CytRx, a biopharmaceutical R&D company specializing in oncology, has announced that the FDA has removed the partial clinical hold on the company's aldoxorubicin clinical trials. Enrollment and dosing of new patients now is permitted after study sites' Institutional Review Boards (IRBs) approve the revised trial protocols.

"CytRx developed modified study parameters intended to avoid potential risks, while allowing the company to evaluate the therapeutic impact of aldoxorubicin for patients with soft tissue sarcoma, glioblastoma, Kaposi's sarcoma and small cell lung cancer, among other trials," said Steven A. Kriegsman, chairman and CEO of CytRx. "Our staff worked closely with the FDA Oncology Division to resolve all partial clinical hold issues as rapidly as possible. We expect enrollment and dosing in the ongoing clinical trials to be back underway soon."

CytRx currently believes that enrollment rates and timelines for its trials will remain materially unchanged. The company expects to complete enrollment in its ongoing pivotal global phase III trial in second-line soft tissue sarcoma by the end of 2015 and unblind the clinical data by mid-2016. Subject to FDA approval, CytRx's market launch of aldoxorubicin for second line soft tissue sarcoma is projected to commence in 2017.

The widely used chemotherapeutic agent 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 450mg/m2.

Aldoxorubicin combines doxorubicin with a novel single-molecule linker that binds directly and specifically to circulating albumin, the most plentiful protein in the bloodstream. Protein-hungry tumors concentrate albumin, thus increasing 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. This allows for greater doses (3 ½ to 4 times) of doxorubicin to be administered while reducing its toxic side effects.

In studies thus far there has been no evidence of clinically significant effects of aldoxorubicin on heart muscle, even at cumulative doses of drug well in excess of 2,000mg/m2.