CytRx Corporation, a biopharmaceutical research and development company specializing in oncology, has received written notice from the United States Food and Drug Administration (FDA) that its clinical trials for aldoxorubicin have been placed on partial clinical hold. The news supplements and is consistent with the prior verbal communications from the FDA.

As previously announced, all currently enrolled patients can continue receiving aldoxorubicin treatment, or comparator drugs, as per study protocols, but no new patients can be enrolled until the clinical hold is lifted.  At the FDA's request, the company will amend all aldoxorubicin study protocols to include an appropriate inclusion/exclusion criteria, an additional patient screening assessment and an evaluation of serum electrolytes prior to aldoxorubicin administration. CytRx is working diligently in collaboration with the US FDA to seek the release of the clinical hold and resume enrollment in its clinical studies.

CytRx currently believes that the partial hold issue will be expeditiously resolved and that enrollment rates and timelines for its ongoing trials will remain materially unchanged, subject to FDA timing.  The company currently expects to announce preliminary results from the ongoing phase 2 clinical trial of aldoxorubicin in Kaposi's Sarcoma in the first half of 2015 and preliminary results from the ongoing phase 2 clinical trial of aldoxorubicin in glioblastoma multiforme in the first half of 2015. CytRx remains committed to completing enrollment of its ongoing pivotal global phase 3 trial in second-line soft tissue sarcoma by the end of 2015.

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 450 mg/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 2,000 mg/m2.