Cytori Therapeutics reports that their compound ATI-0918 is equivalent to Janssen’s Caelyx (doxorubicin) — a previously approved liposomal formulation of doxorubicin hydrochloride for the treatment of ovarian cancer.

The data stems from a so-called bioequivalence study, in which ovarian cancer patients switched from Caelyx to ATI-0918 or vice versa.

Cytori presented data from the study at the American Association of Pharmaceutical Scientists Annual Meeting, held Nov. 12-15 in San Diego.

A bioequivalence study aims to demonstrate that a new version of a biological drug has similar properties as a drug already on the market. In contrast to small molecules, it is not easy to make identical copies of biological drugs and complex formulations such as Caelyx.

So while regulatory authorities do not require a generic version of a small molecule to be extensively tested before market introduction, more complex drugs need to go through comparisons to the original drug.

Cytori’s study explored various aspects of how the drug behaves in the body — such as its blood concentrations after a given dose or how quickly it is eliminated.

The trial enrolled 44 patients with ovarian cancer who were randomly assigned one of two treatment sequences.

One group received a single dose of Caelyx on the first day of a 28-day cycle. They then received the same dose of ATI-0918 on day 1 of the second 28-day cycle. A period of three weeks separated the two treatment cycles.

The second group of patients followed the same set-up, but started with ATI-0918 and then switched to Caelyx. Researchers then took blood samples at various intervals for 216 hours after patients received the medication.

All measures fell within the required boundaries of 80% to 125% of that seen with the original drug.

Janssen’s Caelyx is approved in the European Union for the treatment of ovarian cancer, breast cancer, multiple myeloma, and Kaposi’s sarcoma. Cytori now plans to use the bioequivalence data gathered to seek approval for ATI-0918 in the E.U.

In the U.S., the liposomal formulation of doxorubicin hydrochloride is sold as Lipodox. Cytori will need to conduct additional studies to prove that ATI-0918 is equivalent to Lipodox, which is manufactured by Sun Pharma.