Evaluating the Impact of a Switch to Nilotinib on Imatinib-Related Chronic Low-Grade Adverse Events in Patients With CML-CP: The ENRICH Study

Background: Many patients with chronic myeloid leukemia in chronic phase experience chronic treatment-related adverse events (AEs) during imatinib therapy. These AEs can impair quality of life and lead to reduced treatment adherence, which is associated with poor clinical outcomes.

Patients and methods: In the phase II ENRICH (Exploring Nilotinib to Reduce Imatinib Related Chronic Adverse Events) study (N = 52), the effect of switching patients with imatinib-related chronic low-grade nonhematologic AEs from imatinib to nilotinib was evaluated.

Results: Three months after switching to nilotinib, 84.6% of the patients had overall improvement in imatinib-related AEs (primary endpoint). Of 210 imatinib-related AEs identified at baseline, 62.9% had resolved within 3 months of switching to nilotinib. Of evaluable patients, most had improvements in overall quality of life after switching to nilotinib. At screening, 65.4% of evaluable patients had a major molecular response (BCR-ABL1 ≤ 0.1% on the International Scale). After switching to nilotinib, the rate of the major molecular response was 76.1% at 3 months and 87.8% at 12 months. Treatment-emergent AEs reported with nilotinib were typically grade 1 or 2; however, some patients developed more serious AEs, and 8 patients discontinued nilotinib because of new or worsening AEs.

Conclusion: Overall, results from the ENRICH study demonstrated that switching to nilotinib can mitigate imatinib-related chronic low-grade nonhematologic AEs in patients with chronic myeloid leukemia in chronic phase, in conjunction with acceptable safety and achievement of molecular responses. This trial was registered at www.clinicaltrials.gov as NCT00980018.