NEW YORK – The US Food and Drug Administration on Friday approved Novartis' STAMP inhibitor asciminib (Scemblix) for two chronic myeloid leukemia indications.
The agency granted accelerated approval to asciminib for chronic-phase CML patients previously treated with at least two tyrosine kinase inhibitors, or TKIs, though Novartis will have to submit data from confirmatory trials to convert this accelerated approval into full approval.
Simultaneously, the agency gave full approval to asciminib as a treatment for Philadelphia chromosome-positive CML patients whose cancers harbor a T315I mutation.
The FDA based its decision on the Phase III ASCEMBL trial, in which previously treated patients with Philadelphia chromosome-positive chronic phase CML were randomized to receive either asciminib or Pfizer's bosutinib (Bosulif). After 24 weeks, 25 percent of patients on asciminib had a major molecular response versus 13 percent of those on bosutinib. Seven percent of patients in the asciminib arm discontinued treatment due to toxicities, versus 25 percent of patients in the bosutinib arm. The FDA also considered results from a Phase I study, which included CML patients with T315I mutations.
Asciminib is designed to bind to the ABL myristoyl pocket on cancer cells, and according to Novartis "represents an important development for patients who experience resistance and/or intolerance to currently available TKI therapies." Studies show that around 55 percent of CML patients are intolerant to TKIs and 70 percent receiving TKIs in the second-line setting fail to achieve a major molecular response. Further, patients who acquire T314I mutations also tend to be resistant to existing TKI therapies.
Novartis is also evaluating asciminib as a first-line treatment for chronic-phase CML in the Phase III ASC4FIRST trial.