Maria Menichincheri

A Cdc7 kinase inhibitor restricts initiation of DNA replication and has antitumor activity.

Cdc7 is an essential kinase that promotes DNA replication by activating origins of replication. Here, we characterized the potent Cdc7 inhibitor PHA-767491 (1) in biochemical and cell-based assays, and we tested its antitumor activity in rodents. We found that the compound blocks DNA synthesis and affects the phosphorylation of the replicative DNA helicase at Cdc7-dependent phosphorylation sites. Unlike current DNA synthesis inhibitors, PHA-767491 prevents the activation of replication origins but does not impede replication fork progression, and it does not trigger a sustained DNA damage response. Treatment with PHA-767491 results in apoptotic cell death in multiple cancer cell types and tumor growth inhibition in preclinical cancer models. To our knowledge, PHA-767491 is the first molecule that directly affects the mechanisms controlling initiation as opposed to elongation in DNA replication, and its activities suggest that Cdc7 kinase inhibition could be a new strategy for the development of anticancer therapeutics.

Cdc7 Kinase Inhibitors : Pyrrolopyridinones as Potential Antitumor Agents. 1. Synthesis and Structure-Activity Relationships

Cdc7 kinase is an essential protein that promotes DNA replication in eukaryotic organisms. Genetic evidence indicates that Cdc7 inhibition can cause selective tumor-cell death in a p53-independent manner, supporting the rationale for developing Cdc7 small-molecule inhibitors for the treatment of cancers. In this paper, the synthesis and structure-activity relationships of 2-heteroaryl-pyrrolopyridinones, the first potent Cdc7 kinase inhibitors, are described. Starting from 2-pyridin-4-yl-1,5,6,7-tetrahydro-pyrrolo[3,2-c]pyridin-4-one, progress toward a simple scaffold, tailored for Cdc7 inhibition, is reported.

Entrectinib, a Pan-TRK, ROS1 and ALK Inhibitor with Activity in Multiple Molecularly Defined Cancer Indications

Activated ALK and ROS1 tyrosine kinases, resulting from chromosomal rearrangements, occur in a subset of non–small cell lung cancers (NSCLC) as well as other tumor types and their oncogenic relevance as actionable targets has been demonstrated by the efficacy of selective kinase inhibitors such as crizotinib, ceritinib, and alectinib. More recently, low-frequency rearrangements of TRK kinases have been described in NSCLC, colorectal carcinoma, glioblastoma, and Spitzoid melanoma. Entrectinib, whose discovery and preclinical characterization are reported herein, is a novel, potent inhibitor of ALK, ROS1, and, importantly, of TRK family kinases, which shows promise for therapy of tumors bearing oncogenic forms of these proteins. Proliferation profiling against over 200 human tumor cell lines revealed that entrectinib is exquisitely potent in vitro against lines that are dependent on the drugs pharmacologic targets. Oral administration of entrectinib to tumor-bearing mice induced regression in relevant human xenograft tumors, including the TRKA-dependent colorectal carcinoma KM12, ROS1-driven tumors, and several ALK-dependent models of different tissue origins, including a model of brain-localized lung cancer metastasis. Entrectinib is currently showing great promise in phase I/II clinical trials, including the first documented objective responses to a TRK inhibitor in colorectal carcinoma and in NSCLC. The drug is, thus, potentially suited to the therapy of several molecularly defined cancer settings, especially that of TRK-dependent tumors, for which no approved drugs are currently available. Mol Cancer Ther; 15(4); 628–39. ©2016 AACR.

First Cdc7 kinase inhibitors: pyrrolopyridinones as potent and orally active antitumor agents. 2. Lead discovery.

Cdc7 kinase is a key regulator of the S-phase of the cell cycle, known to promote the activation of DNA replication origins in eukaryotic organisms. Cdc7 inhibition can cause tumor-cell death in a p53-independent manner, supporting the rationale for developing Cdc7 inhibitors for the treatment of cancer. In this paper, we conclude the structure-activity relationships study of the 2-heteroaryl-pyrrolopyridinone class of compounds that display potent inhibitory activity against Cdc7 kinase. Furthermore, we also describe the discovery of 89S, [(S)-2-(2-aminopyrimidin-4-yl)-7-(2-fluoro-ethyl)-1,5,6,7-tetrahydropyrrolo[3,2-c]pyridin-4-one], as a potent ATP mimetic inhibitor of Cdc7. Compound 89S has a Ki value of 0.5 nM, inhibits cell proliferation of different tumor cell lines with an IC50 in the submicromolar range, and exhibits in vivo tumor growth inhibition of 68% in the A2780 xenograft model.

Discovery of Entrectinib: A New 3-Aminoindazole as a Potent Anaplastic Lymphoma Kinase (Alk), C-Ros Oncogene 1 Kinase (Ros1), and Pan-Tropomyosin Receptor Kinases (Pan-Trks) Inhibitor.

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase responsible for the development of different tumor types. Despite the remarkable clinical activity of crizotinib (Xalkori), the first ALK inhibitor approved in 2011, the emergence of resistance mutations and of brain metastases frequently causes relapse in patients. Within our ALK drug discovery program, we identified compound 1, a novel 3-aminoindazole active on ALK in biochemical and in cellular assays. Its optimization led to compound 2 (entrectinib), a potent orally available ALK inhibitor active on ALK-dependent cell lines, efficiently penetrant the blood-brain barrier (BBB) in different animal species and highly efficacious in in vivo xenograft models. Moreover, entrectinib resulted to be strictly potent on the closely related tyrosine kinases ROS1 and TRKs recently found constitutively activated in several tumor types. Entrectinib is currently undergoing phase I/II clinical trial for the treatment of patients affected by ALK-, ROS1-, and TRK-positive tumors.

Cdc7 Kinase Inhibitors: 5-Heteroaryl-3-Carboxamido-2-Aryl Pyrroles as Potential Antitumor Agents. 1. Lead Finding

Cdc7 serine/threonine kinase is a key regulator of DNA synthesis in eukaryotic organisms. Cdc7 inhibition through siRNA or prototype small molecules causes p53 independent apoptosis in tumor cells while reversibly arresting cell cycle progression in primary fibroblasts. This implies that Cdc7 kinase could be considered a potential target for anticancer therapy. We previously reported that pyrrolopyridinones (e.g., 1) are potent and selective inhibitors of Cdc7 kinase, with good cellular potency and in vitro ADME properties but with suboptimal pharmacokinetic profiles. Here we report on a new chemical class of 5-heteroaryl-3-carboxamido-2-substituted pyrroles (1A) that offers advantages of chemistry diversification and synthetic simplification. This work led to the identification of compound 18, with biochemical data and ADME profile similar to those of compound 1 but characterized by superior efficacy in an in vivo model. Derivative 18 represents a new lead compound worthy of further investigation toward the ultimate goal of identifying a clinical candidate.

Cell division cycle 7 kinase inhibitors: 1H-pyrrolo[2,3-b]pyridines, synthesis and structure-activity relationships.

Cdc7 kinase has recently emerged as an attractive target for cancer therapy and low-molecular-weight inhibitors of Cdc7 kinase have been found to be effective in the inhibition of tumor growth in animal models. In this paper, we describe synthesis and structure-activity relationships of new 1H-pyrrolo[2,3-b]pyridine derivatives identified as inhibitors of Cdc7 kinase. Progress from (Z)-2-phenyl-5-(1H-pyrrolo[2,3-b]pyridin-3-ylmethylene)-3,5-dihydro-4H-imidazol-4-one (1) to [(Z)-2-(benzylamino)-5-(1H-pyrrolo[2,3-b]pyridin-3-ylmethylene)-1,3-thiazol-4(5H)-one] (42), a potent ATP mimetic inhibitor of Cdc7 kinase with IC(50) value of 7 nM, is also reported.

Abstract A243: Characterization of NMS‐E628, a small molecule inhibitor of anaplastic lymphoma kinase with antitumor efficacy in ALK‐dependent lymphoma and non‐small cell lung cancer models

The chromosomal translocation t(2;5)(p23;q35) involving the ALK tyrosine kinase gene results in expression of the NPM‐ALK fusion protein which represents the driving force for survival and proliferation of a subset of Anaplastic Large Cell Lymphoma. More recently, a distinct chromosomal rearrangement of the ALK gene leading to a new fusion variant EML4‐ALK, has been identified as a low frequency event, mutually exclusive with respect to EGFR and K‐ras mutation, in Non Small Cell Lung cancer patients. As previously found for NPM‐ALK, this new fusion variant has constitutively active ALK kinase and was demonstrated to have strong oncogenic potential. Taken together these findings support the hypothesis that ALK represents an innovative and valuable target for cancer therapy both in ALCL and NSCLC patients whose tumors harbor translocated ALK. Here we further describe the preclinical characterization of NMS‐E628, an orally available small‐molecule inhibitor of ALK kinase activity. Proliferation profiling on a wide panel of human tumor cell lines demonstrated that the compound selectively blocks proliferation of ALK‐dependent cell lines and potently inhibits ALK‐dependent signaling. In vivo, NMS‐E628 induced complete tumor regression when administered orally for ten consecutive days to SCID mice bearing Karpas‐299 or SR‐786 xenografts, with ex vivo analyses demonstrating dose‐dependent target modulation that was maintained for up to 18 hours after single treatment. NMS‐E628 was also highly efficacious in a transgenic mouse leukemia model in which human NPM‐ALK expression was targeted to T cells. In this latter model, which faithfully recapitulates pathological features of human ALCL, treatment of NPM‐ALK transgenic mice with NMS‐E628 for as little as 3 consecutive days induced complete regression of tumor masses observed in the thymus and in lymph nodes. NMS‐E628 was also highly efficacious in inhibiting the in vitro and in vivo growth of the NSCLC cell line NCI‐H2228, which bears the EML4‐ALK rearrangement. Complete regressions were also achieved in this model, and prolonged inhibition of ALK phosphorylation and downstream effector activation were observed at active doses. NMS‐E628 has favorable pharmacokinetic and toxicological properties and biodistribution analysis revealed that it is able to cross the blood‐brain barrier in different animal species. To confirm that therapeutic doses are reached in the brain, NCI‐H2228 cells were injected intracranially in nude mice and NMS‐E628 was administered orally with different schedules. Dose‐dependent increase in survival, together with inhibition of tumor growth as assessed by MRI, confirmed that NMS‐E628 does indeed possess antitumor activity in this setting, an important finding considering that a significant proportion of NSCLC patients develop brain metastases. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A244.

Pyrazole and pyrimidine phenylacylsulfonamides as dual Bcl-2/Bcl-xL antagonists.

5-Butyl-1,4-diphenyl pyrazole and 2-amino-5-chloro pyrimidine acylsulfonamides were developed as potent dual antagonists of Bcl-2 and Bcl-xL. Compounds were optimized for binding to the I88, L92, I95, and F99 pockets normally occupied by pro-apoptotic protein Bim. An X-ray crystal structure confirmed the proposed binding mode. Observation of cytochrome c release from isolated mitochondria in MV-411 cells provides further evidence of target inhibition. Compounds demonstrated submicromolar antiproliferative activity in Bcl-2/Bcl-xL dependent cell lines.

Abstract A232: In vitro and in vivo activity of NMS-E628 against ALK mutations resistant to Xalkori.

The Anaplastic Lymphoma Kinase (ALK) is a receptor tyrosine kinase with a recognized role in the pathogenesis of different tumors. There is strong preclinical evidence that inhibition of ALK kinase activity results in anti-tumor efficacy and the approval of the ALK inihibitor Xalkori (crizotinib) for treatment of NSCLC patients bearing ALK positive tumor represents the most recent success of targeted therapy. Nevertheless, clinical data show that after initial response to Xalkori, patients experience relapse, the mechanisms of which are still under study, but which at least in some cases appear due to emergence of mutations that confer resistance to the drug. Thus, the development of next-generation ALK inihibitors, able to overcome ALK-dependent Xalkori resistance is needed. We have previously presented the identification of NMS-E628, a potent and selective small-molecule inhibitor of ALK kinase activity. The compound displays strong anti-tumor efficacy in several models of ALK dependent tumors after oral administration, with complete and durable regression observed in treated animals. NMS-E628 passes the blood brain barrier in all the species tested and was found able to effectively control the growth of intracranial tumors. Being structurally distinct from Xalkori, NMS-E628 might be able to overcome mutations in the ALK kinase domain which confer resistance by affecting Xalkori binding. To test this hypothesis, the activity of NMS-E628 on WT ALK and on two mutants identified in Xalkori-relapsed patients, L1196M and C1156Y, was investigated using different approaches. Ki determination revealed that at the biochemical level, NMS-E628 is ca. 7–8 fold more potent than Xalkori on both L1196M and C1156Y. In Ba/F3 cells made dependent upon mutated ALK forms, NMS-E628 was found superior than Xalkori in inhibiting the proliferation of both L1196M ALK and C1156Y ALK-driven cells in vitro. Mechanism of action studies confirmed that of the two drugs, NMS-E628 is better able to downmodulate ALK phosphorylation, having similar potency on wt ALK and mutated forms. To assess antitumor activity in vivo, Ba/F3 xenografts driven by different ALK mutants were generated. As expected from in vitro results, Xalkori showed poor efficacy on L1196M and C1156Y mutants when tested at 100 and 200 mg/kg, while NMS-E628 retains significant anti-tumor activity in both mutant models. Taken together, these data support the idea that NMS-E628 might represent a valid therapeutic opportunity for Xalkori-relapsed patients that experience acquired resistance to specific ALK mutations. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A232.