NEW YORK – The US Food and Drug Administration on Tuesday granted accelerated approval to Novartis' STAMP inhibitor Scemblix (asciminib) as a treatment for patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase.
The agency based its decision on results from the 405-patient Phase III ASC4FIRST trial, in which there was a 68 percent major molecular response rate — assessed using BCR-ABL transcript levels — among Scemblix-treated patients at 48 weeks compared to a major molecular response rate of 49 percent among patients receiving investigator-selected tyrosine kinase inhibitors (TKIs).
Patients were eligible for the study if they had newly diagnosed Philadelphia chromosome-positive CML in chronic phase, had not received prior TKIs, and had typical BCR-ABL1 transcripts as detected by real-time quantitative PCR. Investigators had to select the TKI they would give patients, either Novartis' Gleevec (imatinib) or a second generation TKI, before patients were randomized in the trial. When investigators looked at the subset of patients who were slated to receive Gleevec pre-randomization, the major molecular response rate was 69 percent on Scemblix and 40 percent in the Gleevec comparator arm.
Historically only about half of patients on established frontline TKIs like Gleevec, Novartis' Tasigna (nilotinib), Bristol Myers Squibb's Sprycel (dasatinib), and Pfizer's Bosulif (bosutinib) achieve a major molecular response at 12 months.
Scemblix is already approved in the US and in Europe for treating CML in later-line settings, including patients with Philadelphia chromosome-positive disease in the chronic phase who have received at least two prior TKIs. The drug is also approved in the US for Philadelphia chromosome-positive CML patients in chronic phase who harbor T315l mutations.