March 17 (Reuters) - Pfizer ( PFE ) said on Tuesday its

experimental combination reduced the risk of disease progression

or death by 40% in patients with breast cancer.

Here are some details:

* Pfizer's ( PFE ) atirmociclib in combination with fulvestrant, a

hormone therapy, was being tested in a mid-stage study in

patients whose cancer had spread and had received prior

treatment.

* The experimental drug combo was being compared to

fulvestrant or everolimus plus exemestane, a widely used

targeted therapy regimen for postmenopausal women with the

common type of breast cancer

* Pfizer ( PFE ) said the study enrolled patients whose cancer

returned soon after treatment with widely used CDK4/6 drugs, a

group that is harder to treat.

* The company said more than 90% of patients started

atirmociclib within three months of stopping their previous

cancer medicine.

* The drug had a manageable safety profile, with 6.4% of

patients stopping treatment due to side effects, Pfizer ( PFE ) said.

* The company said overall survival data, a secondary goal,

were still early and not ready for conclusions at this stage.

* Pfizer ( PFE ) said the results support plans to test atirmociclib

in first-line and early-stage of breast cancer, where

longer-lasting disease control could help more patients.

* Atirmociclib is an experimental oral drug that targets

CDK4, a cell-cycle protein that drives tumor growth.

* The company said a large late-stage study of the drug in

newly diagnosed metastatic breast cancer patients is already

underway.