CytRx Corporation (NASDAQ:CYTR) have a smile on their faces Thursday, after the drug maker announced an update on the regulatory pathway for a New Drug Application (NDA) submission for aldoxorubicin in soft tissue sarcomas (STS).

The Company plans to submit a rolling NDA under section 505(b)(2) to the FDA for aldoxorubicin as a treatment for STS. The 505(b)(2) pathway is designed for a new drug that contains the same active ingredient as a previously approved drug, also known as a reference drug. For aldoxorubicin, doxorubicin is the reference drug. The NDA submission is not reliant solely on the recently completed Phase 3 clinical trial in STS or overall survival results. Rather, CytRx’s completed pharmacokinetic clinical trial, Phase 2b and Phase 3 trials in STS, along with preclinical safety and efficacy studies, will serve as “scientific bridges” between aldoxorubicin and doxorubicin. These studies, along with the published literature of doxorubicin’s effectiveness and safety, will form the basis of the NDA filing for aldoxorubicin under the 505(b)(2) regulations.

In reaction, CytRx shares are rising nearly 19% to 0.63 in Thursday’s trading session.

“Having worked on aldoxorubicin’s regulatory strategy and as a participant in the March FDA meeting, the 505(b)(2) regulatory pathway is the most appropriate for aldoxorubicin in STS,” said Scott Wieland, PhD, CytRx’s Senior Vice President of Drug Development. “As noted in the FDA meeting, the aldoxorubicin preclinical and clinical studies will support a 505(b)(2) NDA submission, and no new clinical trials were requested by the FDA at the meeting. Additionally, CytRx’s previously approved special protocol assessment is no longer applicable.”

Aldoxorubicin has received Orphan Drug Designation by the FDA for the treatment of STS. Orphan designation provides several benefits including seven years of market exclusivity after approval, certain R&D related tax credits and protocol assistance by the FDA. European regulators granted aldoxorubicin Orphan Medicinal Product Designation for STS which confers ten years of market exclusivity among other benefits. CytRx plans to discuss with the European Medicines Agency (EMA) a path to filing a Marketing Authorization Application (MAA).

The proposed product label would allow the treatment of soft tissue sarcomas. New data could support future use of aldoxorubicin in neoadjuvant (pre-surgery) settings, as well as a replacement for doxorubicin in chemotherapy combinations. CytRx is also working on a market expansion strategy which would include other indications for aldoxorubicin including combinations with other chemotherapeutics and immunotherapies.

CytRx Corp. operates as a biopharmaceutical research and development company specializing in oncology. It provides clinical development of aldoxorubicin oncology pipeline for the treatment of cancer.