Novartis' Scemblix (asciminib) has shown superior efficacy compared to standard-of-care (SoC) tyrosine kinase inhibitors (TKIs) as a first-line treatment for Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML). The Phase III ASC4FIRST trial results, presented at the American Society of Clinical Oncology (ASCO) Annual Meeting, highlight Scemblix's potential to transform CML treatment.
The open-label Phase III ASC4FIRST study (NCT04971226) met its primary endpoint, demonstrating a significantly higher major molecular response (MMR) rate of 67.7% at week 48 in the Scemblix arm compared to 49% in the investigator-selected SoC TKIs arm (including Pfizer’s Bosulif, Bristol Myers Squibb’s Sprycel, and Novartis’ Gleevec/Glivec and Tasigna). When compared to Gleevec alone, Scemblix showed an even greater MMR rate of 69.3% versus 40.2% at 48 weeks.
Superior Efficacy and Safety Profile
"Scemblix is the first CML treatment to show significantly better efficacy compared to investigator-selected standard-of-care TKIs," said Dr. Tim Hughes from the South Australian Health & Medical Research Institute (SAHMRI). He added that the combination of superior response with the excellent safety and tolerability profile of Scemblix makes it a promising frontline option for newly diagnosed patients.
The Scemblix group also experienced lower rates of Grade 3 or worse adverse events (AEs) at 38%, compared to 55% in the Gleevec monotherapy group and 44% in the investigator-selected SoC group.
Mechanism of Action and Regulatory Pathway
Scemblix functions as a tyrosine kinase inhibitor, specifically blocking the BCR-ABL tyrosine kinase protein found in CML cells, thereby inhibiting cell growth and multiplication. It received accelerated approval from the US Food and Drug Administration (FDA) in 2021 as a third-line therapy for Ph+ CML patients in the chronic phase.
Novartis plans to submit the ASC4FIRST trial data to the FDA through the agency’s Oncology Center of Excellence Real-Time Oncology Review (RTOR) program. The company reported $136 million in sales for Scemblix in Q1 this year, with projections estimating approximately $2.4 billion by 2030.
Implications for CML Treatment
The ASC4FIRST trial's findings suggest that Scemblix could become a preferred first-line treatment for CML, offering improved efficacy and a more favorable safety profile compared to existing standard-of-care options. This development addresses a significant unmet need in CML management, where achieving deep molecular responses and minimizing treatment-related toxicities are critical for long-term patient outcomes.
