Multiple Molecular Pathways Are Influenced by Progranulin in a Neuronal Cell Model–A Parallel Omics Approach

Progranulin (PGRN) is critical in supporting a healthy CNS. Its haploinsufficiency results in frontotemporal dementia, while in experimental models of age-related neurodegenerative diseases, the targeted expression of PGRN greatly slows the onset of disease phenotypes. Nevertheless, much remains unclear about how PGRN affects its target cells. In previous studies we found that PGRN showed a remarkable ability to support the survival of NSC-34 motor neuron cells under conditions that would otherwise lead to their apoptosis. Here we used the same model to investigate other phenotypes of PGRN expression in NSC-34 cells. PGRN significantly influenced morphological differentiation, resulting in cells with enlarged cell bodies and extended projections. At a molecular level this correlated with pathways associated with the cytoskeleton and synaptic differentiation. Depletion of PGRN led to increased expression of several neurotrophic receptors, which may represent a homeostatic mechanism to compensate for loss of neurotrophic support from PGRN. The exception was RET, a neurotrophic tyrosine receptor kinase, which, when PGRN levels are high, shows increased expression and enhanced tyrosine phosphorylation. Other receptor tyrosine kinases also showed higher tyrosine phosphorylation when PGRN was elevated, suggesting a generalized enhancement of receptor activity. PGRN was found to bind to multiple plasma membrane proteins, including RET, as well as proteins in the ER/Golgi apparatus/lysosome pathway. Understanding how these various pathways contribute to PGRN action may provide routes toward improving neuroprotective therapies.

Advances in Biomarker-Driven Targeted Therapies in Thyroid Cancer

Thyroid cancer is the most common type of endocrine malignancy comprising 2–3% of all cancers, with a constant rise in the incidence rate. The standard first-line treatments for thyroid cancer include surgery and radioactive iodine ablation, and a majority of patients show a good response to these therapies. Despite a better response and outcome, approximately twenty percent of patients develop disease recurrence and distant metastasis. With improved knowledge of molecular dysregulation and biological characteristics of thyroid cancer, the development of new treatment strategies comprising novel targets has accelerated. Biomarker-driven targeted therapies have now emerged as a trend for personalized treatments in patients with advanced cancers, and several multiple receptor kinase inhibitors have entered clinical trials (phase I/II/III) to evaluate their safety and efficacy. Most extensively investigated and clinically approved targeted therapies in thyroid cancer include the tyrosine receptor kinase inhibitors that target antiangiogenic markers, BRAF mutation, PI3K/AKT, and MAPK pathway components. In this review, we focus on the current advances in targeted mono- and combination therapies for various types of thyroid cancer.

Localized delivery of β-NGF via injectable microrods accelerates endochondral fracture repair

Currently, there are no biological approaches to accelerate bone fracture repair. Osteobiologics that promote endochondral ossification are an exciting alternative to surgically implanted bone grafts, however, the translation of osteobiologics remains elusive because of the need for localized and sustained delivery that is both safe and effective. In this regard, an injectable system composed of hydrogel-based microparticles designed to release osteobiologics in a controlled and localized manner is ideal in the context of bone fracture repair. Here, we describe poly (ethylene glycol) dimethacrylate (PEGDMA)-based microparticles, in the form of microrods, engineered to be loaded with beta nerve growth factor (β-NGF) for use in a murine tibial fracture model. In-vitro studies demonstrated that protein-loading efficiency is readily altered by varying PEGDMA macromer concentration and that β-NGF loaded onto PEGDMA microrods exhibited sustained release over a period of 7 days. In-vitro bioactivity of β-NGF was confirmed using a tyrosine receptor kinase A (Trk-A) expressing cell line, TF-1. Moreover, TF-1 cell proliferation significantly increased when incubated with β-NGF loaded PEGDMA microrods versus β-NGF in media. In-vivo studies show that PEGDMA microrods injected into the fracture calluses of mice remained in the callus for over 7 days. Importantly, a single injection of β-NGF-loaded PEGDMA microrods resulted in significantly improved fracture healing as indicated by significant increases in bone volume, trabecular connective density, and bone mineral density and a significant decrease in cartilage despite a remarkably lower dose (~111 fold) than the β-NGF in media. In conclusion, we demonstrate a novel and translational method of delivering β-NGF via injectable PEGDMA microrods to improve bone fracture repair.

BIOM-16. NTRK (NEUROTROPHIC TYROSINE RECEPTOR KINASE) FUSIONS IN GLIOMA PATIENTS: A PROMISING MOLECULAR TARGET?

BACKGROUND NTRK gene fusions are rare in gliomas (less than 2%). The use of TRK inhibitors in NTRK-fused solid tumors has generated significant clinical interest. It is likely that the unmet need for effective therapies in glioma will lead to routine testing for NTRK fusions. METHODS We performed a retrospective review of 22 patients with malignant gliomas accrued between 2007 and 2021. We collected tumor samples from those patients and NTRK fusions were tested using either immunohistochemistry or FISH or NGS. We then evaluated their association with clinical characteristics, histology and other markers (IDH1/2 mutation, MGMT methylation, BRAF mutation, EGFR expression, ATRX expression, TERT mutation). RESULTS Median age at diagnosis was 50 years. NTRK1 translocation was detected in 3 out of 22 patient tumors, while NTRK1 duplication was present in 1 patient (probably related to a translocation, but not proven). All NTRK1 translocations were not found in glioblastomas and their median survival was 15.8 months. On the other hand, median survival of gliomas without NTRK translocations was 11 months. In one NTRK1-translocated patient a TRK inhibitor (entrectinib) was used (for a few days), but we cannot evaluate its efficacy as the patient deteriorated and died. As far as the other biomarkers are concerned, 2 out of 3 NTRK1-translocated gliomas were MGMT methylated. CONCLUSION NTRK fusions are rare in gliomas, as confirmed in our small sample analysis. Although adult NTRK-fused gliomas are considered to predominantly involve high-grade histology, in our study all patients had initially lower grade gliomas. NTRK alterations can be detected by different laboratory assays, but each of these approaches has specific advantages and limitations and more data are needed in order to identify the best method. For glioblastomas, NTRK fusions and TRK inhibitors are potentially a new targeted therapeutic strategy but more data are needed.

An updated Review on Therapeutic Potential of Entrectinib as a Promising TrK, ROS 1, and ALK Inhibitor in Solid Tumors and Lung Cancer

Entrectinib is a selective inhibitor of tyrosine kinases , tropomyosin receptor kinases that targets oncogenic rearrangements in Neurotropic Tyrosine Receptor kinase, c-ros oncogene 1 and Anaplastic lymphoma kinase used for the treatment of various solid tumors. Entrectinib gained its first worldwide approval in Japan in June 2019 for the treatment of NTRK fusion-positive, advanced or recurring solid tumours in adults and children. In august 15, 2019 drug got FDA approval for the treatment of solid tumors in adult and children aged 12 and above. This article summarizes current status of Entrectinib from ongoing clinical trails and ideal place for drug in therapy.

Larotrectinib (Vitrakvi)

CADTH recommends that Vitrakvi be reimbursed by public drug plans for treating adult and pediatric patients with locally advanced or metastatic solid tumours who have a neurotrophic tyrosine receptor kinase (NTRK) gene fusion without a known acquired resistance mutation, or where surgical resection is likely to result in severe morbidity and have no satisfactory treatment options, but only if certain conditions are met. Vitrakvi should only be covered to treat patients with advanced solid tumours who have an NTRK gene fusion, who have previously failed on all standard treatments for their current tumour site, and who will be able to tolerate the treatment. Vitrakvi should only be reimbursed as single-agent therapy if it is prescribed by a clinician with expertise in the use of antineoplastic drugs and if the cost of Vitrakvi is reduced.

PU.1 and MYC transcriptional network defines synergistic drug responses to KIT and LSD1 inhibition in acute myeloid leukemia

Activating mutations in the KIT tyrosine receptor kinase confer an adverse prognosis for patients with acute myeloid leukemia (AML). Outside of bone marrow transplantation, treatment options are limited. Here we demonstrate combined KIT and LSD1 inhibition produces synergistic cell death against KIT mutant AML cells. This combination suppresses MYC expression to drive cell cycle exit and apoptosis. This decreased MYC expression results from a loss of PU.1 binding at downstream MYC enhancers. The drug combination also inactivates PI3K/AKT/GSK3a/b signaling to decrease MYC protein abundance. KIT-mutant AML cells rapidly adapt to KIT inhibitor monotherapy by restoring PI3K/AKT activity, but cannot when treated with combined KIT and LSD1 inhibitor. In addition, we validate MYC suppression as a mechanism of synergy in KIT-mutant AML patient samples. Collectively, this work provides rational for a clinical trial to assess the efficacy of KIT and LSD1 inhibition in patients with KIT-mutant AML.Statement of significanceEffective treatment options for AML are limited. We describe the synergistic response to combined KIT and LSD1 inhibition in KIT-mutant AML and identify key biomarkers of drug response. The specificity and efficacy of this combination in cell lines and patient samples provides rationale for investigation in early phase clinical trials.

The evolving role of precision medicine in the management of advanced sarcomas – A mini review

Sarcomas are a heterogenous group of cancers, traditionally with dismal outcomes. They were initially treated with histology agnostic chemotherapy-based regimens usually centered around anthracyclines. With the availability of molecular diagnostics especially next-generation sequencing, the advanced genomics of sarcomas was slowly unveiled. Precision medicine not only enables a better diagnosis in sarcomas but also allows in identifying better targets for treatment of sarcoma subtypes. GENSARC study proved that using correct molecular diagnostics, enabled in a better diagnosis and treatment of soft tissue sarcomas (STSs). Notable examples of targeted therapies with great success in sarcomas include imatinib and other tyrosine kinase inhibitors in gastrointestinal stromal tumors, neurotrophic tyrosine receptor kinase inhibitors infantile fibrosarcoma, and crizotinib in inflammatory myofibroblastic tumors. Thus, treatment of sarcomas has been gradually changing from traditional chemotherapy-based treatments to the modern targeted therapy. In this review, we hope to impress on the evolving role of precision medicine in sarcoma subtypes especially STS.