COMBINED SYK AND JAK INHIBITION BY CERDULATINIB INDUCES APOPTOSIS IN CLL AND OVERCOMES RESISTANCE TO IBRUTINIB
(Abstract release date: 05/19/16)
EHA Library. Wang L. 06/09/16; 132566; E1017
Prof. Lynn Wang
Contributions
Contributions
Abstract
Abstract: E1017
Type: Eposter Presentation
Background
Despite recent advances in the treatment of chronic lymphocytic leukemia, robust and durable complete responses enabling extended periods of time off-therapy are not achieved. One possible reason for this may be explained pre-clinically; agents like ibrutinib and idelalisib induce cell cycle arrest, but not apoptosis, in CLL cells treated in vitro. Consistently, when cells from ibrutinib-treated patients are analyzed, no significant apoptosis is seen even after 3 months of therapy. CLL tumor cells receive growth and survival signals from not only the BCR, but also a variety of cytokine receptors which primarily utilize Janus kinases (JAK) to initiate the signaling cascade, culminating in the upregulation of BCL2 family members and preventing apoptosis. We have therefore been exploring the utility of combining BCR pathway suppression via SYK with JAK/STAT pathway suppression using a novel small molecule inhibitor, cerdulatinib. Cerdulatinib is a selective and potent inhibitor of SYK, JAK1, JAK3, and TYK2, currently in a phase I dose escalation study in patients with B cell malignancies.
Aims
The aim of these studies was to determine the anti-tumor activity of cerdulatinib in primary CLL co-cultures as well as molecular correlates of response.
Methods
Using a repository of previously-banked viable CLL primary tumors (n=60), we evaluated cell death in the presence of cerdulatinib on stromal cell supported CLL cultures. Viability assays were performed by evaluating PARP cleavage and propidium iodide uptake. Western blotting or FACS analysis was used to determine cerdulatinib-impact on survival signaling networks and BCL2 family expression.
Results
In general, tumor specimens were sensitive to cerdulatinib, especially in cases with poor prognosis (e.g. mutation status, ZAP70 expression, cytogenetics). Importantly, sensitive tumor cells actually underwent apoptosis, which was not observed in direct comparisons with ibrutinib. The mechanism of apoptosis induction was demonstrated by western blotting to be cerdulatinib-induced down-regulation of MCL-1, which was associated with induction of tumor PARP cleavage. Apoptosis was induced by this agent irrespective of co-culture with known survival factors, including different stromal cell lines, or media supplementation with IL4, CD40 ligand, anti-IgM, or a combination of the three. Cerdulatinib anti-tumor activity significantly correlated with inhibition of pAKT S473 and pERK T202/Y204 within the tumor cells, and was associated with decreased BCR, JAK/STAT, and NF-kB pathway activation. Moreover, primary CLL samples resistant to ibrutinib remained sensitive to cerdulatinib.
Conclusion
The data suggest an alternate mechanism by which apoptosis may be induced in CLL, and provide a justification to continue clinical studies with cerdulatinb in this disease. Cerdulatinib has the potential to deliver a higher rate of complete responses in CLL, as well as provide another therapeutic option for patients who either did not respond to or relapsed on ibrutinib.
Session topic: E-poster
Type: Eposter Presentation
Background
Despite recent advances in the treatment of chronic lymphocytic leukemia, robust and durable complete responses enabling extended periods of time off-therapy are not achieved. One possible reason for this may be explained pre-clinically; agents like ibrutinib and idelalisib induce cell cycle arrest, but not apoptosis, in CLL cells treated in vitro. Consistently, when cells from ibrutinib-treated patients are analyzed, no significant apoptosis is seen even after 3 months of therapy. CLL tumor cells receive growth and survival signals from not only the BCR, but also a variety of cytokine receptors which primarily utilize Janus kinases (JAK) to initiate the signaling cascade, culminating in the upregulation of BCL2 family members and preventing apoptosis. We have therefore been exploring the utility of combining BCR pathway suppression via SYK with JAK/STAT pathway suppression using a novel small molecule inhibitor, cerdulatinib. Cerdulatinib is a selective and potent inhibitor of SYK, JAK1, JAK3, and TYK2, currently in a phase I dose escalation study in patients with B cell malignancies.
Aims
The aim of these studies was to determine the anti-tumor activity of cerdulatinib in primary CLL co-cultures as well as molecular correlates of response.
Methods
Using a repository of previously-banked viable CLL primary tumors (n=60), we evaluated cell death in the presence of cerdulatinib on stromal cell supported CLL cultures. Viability assays were performed by evaluating PARP cleavage and propidium iodide uptake. Western blotting or FACS analysis was used to determine cerdulatinib-impact on survival signaling networks and BCL2 family expression.
Results
In general, tumor specimens were sensitive to cerdulatinib, especially in cases with poor prognosis (e.g. mutation status, ZAP70 expression, cytogenetics). Importantly, sensitive tumor cells actually underwent apoptosis, which was not observed in direct comparisons with ibrutinib. The mechanism of apoptosis induction was demonstrated by western blotting to be cerdulatinib-induced down-regulation of MCL-1, which was associated with induction of tumor PARP cleavage. Apoptosis was induced by this agent irrespective of co-culture with known survival factors, including different stromal cell lines, or media supplementation with IL4, CD40 ligand, anti-IgM, or a combination of the three. Cerdulatinib anti-tumor activity significantly correlated with inhibition of pAKT S473 and pERK T202/Y204 within the tumor cells, and was associated with decreased BCR, JAK/STAT, and NF-kB pathway activation. Moreover, primary CLL samples resistant to ibrutinib remained sensitive to cerdulatinib.
Conclusion
The data suggest an alternate mechanism by which apoptosis may be induced in CLL, and provide a justification to continue clinical studies with cerdulatinb in this disease. Cerdulatinib has the potential to deliver a higher rate of complete responses in CLL, as well as provide another therapeutic option for patients who either did not respond to or relapsed on ibrutinib.
Session topic: E-poster
Abstract: E1017
Type: Eposter Presentation
Background
Despite recent advances in the treatment of chronic lymphocytic leukemia, robust and durable complete responses enabling extended periods of time off-therapy are not achieved. One possible reason for this may be explained pre-clinically; agents like ibrutinib and idelalisib induce cell cycle arrest, but not apoptosis, in CLL cells treated in vitro. Consistently, when cells from ibrutinib-treated patients are analyzed, no significant apoptosis is seen even after 3 months of therapy. CLL tumor cells receive growth and survival signals from not only the BCR, but also a variety of cytokine receptors which primarily utilize Janus kinases (JAK) to initiate the signaling cascade, culminating in the upregulation of BCL2 family members and preventing apoptosis. We have therefore been exploring the utility of combining BCR pathway suppression via SYK with JAK/STAT pathway suppression using a novel small molecule inhibitor, cerdulatinib. Cerdulatinib is a selective and potent inhibitor of SYK, JAK1, JAK3, and TYK2, currently in a phase I dose escalation study in patients with B cell malignancies.
Aims
The aim of these studies was to determine the anti-tumor activity of cerdulatinib in primary CLL co-cultures as well as molecular correlates of response.
Methods
Using a repository of previously-banked viable CLL primary tumors (n=60), we evaluated cell death in the presence of cerdulatinib on stromal cell supported CLL cultures. Viability assays were performed by evaluating PARP cleavage and propidium iodide uptake. Western blotting or FACS analysis was used to determine cerdulatinib-impact on survival signaling networks and BCL2 family expression.
Results
In general, tumor specimens were sensitive to cerdulatinib, especially in cases with poor prognosis (e.g. mutation status, ZAP70 expression, cytogenetics). Importantly, sensitive tumor cells actually underwent apoptosis, which was not observed in direct comparisons with ibrutinib. The mechanism of apoptosis induction was demonstrated by western blotting to be cerdulatinib-induced down-regulation of MCL-1, which was associated with induction of tumor PARP cleavage. Apoptosis was induced by this agent irrespective of co-culture with known survival factors, including different stromal cell lines, or media supplementation with IL4, CD40 ligand, anti-IgM, or a combination of the three. Cerdulatinib anti-tumor activity significantly correlated with inhibition of pAKT S473 and pERK T202/Y204 within the tumor cells, and was associated with decreased BCR, JAK/STAT, and NF-kB pathway activation. Moreover, primary CLL samples resistant to ibrutinib remained sensitive to cerdulatinib.
Conclusion
The data suggest an alternate mechanism by which apoptosis may be induced in CLL, and provide a justification to continue clinical studies with cerdulatinb in this disease. Cerdulatinib has the potential to deliver a higher rate of complete responses in CLL, as well as provide another therapeutic option for patients who either did not respond to or relapsed on ibrutinib.
Session topic: E-poster
Type: Eposter Presentation
Background
Despite recent advances in the treatment of chronic lymphocytic leukemia, robust and durable complete responses enabling extended periods of time off-therapy are not achieved. One possible reason for this may be explained pre-clinically; agents like ibrutinib and idelalisib induce cell cycle arrest, but not apoptosis, in CLL cells treated in vitro. Consistently, when cells from ibrutinib-treated patients are analyzed, no significant apoptosis is seen even after 3 months of therapy. CLL tumor cells receive growth and survival signals from not only the BCR, but also a variety of cytokine receptors which primarily utilize Janus kinases (JAK) to initiate the signaling cascade, culminating in the upregulation of BCL2 family members and preventing apoptosis. We have therefore been exploring the utility of combining BCR pathway suppression via SYK with JAK/STAT pathway suppression using a novel small molecule inhibitor, cerdulatinib. Cerdulatinib is a selective and potent inhibitor of SYK, JAK1, JAK3, and TYK2, currently in a phase I dose escalation study in patients with B cell malignancies.
Aims
The aim of these studies was to determine the anti-tumor activity of cerdulatinib in primary CLL co-cultures as well as molecular correlates of response.
Methods
Using a repository of previously-banked viable CLL primary tumors (n=60), we evaluated cell death in the presence of cerdulatinib on stromal cell supported CLL cultures. Viability assays were performed by evaluating PARP cleavage and propidium iodide uptake. Western blotting or FACS analysis was used to determine cerdulatinib-impact on survival signaling networks and BCL2 family expression.
Results
In general, tumor specimens were sensitive to cerdulatinib, especially in cases with poor prognosis (e.g. mutation status, ZAP70 expression, cytogenetics). Importantly, sensitive tumor cells actually underwent apoptosis, which was not observed in direct comparisons with ibrutinib. The mechanism of apoptosis induction was demonstrated by western blotting to be cerdulatinib-induced down-regulation of MCL-1, which was associated with induction of tumor PARP cleavage. Apoptosis was induced by this agent irrespective of co-culture with known survival factors, including different stromal cell lines, or media supplementation with IL4, CD40 ligand, anti-IgM, or a combination of the three. Cerdulatinib anti-tumor activity significantly correlated with inhibition of pAKT S473 and pERK T202/Y204 within the tumor cells, and was associated with decreased BCR, JAK/STAT, and NF-kB pathway activation. Moreover, primary CLL samples resistant to ibrutinib remained sensitive to cerdulatinib.
Conclusion
The data suggest an alternate mechanism by which apoptosis may be induced in CLL, and provide a justification to continue clinical studies with cerdulatinb in this disease. Cerdulatinib has the potential to deliver a higher rate of complete responses in CLL, as well as provide another therapeutic option for patients who either did not respond to or relapsed on ibrutinib.
Session topic: E-poster
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