German drugmaker Schering has entered into a deal with AstraZeneca to jointly develop a new breast cancer drug, the companies said on Friday.

Schering, which has been bought by Bayer, said that AstraZeneca would lead the clinical development of the drug, while Schering would lead the process development and manufacturing.

The companies will co promote the drug in major territories and share costs and profits, Schering said, but did not disclose financial details.

The deal marks the latest step by AstraZeneca to rebuild its pipeline following past high profile setbacks, including the failure in clinical trials of anti coagulant Exanta, Iressa for lung cancer and diabetes drug Galida.

New Chief Executive David Brennan has struck a series of deals to bring in new drugs since taking over at the start of this year, including the acquisition of leading British biotech firm Cambridge Antibody.

AstraZeneca already has a strong presence in anti hormonal oncology drugs, with products such as Arimidex for breast cancer and Casodex for prostate cancer.

The drug that the two companies plan to jointly develop, which Schering currently is putting through pre clinical trials, is a SERD, or selective oestrogen receptor downregulator.

SERDs are a new class of compounds which work by breaking down resistance to hormone oriented treatments for breast cancer. The growth and progression of cancers are stimulated by the hormone oestrogen.

The drugs could potentially be used alone for treatment of hormone sensitive breast cancer or in combination with other targeted agents for the prevention or treatment of hormone resistant forms of the disease, Schering said.

AstraZeneca stock was flat at 33.31 pounds while Schering stock was 0.1 percent lower in Frankfurt at 91.36 euros by 8:34 a.m. British time.

(Additional reporting by Ben Hirschler in London)