Results of this trial, however, contradicted those of a subgroup analysis of patients with liposarcoma (LPS), which showed better OS with eribulin compared with dacarbazine. [J Clin Oncol 2017;35:3433-3439]
“Outcome heterogeneity within the LMS subgroup may represent biologic differences in this sarcoma subtype,” researchers said.
The present study randomized patients aged ≥18 years with LPS or LMS, ECOG PS ≤2, and ≥2 prior treatment regimens to eribulin mesylate (1.4 mg/m2 intravenously on day 1 and day 8) or dacarbazine (either 850, 1,000 or 1,200 mg/m2 intravenously) every 21 days until disease progression. OS was the primary endpoint, while PFS and ORR were secondary endpoints.
This phase III study was not powered to draw definitive conclusions on the activity of eribulin in histologic subgroups and was also not designed to be a noninferiority trial.
“To further understand unique sarcoma subtypes, future prospective trials in STS should aim to examine treatment outcomes as a function of histology, molecular alteration, anatomic site and gender. The LMS subtype encompasses different disease types based on clinical and pathologic features, and future research should benefit from additional stratification criteria. Such research may contribute to further improvement in outcomes for patients with LMS,” researchers said.