Kay Huh

Identification of NVP-BKM120 as a Potent, Selective, Orally Bioavailable Class I PI3 Kinase Inhibitor for Treating Cancer

Phosphoinositide-3-kinases (PI3Ks) are important oncology targets due to the deregulation of this signaling pathway in a wide variety of human cancers. Herein we describe the structure guided optimization of a series of 2-morpholino, 4-substituted, 6-heterocyclic pyrimidines where the pharmacokinetic properties were improved by modulating the electronics of the 6-position heterocycle, and the overall druglike properties were fine-tuned further by modification of the 4-position substituent. The resulting 2,4-bismorpholino 6-heterocyclic pyrimidines are potent class I PI3K inhibitors showing mechanism modulation in PI3K dependent cell lines and in vivo efficacy in tumor xenograft models with PI3K pathway deregulation (A2780 ovarian and U87MG glioma). These efforts culminated in the discovery of 15 (NVP-BKM120), currently in Phase II clinical trials for the treatment of cancer.

Structure Guided Optimization, in Vitro Activity, and in Vivo Activity of Pan-PIM Kinase Inhibitors.

Proviral insertion of Moloney virus (PIM) 1, 2, and 3 kinases are serine/threonine kinases that normally function in survival and proliferation of hematopoietic cells. As high expression of PIM1, 2, and 3 is frequently observed in many human malignancies, including multiple myeloma, non-Hodgkins lymphoma, and myeloid leukemias, there is interest in determining whether selective PIM inhibition can improve outcomes of these human cancers. Herein, we describe our efforts toward this goal. The structure guided optimization of a singleton high throughput screening hit in which the potency against all three PIM isoforms was increased >10,000-fold to yield compounds with pan PIM K is < 10 pM, nanomolar cellular potency, and in vivo activity in an acute myeloid leukemia Pim-dependent tumor model is described.

Abstract 4498: Biological characterization of NVP-BKM120, a novel inhibitor of phosphoinosotide 3-kinase in Phase I/II clinical trials

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC The PI3K/Akt/mTor signaling pathway plays an important role in controlling cell growth, proliferation and survival. Through various mechanisms, the pathway is frequently dysregulated in human cancers, suggesting the use of PI3K inhibitors as novel targeted anticancer therapeutic agents. To this end, substantial drug discovery efforts have been devoted both in pharmaceutical companies and in academia to identify and develop therapeutic agents able to specifically down regulate PI3K or other components of this pathway in tumors cells. Following the discovery of NVP-BEZ235, our first dual pan-PI3K/mTOR clinical compound, we sought to identify additional PI3K inhibitors from different chemical classes with more stringent selectivity profiles. The key to achieve these objectives was to pursue a structure-based design approach coupled with intensive pharmacological evaluation of selected compounds during the medicinal chemistry optimization process. Here we report on the biological characterization of the pan-PI3K pyrimidine-derived inhibitor NVP-BKM120. This compound inhibits all four Class I PI3K isoforms (IC50 values in the 35 to 248 nM range) with at least 50-fold selectivity (compared to p110α) towards protein kinases. The compound is also active against the most common somatic PI3Kα mutations (H1047R, E542K and E545K). NVP-BKM120 does not significantly inhibit the related Class III (Vps34) and Class IV (mTOR, DNA-PK) PI3K kinases. Consistent with its mechanism of action, NVP-BKM120 decreases the cellular levels of p-Akt in mechanistic and relevant tumor cell lines (e.g., IC50 for S473P-Akt in Rat1-p110α cells of 93 nM). This biological activity correlates with inhibition of various Akt downstream signaling pathway components, and with its anti-proliferative activity. Thus, the compound demonstrates significant, concentration dependent cell growth inhibition and induction of apoptosis in a variety of tumor cancer cells, particularly for those harboring p110α mutants and/or over-expressing erbB2. In addition, NVP-BKM120 demonstrates significant, dose dependent in vivo pharmacodynamic activity as measured by inhibition of p-Akt in relevant xenograft models. The pharmacological, biological and preclinical safety profile of NVP-BKM120 supports its clinical development and the compound is currently undergoing Phase 1/II clinical trials in cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4498.

Identification of N-(4-((1R,3S,5S)-3-Amino-5-methylcyclohexyl)pyridin-3-yl)-6-(2,6-difluorophenyl)-5-fluoropicolinamide (PIM447), a Potent and Selective Proviral Insertion Site of Moloney Murine Leukemia (PIM) 1, 2, and 3 Kinase Inhibitor in Clinical Trials for Hematological Malignancies.

Pan proviral insertion site of Moloney murine leukemia (PIM) 1, 2, and 3 kinase inhibitors have recently begun to be tested in humans to assess whether pan PIM kinase inhibition may provide benefit to cancer patients. Herein, the synthesis, in vitro activity, in vivo activity in an acute myeloid leukemia xenograft model, and preclinical profile of the potent and selective pan PIM kinase inhibitor compound 8 (PIM447) are described. Starting from the reported aminopiperidyl pan PIM kinase inhibitor compound 3, a strategy to improve the microsomal stability was pursued resulting in the identification of potent aminocyclohexyl pan PIM inhibitors with high metabolic stability. From this aminocyclohexyl series, compound 8 entered the clinic in 2012 in multiple myeloma patients and is currently in several phase 1 trials of cancer patients with hematological malignancies.

Structure guided optimization of a fragment hit to imidazopyridine inhibitors of PI3K.

PI3 kinases are a family of lipid kinases mediating numerous cell processes such as proliferation, migration and differentiation. The PI3 Kinase pathway is often de-regulated in cancer through PI3Kα overexpression, gene amplification, mutations and PTEN phosphatase deletion. PI3K inhibitors represent therefore an attractive therapeutic modality for cancer treatment. Herein we describe how the potency of a benzothiazole fragment hit was quickly improved based on structural information and how this early chemotype was further optimized through scaffold hopping. This effort led to the identification of a series of 2-acetamido-5-heteroaryl imidazopyridines showing potent in vitro activity against all class I PI3Ks and attractive pharmacokinetic properties.

Abstract 3629: BLZ945, a selective c-fms (CSF-1R) kinase inhibitor for the suppression of tumor-induced osteolytic lesions in bone

Aberrant activation of osteoclasts due to bone metastasis causes osteolysis, skeletal-related events and severe pain in cancer patients. Macrophage-Colony-stimulating Factor (M-CSF) signaling through its receptor c-fms / Colony-Stimulating Factor-1 Receptor (CSF-1R) in the monocytic lineage is essential for osteoclastogenesis, providing an opportunity to inhibit this pathway and suppress tumor-induced osteolysis. BLZ945 is an orally active, potent and selective CSF-1R inhibitor. BLZ945 inhibits CSF-1R activity with an IC50 of 1nM and is more than 1000-fold selective against its closest receptor tyrosine kinase homologs c-KIT and Platelet-derived Growth Factor Receptor beta (PDGFRb) as well as more than 200 additional kinases, confirming the selectivity of the compound. BLZ945 potently inhibited proliferation of the M-CSF-dependent murine leukemia cell line MNFS60 (EC50 67 nM) consistent with the inhibition of the CSF-1R kinase activity. Tyrosine phosphorylation in HEK293 cells overexpressing human CSF-1R was inhibited with an EC50 of 58 nM. Functional activity of BLZ945 was shown by inhibition of osteoclastogenesis using human osteoclast precursors. The MNFS60 allograft model was used to evaluate the pharmacodynamics of BLZ945 by monitoring dose and time dependent changes in tyrosine phoshorylation of CSF-1R to select doses and regimens for in vivo efficacy studies. A single dose of BLZ945 at 200 mg/kg maximally suppressed CSF-1R phosphorylation of >50% for more than 16 hours in this model and was selected for further evaluation in mouse models of breast (MDA-MB-231Luc) and prostate (PC-3MLuc) tumor-induced osteolysis (TIO). In these models human tumor cells are injected directly into the tibia of nude mice and bone destruction is measured by x-ray analysis and serum levels of tartrate-resistant acid phosphatase 5b (TRAP5b), a marker of osteoclast activity. Daily dosing of BLZ945 at 200 mg/kg resulted in a significant reduction in the progression of osteolysis, with > 50% reduction in osteolytic lesion severity in both TIO models, as compared to vehicle-treated animals. Reductions in serum TRAP5b were also observed at the end of the studies. BLZ945 showed enhanced activity in combination with zoledronate in the PC-3MLuc model, with the combination reducing osteolytic severity scores by 90%. In addition anti-osteolytic activity was observed in a nude rat model of osteolysis induced by intratibial injection of MDA-MB-231 cells. In naive cynomolgus monkeys, treatment with BLZ945 resulted in dose-dependent reductions of serum TRAP5b and cross-linked collagen (CTX) in both serum and urine, consistent with the expected effect of inhibiting bone resorption. These data support the testing of CSF-1R inhibitors in advanced cancer patients with bone metastases and skeletal related events. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3629.

Imidazo[1,2-a]pyridin-6-yl-benzamide Analogs as Potent RAF Inhibitors

A series of imidazo[1,2-a]pyridin-6-yl-benzamide analogs was designed as inhibitors of B-RAFV600E. Medicinal chemistry techniques were employed to explore the SAR for this series and improve selectivity versus P38 and VEGFR2.