NEW YORK (TheStreet) -- CytRx Corp. (CYTR)  saw share price growth in the double-digits on Wednesday on the news its cancer drug had succeeded in a mid-stage clinical trial. By early afternoon, the stock was up 62.8% to $3.88.

A phase IIb study of aldoxorubicin, the drugmaker's experimental treatment for advanced soft tissue sarcomas such as those found in muscle, fat and blood vessels, proved successful in improving progression-free survival rates.

The study demonstrated 80% to 100% superiority over a treatment using chemotherapeutic agent doxorubicin alone. CytRx's aldoxorubicin is a novel, improved formulation of doxorubicin designed to allow for more efficient delivery inside cancerous cells.

"These results are extraordinary for a single agent treating these chemotherapy-resistant tumors," the study's principal investigator Sant Chawla of the Sarcoma Oncology Center in Santa Monica said in a statement. "Aldoxorubicin is the first and only single agent to surpass doxorubicin as a first-line treatment for soft tissue sarcomas."

"Aldoxorubicin is a major advance for treating soft tissue sarcomas," added CytRx CEO Steven A. Kriegsman. "By applying our proprietary linker technology to target the release of doxorubicin directly at the site of cancer we are able to safely increase the dosage of doxorubicin by approximately three and one-half to four times with tremendous clinical benefit to the patient."

--Written by Keris Alison Lahiff.