First results of migoprotafib, a potent and highly selective Src homology-2 domain-containing phosphatase 2 (SHP2) inhibitor in patients with advanced solid tumors.

Src homology-2 domain-containing phosphatase 2 (SHP2) promotes RAS-MAPK signaling and tumorigenesis and is a promising therapeutic target for multiple solid tumors. Migoprotafib is a potent and highly selective SHP2 inhibitor designed for the treatment of RAS-MAPK driven cancers, particularly in combination with other targeted agents. Here we report first-in-human study results of single agent migoprotafib in advanced solid tumor patients.

Safety and efficacy of avapritinib in advanced systemic mastocytosis: the phase 1 EXPLORER trial.

Advanced systemic mastocytosis (AdvSM) is a rare hematologic neoplasm driven by the KIT D816V mutation and associated with poor survival. This phase 1 study ( NCT02561988 ) evaluated avapritinib (BLU-285), a selective KIT D816V inhibitor, in patients with AdvSM. The primary endpoints were the maximum tolerated dose, recommended phase 2 dose and safety of avapritinib.

Resistance to Avapritinib in PDGFRA-Driven GIST Is Caused by Secondary Mutations in the PDGFRA Kinase Domain.

Gastrointestinal stromal tumors (GIST) harboring activating mutations of respond to imatinib, with the notable exception of the most common mutation, D842V. Avapritinib is a novel, potent KIT/PDGFRA inhibitor with substantial clinical activity in patients with the D842V genotype. To date, only a minority of -mutant patients treated with avapritinib have developed secondary resistance.

First-in-Human Phase I Study of Fisogatinib (BLU-554) Validates Aberrant FGF19 Signaling as a Driver Event in Hepatocellular Carcinoma.

Outcomes for patients with advanced hepatocellular carcinoma (HCC) remain poor despite recent progress in drug development. Emerging data implicate FGF19 as a potential HCC driver, suggesting its receptor, FGFR4, as a novel therapeutic target. We evaluated fisogatinib (BLU-554), a highly potent and selective oral FGFR4 inhibitor, in a phase I dose-escalation/dose-expansion study in advanced HCC using FGF19 expression measured by IHC as a biomarker for pathway activation.

Acquired On-Target Clinical Resistance Validates FGFR4 as a Driver of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a leading cause of cancer mortality worldwide with no clinically confirmed oncogenic driver. Although preclinical studies implicate the FGF19 receptor FGFR4 in hepatocarcinogenesis, the dependence of human cancer on FGFR4 has not been demonstrated. Fisogatinib (BLU-554) is a potent and selective inhibitor of FGFR4 and demonstrates clinical benefit and tumor regression in patients with HCC with aberrant FGF19 expression.

A precision therapy against cancers driven by mutations.

Targeting oncogenic kinase drivers with small-molecule inhibitors can have marked therapeutic benefit, especially when administered to an appropriate genomically defined patient population. Cancer genomics and mechanistic studies have revealed that heterogeneous mutations within a single kinase can result in various mechanisms of kinase activation. Therapeutic benefit to patients can best be optimized through an in-depth understanding of the disease-driving mutations combined with the ability to match these insights to tailored highly selective drugs.

Multiplexed gene expression profiling identifies the FGFR4 pathway as a novel biomarker in intrahepatic cholangiocarcinoma.

Background: The fibroblast growth factor receptor 4 (FGFR4) pathway is an essential regulatory component of bile acid synthesis, and its relationship with hepatocellular carcinoma (HCC) has been reported. We investigated the gene expression and clinical significance of FGFR4 and related pathways in intrahepatic cholangiocarcinoma (iCCA).

Results: The median age was 56 years (range 30-78) and 34 patients (74%) were male.

Structural basis of nSH2 regulation and lipid binding in PI3Kα.

We report two crystal structures of the wild-type phosphatidylinositol 3-kinase α (PI3Kα) heterodimer refined to 2.9 Å and 3.4 Å resolution: the first as the free enzyme, the second in complex with the lipid substrate, diC4-PIP₂, respectively.

Definition of the binding mode of a new class of phosphoinositide 3-kinase α-selective inhibitors using in vitro mutagenesis of non-conserved amino acids and kinetic analysis.

The binding mechanism of a new class of lipid-competitive, ATP non-competitive, p110α isoform-selective PI3K (phosphoinositide 3-kinase) inhibitors has been elucidated. Using the novel technique of isoform reciprocal mutagenesis of non-conserved amino acids in the p110α and p110β isoforms, we have identified three unique binding mechanisms for the p110α-selective inhibitors PIK-75, A-66S and J-32. Each of the inhibitor's p110α-isoform-selective binding was found to be due to interactions with different amino acids within p110.

Synthesis and Pharmacological Evaluation of 4-Iminothiazolidinones for Inhibition of PI3 Kinase.

The thiazolidinedione, compound , has previously shown pan-inhibition of the phosphoinositide 3-kinase (PI3K) class I isoforms. We hypothesized the derivatization of the thiazolidinedione core of compound could introduce isoform selectivity. We report the synthesis, characterization, and inhibitory activity of a novel series of 4-iminothiazolidin-2-ones for inhibition of the class I PI3K isoforms.

Thiazolidinedione-based PI3Kα inhibitors: an analysis of biochemical and virtual screening methods.

A series of synthesized and commercially available compounds were assessed against PI3Kα for in vitro inhibitory activity and the results compared to binding calculated in silico. Using published crystal structures of PI3Kγ and PI3Kδ co-crystallized with inhibitors as a template, docking was able to identify the majority of potent inhibitors from a decoy set of 1000 compounds. On the other hand, PI3Kα in the apo-form, modeled by induced fit docking, or built as a homology model gave only poor results.

2-hydroxyglutarate production, but not dominant negative function, is conferred by glioma-derived NADP-dependent isocitrate dehydrogenase mutations.

Background: Gliomas frequently contain mutations in the cytoplasmic NADP(+)-dependent isocitrate dehydrogenase (IDH1) or the mitochondrial NADP(+)-dependent isocitrate dehydrogenase (IDH2). Several different amino acid substitutions recur at either IDH1 R132 or IDH2 R172 in glioma patients. Genetic evidence indicates that these mutations share a common gain of function, but it is unclear whether the shared function is dominant negative activity, neomorphic production of (R)-2-hydroxyglutarate (2HG), or both.

PI3Kα inhibitors that inhibit metastasis.

Previous genetic analyses have suggested that mutations of the genes encoding PI3Kα facilitate invasion and metastasis but have less effect on primary tumor growth. These findings have major implications for therapeutics but have not been factored into pre-clinical drug development designs. Here we show that the inhibition of PI3Kα by newly designed small molecule inhibitors prevented metastasis formation in mice but had much less effect on the growth of subcutaneous xenografts or primary intra-abdominal tumors.

Structural effects of oncogenic PI3Kα mutations.

Physiological activation of PI3Kα is brought about by the release of the inhibition by p85 when the nSH2 binds the phosphorylated tyrosine of activated receptors or their substrates. Oncogenic mutations of PI3Kα result in a constitutively activated enzyme that triggers downstream pathways that increase tumor aggressiveness and survival. Structural information suggests that some mutations also activate the enzyme by releasing p85 inhibition.

Somatic mutations in PI3Kalpha: structural basis for enzyme activation and drug design.

The PI3K pathway is a communication hub coordinating critical cell functions including cell survival, cell growth, proliferation, motility and metabolism. Because PI3Kalpha harbors recurrent somatic mutations resulting in gains of function in human cancers, it has emerged as an important drug target for many types of solid tumors. Various PI3K isoforms are also being evaluated as potential therapeutic targets for inflammation, heart disease, and hematological malignancies.

A frequent kinase domain mutation that changes the interaction between PI3Kalpha and the membrane.

Mutations in oncogenes often promote tumorigenesis by changing the conformation of the encoded proteins, thereby altering enzymatic activity. The PIK3CA oncogene, which encodes p110alpha, the catalytic subunit of phosphatidylinositol 3-kinase alpha (PI3Kalpha), is one of the two most frequently mutated oncogenes in human cancers. We report the structure of the most common mutant of p110alpha in complex with two interacting domains of its regulatory partner (p85alpha), both free and bound to an inhibitor (wortmannin).

Dissecting isoform selectivity of PI3K inhibitors: the role of non-conserved residues in the catalytic pocket.

The last few years have seen the identification of numerous small molecules that selectively inhibit specific class I isoforms of PI3K (phosphoinositide 3-kinase), yet little has been revealed about the molecular basis for the observed selectivities. Using site-directed mutagenesis, we have investigated one of the areas postulated as being critical to the observed selectivity. The residues Thr(886) and Lys(890) of the PI3Kgamma isoform project towards the ATP-binding pocket at the entrance to the catalytic site, but are not conserved.

High-resolution array comparative genomic hybridization of single micrometastatic tumor cells.

Only few selected cancer cells drive tumor progression and are responsible for therapy resistance. Their specific genomic characteristics, however, are largely unknown because high-resolution genome analysis is currently limited to DNA pooled from many cells. Here, we describe a protocol for array comparative genomic hybridization (array CGH), which enables the detection of DNA copy number changes in single cells.

The structure of a human p110alpha/p85alpha complex elucidates the effects of oncogenic PI3Kalpha mutations.

PIK3CA, one of the two most frequently mutated oncogenes in human tumors, codes for p110alpha, the catalytic subunit of a phosphatidylinositol 3-kinase, isoform alpha (PI3Kalpha, p110alpha/p85). Here, we report a 3.0 angstrom resolution structure of a complex between p110alpha and a polypeptide containing the p110alpha-binding domains of p85alpha, a protein required for its enzymatic activity.

Genomic analysis of single cytokeratin-positive cells from bone marrow reveals early mutational events in breast cancer.

Chromosomal instability in human breast cancer is known to take place before mammary neoplasias display morphological signs of invasion. We describe here the unexpected finding of a tumor cell population with normal karyotypes isolated from bone marrow of breast cancer patients. By analyzing the same single cells for chromosomal aberrations, subchromosomal allelic losses, and gene amplifications, we confirmed their malignant origin and delineated the sequence of genomic events during breast cancer progression.

Mutant PIK3CA promotes cell growth and invasion of human cancer cells.

PIK3CA is mutated in diverse human cancers, but the functional effects of these mutations have not been defined. To evaluate the consequences of PIK3CA alterations, the two most common mutations were inactivated by gene targeting in colorectal cancer (CRC) cells. Biochemical analyses of these cells showed that mutant PIK3CA selectively regulated the phosphorylation of AKT and the forkhead transcription factors FKHR and FKHRL1.

Immunomagnetic enrichment, genomic characterization, and prognostic impact of circulating melanoma cells.

Purpose: The finding of melanoma cells in the peripheral blood, thus far mainly inferred from the PCR-based demonstration of tyrosinase mRNA, has been associated with metastatic melanoma. Neither the malignant nature nor the prognostic significance of circulating cells could be established. To address this question, we analyzed immunomagnetically isolated circulating melanoma cells for chromosomal aberrations and performed a clinical follow-up study of the enrolled patients.

From latent disseminated cells to overt metastasis: genetic analysis of systemic breast cancer progression.

According to the present view, metastasis marks the end in a sequence of genomic changes underlying the progression of an epithelial cell to a lethal cancer. Here, we aimed to find out at what stage of tumor development transformed cells leave the primary tumor and whether a defined genotype corresponds to metastatic disease. To this end, we isolated single disseminated cancer cells from bone marrow of breast cancer patients and performed single-cell comparative genomic hybridization.

Genetic heterogeneity of single disseminated tumour cells in minimal residual cancer.

Background: Because cancer patients with small tumours often relapse despite local and systemic treatment, we investigated the genetic variation of the precursors of distant metastasis at the stage of minimal residual disease. Disseminated tumour cells can be detected by epithelial markers in mesenchymal tissues and represent targets for adjuvant therapies.

Methods: We screened 525 bone-marrow, blood, and lymph-node samples from 474 patients with breast, prostate, and gastrointestinal cancers for single disseminated cancer cells by immunocytochemistry with epithelial-specific markers.