Inhibition of BCR-ABL by imatinib induces durable responses in many patients with chronic myeloid leukemia (CML), but resistance attributable to kinase domain mutations can lead to relapse and a switch to second-line therapy with nilotinib or dasatinib. Despite three approved therapeutic options, the cross-resistant BCR-ABL(T315I) mutation and compound mutants selected on sequential inhibitor therapy remain major clinical challenges. We report design and preclinical evaluation of AP24534, a potent, orally available multitargeted kinase inhibitor active against T315I and other BCR-ABL mutants. AP24534 inhibited all tested BCR-ABL mutants in cellular and biochemical assays, suppressed BCR-ABL(T315I)-driven tumor growth in mice, and completely abrogated resistance in cell-based mutagenesis screens. Our work supports clinical evaluation of AP24534 as a pan-BCR-ABL inhibitor for treatment of CML.

The anions of the nucleic acid bases, uracil and thymine, were studied by negative ion photoelectron spectroscopy. Both monomer anions exhibit spectroscopic signatures that are indicative of dipole bound excess electrons. The adiabatic electron affinities of these molecules were found to be 93Ϯ7 meV for uracil and 69Ϯ7 meV for thymine. No conventional ͑valence͒ anions of these molecules were observed.

In the treatment of chronic myeloid leukemia (CML) with BCR-ABL kinase inhibitors, the T315I gatekeeper mutant has emerged as resistant to all currently approved agents. This report describes the structure-guided design of a novel series of potent pan-inhibitors of BCR-ABL, including the T315I mutation. A key structural feature is the carbon-carbon triple bond linker which skirts the increased bulk of Ile315 side chain. Extensive SAR studies led to the discovery of development candidate 20g (AP24534), which inhibited the kinase activity of both native BCR-ABL and the T315I mutant with low nM IC(50)s, and potently inhibited proliferation of corresponding Ba/F3-derived cell lines. Daily oral administration of 20g significantly prolonged survival of mice injected intravenously with BCR-ABL(T315I) expressing Ba/F3 cells. These data, coupled with a favorable ADME profile, support the potential of 20g to be an effective treatment for CML, including patients refractory to all currently approved therapies.

We have recorded the photoelectron (photodetachment) spectra of the gas-phase negative cluster ions NO−(N2 O)1 and NO−(N2 O)2 using 2.540 eV photons. Both spectra exhibit structured photoelectron spectral patterns which strongly resemble that of free NO−, but which are shifted to successively lower electron kinetic energies with their individual peaks broadened. Each of these spectra is interpreted in terms of a largely intact NO−subion which is solvated and stabilized by nitrous oxide. For both NO−(N2 O)1 and NO−(N2 O)2, the ion–solvent dissociation energies for the loss of single N2 O solvent molecules were determined to be ∼0.2 eV. Electron affinities were also determined and found to increase with cluster size. The localization of the cluster ion’s excess negative charge onto its nitric oxide rather than its nitrous oxide subunit is discussed in terms of kinetic factors and a possible barrier between the two forms of the solvated ion.

We have recorded the photoelectron spectrum of SeO− using a newly constructed negative ion photoelectron spectrometer. The adiabatic electron affinity of SeO is determined to be 1.456±0.020 eV. Values of ν00(a 1Δ–X 3Σ−0+) and ΔG1/2(a 1Δ) are found to be 5530±200 and 916±35 cm−1, respectively, in substantial accord with previous measurements. The negative ion parameters determined in this work are: B″e(SeO−) =0.4246±0.0050 cm−1 which leads to  r′e(SeO−)=1.726±0.010 Å, ω″e(SeO−)=730±25 cm−1, ω′e x″e(SeO−)=2±4 cm−1, and  D0(SeO−)=3.84±0.09 eV. In addition, the spectroscopic parameters of SeO− are compared with those of the electronically analogous negative ions: O−2, SO−, and S−2.