A new drug that works by blocking molecules responsible for cancer cell growth has been found to be effective for advanced breast cancer patients.

The drug called palbociclib, an investigational oral medication, has been found to be well tolerated and extends progression-free survival (PFS) in newly diagnosed cancer.

The palbociclib was recently approved by the US Food and Drug Administration (FDA) for metastatic breast cancer patients just beginning to undergo endocrine therapy.

"The FDA approval has expanded treatments options for many metastatic breast cancer patients, but these new results are showing how effective the drug can also be for breast cancer patients who have already tried endocrine therapies and may be running out of options," said Angela DeMichele from Perelman School of Medicine at University of Pennsylvania.

The drug was developed by researchers at Penn Medicine.

Patients enrolled in the trial had previously undergone several prior chemotherapy and hormonal regimen for metastatic disease.

"The drug was extremely well-tolerated in this trial, and the absence of symptoms commonly associated with cancer treatment, such as nausea, diarrhoea, or pain was remarkable," said professor Peter O'Dwyer at Perelman School of Medicine at University of Pennsylvania.

"The palbociclib drug may be effective in other types of cancer that operate by a similar mechanism. These trials are currently ongoing," said Amy Clark, from Perelman School of Medicine at University of Pennsylvania.

The results appeared in Clinical Cancer Research.