Taking aim at relapsed ovarian cancer patients considered incurable, Madrid, Spain-based PharmaMar SA is starting a Phase III trial with Yondelis (trabectedin), a compound first isolated from marine tunicates.

The study, to be conducted under a special protocol assessment by the FDA, will enroll 650 patients in 110 hospitals across 16 countries, including the U.S. and Europe, testing Yondelis in combination with pegylated-liposomal doxorubicin from ALZA Corp., a unit of New Brunswick, N.J.-based Johnson & Johnson.

Already approved for ovarian cancer, the doxorubicin product is sold by ALZA as Doxil in the U.S. and Caelyx in Canada, and Yondelis is partnered with ALZA's parent firm J&J through the latter's research and development arm in La Jolla, Calif.

Synthetic Yondelis is based on a peptide originally from the marine tunicate Ecteinascidia turbinate. Tunicates, or sea squirts, are tiny, barrel-shaped organisms that attach to objects such as piers and boats. They belong to the phylum Urochordata, which is related to the phylum Chordata - of which vertebrates also are members, hence the close study of tunicates.

PharmaMar, a subsidiary of the Zeltia Group, most recently offered Yondelin data at the 29th European Society for Medical Oncology in Vienna, Austria, proving the drug combined with Doxil is safe and feasible.

The company also has Aplidin, another marine-derived peptide, which comes from Aplidium albicans, a Mediterranean tunicate. At the same Austrian scientific meeting in November, results from a Phase II study with Aplidin found the drug active in patients with advanced or metastatic melanoma.

PharmaMar is developing Aplidin for acute lymphoblastic leukemia, and has a compound called Kahalalide F in Phase II trials. In June, the firm said Phase I data with Kahalalide F in patients with advanced or metastatic androgen-refractory prostate cancer showed the therapy can be administered safely as a one-hour intravenous infusion during five consecutive days.

Derived from the sea slug Elysia rufescens, the TGF-alpha inhibitor also is in Phase II trials against melanoma, non-small-cell lung cancer and hepatocellular carcinoma, as well as severe psoriasis.