Aug 7 (Reuters) - Grail said on Friday the U.S. FDA plans to hold a meeting of outside experts to review its multi-cancer screening test ⁠Galleri in September, sending its shares up 5%.

The panel will review Grail's request for premarket approval, the Food and Drug Administration's most stringent ⁠review process for medical devices. The agency is not required to follow the panel's recommendation.

The review follows disappointing results ⁠earlier this year from a three-year ‌UK trial in asymptomatic adults aged 50 to 77 years, in which Galleri did not significantly improve early cancer detection or reduce late-stage diagnoses versus standard care.

Full results from the trial presented in May showed that by the third round of screening, the test reduced stage IV cancer diagnoses by 26% for ‌12 deadly cancers. The addition Galleri to standard screening also increased cancer detection fourfold ​compared with standard ‌screening alone.

The test, along with Abbott Laboratories' ‌Cancerguard, is already available on the market, but neither is FDA-approved. Both are offered as laboratory-developed tests under Clinical Laboratory Improvement ⁠Amendments regulations, which means doctors can order them.

A January U.S. ‌congressional funding bill, however, created ⁠a pathway for Medicare coverage of ​FDA-approved multi-cancer early detection (MCED) tests for individuals aged ‌50 to 65 from 2029, subject to clinical benefit, but analysts have questioned Galleri's reimbursement prospects.

MCED tests analyze molecular signals shed by tumors into the bloodstream from a single blood draw. AI and ​machine learning algorithms then interpret these signals to detect potential cancers ‌and, ‌in many cases, predict their tissue of origin.

Grail said it submitted its regulatory application for Galleri on January ‌29, which included findings ​from a U.S. study of 25,490 people tracked for one year and from the first year of a UK study of more than 70,000 people.

The test screens for signals of more ⁠than 50 cancers from a single blood sample and is meant to ‌complement, not replace, established screenings such as mammograms and colonoscopies.

(Reporting by Sneha S K and Padmanabhan ​Ananthan; Editing by Vijay Kishore and Diti Pujara)