On June 1, 2026 Novartis reported positive 144-week data from the pivotal ASC4FIRST trial of Scemblix (asciminib) presented at the 2026 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting. These results provide longer-term evidence that Scemblix demonstrated increasingly superior molecular responses at week 144 compared with established tyrosine kinase inhibitors (TKIs), strengthening confidence in its sustained response1.
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ASC4FIRST compared the MMR rate of Scemblix to investigator-selected (IS) standard-of-care (SoC) TKIs (imatinib and 2G TKIs nilotinib, dasatinib, and bosutinib) and to imatinib alone in adult patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase (Ph+ CML-CP)2,3. The longer-term data showed a progressively larger difference in MMR rates favorable to Scemblix vs. SoC TKIs, vs. imatinib and vs. 2G TKIs1.
"Because CML patients often need to remain on therapy long term, treatments must combine robust efficacy with a favorable safety and tolerability profile," said Jorge Cortes, M.D., Chief of Hematology, UAB O’Neal Cancer Center. "These data show asciminib continued to deliver significantly higher response rates versus the comparator TKIs and offers improved response that widens over time, including compared to second-generation TKIs."
"Drawing on more than 25 years in CML and a Scemblix clinical program of over 10 years, Novartis is focused on addressing treatment challenges for people living with CML," said Mark Rutstein, M.D., Global Head, Oncology Development, Novartis. "With now nearly 3 years of extended follow-up in ASC4FIRST, we continue to see results that support Scemblix as an important option for newly diagnosed adult CML patients."
In addition to meeting all primary and key secondary endpoints at weeks 48 and 96, Scemblix continued to extend the treatment benefit for patients vs. SoC TKIs at week 1441,2,3,4. At the cutoff, more patients remained on treatment with Scemblix vs. SoC (78.6% vs. 55.9%), imatinib (81.2% vs. 50.0%), and 2G TKIs (76.0% vs. 61.8%)1. At week 144, nearly 24% more patients treated with Scemblix achieved MMR vs. all SoC TKIs, and over 32% more patients achieved MMR vs. imatinib alone1. The Scemblix MMR rate was 15.2% higher vs. 2G TKIs (75.0% vs. 59.8%; P=0.01*)1. Patients treated with Scemblix also achieved deeper molecular responses (MR4 and MR4.5) compared with SoC TKIs1.
*Unadjusted nominal p-value for descriptive purposes only
Overalla
Scemblix (n=201)
vs. IS SoC TKIs
(n=204) Imatinib stratumb
Scemblix (n=101)
vs. imatinib (n=102) 2G TKI stratumc
Scemblix (n=100)
vs. 2G TKIs
(n=102)
Secondary objectivesd MMR rates
at week 144 77.1% vs. 53.4% 79.2% vs. 47.1% 75.0% vs. 59.8%
MR4
at week 144 55.7% vs. 36.3% 58.4% vs. 33.3% 53.0% vs. 39.2%
MR4.5
at week 144 42.3% vs. 24.5% 43.6% vs. 19.6% 41.0% vs. 29.4%
a All patients receiving Scemblix (n=201) or IS SoC TKIs (n=204). Treatment difference after adjusting for pre-randomization selected TKI and EUTOS long-term survival (ELTS) risk groups at baseline.
b The 203 patients within the pre-randomization-selected imatinib stratum were randomized to receive either Scemblix (n=101) or imatinib (n=102). Treatment difference after adjusting for ELTS risk groups at baseline.
c The 202 patients within the pre-randomization selected 2G TKIs stratum were randomized to receive either Scemblix (n=100) or 2G TKIs (n=102: nilotinib, 48%; dasatinib, 41%; bosutinib, 11%).
d Secondary objectives were not powered for statistical significance.
"For many patients living with CML, managing a lifelong condition means balancing disease control with the real impact of treatment on daily life, and too often side effects can stand in the way of staying on therapy," said Joannie Clements, CML patient and founder of CML Buster Foundation. "There remains a clear unmet need for treatments that are highly effective and also have a safety and tolerability profile favorable enough to be suitable for long-term use."
Scemblix demonstrated a safety profile at 144 weeks consistent with the 4-year follow-up of the Phase III ASCEMBL trial, with no new safety concerns observed to date1,2,5. Compared with both imatinib and 2G TKIs, Scemblix showed fewer grade ≥3 AEs, fewer dose adjustments to manage adverse events, and more than 50% lower discontinuation due to adverse events2,4,6. The most frequent AEs (≥15%) were diarrhea, headache, fatigue, musculoskeletal pain, and rash4,7.
Week 144 Scemblix
n=200 Imatinib
n=99 2G TKIs
n=102
Grade ≥3 AEsa 49% 52% 63%
Discontinuation due to AEsa 6% 13% 14%
AEs leading to dose adjustments/interruptionsa 37% 44% 63%
aIn patients who experienced ≥1 adverse event.
These data will also be presented as an oral presentation at the European Hematology Association (EHA) (Free EHA Whitepaper) 2026 Congress in June.
About the ASC4FIRST Phase III Clinical Trial
ASC4FIRST (NCT04971226) is a Phase III, head-to-head, multi-center, open-label, randomized study of oral Scemblix 80 mg QD vs. IS first- or second-generation TKIs (imatinib, nilotinib, dasatinib or bosutinib) in 405 adult patients with newly diagnosed Ph+ CML-CP2,3. The trial met both primary endpoints with Scemblix demonstrating superior MMR rates at week 48 vs. investigator-selected SoC TKIs (imatinib, nilotinib, dasatinib, and bosutinib) (67.7% vs. 49.0%) and imatinib alone (69.3% vs. 40.2%) as well as the secondary, non-powered endpoint for the 2G TKI stratum of (66% vs. 57.8%)3. The study remains ongoing with further efficacy and safety readouts planned.
About Scemblix (asciminib)
Scemblix is the first CML treatment that works by Specifically Targeting the ABL Myristoyl Pocket (referred to as a STAMP inhibitor in scientific literature)5,8,9. Other currently approved CML treatments are TKIs that target the ATP-binding site (ATP-competitive)9.
In the US, Scemblix was granted accelerated approval to treat newly diagnosed adults with Ph+ CML-CP. Outside the US, Scemblix is approved to treat newly diagnosed adults with Ph+ CML-CP in more than 60 countries, including the EU, China, and Japan. It is also approved in 61 countries, including the US and the EU, for previously treated adults with Ph+ CML-CP, regardless of prior therapy, and in 58 countries, including the US and the EU, for patients with Ph+ CML-CP with the T315I mutation10.
(Press release, Novartis, JUN 1, 2026, View Source [SID1234666314])