On October 10, 2016 CytRx Corporation (NASDAQ: CYTR), a biopharmaceutical research and development company specializing in oncology, reported results from its on-going Phase 1b/2 trial of aldoxorubicin in combination with ifosfamide/mesna in patients with advanced sarcomas at the European Society for Medical Oncology (ESMO) (Free ESMO Whitepaper) 2016 Congress being held in Copenhagen, Denmark.
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Of the 36 evaluable patients receiving either 170mg/m2 or 250mg/m2 of aldoxorubicin plus ifosfamide and mesna, 13 of 36 (36%) achieved a partial response of the target lesion by RECIST 1.1 criteria, 22 of 36 (61%) had stable disease, and one patient had progressive disease. Median progression-free survival has not been reached, and dose-limiting toxicities were not observed in either cohort. No clinically significant cardiac toxicities were seen. The most common Grade 3 or 4 adverse events were neutropenia (71%), anemia (54%), thrombocytopenia (17%) and febrile neutropenia (14%). There were nine treatment-related serious adverse events, and no treatment-related deaths. The trial has been expanded to allow continued enrollment of additional sarcoma patients at the 250 mg/m2 dose of aldoxorubicin with ifosfamide and mesna.
"The results to date demonstrate that aldoxorubicin combined with ifosfamide provides significant clinical benefit for sarcoma patients," said Sant Chawla, M.D., F.R.A.C.P., the trial’s principal investigator and Director of the Sarcoma Oncology Center in Santa Monica, California. "More than one-third of sarcoma patients achieved a partial response for the target lesion and 61% had prolonged stable disease. Importantly, six patients with unresectable tumors achieved greater than 50% tumor shrinkage allowing some of them to become eligible for surgery. Further, we did not see any signs of cardiotoxicity including in patients that received approximately 10 times the cumulative maximum dose of doxorubicin."
The Phase 1b/2 clinical study is a single-center trial that has enrolled 40 patients to date with locally advanced, unresectable, and/or metastatic soft tissue sarcoma, intermediate-grade or high-grade chondrosarcoma or osteosarcoma. In the dose escalation phase, patients received either 170mg/m2 or 250mg/m2 of aldoxorubicin in combination with up to a 14-day continuous infusion of ifosfamide (1g/m2/day) plus mesna over a 28-day cycle. Up to six cycles of ifosfamide/mesna with aldoxorubicin can be administered, and aldoxorubicin may be continued until tumor progression or unacceptable toxicity occurs. The expansion phase will enroll patients at the 250mg/m2 dose of aldoxorubicin and will allow for patients that had received prior chemotherapy to be included. The primary endpoint of the study is safety, and secondary endpoints include overall response rates and progression-free survival.
About Aldoxorubicin
Aldoxorubicin is a rationally-engineered cytotoxic which combines doxorubicin, a widely used chemotherapeutic agent, with a novel linker molecule that binds directly and specifically to circulating albumin, the most abundant protein in the bloodstream. Protein-hungry tumors concentrate albumin, which facilitates the delivery of the linker molecule with the attached doxorubicin to tumor sites. In the acidic environment of the tumor, but not the neutral environment of healthy tissues, doxorubicin is released. Typically, doxorubicin is delivered systemically and is highly toxic, which limits its dose to a level below its maximum therapeutic benefit. Doxorubicin also is associated with many side effects, especially the potential for damage to heart muscle at cumulative doses greater than 450 mg/m2. Using this acid-sensitive linker technology, aldoxorubicin delivers greater doses of doxorubicin (3 ½ to 4 times). To date, there has been no evidence of clinically significant effects of aldoxorubicin on heart muscle, even at cumulative doses of doxorubicin in excess of 5,000 mg/m2. Aldoxorubicin is the first-ever single agent to show superiority over doxorubicin in a randomized global Phase 2b clinical trial in first-line STS.