May 31 (Reuters) - Swiss drugmaker Novartis

said patients with a type of leukemia who took its Scemblix had

a significantly better response and a lower dropout rate than

those who received current standard-of-care drugs in a

late-stage study with details presented on Friday.

The company said in January that the oral drug met the main

goals of the 405-patient trial.

More detailed data unveiled at the American Society of

Clinical Oncology meeting in Chicago showed that Scemblix helped

67.7% of patients achieve a major molecular response (MMR),

nearly 20% higher than for patients who received current

standard treatments.

The study tested Scemblix in newly diagnosed patients with

the blood cancer chronic myeloid leukemia (CML) against a class

of drugs called tyrosine-kinase inhibitors (TKIs), such as

Novartis' own Glivec, that turned the disease from a death

sentence into a treatable condition in which many patients had

good, long-lasting responses.

CML affects more than 9,000 people and leads to 1,000 deaths

in the U.S. annually.

A major molecular response is considered achieved with a

significant decrease in a cancer-causing gene called BCR-ABL,

which is believed to be necessary for initiation and maintenance

of CML.

Scemblix was also tested against Novartis' Tasigna, Bristol

Myers Squibb's ( BMY ) Sprycel and Pfizer's ( PFE ) Bosulif.

It helped almost 30% more patients achieve MMR compared to

Glivec at the end of 48 weeks.

While older TKIs have revolutionized the treatment of CML,

many patients eventually see their symptoms return or are unable

to continue therapy due to side effects.

During the trial, just 5% of Scemblix patients discontinued

treatment due to adverse side effects, compared to a dropout

rate of 10% of those being treated with any of the TKIs, which

can cause fatigue, depression, disrupted sleep, diarrhea, and

other side effects.

Earlier this month, Jefferies analysts said a MMR rate

greater than 60% and a discontinuation rate less than 10% would

be the best case scenario for Scemblix, likely positioning the

drug as the new standard of care.

They forecast worldwide annual peak sales reaching $4.5

billion.

Scemblix is approved in more than 70 countries, including an

accelerated approval in the U.S., to treat adults with CML who

have previously received two or more standard-of-care

treatments. The new results could make the case for expanded use

in patients who had not previously been treated for the disease.

The trial is ongoing, with the next scheduled analysis at

week 96 to further evaluate MMR and discontinuation rates.