Contributions
Abstract: PB1893
Type: Publication Only
Background
The JAK-STAT pathway is involved in the transduction of signals mediated by cytokines, interferons and growth factors with consequent support of neoplastic cell growth and invasion in many types of cancer. Additional implications in inflammation and immunity in the tumor microenvironment have been recently recognized, because this pathway seems to sustain the stem cell maintenance. Moreover, persistent STAT3 activation would confer resistance to therapy with tyrosine kinase inhibitors in chronic myeloid leukemia (CML) by controlling the leukemia stem cell (LSC) self-renewal and favoring its hiding in the bone marrow niche (Groner, 2017). Inhibition of this pathway might represent a potential way to ameliorate the molecular response in warning or failed CML patients or to sustain deep responses in cases tempting the discontinuation of therapy.
Aims
Our purpose was the evaluation of some BCR/ABL1-independent molecular predictive markers of response in CML patients. Thus, we analyzed the expression of 86 genes belonging to the JAK-STAT pathway in 10 cases assessed at diagnosis and after 6 months of therapy with TKIs.
Methods
10 patients received TKIs as first-line treatment (7 imatinib, 2 nilotinib, 1 dasatinib). Concomitantly to the BCR/ABL1 transcript, we quantitated the expression level of 86 JAK-STAT genes by RT-qPCR (PrimePCR SYBR® Green assay, Biorad©, Milan, Italy) at baseline and after 6 months of therapy. Expression values were calculated by the Vandesompele method using four housekeeping genes.
Results
According to European Leukemia Network guidelines, after six months of treatment 9 patients were in optimal response and 1 was in failure, and the gene expression analysis showed a relevant deregulation of the pathway. Indeed, 79 genes resulted up-regulated, while only 7 were down-expressed. To evaluate a possible clinical role of the JAK-STAT pathway, we correlated the gene expression results with the achievement of MR3. At 6 months of treatment, we identified correlation of MR3 with up-regulation of LRG1 (p=0.030), a gene belonging to the leucine-rich repeat (LRR) family that is overexpressed during the granulocyte differentiation, and down-regulation of IL2RA (p=0.030) and MPL (p=0.029). IL2RA is involved in the LSC growth and MPL is linked to persistent activation of JAK-STAT. Moreover, the up-regulation in responsive patients also involved the immunity signaling linked to interferon (IFN) receptors complex, and induced interferon-related factors with anti-proliferative and pro-apoptotic effects, such as CSF1R, IRF1, IRF9, and ISG15. The increased expression of GATA3, SOCS3, JAK3 is involved in NK and T cell recruitment as immunology protection in responsive patients. Finally, in responsive cases we observed a significant up-regulation of: 1) OSM, involved in bone remodelling and reduction of fibrosis damaging the LSC survival in the niche and 2) IFN receptor type 1 that is usually expressed in stromal cells as a protection factor against cancer progression.
Conclusion
In this work, we demonstrated that the JAK-STAT pathway is really implicated in the resistance to TKIs and, on the other hand, that the de-regulation of some genes of this family might be related to the achievement of better molecular responses. This observation could have a practical clinical output, suggesting the effectiveness of the combination of JAK-STAT inhibitors (ruxolitinib or methotrexate) with TKIs in resistant CML patients.
Session topic: 7. Chronic myeloid leukemia – Biology & Translational Research
Keyword(s): Gene expression, STAT3, Tyrosine kinase inhibitor
Abstract: PB1893
Type: Publication Only
Background
The JAK-STAT pathway is involved in the transduction of signals mediated by cytokines, interferons and growth factors with consequent support of neoplastic cell growth and invasion in many types of cancer. Additional implications in inflammation and immunity in the tumor microenvironment have been recently recognized, because this pathway seems to sustain the stem cell maintenance. Moreover, persistent STAT3 activation would confer resistance to therapy with tyrosine kinase inhibitors in chronic myeloid leukemia (CML) by controlling the leukemia stem cell (LSC) self-renewal and favoring its hiding in the bone marrow niche (Groner, 2017). Inhibition of this pathway might represent a potential way to ameliorate the molecular response in warning or failed CML patients or to sustain deep responses in cases tempting the discontinuation of therapy.
Aims
Our purpose was the evaluation of some BCR/ABL1-independent molecular predictive markers of response in CML patients. Thus, we analyzed the expression of 86 genes belonging to the JAK-STAT pathway in 10 cases assessed at diagnosis and after 6 months of therapy with TKIs.
Methods
10 patients received TKIs as first-line treatment (7 imatinib, 2 nilotinib, 1 dasatinib). Concomitantly to the BCR/ABL1 transcript, we quantitated the expression level of 86 JAK-STAT genes by RT-qPCR (PrimePCR SYBR® Green assay, Biorad©, Milan, Italy) at baseline and after 6 months of therapy. Expression values were calculated by the Vandesompele method using four housekeeping genes.
Results
According to European Leukemia Network guidelines, after six months of treatment 9 patients were in optimal response and 1 was in failure, and the gene expression analysis showed a relevant deregulation of the pathway. Indeed, 79 genes resulted up-regulated, while only 7 were down-expressed. To evaluate a possible clinical role of the JAK-STAT pathway, we correlated the gene expression results with the achievement of MR3. At 6 months of treatment, we identified correlation of MR3 with up-regulation of LRG1 (p=0.030), a gene belonging to the leucine-rich repeat (LRR) family that is overexpressed during the granulocyte differentiation, and down-regulation of IL2RA (p=0.030) and MPL (p=0.029). IL2RA is involved in the LSC growth and MPL is linked to persistent activation of JAK-STAT. Moreover, the up-regulation in responsive patients also involved the immunity signaling linked to interferon (IFN) receptors complex, and induced interferon-related factors with anti-proliferative and pro-apoptotic effects, such as CSF1R, IRF1, IRF9, and ISG15. The increased expression of GATA3, SOCS3, JAK3 is involved in NK and T cell recruitment as immunology protection in responsive patients. Finally, in responsive cases we observed a significant up-regulation of: 1) OSM, involved in bone remodelling and reduction of fibrosis damaging the LSC survival in the niche and 2) IFN receptor type 1 that is usually expressed in stromal cells as a protection factor against cancer progression.
Conclusion
In this work, we demonstrated that the JAK-STAT pathway is really implicated in the resistance to TKIs and, on the other hand, that the de-regulation of some genes of this family might be related to the achievement of better molecular responses. This observation could have a practical clinical output, suggesting the effectiveness of the combination of JAK-STAT inhibitors (ruxolitinib or methotrexate) with TKIs in resistant CML patients.
Session topic: 7. Chronic myeloid leukemia – Biology & Translational Research
Keyword(s): Gene expression, STAT3, Tyrosine kinase inhibitor