Interim Analysis of the Phase II Study: Noninferiority Study of Doxorubicin with Upfront Dexrazoxane plus Olaratumab for Advanced or Metastatic Soft-Tissue Sarcoma

Abstract

Purpose: To report the interim analysis of the phase II single-arm noninferiority trial, testing the upfront use of dexrazoxane with doxorubicin on progression-free survival (PFS) and cardiac function in soft-tissue sarcoma (STS).

Patients and methods: Patients with metastatic or unresectable STS who were candidates for first-line treatment with doxorubicin were deemed eligible. An interim analysis was initiated after 33 of 65 patients were enrolled. Using the historical control of 4.6 months PFS for doxorubicin in the front-line setting, we tested whether the addition of dexrazoxane affected the efficacy of doxorubicin in STS. The study was powered so that a decrease of PFS to 3.7 months would be considered noninferior. Secondary aims included cardiac-related mortality, incidence of heart failure/cardiomyopathy, and expansion of cardiac monitoring parameters including three-dimensional echocardiography. Patients were allowed to continue on doxorubicin beyond 600 mg/m² if they were deriving benefit and were not demonstrating evidence of symptomatic cardiac dysfunction.

Results: At interim analysis, upfront use of dexrazoxane with doxorubicin demonstrated a PFS of 8.4 months (95% confidence interval: 5.1-11.2 months). Only 3 patients were removed from study for cardiotoxicity, all on > 600 mg/m² doxorubicin. No patients required cardiac hospitalization or had new, persistent cardiac dysfunction with left ventricular ejection fraction remaining below 50%. The median administered doxorubicin dose was 450 mg/m² (interquartile range, 300-750 mg/m²).

Conclusions: At interim analysis, dexrazoxane did not reduce PFS in patients with STS treated with doxorubicin. Involvement of cardio-oncologists is beneficial for the monitoring and safe use of high-dose anthracyclines in STS.See related commentary by Benjamin and Minotti, p. 3809.

Figure 1:. Median Progression Free Survival

Progression-free survival (PFS) for patients on study. Median PFS is estimated to be 8.4 months with 95% confidence interval (5.1 months, 11.2 months).

Figure 2:. Cardiac Measurements Stratified by Dose.

A: The 2D Ejection fractions calculated by the CORE Laboratory presented in patients grouped by dose of doxorubicin. B: The GLS calculated by the CORE laboratory in patients grouped by dose of doxorubicin, presented as absolute value for clarity. In cases where doxorubicin was discontinued, the curves are indicated in red; otherwise, while receiving doxorubicin the curves are black.