Breast cancer drug shows potential

Cyclacel Pharmaceuticals has announced the results of a study involving its drug, seliciclib (CYC202 or R-roscovitine) which has shown positive results in treating breast cancer cells resistant to hormone therapy.

The study, published in Clinical Cancer Research, a journal of the American Association for Cancer Research, showed that seliciclib, an oral inhibitor of multiple cyclin-dependent kinases (CDKs), was able to reverse resistance to the inhibitor letrozole, and killed breast cancer cells insensitive to letrozole's effects.

Letrozole is a common treatment for breast cancer in postmenopausal women, reducing the risk of early metastasis in women with estrogen receptor–positive breast cancer, and regulating the development of potentially cancerous cells.

Approximately three out of four women suffering from breast cancer after menopause have cancers that express the hormonal receptors for estrogen and progesterone and are offered treatment with such inhibitors as letrozole.

Over time though, breast cancer cells develop resistance to these inhibitors and the therapy becomes ineffective.

"Resistance to aromatase inhibitors, such as letrozole, is a major challenge for the long-term management of hormone receptor positive breast cancer," said chief scientist with Cyclacel, Professor David Glover.

"The data published in Clinical Cancer Research are encouraging as they show that seliciclib can kill resistant breast cancer cells by targeting a form of cyclin E that is a major cause of the resistance. This is further evidence that seliciclib's unique mechanism of action can be effective against certain cancer cells, such as breast and lung cancer, that fail to respond to standard cancer treatments."

Seliciclib is currently being evaluated in the APPRAISE trial, a phase IIb randomised, double-blinded, placebo-controlled study, as a treatment in patients with non-small cell lung cancer (NSCLC) who failed at least two prior therapies and in a randomised phase II study as a single agent in patients with nasopharyngeal cancer.