Cholangiocellular carcinoma (CCA) is the second most common primary liver cancer, with increasing incidence worldwide and inadequate therapeutic options. Intra- and extrahepatic bile ducts have distinctly different embryonic origins and developmental behavior, and accordingly, intra- and extrahepatic CCAs (ICC vs. ECC) are molecularly different. A promising strategy in oncotherapy is targeted therapy, targeting proteins that regulate cell survival and proliferation, such as the MAPK/ERK and PI3K/AKT/mTOR signaling pathways. Inhibitors of these pathways have been tested previously in CCA cell lines. However, these cell lines could not be clearly assigned to ICC or ECC, and the results indicated apoptosis induction by targeted therapeutics. We tested targeted therapeutics (selumetinib, MK2206) in three defined ICC cell lines (HuH28, RBE, SSP25). We observed additive effects of the dual inhibition of the two pathways, in accordance with the inhibition of phospho-AKT and phospho-ERK1/2 expression. Proliferation was blocked more effectively with dual inhibition than with each single inhibition, but cell numbers did not drop below baseline. Accordingly, we observed G1 phase arrest but not apoptosis or cell death (measured by cleaved caspase-3, AIFM1 regulation, sub-G0/G1 phase). We conclude that the dual inhibition of the MAPK/ERK and PI3K/AKT/mTOR pathways is highly effective to block the proliferation of ICC cell lines in vitro; however, potential clinical applications must be critically examined, as a proliferation block could also induce resistance to standard therapies.

The RASopathies are a group of syndromes caused by genetic variants that affect the RAS-MAPK signaling pathway, which is essential for cell response to diverse stimuli. These variants functionally converge towards the overactivation of the pathway, leading to various constitutional and mosaic conditions. These syndromes show overlapping though distinct clinical presentations and share congenital heart defects, hypertrophic cardiomyopathy (HCM), and lymphatic dysplasia as major clinical features, with highly variable prevalence and severity. Available treatments have mainly been directed to target the symptoms. However, repurposing MEK inhibitors (MEKis), which were originally developed for cancer treatment, to target evolutive aspects occurring in these disorders is a promising option. Animal models have shown encouraging results in treating various RASopathy manifestations, including HCM and lymphatic abnormalities. Clinical reports have also provided first evidence supporting the effectiveness of MEKi, especially trametinib, in treating life-threatening conditions associated with these disorders. Nevertheless, despite notable improvements, there are adverse events that occur, necessitating careful monitoring. Moreover, there is evidence indicating that multiple pathways can contribute to these disorders, indicating a current need to more accurate understand of the underlying mechanism of the disease to apply an effective targeted therapy. In conclusion, while MEKi holds promise in managing life-threatening complications of RASopathies, dedicated clinical trials are required to establish standardized treatment protocols tailored to take into account the individual needs of each patient and favor a personalized treatment.

Neurofibromatosis Type 1 (NF1) is caused by loss of function variants in the NF1 gene. Most patients with NF1 develop skin lesions called cutaneous neurofibromas (cNFs). Currently the only approved therapeutic for NF1 is selumetinib, a mitogen -activated protein kinase (MEK) inhibitor. The purpose of this study was to analyze the transcriptome of cNF tumors before and on selumetinib treatment to understand both tumor composition and response. We obtained biopsy sets of tumors both pre- and on- selumetinib treatment from the same individuals and were able to collect sets from four separate individuals. We sequenced mRNA from 5844 nuclei and identified 30,442 genes in the untreated group and sequenced 5701 nuclei and identified 30,127 genes in the selumetinib treated group. We identified and quantified distinct populations of cells (Schwann cells, fibroblasts, pericytes, myeloid cells, melanocytes, keratinocytes, and two populations of endothelial cells). While we anticipated that cell proportions might change with treatment, we did not identify any one cell population that changed significantly, likely due to an inherent level of variability between tumors. We also evaluated differential gene expression based on drug treatment in each cell type. Ingenuity pathway analysis (IPA) was also used to identify pathways that differ on treatment. As anticipated, we identified a significant decrease in ERK/MAPK signaling in cells including Schwann cells but most specifically in myeloid cells. Interestingly, there is a significant decrease in opioid signaling in myeloid and endothelial cells; this downward trend is also observed in Schwann cells and fibroblasts. Cell communication was assessed by RNA velocity, Scriabin, and CellChat analyses which indicated that Schwann cells and fibroblasts have dramatically altered cell states defined by specific gene expression signatures following treatment (RNA velocity). There are dramatic changes in receptor-ligand pairs following treatment (Scriabin), and robust intercellular signaling between virtually all cell types associated with extracellular matrix (ECM) pathways (Collagen, Laminin, Fibronectin, and Nectin) is downregulated after treatment. These response specific gene signatures and interaction pathways could provide clues for understanding treatment outcomes or inform future therapies.

BACKGROUND: Colorectal cancer (CRC) is the third most malignant tumor in the world. 5-fluorouracil (5‑FU) -based chemotherapy is the first-line chemotherapy scheme for CRC, whereas acquired drug resistance poses a huge obstacle to curing CRC patients and the mechanism is still obscure. Therefore, identification of genes associated with 5‑FU chemotherapy and seeking second-line treatment are necessary means to improve survival and prognosis of patients with CRC.
METHODS: The Cancer Therapeutics Response Portal (CTRP) database and Genomics of Drug Sensitivity in Cancer (GDSC) database were used to identify CRC-related genes and potential second-line therapies for 5-FU-resistant CRC. The single-cell RNA sequencing data for CRC tissues were obtained from a GEO dataset. The relationship between ITGA2 and 5-FU-resistant was investigated in vitro and in vivo models.
RESULTS: ACOX1 and ITGA2 were identified as risk biomarkers associated with 5-FU-resistance. We developed a risk signature, consisting of ACOX1 and ITGA2, that was able to distinguish well between 5-FU-resistance and 5-FU-sensitive. The single-cell sequencing data showed that ITGA2 was mainly enriched in malignant cells. ITGA2 was negatively correlated with IC50 values of most small molecule inhibitors, of which selumetinib had the highest negative correlation. Finally, knocking down ITGA2 can make 5-FU-resistant CRC cells sensitive to 5-FU and combining with selumetinib can improve the therapeutic effect of 5-FU resistant cells.
CONCLUSIONS: In summary, our findings demonstrated the critical role of ITGA2 in enhancing chemotherapy resistance in CRC cells and suggested that selumetinib can restore the sensitivity of chemotherapy-resistant CRC cells to 5-FU by inhibiting ITGA2 expression.

UNASSIGNED: This summary describes a publication about a study called SPRINT. The SPRINT study included 50 children with neurofibromatosis type 1 (NF1) and plexiform neurofibroma (PN) that could not be removed with surgery. PNs are tumors that grow along nerves and can cause various problems for children, such as pain, changes to appearance, and muscle weakness. In SPRINT, the study team wanted to learn whether a medication called selumetinib was able to shrink the PN caused by NF1 (also known as NF1-related PN), and if shrinking PNs helped relieve children of the problems caused by it. To assess how selumetinib might help, children had scans to measure the size of their PN, completed questionnaires, and had a variety of other tests done by their doctor. Their caregivers also completed questionnaires about their child. The children took selumetinib capsules twice a day on an empty stomach.
UNASSIGNED: The results showed that selumetinib was able to shrink the PN for most children (68%). The results also showed that the problems caused by the children\'s PNs mostly improved while on selumetinib treatment. SPRINT also showed that the side effects of selumetinib were mainly mild and could be managed by doctors.
UNASSIGNED: Before SPRINT, there were not many treatment options for children with NF1 and PN as there were no medications that had been shown to shrink PN, and surgery was not always possible. SPRINT showed that this medication shrinks most PNs and could help children with NF1 and PN. In April 2020, selumetinib was approved by the US Food and Drug Administration (FDA) because of the results of SPRINT. Selumetinib was the first and, as of February 2024, is the only medicine that can be prescribed by doctors to help children with NF1-related PN. Clinical Trial Registration: NCT01362803 (SPRINT) (ClinicalTrials.gov).

Selumetinib is an oral, effective, and selective tyrosine kinase inhibitor targeting mitogen-activated protein kinase 1 and 2 (MEK1/2), which is clinically active in multiple tumor types, such as neurofibromatosis type 1 (NF1), melanoma, gliomas and non-small cell lung cancer (NSCLC). The purpose of this article was to assess the effects of selumetinib on the activities of twelve human UDP-glucosyltransferases (UGTs) including UGT1A1, 1A3, 1A4, 1A6, 1A7, 1A8, 1A9, 1A10, 2B4, 2B7, 2B15, and 2B17, and its potential for inducing clinical drug-drug interactions (DDIs). The results demonstrated that selumetinib potently inhibited the activity of UGT2B7 through the mechanism of mixed inhibition with the inhibition constant value of 5.79 ± 0.65 μM. Furthermore, the plasma concentration of UGT2B7 substrate as the co-administered drug was predicted to be increased by at least 84 % when patients took selumetinib 75 mg twice daily, suggesting a high potential to induce clinical DDIs. Selumetinib exhibited weak inhibitory effects on other human UGTs and was unlikely to trigger off UGTs-mediated DDIs except for UGT2B7. Therefore, the combination of selumetinib with the substrate drug of UGT2B7 requires additional attention to avoid adverse events in clinical treatment.

OBJECTIVE: Selumetinib is an FDA-approved targeted therapy for plexiform neurofibromas in neurofibromatosis type 1(NF1) with durable response rates seen in most, but not all patients. In this proof-of-concept study, we demonstrate single-cell RNA sequencing(scRNAseq) as a technique for quantifying drug response to selumetinib at the single cell level.
METHODS: scRNAseq data from neurofibroma biopsies was obtained from a public genomics repository. Schwann cell populations were identified through standard clustering techniques and single-cell selumetinib sensitivity was quantified on a scale of 0(resistant) to 1(sensitive) based on the expression pattern of a 500 gene selumetinib sensitivity signature from the BeyondCell sensitivity library.
RESULTS: A total of seven plexiform neurofibromas were included in our final analysis. The median absolute number of Schwann cells across samples was 658 cells (IQR: 1,029 cells, Q1-Q3: 135 cells to 1,163 cells). There was a statistically significant difference in selumetinib sensitivity profiles across samples (p < 0.001). The tumor with the highest median selumetinib sensitivity score had a median selumetinib sensitivity score of 0.64(IQR: 0.14, Q1-Q3: 0.59-0.70, n = 112 cells) and the tumor with the lowest median selumetinib sensitivity score had a median score of 0.37 (IQR: 0.21, Q1-Q3: 0.27-0.48, n = 1,034 cells).
CONCLUSIONS: scRNAseq of plexiform neurofibroma biopsies reveals differential susceptibilities to selumetinib on a single cell level. These findings may explain the partial responses seen in clinical trials of selumetinib for NF1 and demonstrate the value of collecting scRNAseq data for future NF1 trials.

UNASSIGNED: Selumetinib is approved for the treatment of pediatric patients with neurofibromatosis type 1 (NF1) who have symptomatic, inoperable plexiform neurofibromas (PN) in multiple countries, including the USA (≥ 2 years). Until recently, individuals had to take selumetinib twice daily (BID) in a fasted state. This study evaluated the effect of a low-fat meal on selumetinib PK parameters and gastrointestinal (GI) tolerability in adolescent participants with NF1-PN.
UNASSIGNED: Eligible participants aged ≥ 12 to < 18 years took 25 mg/m2 selumetinib BID with a low-fat meal (T1) for 28 days, followed by a 7-day washout, and then administration in a fasted state (T2) for another 28 days. Primary objectives were to evaluate the effect of a low-fat meal on AUC0-12,ss and GI tolerability after multiple selumetinib doses in T1 versus T2. Key secondary objectives were additional PK parameters and adverse events (AEs).
UNASSIGNED: At primary data cut-off, all 24 participants completed T1, and 23 participants completed T2. There were no significant differences in AUC0-12,ss between T1 and T2. In T1 and T2, 29.2% and 33.3% participants, respectively, reported ≥ 1 GI AE. No GI AEs Grade ≥ 3, or serious AEs, or GI AEs resulting in treatment interruptions, discontinuation, or dose reductions were reported in T1 and T2.
UNASSIGNED: Dosing selumetinib with a low-fat meal had no clinically relevant impact on selumetinib AUC0-12,ss nor GI tolerability in adolescents with NF1-PN.
UNASSIGNED: NCT05101148.

The binding of drugs to plasma proteins determines its fate within the physiological system, hence profound understanding of its interaction within the bloodstream is important to understand its pharmacodynamics and pharmacokinetics and thereby its therapeutic potential. In this regard, our work delineates the mechanism of interaction of Selumetinib (SEL), a potent anti-cancer drug showing excellent effect against multiple solid tumors, with plasma protein bovine serum albumin (BSA), using methods such as absorption, steady-state fluorescence, time-resolved, fluorescence resonance energy transfer, Fourier transform infrared spectra (FTIR), circular dichroism (CD), synchronous and 3D-fluorescence, salt fluorescence, molecular docking and molecular dynamic simulations. The BSA fluorescence intensity was quenched with increasing concentration of SEL which indicates interactions of SEL with BSA. Stern-Volmer quenching analysis and lifetime studies indicate the involvement of dynamic quenching. However, some contributions from the static quenching mechanism could not be ruled out unambiguously. The association constant was found to be 5.34 × 105 M-1 and it has a single binding site. The Förster distance (r) indicated probable energy transmission between the BSA and SEL. The positive entropy changes and enthalpy change indicate that the main interacting forces are hydrophobic forces, also evidenced by the results of molecular modeling studies. Conformation change in protein framework was revealed from FTIR, synchronous and 3D fluorescence and CD studies. Competitive binding experiments as well as docking studies suggest that SEL attaches itself to site I (subdomain IIA) of BSA where warfarin binds. Molecular dynamic simulations indicate the stability of the SEL-BSA complex. The association energy between BSA and SEL is affected in the presence of different metals differently.

Selumetinib is clinically used for pediatric patients with neurofibromatosis type 1 and symptomatic, inoperable plexiform neurofibromas. Until recently, selumetinib had to be taken twice daily, after 2 hours of fasting and followed by 1 hour of fasting, which could be inconvenient. This population analysis evaluated the effect of low- and high-fat meals on the pharmacokinetic (PK) parameters of selumetinib and its active metabolite N-desmethyl selumetinib. The dataset comprised 511 subjects from 15 clinical trials who received ≥1 dose of selumetinib and provided ≥1 measurable postdose concentration of selumetinib and N-desmethyl selumetinib. A 2-compartment model with sequential 0- and 1st-order delayed absorption and 1st-order elimination adequately described selumetinib PK characteristics. A 1-compartment model reasonably described N-desmethyl selumetinib PK characteristics over time simultaneously with selumetinib. Selumetinib geometric mean area under the concentration-time curve ratio (1-sided 90% confidence interval [CI] lower bound) was 76.9% (73.3%) with a low-fat meal and 79.3% (76.3%) with a high-fat meal versus fasting. The lower bound of the 1-sided 90% CI demonstrated a difference of <30% between fed and fasted states. Considering the flat exposure-response relationship within the dose range (20-30 mg/m2), the observed range of exposure, and the variability in the SPRINT trial, this was not considered clinically relevant.