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Updated: Oct 17, 2025
A Method for Screening and Validation of Resistant Mutations Against Kinase Inhibitors
Published on: December 7, 2014
Carfilzomib Enhances the Suppressive Effect of Ruxolitinib in Myelofibrosis
Simone Claudiani1, Clinton C Mason2, Dragana Milojkovic1
1Centre for Haematology, Department of Immunology and Inflammation, Imperial College, London W12 0NN, UK.
Abstract:
As the first FDA-approved tyrosine kinase inhibitor for treatment of patients with myelofibrosis (MF), ruxolitinib improves clinical symptoms but does not lead to eradication of the disease or significant reduction of the mutated allele burden. The resistance of MF clones against the suppressive action of ruxolitinib may be due to intrinsic or extrinsic mechanisms leading to activity of additional pro-survival genes or signalling pathways that function independently of JAK2/STAT5. To identify alternative therapeutic targets, we applied a pooled-shRNA library targeting ~5000 genes to a JAK2V617F-positive cell line under a variety of conditions, including absence or presence of ruxolitinib and in the presence of a bone marrow microenvironment-like culture medium. We identified several proteasomal gene family members as essential to HEL cell survival. The importance of these genes was validated in MF cells using the proteasomal inhibitor carfilzomib, which also enhanced lethality in combination with ruxolitinib. We also showed that proteasome gene expression is reduced by ruxolitinib in MF CD34+ cells and that additional targeting of proteasomal activity by carfilzomib enhances the inhibitory action of ruxolitinib in vitro. Hence, this study suggests a potential role for proteasome inhibitors in combination with ruxolitinib for management of MF patients.
Insights
Ruxolitinib helps myelofibrosis symptoms but doesn't eliminate the disease. Targeting proteasome genes with carfilzomib alongside ruxolitinib may improve treatment outcomes for myelofibrosis patients.
Area of Science:
- Hematology
- Oncology
- Molecular Biology
Background:
- Ruxolitinib is the first FDA-approved tyrosine kinase inhibitor for myelofibrosis (MF), improving symptoms but not eradicating the disease.
- MF clones can develop resistance to ruxolitinib through alternative pro-survival pathways independent of JAK2/STAT5 signaling.
- Identifying novel therapeutic targets is crucial for overcoming resistance and improving MF management.
Purpose of the Study:
- To identify alternative therapeutic targets for myelofibrosis by screening genes involved in cell survival.
- To investigate the role of proteasomal genes in MF cell survival and their interaction with ruxolitinib.
- To evaluate the efficacy of combining proteasome inhibitors with ruxolitinib in MF treatment.
Main Methods:
- Utilized a pooled shRNA library targeting approximately 5000 genes in a JAK2V617F-positive cell line under various conditions, including ruxolitinib treatment and bone marrow microenvironment mimicry.
- Validated the importance of identified proteasomal genes in MF cells using the proteasome inhibitor carfilzomib.
- Assessed proteasome gene expression in MF CD34+ cells treated with ruxolitinib and evaluated the combined effect of carfilzomib and ruxolitinib in vitro.
Main Results:
- Several proteasomal gene family members were identified as essential for HEL cell survival.
- Carfilzomib, a proteasome inhibitor, demonstrated enhanced lethality in combination with ruxolitinib in MF cells.
- Ruxolitinib treatment reduced proteasome gene expression in MF CD34+ cells, and carfilzomib addition potentiated ruxolitinib's inhibitory action.
Conclusions:
- Proteasome gene family members are critical for MF cell survival.
- Combining proteasome inhibitors like carfilzomib with ruxolitinib shows potential for enhanced efficacy in managing myelofibrosis.
- This study suggests a promising therapeutic strategy involving dual targeting of proteasomal activity and JAK/STAT signaling in MF patients.
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