Ariful Haque

Nilotinib versus Imatinib for Newly Diagnosed Chronic Myeloid Leukemia

BACKGROUND Nilotinib has been shown to be a more potent inhibitor of BCR-ABL than imatinib. We evaluated the efficacy and safety of nilotinib, as compared with imatinib, in patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia (CML) in the chronic phase. METHODS In this phase 3, randomized, open-label, multicenter study, we assigned 846 patients with chronic-phase Philadelphia chromosome-positive CML in a 1:1:1 ratio to receive nilotinib (at a dose of either 300 mg or 400 mg twice daily) or imatinib (at a dose of 400 mg once daily). The primary end point was the rate of major molecular response at 12 months. RESULTS At 12 months, the rates of major molecular response for nilotinib (44% for the 300-mg dose and 43% for the 400-mg dose) were nearly twice that for imatinib (22%) (P<0.001 for both comparisons). The rates of complete cytogenetic response by 12 months were significantly higher for nilotinib (80% for the 300-mg dose and 78% for the 400-mg dose) than for imatinib (65%) (P<0.001 for both comparisons). Patients receiving either the 300-mg dose or the 400-mg dose of nilotinib twice daily had a significant improvement in the time to progression to the accelerated phase or blast crisis, as compared with those receiving imatinib (P=0.01 and P=0.004, respectively). No patient with progression to the accelerated phase or blast crisis had a major molecular response. Gastrointestinal and fluid-retention events were more frequent among patients receiving imatinib, whereas dermatologic events and headache were more frequent in those receiving nilotinib. Discontinuations due to aminotransferase and bilirubin elevations were low in all three study groups. CONCLUSIONS Nilotinib at a dose of either 300 mg or 400 mg twice daily was superior to imatinib in patients with newly diagnosed chronic-phase Philadelphia chromosome-positive CML. (ClinicalTrials.gov number, NCT00471497.)

Impact of Baseline BCR-ABL Mutations on Response to Nilotinib in Patients With Chronic Myeloid Leukemia in Chronic Phase

PURPOSE Nilotinib is a second-generation tyrosine kinase inhibitor indicated for the treatment of patients with chronic myeloid leukemia (CML) in chronic phase (CP; CML-CP) and accelerated phase (AP; CML-AP) who are resistant to or intolerant of prior imatinib therapy. In this subanalysis of a phase II study of nilotinib in patients with imatinib-resistant or imatinib-intolerant CML-CP, the occurrence and impact of baseline and newly detectable BCR-ABL mutations were assessed. PATIENTS AND METHODS Baseline mutation data were assessed in 281 (88%) of 321 patients with CML-CP in the phase II nilotinib registration trial. RESULTS Among imatinib-resistant patients, the frequency of mutations at baseline was 55%. After 12 months of therapy, major cytogenetic response (MCyR) was achieved in 60%, complete cytogenetic response (CCyR) in 40%, and major molecular response (MMR) in 29% of patients without baseline mutations versus 49% (P = .145), 32% (P = .285), and 22% (P = .366), respectively, of patients with mutations. Responses in patients who harbored mutations with high in vitro sensitivity to nilotinib (50% inhibitory concentration [IC(50)] <or= 150 nM) or mutations with unknown nilotinib sensitivity were equivalent to those responses for patients without mutations (not significant). Patients with mutations that were less sensitive to nilotinib in vitro (IC(50) > 150 nM; Y253H, E255V/K, F359V/C) had less favorable responses, as 13%, 43%, and 9% of patients with each of these mutations, respectively, achieved MCyR; none achieved CCyR. CONCLUSION For most patients with imatinib resistance and with mutations, nilotinib offers a substantial probability of response. However, mutational status at baseline may influence response. Less sensitive mutations that occurred at three residues defined in this study, as well as the T315I mutation, may be associated with less favorable responses to nilotinib.

Initial molecular response at 3 months may predict both response and event-free survival at 24 months in imatinib-resistant or -intolerant patients with Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase treated with nilotinib.

PURPOSE The association between initial molecular response and longer-term outcomes with nilotinib was examined. PATIENTS AND METHODS Patients with imatinib-resistant or -intolerant chronic myeloid leukemia in chronic phase from the phase II nilotinib registration study with available postbaseline BCR-ABL1 transcript assessments were included (N = 237). RESULTS BCR-ABL1 transcript levels (International Scale [IS]) at 3 months correlated with complete cytogenetic response (CCyR) by 24 months. Patients with BCR-ABL1 (IS) of > 1% to ≤ 10% at 3 months with nilotinib had higher cumulative incidence of CCyR by 24 months than patients with BCR-ABL1 (IS) of > 10% (53% v 16%). BCR-ABL1 (IS) at 3 months predicted major molecular response (MMR) by 24 months. Cumulative incidence of MMR by 24 months for patients with BCR-ABL1 (IS) of > 0.1% to ≤ 1%, > 1% to ≤ 10%, and > 10% was 65%, 27%, and 9%, respectively. These differences were observed for patients with or without baseline BCR-ABL1 mutations and for those with imatinib resistance or intolerance. Estimated event-free survival (EFS) rates at 24 months decreased with higher transcript levels at 3 months; patients with BCR-ABL1 (IS) of ≤ 1% had an estimated 24-month EFS rate of 82%, compared with 70% for patients with BCR-ABL1 (IS) of > 1% to ≤ 10% and 48% for patients with BCR-ABL1 (IS) of > 10%. CONCLUSION Patients with BCR-ABL1 (IS) of > 10% at 3 months had a lower cumulative incidence of CCyR and MMR and lower rates of EFS versus patients with BCR-ABL1 (IS) of ≤ 10%. Prospective studies may determine whether close monitoring or alternative therapies are warranted for patients with minimal initial molecular response.