ASCO: Novartis eyes full nod for Gleevec follow-on Scemblix thanks to new leukemia data

Novartis boasts an accelerated approval for its Gleevec follow-on drug Scemblix in previously treated chronic myeloid leukemia. Now with new clinical data, the company hopes to turn it into a full nod.

Scemblix triggered a major molecular response in 37.6% of chronic myeloid leukemia (CML) patients who had tried at least two prior treatments. That was much higher than the 15.8% by Pfizer’s Bosulif.

The latest data come from the phase 3 Ascembl trial after patients received their drugs for 96 weeks. They build on the previous 24-week readout that got Scemblix its FDA nod in October 2021, and the longer-term follow-up is the confirmatory evidence the FDA had asked for to convert the accelerated approval into a full one, Jeff Legos, Ph.D., Novartis’ global head of oncology & hematology development, told Fierce Pharma.

“This really gives us additional confidence that Scemblix has the ability to potentially transform the standard of care in these CML patients based on its novel mechanism of action,” Legos said.

As a first-in-class STAMP inhibitor, Scemblix targets the ABL myristoyl part of the BCR-ABL protein rather than being a competitive binder of the ATP pocket of the protein. With that design, Scemblix could potentially avoid some resistance mechanisms in other CML drugs, according to Novartis.

In the latest update, Scemblix’s major molecular response difference with Bosulif has widened. At 24 weeks, Scemblix’s rate was 25% versus 13% for Bosulif.

Achieving major molecular response means that the BCR-ABL protein is no longer detectable in the blood, Legos explained, and this marker is highly correlated with long-term clinical benefit.

In terms of safety, after 96 weeks, side effects had forced 7.7% of patients in the Scemblix arm to discontinue treatment, lower than 26.3% for Bosulif takers.

Novartis launched Scemblix as its earlier Gleevec follow-up drug Tasigna is slated to lose patent protection in 2023.  Last year, Tasigna grew sales by 5% to $2.06 billion as Gleevec’s dropped 14% to $1.02 billion.

Scemblix is one of the key launch medicines with over $2 billion peak sales potential that Novartis is counting on for growth after megablockbuster heart drug Entresto falls off the patent cliff.

During the first quarter, Scemblix sold $25 million. It has snagged a 20% share in new CML scripts across lines and has secured a 49% total patient share in third-line and beyond treatment, Novartis CEO Vas Narasimhan said during the company’s first-quarter earnings call.

Novartis is running the phase 3 ASC4FIRST trial testing Scemblix in treatment-naïve patients, a population that’s expected to make up the bulk of Scemblix’s sales at its peak. That trial has been enrolling patients ahead of plan, Narasimhan said.