UPDATE 1-Eisai brings in SFJ to help develop thyroid cancer drug

* Eisai to conduct E7080 Phase III trials with SFJ

* SFJ to fund study, Eisai to pay milestone rights

* New type of pact aimed at quickening drug development (Adds details, background)

TOKYO, Sept 7 (Reuters) - Japan's No.4 drug maker Eisai Co said on Wednesday it will conduct Phase III studies of its thyroid cancer drug E7080, also known as lenvatinib, with U.S.-based SFJ Pharmaceuticals.

The Japanese drug maker said the pact with the private U.S. biotech firm is a new type of agreement aimed at accelerating late-stage clinical development of its pipeline while taking advantage of external resources.

Eisai said the study will be funded by SFJ, with Eisai to pay milestone payments to SFJ. Eisai will retain commercial rights to the drug.

E7080 is a mutli-kinase inhibitor which Eisai is developing as a molecular-targeted agent for potential anti-cancer treatments.

In March, Eisai said it expects its overall sales to stay slack over the next five years after the loss of U.S. patent protection for Aricept, its top-selling Alzheimer's drug, leading it to cut jobs.

Shares of Eisai ended Tokyo trade down 0.6 percent at 3,240 yen, against a 2 percent gain in the benchmark Nikkei average . (Reporting by James Topham; Editing by Edwina Gibbs and Michael Watson)