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DIPG Harbors Alterations Targetable by MEK Inhibitors, with Acquired Resistance Mechanisms Overcome by Combinatorial Inhibition.

ABSTRACT: The survival of children with diffuse intrinsic pontine glioma (DIPG) remains dismal, with new treatments desperately needed. In a prospective biopsy-stratified clinical trial, we combined detailed molecular profiling and drug screening in newly established patient-derived models in vitro and in vivo. We identified in vitro sensitivity to MEK inhibitors in DIPGs harboring MAPK pathway alterations, but treatment of patient-derived xenograft models and a patient at relapse failed to elicit a significant response. We generated trametinib-resistant clones in a BRAFG469V model through continuous drug exposure and identified acquired mutations in MEK1/2 with sustained pathway upregulation. These cells showed hallmarks of mesenchymal transition and expression signatures overlapping with inherently trametinib-insensitive patient-derived cells, predicting sensitivity to dasatinib. Combined trametinib and dasatinib showed highly synergistic effects in vitro and on ex vivo brain slices. We highlight the MAPK pathway as a therapeutic target in DIPG and show the importance of parallel resistance modeling and combinatorial treatments for meaningful clinical translation.

Significance

We report alterations in the MAPK pathway in DIPGs to confer initial sensitivity to targeted MEK inhibition. We further identify for the first time the mechanism of resistance to single-agent targeted therapy in these tumors and suggest a novel combinatorial treatment strategy to overcome it in the clinic. This article is highlighted in the In This Issue feature, p. 587.

SUBMITTER: Izquierdo E

PROVIDER: S-EPMC7612484 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature

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DIPG Harbors Alterations Targetable by MEK Inhibitors, with Acquired Resistance Mechanisms Overcome by Combinatorial Inhibition.

Izquierdo Elisa E Carvalho Diana M DM Mackay Alan A Temelso Sara S Boult Jessica K R JKR Pericoli Giulia G Fernandez Elisabet E Das Molina M Molinari Valeria V Grabovska Yura Y Rogers Rebecca F RF Ajmone-Cat Maria Antonietta MA Proszek Paula Z PZ Stubbs Mark M Depani Sarita S O'Hare Patricia P Yu Lu L Roumelioti Georgia G Choudhary Jyoti S JS Clarke Matthew M Fairchild Amy R AR Jacques Thomas S TS Grundy Richard G RG Howell Lisa L Picton Susan S Adamski Jenny J Wilson Shaun S Gray Juliet C JC Zebian Bassel B Marshall Lynley V LV Carceller Fernando F Grill Jacques J Vinci Maria M Robinson Simon P SP Hubank Michael M Hargrave Darren D Jones Chris C

Cancer discovery 20220301 3

The survival of children with diffuse intrinsic pontine glioma (DIPG) remains dismal, with new treatments desperately needed. In a prospective biopsy-stratified clinical trial, we combined detailed molecular profiling and drug screening in newly established patient-derived models in vitro and in vivo. We identified in vitro sensitivity to MEK inhibitors in DIPGs harboring MAPK pathway alterations, but treatment of patient-derived xenograft models and a patient at relapse failed to elicit a signi ...[more]

PMID: 34737188

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Project description:BackgroundThyroid carcinoma, which is rare in pediatric patients (age 0-18 years) but more common in adolescent and young adult (AYA) patients (age 15-39 years), carries the potential for morbidity and mortality.MethodsHybrid-capture-based comprehensive genomic profiling (CGP) was performed prospectively on 512 consecutively submitted thyroid carcinomas, including 58 from pediatric and AYA (PAYA) patients, to identify genomic alterations (GAs), including base substitutions, insertions/deletions, copy number alterations, and rearrangements. This PAYA data series includes 41 patients with papillary thyroid carcinoma (PTC), 3 with anaplastic thyroid carcinoma (ATC), and 14 with medullary thyroid carcinoma (MTC).ResultsGAs were detected in 93% (54/58) of PAYA cases, with a mean of 1.4 GAs per case. In addition to BRAF V600E mutations, detected in 46% (19/41) of PAYA PTC cases and in 1 of 3 AYA ATC cases, oncogenic fusions involving RET, NTRK1, NTRK3, and ALK were detected in 37% (15/41) of PAYA PTC and 33% (1/3) of AYA ATC cases. Ninety-three percent (13/14) of MTC patients harbored RET alterations, including 3 novel insertions/deletions in exons 6 and 11. Two of these MTC patients with novel alterations in RET experienced clinical benefit from vandetanib treatment.ConclusionCGP identified diverse clinically relevant GAs in PAYA patients with thyroid carcinoma, including 83% (34/41) of PTC cases harboring activating kinase mutations or activating kinase rearrangements. These genomic observations and index cases exhibiting clinical benefit from targeted therapy suggest that young patients with advanced thyroid carcinoma can benefit from CGP and rationally matched targeted therapy. The Oncologist 2017;22:255-263 IMPLICATIONS FOR PRACTICE: The detection of diverse clinically relevant genomic alterations in the majority of pediatric, adolescent, and young adult patients with thyroid carcinoma in this study suggests that comprehensive genomic profiling may be beneficial for young patients with papillary, anaplastic, or medullary thyroid carcinoma, particularly for advanced or refractory cases for which clinical trials involving molecularly targeted therapies may be appropriate.

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DIPG Harbors Alterations Targetable by MEK Inhibitors, with Acquired Resistance Mechanisms Overcome by Combinatorial Inhibition.

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Publications

DIPG Harbors Alterations Targetable by MEK Inhibitors, with Acquired Resistance Mechanisms Overcome by Combinatorial Inhibition.

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