CytRx Corporation (NASDAQ: CYTR), a biopharmaceutical research and development company specializing in oncology, today announced highly positive top-line efficacy results from a multicenter, randomized, open-label global Phase 2b clinical trial. The trial investigated the efficacy and safety of aldoxorubicin compared with doxorubicin in subjects with first-line metastatic, locally advanced or unresectable soft tissue sarcomas (STS). Aldoxorubicin combines the chemotherapeutic agent doxorubicin with a novel linker-molecule that binds specifically to albumin in the blood to allow for delivery of higher amounts of doxorubicin (3½ to 4 times) without the major dose-limiting toxicities seen with administration of doxorubicin alone.
In this 123-subject, 31-center global Phase 2b clinical trial, subjects with advanced soft tissue sarcomas were administered either 350 mg/m 2 of aldoxorubicin (83 subjects) or 75 mg/m 2 of doxorubicin (40 subjects) every 3 weeks for up to 6 cycles. Subjects were followed every 6 weeks with CT scans to monitor tumor size. The primary endpoint was progression-free survival (PFS) as determined by both investigators at study sites and by a blinded radiology review performed at an independent central laboratory. Secondary endpoints included overall response rates (complete and partial) and PFS at 6 months for each group, and overall survival which will be reported when the clinical trial is complete.
Consistent with the trial protocol, CytRx used two approaches to evaluate the efficacy of aldoxorubicin compared to doxorubicin in patients with soft tissue sarcomas: assessment by the study investigators, as well as assessment by a blinded central laboratory review. In this study, both investigator assessment and central lab review showed an unambiguous 80-100% improvement in PFS among patients treated with aldoxorubicin. In an intent-to-treat analysis, the investigator-assessed median PFS was 8.4 months for aldoxorubicin patients versus 4.7 months for doxorubicin patients (p=0.0002), while the blinded central lab review indicated that median PFS for aldoxorubicin patients was 5.7 months versus 2.8 months for doxorubicin patients (p=0.018). Per investigators, 67.1% of aldoxorubicin patients had not progressed at 6 months, compared with 36.1% of doxorubicin-treated patients (p=0.005). By blinded central lab review, 46.8% of aldoxorubicin patients had not progressed at 6 months, compared with 23.7% of doxorubicin patients (p=0.038).
The overall response rate as determined by the investigators was 25.4% for aldoxorubicin subjects (2.7% complete response and 22.7% partial response) versus 5.4% for doxorubicin subjects (0% complete response and 5.4% partial response). As assessed by blinded central lab review, 23.0% of aldoxorubicin subjects had a partial response while 0.0% of doxorubicin subjects exhibited any objective response.