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 Sprycel and Pfizer's 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.