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Simple Summary: Although gastrointestinal stromal tumor (GIST) is a relatively rare mesenchymal neoplasm of the digestive tract, molecular advancements in GISTs over the past two decades have caused a paradigm shift in the field of precision oncology. GISTs are mainly driven by activating mutations in the KIT or PDGFRA oncogenes, rendering them sensitive to targeted therapies. However, there is a significant lack of data from Kuwait that needs to be addressed. We carried out this retrospective analysis of a cohort of 200 GIST patients at the Kuwait Cancer Center to provide much-needed insights into the genetic makeup and clinicopathological characteristics of our population. We detailed the mutational spectrum in KIT and PDGFRA, identified a small subgroup of wild-type tumors, and shed some light on the clinical implications. This study opens the doors for potential larger-scale, multi-institutional outcome studies in the Arabian Gulf region. In gastrointestinal stromal tumors (GISTs), identifying prototypical mutations in the KIT/PDGFRA oncogenes, or in rare alternate genes, is essential for prognostication and predicting response to tyrosine kinase inhibitors. Conversely, wild-type GISTs (WT-GIST), which lack known mutations, have limited treatment options. Data on the mutational landscape of GISTs and their impact on disease progression are very limited in Kuwait. Using a targeted next-generation sequencing panel, we investigated the spectrum and frequency of KIT, PDGFRA, and RAS-pathway-related mutations in 95 out of 200 GISTs diagnosed at Kuwait Cancer Center from 2005 to 2023 and assessed their correlation with clinicopathological parameters. Among the 200 tumors (median age 55 years; 15–91), 54% originated in the stomach, 33% in the small bowel, 7% in the colorectum, 1.5% in the peritoneum, and 4.5% had an unknown primary site. Of the 95 molecularly profiled cases, 88% had a mutation: KIT (61%), PDGFRA (25%), NF1 (2%), and one NTRK1 rearrangement. Ten WT-GISTs were identified (stomach = 6, small bowel = 2, and colorectum = 2). WT-GISTs tended to be smaller (median 4.0 cm; 0.5–8.0) (p = 0.018), with mitosis ≤5/5 mm2, and were of lower risk (p = 0.019). KIT mutations were an adverse indicator of disease progression (p = 0.049), while wild-type status did not significantly impact progression (p = 0.934). The genetic landscape in this cohort mirrors that of global studies, but regional collaborations are needed to correlate outcomes with genetic variants. [ABSTRACT FROM AUTHOR]

Abstract Background The antibody targeting platelet-derived growth factor receptor alpha (PDGFRA), olaratumab, was approved in 2016 for metastatic soft tissue sarcoma (STS) in combination with doxorubicin based on promising results of a phase Ib/II trial by the Food and Drug Administration (FDA). However, recently the phase III ANNOUNCE trial could not confirm the additional value of olaratumab in this context. Methods Here, in a retrospective analysis we share our single-centre experience with olaratumab/doxorubicin in STS by including n = 32 patients treated with olaratumab/doxorubicin between 2016 and 2019. Results Median progression-free survival (PFS) in the overall cohort was 3.1 months (range 0.6–16.2). A response [complete remission (CR), partial remission (PR) or stable disease (SD)] was seen in n = 11 (34%) cases, whereas n = 21 (66%) patients showed progressive disease (PD). In n = 9 patients surgery was performed subsequently in an individual therapeutic approach. Out of n = 5 patients receiving additional regional hyperthermia, n = 3 achieved PR or SD. Conclusions This single-centre experience does also not support the promising phase Ib/II results for olaratumab/doxorubicin in STS. However, our findings do not preclude that olaratumab combination therapy could be valuable in a neoadjuvant setting. This warrants further exploration also taking into account the heterogeneous nature of STS.

Abstract Background Soft tissue sarcoma (STS) comprises a family of rare, heterogeneous tumors of mesenchymal origin. Single-agent doxorubicin remains the first-line standard-of-care treatment for advanced and inoperable STS, but response rates are only around 15%. In 2016, phase Ib/II clinical trial results reported an overall survival benefit of 11.8 months when combining doxorubicin and the platelet-derived growth factor receptor alpha (PDGFRA)-directed antibody olaratumab compared to doxorubicin alone, without providing a scientific rationale for such unprecedented therapeutic effect. We decided to evaluate the efficacy of olaratumab in a panel of STS patient-derived xenografts (PDX). Methods NMRI nu/nu mice were bilaterally transplanted with tumor tissue of patient-derived xenograft models expressing PDGFRA, including models of leiomyosarcoma (UZLX-STS22), malignant peripheral nerve sheath tumor (UZLX-STS39), myxofibrosarcoma (UZLX-STS59) and undifferentiated pleomorphic sarcoma (UZLX-STS84). Mice were randomly divided into four different treatment groups: (1) control, (2) doxorubicin (3 mg/kg once weekly), (3) anti-PDGFRA [olaratumab (60 mg/kg twice weekly) + mouse anti-PDGFRA antibody 1E10 (20 mg/kg twice weekly)] and (4) the combination of doxorubicin and anti-PDGFRA (same dose/schedule as in the single treatment arms). Tumor volume, histopathology and Western blotting were used to assess treatment efficacy. Results Anti-PDGFRA treatment as a single agent did not reduce tumor growth and did not result in significant anti-proliferative or pro-apoptotic activity. Combining doxorubicin and anti-PDGFRA did not reduce tumor burden, though a mild inhibition of proliferation was observed in UZLX-STS39 and -STS59. A pro-apoptotic effect was observed in all models except UZLX-STS22. Antitumor effects on histology were not significantly different comparing doxorubicin and the combination treatment. Moreover, anti-PDGFRA treatment, both as a single agent as well as combined with doxorubicin, did not result in inhibition of the downstream MAPK and PI3K/AKT signaling pathways. Conclusions We were not able to demonstrate significant antitumor effects of anti-PDGFRA treatment in selected STS PDX models, neither alone nor in combination with doxorubicin. This is in line with the very recent results of the phase III clinical trial NCT02451943 ANNOUNCE, which did not confirm the clinical benefit of olaratumab in combination with doxorubicin over single agent doxorubicin.

Background: The antibody targeting platelet-derived growth factor receptor alpha (PDGFRA), olaratumab, was approved in 2016 for metastatic soft tissue sarcoma (STS) in combination with doxorubicin based on promising results of a phase Ib/II trial by the Food and Drug Administration (FDA). However, recently the phase III ANNOUNCE trial could not confirm the additional value of olaratumab in this context.Methods: Here, in a retrospective analysis we share our single-centre experience with olaratumab/doxorubicin in STS by including n = 32 patients treated with olaratumab/doxorubicin between 2016 and 2019.Results: Median progression-free survival (PFS) in the overall cohort was 3.1 months (range 0.6-16.2). A response [complete remission (CR), partial remission (PR) or stable disease (SD)] was seen in n = 11 (34%) cases, whereas n = 21 (66%) patients showed progressive disease (PD). In n = 9 patients surgery was performed subsequently in an individual therapeutic approach. Out of n = 5 patients receiving additional regional hyperthermia, n = 3 achieved PR or SD.Conclusions: This single-centre experience does also not support the promising phase Ib/II results for olaratumab/doxorubicin in STS. However, our findings do not preclude that olaratumab combination therapy could be valuable in a neoadjuvant setting. This warrants further exploration also taking into account the heterogeneous nature of STS. [ABSTRACT FROM AUTHOR]

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract, arising from the interstitial cells of Cajal. They are known to occur in all parts of the gastrointestinal tract from the oesophagus to the anorectum, with the stomach being the most commonly affected organ (60%). GISTs are commonly known to occur within the fifth and sixth decades of life, carry an equal predisposition between females and males, and are associated with tyrosine-protein kinase (KIT) or platelet-derived growth factor receptor alpha (PDGFRA) mutations in 85–90% of cases. Familial syndromes associated with GISTs are neurofibromatosis Type 1, Carney’s triad (gastric GIST, pulmonary chordoma, and paraganglioma), Carney–Stratakis syndrome (GIST and paraganglioma), and familial GISTs. Lesions vary in size from a few mm to >30 cm, with a median size between 5 and 8 cm. Immunohistochemical staining with KIT and DOG1 show the highest sensitivity for GISTs. While 20% of GISTs are diagnosed asymptomatically, and 10% at autopsy, 70% are symptomatic. Bleeding followed by abdominal pain and a mass growth are the most common symptoms. Forty to fifty percent of GISTs are biologically malignant. Malignant GISTs spread haematogenously to the liver and peritoneum, while lymphatic spread is rare. Risk stratification subdivides GISTs into very low, low, intermediate, and high-risk groups. Computed tomography (CT) scan is the mainstay of diagnosis, though they are often incidentally detected on endoscopy. Surgery offers the best chance of cure in resectable lesions, while tyrosine kinase inhibitors are the treatment of choice in non-resectable and metastatic GISTs. Neoadjuvant and adjuvant tyrosine kinase inhibitors increase resectability, time to recurrence, recurrence-free survival, and overall survival in GISTs.

Background: The regulatory roles of human epidermal growth factor receptor [erb-b2 receptor tyrosine kinase 4 (ERBB)] family in tumors was received widespread attention. Although ERBB4 was crucial regulator in metastasis of malignant tumors, the exact mechanism of ERBB4 in inflammatory breast cancer (IBC) remains unclarified., Methods: In this study, we collected IBC tissues and cell lines, and explored the expression levels of ERBB4 and platelet-derived growth factor receptor alpha (PDGFRA) using real-time quantitative polymerase chain reaction (RT-PCR), immunohistochemistry (IHC) and western blot assays. Furthermore, cell viability with ERBB4 silencing in SUM149 cells was examined by MTT assay and cell migration and invasion were detected by transwell assay., Results: The data indicated thatERBB4abolishing dramatically depressed capacity of proliferation, migration and invasion of IBC cells. Moreover, PDGFRA was an important factor for the function of ERBB4 and PDGFRA overexpression could, at least, partly rescue the ERBB4 silencing-mediated inhibition in proliferation and metastasis of IBC cells., Conclusions: Take together, we verified the first time that ERBB4 promoted the progression of IBC through regulating PDGFRA. Thus, inhibition of ERBB4 might be a novel therapeutic candidate against IBC., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/tcr-19-2132). The authors have no conflicts of interest to declare., (2020 Translational Cancer Research. All rights reserved.)

Most gastrointestinal stromal tumors (GISTs) harbor activating mutations in the receptor tyrosine kinase gene KIT or platelet-derived growth factor receptor alpha ( PDGFRA ), and the resultant activation of downstream signals plays a pivotal role in the development of GISTs. The sites of the tyrosine kinase gene mutations are associated with the biological behavior of GISTs, including risk category, clinical outcome and drug response. Mutations in RAS signaling pathway genes, including KRAS and BRAF, have also been reported in KIT/PDGFRA wild-type GISTs, though they are rare. Neurofibromin 1 ( NF1 ) is a tumor suppressor gene mutated in neurofibromatosis type 1. Patients with NF1 mutations are at high risk of developing GISTs. Recent findings suggest that altered expression or mutation of members of succinate dehydrogenase (SDH) heterotetramer are causally associated with GIST development through induction of aberrant DNA methylation. At present, GISTs with no alterations in KIT, PDGFRA , RAS signaling genes or SDH family genes are referred to as true wild-type GISTs. KIT and PDGFRA mutations are thought as the earliest events in GIST development, and subsequent accumulation of chromosomal aberrations and other molecular alterations are required for malignant progression. In addition, recent studies have shown that epigenetic alterations and noncoding RNAs also play key roles in the pathogenesis of GISTs., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare.