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Nilotinib treatment in mouse models of P190 Bcr/Abl lymphoblastic leukemia.

Kaur P, Feldhahn N, Zhang B, Trageser D, Müschen M, Pertz V, Groffen J, Heisterkamp N - Mol. Cancer (2007)

Bottom Line: In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out.Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced.These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Molecular Carcinogenesis, Division of Hematology/Oncology, Saban Research Institute, Childrens Hospital Los Angeles and the Keck School of Medicine, University of Southern California, Los Angeles, California, USA. pavinder@gmail.com

ABSTRACT

Background: Ph-positive leukemias are caused by the aberrant fusion of the BCR and ABL genes. Nilotinib is a selective Bcr/Abl tyrosine kinase inhibitor related to imatinib, which is widely used to treat chronic myelogenous leukemia. Because Ph-positive acute lymphoblastic leukemia only responds transiently to imatinib therapy, we have used mouse models to test the efficacy of nilotinib against lymphoblastic leukemia caused by the P190 form of Bcr/Abl.

Results: After transplant of 10,000 highly malignant leukemic cells into compatible recipients, untreated mice succumbed to leukemia within 21 days, whereas mice treated with 75 mg/kg nilotinib survived significantly longer. We examined cells from mice that developed leukemia while under treatment for Bcr/Abl kinase domain point mutations but these were not detected. In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out. Nilotinib also exhibited impressive anti-leukemia activity in P190 Bcr/Abl transgenic mice that had developed overt leukemia/lymphoma masses and that otherwise would have been expected to die within 7 days. Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced. Treated mice survived more than 30 days.

Conclusion: These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

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Related in: MedlinePlus

Long term viability of three lymphoma cell lines 8093, A-5 and A-21 treated with 20 nM nilotinib either in the presence (A) or absence (B)of irradiated stroma (mouse E14.5 embryonic fibroblasts). 3 × 106 lymphoma cells were seeded in 6 well tissue culture plates and treated with 20 nM nilotinib. Fresh drug was added every third day with the change of medium. Viability was assessed by the Trypan Blue exclusion method and is expressed as percentage of viable cells/total cells. Each point represents the average of triplicate values ± SEM.
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Figure 5: Long term viability of three lymphoma cell lines 8093, A-5 and A-21 treated with 20 nM nilotinib either in the presence (A) or absence (B)of irradiated stroma (mouse E14.5 embryonic fibroblasts). 3 × 106 lymphoma cells were seeded in 6 well tissue culture plates and treated with 20 nM nilotinib. Fresh drug was added every third day with the change of medium. Viability was assessed by the Trypan Blue exclusion method and is expressed as percentage of viable cells/total cells. Each point represents the average of triplicate values ± SEM.

Mentions: To investigate whether the cells isolated from the nilotinib-treated mice, A-5 and A-21 had any other cell-inherent mechanism of resistance against nilotinib therapy, we evaluated their in vitro ability to proliferate in the presence of nilotinib. Interestingly, we did not observe any difference in the sensitivity of A-5 and A-21 towards nilotinib as compared to 8093 (Fig. 5). We assessed the viability of the three cell lines during treatment with 20 nM nilotinib both in the presence and absence of stromal support (consisting of a layer of mitotically inactivated mouse embryonic fibroblasts). All three cell lines behaved very similarly: their viability dropped to less than 20% within 48 hours of 20 nM nilotinib treatment. However, we obtained very different results in long-term cultures between cells cultured with and without stroma. Their viability without stroma in the presence of 20 nM nilotinib progressively declined over the course of 3–4 days. By the sixth day, viability was reduced to zero (Fig. 5B). In contrast, though the three cell lines cultured in the presence of irradiated stroma experienced a drastic drop in viability for the initial 4–5 days of treatment, the viability started to improve by the sixth day of treatment. All three cell lines recovered and had a viability of >60% on tenth day of treatment (Fig. 5A). Thus the cells that were obtained after the initial drop in viability were able to proliferate and maintain good viability in the presence of 20 nM nilotinib in vitro.


Nilotinib treatment in mouse models of P190 Bcr/Abl lymphoblastic leukemia.

Kaur P, Feldhahn N, Zhang B, Trageser D, Müschen M, Pertz V, Groffen J, Heisterkamp N - Mol. Cancer (2007)

Long term viability of three lymphoma cell lines 8093, A-5 and A-21 treated with 20 nM nilotinib either in the presence (A) or absence (B)of irradiated stroma (mouse E14.5 embryonic fibroblasts). 3 × 106 lymphoma cells were seeded in 6 well tissue culture plates and treated with 20 nM nilotinib. Fresh drug was added every third day with the change of medium. Viability was assessed by the Trypan Blue exclusion method and is expressed as percentage of viable cells/total cells. Each point represents the average of triplicate values ± SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2169263&req=5

Figure 5: Long term viability of three lymphoma cell lines 8093, A-5 and A-21 treated with 20 nM nilotinib either in the presence (A) or absence (B)of irradiated stroma (mouse E14.5 embryonic fibroblasts). 3 × 106 lymphoma cells were seeded in 6 well tissue culture plates and treated with 20 nM nilotinib. Fresh drug was added every third day with the change of medium. Viability was assessed by the Trypan Blue exclusion method and is expressed as percentage of viable cells/total cells. Each point represents the average of triplicate values ± SEM.
Mentions: To investigate whether the cells isolated from the nilotinib-treated mice, A-5 and A-21 had any other cell-inherent mechanism of resistance against nilotinib therapy, we evaluated their in vitro ability to proliferate in the presence of nilotinib. Interestingly, we did not observe any difference in the sensitivity of A-5 and A-21 towards nilotinib as compared to 8093 (Fig. 5). We assessed the viability of the three cell lines during treatment with 20 nM nilotinib both in the presence and absence of stromal support (consisting of a layer of mitotically inactivated mouse embryonic fibroblasts). All three cell lines behaved very similarly: their viability dropped to less than 20% within 48 hours of 20 nM nilotinib treatment. However, we obtained very different results in long-term cultures between cells cultured with and without stroma. Their viability without stroma in the presence of 20 nM nilotinib progressively declined over the course of 3–4 days. By the sixth day, viability was reduced to zero (Fig. 5B). In contrast, though the three cell lines cultured in the presence of irradiated stroma experienced a drastic drop in viability for the initial 4–5 days of treatment, the viability started to improve by the sixth day of treatment. All three cell lines recovered and had a viability of >60% on tenth day of treatment (Fig. 5A). Thus the cells that were obtained after the initial drop in viability were able to proliferate and maintain good viability in the presence of 20 nM nilotinib in vitro.

Bottom Line: In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out.Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced.These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Molecular Carcinogenesis, Division of Hematology/Oncology, Saban Research Institute, Childrens Hospital Los Angeles and the Keck School of Medicine, University of Southern California, Los Angeles, California, USA. pavinder@gmail.com

ABSTRACT

Background: Ph-positive leukemias are caused by the aberrant fusion of the BCR and ABL genes. Nilotinib is a selective Bcr/Abl tyrosine kinase inhibitor related to imatinib, which is widely used to treat chronic myelogenous leukemia. Because Ph-positive acute lymphoblastic leukemia only responds transiently to imatinib therapy, we have used mouse models to test the efficacy of nilotinib against lymphoblastic leukemia caused by the P190 form of Bcr/Abl.

Results: After transplant of 10,000 highly malignant leukemic cells into compatible recipients, untreated mice succumbed to leukemia within 21 days, whereas mice treated with 75 mg/kg nilotinib survived significantly longer. We examined cells from mice that developed leukemia while under treatment for Bcr/Abl kinase domain point mutations but these were not detected. In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out. Nilotinib also exhibited impressive anti-leukemia activity in P190 Bcr/Abl transgenic mice that had developed overt leukemia/lymphoma masses and that otherwise would have been expected to die within 7 days. Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced. Treated mice survived more than 30 days.

Conclusion: These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

Show MeSH
Related in: MedlinePlus