JAK/STAT pathway directed therapy of T-cell leukemia/lymphoma: Inspired by functional and structural genomics

Area of Science:

• Oncology
• Molecular Biology
• Immunology

Background:

• The JAK/STAT signaling pathway, particularly involving the common gamma chain (γc) cytokine receptor, is frequently aberrantly activated in T-cell malignancies.
• STAT3 and STAT5b phosphorylation are key indicators of this abnormal activation, observed in a subset of T-cell cancers.

Purpose of the Study:

• To investigate the role of JAK/STAT pathway activation in T-cell malignancies.
• To explore the therapeutic potential of targeting the JAK/STAT pathway and its downstream effectors.

Main Methods:

• Analysis of STAT3/STAT5b and JAK1/3 mutations in T-cell malignancies.
• shRNA-mediated knockdown to assess dependency on JAK/STAT signaling in malignant T-cell lines.
• Evaluation of the combination therapy using a JAK1/2 inhibitor and navitoclax (Bcl-xL inhibitor) in cell lines and a mouse model.

Main Results:

• Constitutive JAK/STAT pathway activation was observed in T-cell malignancies, with or without specific mutations in STAT3/STAT5b or JAK1/3.
• Malignant T-cells demonstrated addiction to JAK/STAT signaling, irrespective of mutations.
• Activating JAK/STAT mutations augmented signaling but were insufficient for proliferation alone; functional cytokine receptors were essential for pSTAT expression.
• Combination therapy with a JAK1/2 inhibitor and navitoclax exhibited additive/synergistic effects in IL-2 dependent ATLL cell lines and a relevant mouse model.

Conclusions:

• Aberrant activation of the γc cytokine JAK/STAT pathway is a common feature across various T-cell malignancies.
• Targeting the JAK/STAT pathway, potentially in combination with other agents like Bcl-xL inhibitors, represents a promising therapeutic strategy for T-cell malignancies.