Switching to 2-year consolidation therapy with nilotinib may lead to improved rates of deep molecular responses (DMR; MR4.5, BCR-ABL1IS ≤ 0.0032%) among patients with chronic-phase chronic myeloid leukemia (CMP-CP) who achieved major molecular response (MMR) with long-term imatinib therapy, according to a study published in the International Journal of Hematology.1

Previous studies have shown that first-line therapy with nilotinib, as well as switching to nilotinib after prolonged imatinib, may lead to higher rates of DMR and perhaps even treatment-free remission among patients with newly diagnosed CML-CP.

In the STAT1 phase 2 study in Japan, researchers enrolled 76 patients with CML-CP who had achieved MMR but still had persistent BCR-ABL1 positivity with imatinib, and switched them to nilotinib 300 mg twice daily for 2 years. Patients were treated with imatinib for a median of 69.0 months, and the median time to MMR on imatinib therapy was 20.4 months. The median age of participants was 55 years old.

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Results showed that the cumulative rate of MR4.5 increased over time. Overall, 63.5% of patients achieved MR4.5; the rate of DMR at 12 and 24 months was 27.0% (90% CI, 18.7%-36.8%) and 44.6% (90% CI, 34.7%-54.8%), respectively. Researchers estimated that the median duration of therapy to reach MR4.5 was 18.2 months.

The only independent predictive biomarker across multiple logistic regression analysis for achieving 24-month MR4.5 was the frequency of ABCG2 431C/A + A/A genotype.

All-grade adverse events (AEs) were reported in 56.6% of patients, and 17.5% of patients experienced grade 3 to 4 AEs. The most commonly observed treatment-related AEs included elevated total bilirubin, elevated ALT/AST, fatigue, and rash.

The authors concluded that findings “suggested that switching to [nilotinib] safely led to a DMR in patients with MMR, but without MR4.5 on [imatinib] therapy. Switching to nilotinib from imatinib and a 2-year consolidation therapy with this agent may be an efficacious strategy to achieve DMR and it may enable a greater proportion of CML-CP patients to be eligible for future discontinuation studies.”

Reference

  1. Noguchi S, Nakaseko C, Nishiwaki K, et al. Switching to nilotinib is associated with deeper molecular response in chronic myeloid leukemia chronic phase with major molecular responses to imatinib: STAT1 trial in Japan [published online April 30, 2018]. Inter J Hematol. doi: 10.1007/s12185-018-2459-6