By Nicola Leske and Rajiv Sekhri
LONDON, Feb 22 (Reuters) - Spanish biotechnology firm Zeltia (ZEL.MC: Quote, Profile, Research) expects to file soon for approval of its cancer drug Yondelis, which was rejected by European regulators in 2003, its chairman said on Wednesday.
"We hope to file in a short period of time," Jose Maria Fernandez said at the Reuters Biotechnology Summit in London. "It is a matter of weeks or months."
Yondelis is in late-stage clinical trials for soft tissue sarcoma -- rare and usually fatal forms of cancer that attack muscles, fat or blood vessels -- and a filing had initially been expected by the end of 2005.
However, a clinical study into the benefits of the drug, which is derived from a marine organism, has taken longer than expected to complete.
The trial will end when a certain number of patients either die or their illness progresses, and Fernandez said the delay suggested Yondelis was keeping people alive longer than anticipated.
"The drug Yondelis is probably keeping patients alive more than we expect. That is the good news. The bad news is that we would liked to have sent it (the study) already," he said.
Zeltia's biotechnology unit PharmaMar is also developing the drug for treatment against other forms of cancer.
Fernandez said the drug could -- if approved for soft tissue sarcoma, ovarian and prostate or breast cancer -- have a mid-term blockbuster sales potential of 1 billion euros ($1.19 billion) a year.