BACKGROUND: In this report, we present results from studies of eribulin as monotherapy (Study 223) and in combination with irinotecan (the phase II part of Study 213) for patients with relapsed/refractory pediatric rhabdomyosarcoma (RMS), non-rhabdomyosarcoma soft tissue sarcoma (NRSTS), or Ewing sarcoma (EWS). PATIENTS AND METHODS: Studies 223 and 213 were phase II multicenter trials that enrolled pediatric patients with histologically confirmed disease. Treatment comprised 21-day cycles of eribulin mesylate 1.4 mg/m RESULTS: In Study 223, 21 patients (RMS, n = 8
NRSTS, n = 8
EWS, n = 5) were enrolled and treated. No responses were observed, resulting in early termination of enrollment. By the data cut-off date (22 February 2021), six patients (RMS, n = 3
NRSTS, n = 1
EWS, n = 2) had stable disease for ≥5 weeks. All patients had one or more treatment-emergent adverse event (TEAE), most commonly neutrophil count decreased (71.4%). In Study 213 (phase II part), 27 patients (RMS, n = 9
NRSTS, n = 9
EWS, n = 9) were enrolled/treated. By the data cut-off date (9 July 2021), three patients (one in each cohort) had had a response, resulting in an ORR of 11.1% and DORs of 2.9 (RMS), 1.4 (NRSTS), and 15.4 (EWS) months. All patients had one or more TEAE, most commonly diarrhea and neutrophil count decreased (51.9% each). CONCLUSIONS: Eribulin, as monotherapy or combination therapy, exhibited a safety profile consistent with that observed previously in adult populations
however, efficacy in both studies was not considered adequate to advance investigation in these disease areas.