Efficacy and Safety of Nilotinib in Elderly Patients with Imatinib-Resistant or -;Intolerant Chronic Myeloid Leukemia (CML) in Chronic Phase (CP): A Sub-Analysis of the ENACT (Expanding Nilotinib Access in Clinical Trials) Study.

Nilotinib, a potent and highly selective BCR-ABL kinase inhibitor, is approved for the treatment of patients (pts) with Philadelphia chromosome-positive chronic myelogeneous leukemia (Ph+ CML) in chronic phase (CML-CP) and accelerated phase (CML-AP) who are resistant or intolerant to prior therapy including imatinib. The ENACT study is a Phase IIIb, open-label, multicenter study that evaluated the efficacy and safety of nilotinib in adult pts with imatinib-resistant or intolerant CML in a clinical practice setting outside of a registration program. It is the largest single source of efficacy and safety information of any available tyrosine kinase inhibitor (TKI) in CML, particularly among the elderly.

The present is a sub-analysis of the ENACT study on the efficacy and safety of 400 mg twice daily nilotinib in elderly (aged =60 years) pts initiating treatment in CML-CP who were resistant and/or intolerant to imatinib.

Of the 1,422 CML-CP pts enrolled in the ENACT study between January 2006 and October 2008, 452 (32%) were elderly (=60 years) at study initiation and 165 (37%) of these pts were =70 years [10 (2%) were =80 years]. Countries that enrolled =20 elderly pts include France, Italy, USA, Germany, UK, Spain, Canada, and Brazil. At study initiation, elderly pts had longer median durations of CML (<60: 51.1 months; =60: 69.3; =70: 66.6) and higher proportions with CML duration >5 years (<60: 43%; =60: 56%; =70: 52%). Besides imatinib, prior CML treatments received by elderly pts included dasatinib (=60: 20%; =70: 19%), cytarabine (=60: 23%; =70: 19%), busulfan (=60: 10%; =70: 7%), and interferons (=60: 50%; =70: 42%). Elderly pts were previously treated with imatinib for longer median durations (<60: 27.4 months; =60: 32.7; =70: 29.9), with higher proportions treated for >5 years (<60: 12%; =60: 19%; =70: 18%). The proportion of imatinib-intolerant to resistant elderly pts was about 1:1, which was higher than the proportion among <60 pts at about 0.6:1, such that relatively few elderly pts had prior highest imatinib dose >800 mg (<60: 34%; =60: 26%; =70: 21%). While response rates to prior imatinib were similar, among pts who required therapy after failing imatinib, elderly pts had lower cytogenetic response rates (<60: 22%; =60: 17%; =70: 19%) to prior dasatinib. During ENACT, less than 50% of elderly pts experienced nilotinib dose interruptions (=60: 46%; =70: 41%) and reductions (=60: 7%; =70: 6%) lasting >5 days, which was consistent with the overall ENACT dataset. The median duration of dose interruptions and reductions was 15 (=70: also 15) and 41 (=70: 32) days, respectively. The main reason for dose interruptions and reductions was adverse events (AEs). The median duration of nilotinib exposure was 227 days (=70: 219) and the median dose intensity was 749 mg/day (=70: 775). Efficacy was similar among elderly pts, with 39% (=70: 35%) of pts achieving complete hematologic response (CHR), 41% (=70: 39%) achieving major cytogenetic response (MCyR) and 31% (=70: 33%) achieving complete cytogenetic response (CCyR). MCyR rate was also similar among elderly hematologic responders (=60: 64%; =70: 65%). Among elderly pts requiring nilotinib therapy after both imatinib and dasatinib, and therefore have more resistant CML, CHR rate was 39% (=70: 32%), MCyR rate was 28% (=70: 29%) and CCyR rate was 20% (=70: 16%). Safety was likewise similar among elderly pts, with grade 3/4 study drug-related AEs occurring in 56% of pts (=70: 53%). The most frequent of these AEs were thrombocytopenia (=60: 24%; =70: 21%) and neutropenia (=60: 14%; =70: 11%). The most common method of managing these AEs was brief dose interruptions and/or reductions [thrombocytopenia (=60:86/108 pts; =70: 30/35), neutropenia (=60: 42/62 pts; =70: 9/18)]. Among elderly pts with prior dasatinib, 53% (=70: 58%) experienced grade 3/4 study drug-related AEs, while 7 out of 8 pts with pleural effusion on dasatinib no longer had it on nilotinib.

In ENACT, pts aged =60 years at study initiation appear to have longer durations of CML, be more heavily pre-treated and more intolerant to imatinib than the younger cohort. Nonetheless, nilotinib induced comparable clinical responses in CML-CP pts regardless of age. Importantly, the safety profile of nilotinib is maintained in elderly pts.

le Coutre:Novartis: Honoraria, Research Funding; BMS: Honoraria. Turkina:Novartis Pharmaceuticals: Honoraria. Kim:Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Wyeth: Research Funding. Ceglarek:Novartis Pharmaceuticals: Honoraria. Shen:Novartis Pharmaceuticals: Honoraria. Smith:Novartis Pharmaceuticals: Honoraria. Rizzieri:Novartis Pharma: Honoraria, Research Funding, Speakers Bureau. Szczudlo:Novartis: Employment. Berton:Novartis Pharmaceuticals: Employment. Wang:Novartis Pharmaceuticals: Employment. Wang:Novartis Pharmaceuticals: Research Funding. Nicolini:Novartis Pharma: Consultancy, Honoraria, Research Funding, Speakers Bureau; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding, Speakers Bureau; Chemgenex: Honoraria, Speakers Bureau.