Phase Ib trial of combining aldoxorubicin plus doxorubicin.

Abstract

2550 Background: Aldoxorubicin is a novel drug that covalently binds to albumin in the circulation with release in low pH environments. Preclinical studies in pancreatic and ovarian tumor xenograft models demonstrated that aldoxorubicin plus doxorubicin administered at 50% of their MTD provided complete and prolonged tumor remission in these models with less toxicity than each drug administered at their MTD. We evaluated the toxicity profile of a fixed dose of doxorubicin and escalating doses of aldoxorubicin in subjects with advanced solid tumors. Methods: Phase 1b open label, dose-escalation study of aldoxorubicin administered at either 175, 240 or 320 mg/m2 (130, 180, or 240 mg/m2 doxorubicin equivalents) iv + 35 mg/m2doxorubicin iv, both on Day 1 of 21 day cycles, for up to 8 cycles. The MTD is the dose level immediately below where 2/6 subjects experience a dose limiting toxicity (DLT) , or the maximum dose of 320 mg/m2aldoxorubicin. Additional subjects may be enrolled at the MTD to provide more safety data. Results: 10 subjects have been treated as of January 21, 2013. No DLT was observed and the MTD was defined as 320 mg/m2 aldoxorubicin and 35 mg/m2 doxorubicin iv administered on Day 1 of 21 day cycles. A median of 4.5 cycles have been received. 3/10 subjects were terminated due to either progressive disease (2) or death (1). No subject was terminated due to an adverse event. Grade 3 or 4 neutropenia was seen at all dose levels (8/10 subjects). 4/10 subjects exhibited grade 3 or 4 thrombocytopenia and 3/10 subjects had grade 3 or 4 anemia. Neutropenic fever occurred in 3/10 subjects. Other grade 3/4 adverse events seen in 2 or fewer subjects included fatigue, increased liver enzymes and dehydration. No significant mucositis or cardiotoxicity was observed. At this time the best response has been stable disease in 6/10 subjects and a partial response in 1 subject (malignant fibrous histiocytoma). Conclusions: The combination of aldoxorubicin (320 mg/m2)) + doxorubicin (35 mg/m2) can be safely administered to subjects with solid tumors. Hematologic toxicity is common and can be controlled with growth factors. The dose of aldoxorubicin is 90% of the MTD of aldoxorubicin administered as a single agent. Thus, doxorubicin does not appear to add to the toxicity of this combination. Clinical trial information: NCT01673438.