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Molecular modulators of cyclin-dependent kinase 4/6 inhibitor response in experimental glioma identified through
Surender Surender1,2,3, Lara Annina Haeusser1,2,3, Laurence Kuhlburger1,4,5
1Department of Neurology and Interdisciplinary Neuro-Oncology, Hertie Institute for Clinical Brain Research, University Hospital Tübingen, Eberhard Karls University, Tübingen, Germany.
Background:
Glioblastoma harbors frequent alterations in the retinoblastoma pathway, providing a genetic rationale for therapeutic targeting with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors. The NOA-20 trial did not reveal a progression-free survival benefit of CDK4/6 inhibition plus radiation therapy in newly diagnosed, O6-methylguanine DNA methyltransferase (MGMT)-unmethylated glioblastoma. In fact, CDK4/6 inhibitor monotherapy has not demonstrated efficacy in solid tumors. We aimed at discovering response modulators to CDK4/6 inhibition, paving the way for rational combination therapies.
Methods:
We conducted genome-wide CRISPR-Cas9 screens in human glioma cell lines and stem-like cells (LN229, LN18, LNZ308, T98G, and GS-9) under CDK4/6 inhibition, employing knockout (Brunello library) and activation strategies (Calabrese library), followed by genetic and pharmacological validation of selected candidate genes in vitro and ex vivo (primary cultures) as well as the investigation of 1 functionally instructed combination therapy in vivo.
Results:
Loss of AMBRA1 and gain of function of CCNE1 reduced sensitivity to CDK4/6 inhibition in glioma cells, whereas disruption of checkpoint kinase 1 (CHEK1) or FAM122A resulted in synthetic lethality in combination with CDK4/6 inhibition. AMBRA1-deficient glioma cells exhibited increased sensitivity to CHK1 inhibition, revealing a context-specific vulnerability. Combined inhibition of CHK1 and CDK4/6 led to synergistic antiglioma activity in vitro, ex vivo, and in vivo.
Conclusions:
Our data identify AMBRA1, CCNE1, CHEK1, and FAM122A as potential molecular modifiers of CDK4/6 inhibition response in experimental glioma and provide a biological rationale for combinatorial targeting with CDK4/6 inhibition in glioblastoma.
Insights
Targeting glioblastoma with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors shows promise. Combining CHK1 and CDK4/6 inhibition synergistically targets glioma, identifying key molecular modifiers for improved therapeutic strategies.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Glioblastoma (GBM) frequently exhibits alterations in the retinoblastoma (RB1) pathway, suggesting potential for targeting with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors.
- Previous trials showed limited benefit of CDK4/6 inhibitors plus radiation in newly diagnosed GBM, and monotherapy efficacy remains unproven in solid tumors.
- Identifying response modulators is crucial for developing effective combination therapies for glioblastoma.
Purpose of the Study:
- To discover molecular modulators that influence response to CDK4/6 inhibition in glioblastoma.
- To identify novel combination therapies for glioblastoma by understanding resistance mechanisms.
- To provide a biological rationale for combinatorial targeting strategies in glioblastoma treatment.
Main Methods:
- Genome-wide CRISPR-Cas9 screens (knockout and activation) were performed in human glioma cell lines and stem-like cells under CDK4/6 inhibition.
- Candidate genes were validated genetically and pharmacologically in vitro and ex vivo using primary cultures.
- A functionally-instructed combination therapy was investigated in vivo.
Main Results:
- Loss of AMBRA1 and gain of function of CCNE1 reduced sensitivity to CDK4/6 inhibition in glioma cells.
- Disruption of CHEK1 or FAM122A led to synthetic lethality when combined with CDK4/6 inhibition.
- Combined inhibition of CHK1 and CDK4/6 demonstrated synergistic anti-glioma activity across in vitro, ex vivo, and in vivo models.
Conclusions:
- AMBRA1, CCNE1, CHEK1, and FAM122A are identified as potential molecular modifiers of CDK4/6 inhibitor response in experimental glioma.
- AMBRA1 deficiency confers sensitivity to CHK1 inhibition, highlighting a context-specific vulnerability.
- Combined CHK1 and CDK4/6 inhibition presents a promising therapeutic strategy for glioblastoma.
