Paired primary-metastasis patient-derived organoids and mouse models identify phenotypic evolution and druggable dependencies of peritoneal metastasis from appendiceal cancer.

Peritoneal carcinomatosis is a common yet deadly manifestation of gastrointestinal cancers, with few effective treatments. To identify targetable determinants of peritoneal metastasis, we focused on appendiceal adenocarcinoma (AC), a gastrointestinal cancer that metastasizes almost exclusively to the peritoneum. Current treatments are extrapolated from colorectal cancer (CRC), yet AC has distinct genomic alterations, mucinous morphology and peritoneum restricted metastatic pattern.

Tumorigenesis Driven by BRAFV600E Requires Secondary Mutations that Overcome it's Feedback Inhibition of RAC1 and Migration.

BRAFV600E mutations occur in 46% of melanomas and drive high levels of ERK activity and ERK-dependent proliferation. However, BRAFV600E is insufficient to drive melanoma in genetically engineered mouse models, and 82% of human benign nevi harbor BRAFV600E mutations. We found that BRAFV600E inhibited mesenchymal migration by causing feedback inhibition of RAC1 activity.

Combined inhibition of KRAS and mTORC1 kinase is synergistic in non-small cell lung cancer.

Current KRAS (OFF) inhibitors that target inactive GDP-bound KRAS cause responses in less than half of patients and these responses are not durable. A class of RAS (ON) inhibitors that targets active GTP-bound KRAS blocks ERK signaling more potently than the inactive-state inhibitors. Sensitivity to either class of agents is strongly correlated with inhibition of mTORC1 activity.

Diet induced insulin resistance is due to induction of PTEN expression.

Type 2 Diabetes (T2D) is a condition that is often associated with obesity and defined by reduced sensitivity of PI3K signaling to insulin (insulin resistance), hyperinsulinemia and hyperglycemia. Molecular causes and early signaling events underlying insulin resistance are not well understood. Insulin activation of PI3K signaling causes mTOR dependent induction of PTEN translation, a negative regulator of PI3K signaling.

Tumor-Agnostic Genomic and Clinical Analysis of BRAF Fusions Identifies Actionable Targets.

Purpose: Even though BRAF fusions are increasingly detected in standard multigene next-generation sequencing panels, few reports have explored their structure and impact on clinical course.

Experimental Design: We collected data from patients with BRAF fusion-positive cancers identified through a genotyping protocol of 97,024 samples. Fusions were characterized and reviewed for oncogenic potential (in-frame status, non-BRAF partner gene, and intact BRAF kinase domain).

Intermittent MEK Inhibition with GITR Costimulation Rescues T-cell Function for Increased Efficacy with CTLA-4 Blockade in Solid Tumor Models.

MEK inhibitors (MEKi) have shown limited success as a treatment for MAPK/ERK pathway-dependent cancers due to various resistance mechanisms tumor cells can employ. CH5126766 (CKI27) is an inhibitor that binds to MEK and prevents release of RAF, reducing the relief of negative feedback commonly observed with other MEKis. We observed that CKI27 increased MHC expression in tumor cells and improved T cell-mediated killing.

eIF4A controls translation of estrogen receptor alpha and is a therapeutic target in advanced breast cancer.

The majority of human breast cancers are dependent on hormone-stimulated estrogen receptor alpha (ER) and are sensitive to its inhibition. Treatment resistance arises in most advanced cancers due to genetic alterations that promote ligand independent activation of ER itself or ER target genes. Whereas re-targeting of the ER ligand binding domain (LBD) with newer ER antagonists can work in some cases, these drugs are largely ineffective in many genetic backgrounds including ER fusions that lose the LBD or in cancers that hyperactivate ER targets.

Tumorigenesis driven by the BRAF oncoprotein requires secondary mutations that overcome its feedback inhibition of migration and invasion.

mutation occurs in 46% of melanomas and drives high levels of ERK activity and ERK-dependent proliferation. However, is insufficient to drive melanoma in GEMM models, and 82% of human benign nevi harbor mutations. We show here that BRAF inhibits mesenchymal migration by causing feedback inhibition of RAC1 activity.

BRAF - a tumour-agnostic drug target with lineage-specific dependencies.

In June 2022, the FDA granted Accelerated Approval to the BRAF inhibitor dabrafenib in combination with the MEK inhibitor trametinib for the treatment of adult and paediatric patients (≥6 years of age) with unresectable or metastatic BRAF-mutant solid tumours, except for BRAF-mutant colorectal cancers. The histology-agnostic approval of dabrafenib plus trametinib marks the culmination of two decades of research into the landscape of BRAF mutations in human cancers, the biochemical mechanisms underlying BRAF-mediated tumorigenesis, and the clinical development of selective RAF and MEK inhibitors. Although the majority of patients with BRAF-mutant tumours derive clinical benefit from BRAF inhibitor-based combinations, resistance to treatment develops in most.

Molecular Characterization of Acquired Resistance to KRASG12C-EGFR Inhibition in Colorectal Cancer.

Unlabelled: With the combination of KRASG12C and EGFR inhibitors, KRAS is becoming a druggable target in colorectal cancer. However, secondary resistance limits its efficacy. Using cell lines, patient-derived xenografts, and patient samples, we detected a heterogeneous pattern of putative resistance alterations expected primarily to prevent inhibition of ERK signaling by drugs at progression.

Impaired Proteolysis of Noncanonical RAS Proteins Drives Clonal Hematopoietic Transformation.

Unlabelled: Recently, screens for mediators of resistance to FLT3 and ABL kinase inhibitors in leukemia resulted in the discovery of LZTR1 as an adapter of a Cullin-3 RING E3 ubiquitin ligase complex responsible for the degradation of RAS GTPases. In parallel, dysregulated LZTR1 expression via aberrant splicing and mutations was identified in clonal hematopoietic conditions. Here we identify that loss of LZTR1, or leukemia-associated mutants in the LZTR1 substrate and RAS GTPase RIT1 that escape degradation, drives hematopoietic stem cell (HSC) expansion and leukemia in vivo.

Anatomic position determines oncogenic specificity in melanoma.

Oncogenic alterations to DNA are not transforming in all cellular contexts. This may be due to pre-existing transcriptional programmes in the cell of origin. Here we define anatomic position as a major determinant of why cells respond to specific oncogenes.

Targeted drug delivery strategies for precision medicines.

Progress in the field of precision medicine has changed the landscape of cancer therapy. Precision medicine is propelled by technologies that enable molecular profiling, genomic analysis, and optimized drug design to tailor treatments for individual patients. Although precision medicines have resulted in some clinical successes, the use of many potential therapeutics has been hindered by pharmacological issues, including toxicities and drug resistance.

HER2 + breast cancers evade anti-HER2 therapy via a switch in driver pathway.

Inhibition of HER2 in HER2-amplified breast cancer has been remarkably successful clinically, as demonstrated by the efficacy of HER-kinase inhibitors and HER2-antibody treatments. Whilst resistance to HER2 inhibition is common in the metastatic setting, the specific programs downstream of HER2 driving resistance are not established. Through genomic profiling of 733 HER2-amplified breast cancers, we identify enrichment of somatic alterations that promote MEK/ERK signaling in metastatic tumors with shortened progression-free survival on anti-HER2 therapy.

INK4 Tumor Suppressor Proteins Mediate Resistance to CDK4/6 Kinase Inhibitors.

Cyclin-dependent kinases 4 and 6 (CDK4/6) represent a major therapeutic vulnerability for breast cancer. The kinases are clinically targeted via ATP competitive inhibitors (CDK4/6i); however, drug resistance commonly emerges over time. To understand CDK4/6i resistance, we surveyed over 1,300 breast cancers and identified several genetic alterations (e.

Defining the therapeutic selective dependencies for distinct subtypes of PI3K pathway-altered prostate cancers.

Previous studies have suggested that PTEN loss is associated with p110β signaling dependency, leading to the clinical development of p110β-selective inhibitors. Here we use a panel pre-clinical models to reveal that PI3K isoform dependency is not governed by loss of PTEN and is impacted by feedback inhibition and concurrent PIK3CA/PIK3CB alterations. Furthermore, while pan-PI3K inhibition in PTEN-deficient tumors is efficacious, upregulation of Insulin Like Growth Factor 1 Receptor (IGF1R) promotes resistance.

Selective inhibitors of mTORC1 activate 4EBP1 and suppress tumor growth.

The clinical benefits of pan-mTOR active-site inhibitors are limited by toxicity and relief of feedback inhibition of receptor expression. To address these limitations, we designed a series of compounds that selectively inhibit mTORC1 and not mTORC2. These 'bi-steric inhibitors' comprise a rapamycin-like core moiety covalently linked to an mTOR active-site inhibitor.