A Phase I/II Study of AMN107, a Novel Aminopyrimidine Inhibitor of Bcr-Abl, on a Continuous Daily Dosing Schedule in Adult Patients (pts) with Imatinib-Resistant Advanced Phase Chronic Myeloid Leukemia (CML) or Relapsed/Refractory Philadelphia Chromosome (Ph+) Acute Llymphocytic Leukemia (ALL).

AMN107 is a novel aminopyrimidine ATP-competitive inhibitor of Bcr-Abl. In proliferation assays AMN107 ≥10-fold more is potent than IM against Bcr-Abl expressing cell lines. AMN107 is effective against cell lines expressing the following IM-resistant Bcr-Abl mutants: Glu255Val, Phe317Leu, and Met351Thr. In addition, preliminary studies indicate that AMN107 has similar potency to IM against c-Kit and PDGFR-dependent cell proliferation. The ↑ potency and broader spectrum of activity of AMN107 against Bcr-Abl, relative to IM, may result in clinical benefit for pts with CML or Ph+ ALL. In the phase I portion of this phase I/II study, pts with IM-resistant CML-AP, CML-BC, and Ph+ ALL were eligible for treatment with AMN107 as an oral daily dose. 21 pts [median age:61 yrs (range 29–77); 15 male 6 female; performance status: 0(12 pts), 1(6 pts) or 2(3 pts)] have been enrolled in the following dose cohorts (mg/day): 50(7 pts), 100(7 pts), 200(7 pts) and have been on treatment for 8–70 days. Disease types: CML-AP (12 pts), CML-BC (6 pts), Ph+ ALL (3 pts). Intra-pts dose escalations were permitted for persistent disease in peripheral blood and/or marrow. 6/7 pts in the 50mg dose level, and 7/7 pts in the 100mg dose level have dose-escalated. No AMN107-related AE have been observed. Biologic activity, defined as at least a 50% ↓ in blasts or basophils in the peripheral blood and/or marrow lasting for at least 7 days was observed in 0/7 pts treated with 50mg/day, 4/13 pts treated with 100mg/day, and 7/15 pts treated with 200mg/day. Of the 7 pts who demonstrated biologic activity at 200mg/day, 2 pts with CML-AP had complete hematologic responses in marrow, and 1 pts with CML-AP had return to CP in marrow. Pts were not pre-selected for treatment based on mutational status of Bcr-Abl. Mutational analysis is being performed on all pts and will be correlated with response. Initial data reveal Bcr-Abl mutations in the majority (> 80%) of baseline pts samples. Preliminary data from the 50mg cohort comparing baseline peripheral blood samples with day 2 samples showed: significant ↑ in apoptosis as determined by mitochondrial potential, reduction in proliferation of CD34+ cells as measured by BrdU incorporation, and significant reductions in STAT1 phosphorylation. Reduction in CRKL phosphorylation in CD34+ cells was observed. Similar changes were noted in marrow. PK samples were collected on days 1, 2, 8, 15, 22 & 28 of cycle 1 and at time of any intra-pts dose escalation. Pharmacokinetics after 1 daily oral dose of AMN107 were characterized as little accumulation after multiple administrations with moderate inter-pts variability in exposure. Peak concentrations of AMN107 were generally achieved by 3 hrs post-dose. Preliminary PK data support 1-daily dosing. This phase I study, AMN107 given orally appears to be well tolerated with biologic effects in some pts treated with ≥100mg/day & marrow responses in some pts treated with 200mg/day. Once MTD has been determined, pts will be enrolled to multiple expansion cohorts in the phase II portion to assess activity.