Background. Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase, and its mutation, over-expression and gene fusion have been associated with various cancers. EML4-ALK fusion has been confirmed to be an oncogenic driver for a small subset of the lung cancers (∼4% of NSCLC)1, and becomes an excellent drug target that led to the development of the first effective therapy, crizotinib, a tyrosine kinase inhibitor for anaplastic lymphoma kinase, for this disease 2,3. However, like any other cancer therapy so far, the treatment always led to the development of resistance, rendering them ineffective in the end4. Understanding the mechanisms causing these resistances can potentially facilitate overcoming the resistance and extend patients' life5,6. However, lack of experimental model hinders this understanding.

Method. We have recently established a large collection of patient derived xenografts (∼350 PDXs)7, and we screened some of them for alk gene fusions. We then tested the positive model for sensitivity to crizothinib, and keep it under several rounds of crizotinib treatments to select resistant model. The induced resistant model was subjected to genomic analysis to identify the changes that might potentially be responsible for the resistance.

Results. We identified one model, NSCLC LU1656, containing EML4-ALK fusion with elevated ALK expression. It has also been shown to respond well to crizotinib in vivo. The continued treatment eventually led to the development of resistance to crizotinib (LU2445), a situation that might occur in patients in the clinic under the same treatment. We have performed transcriptome sequencing of the parental sensitive tumor (LU1656) and the selected resistant tumor (LU2445). So far, we found both models expressed similar high levels of expression of ALK, but no additional mutations in ALK gene. There are other alterations either genetically or epigenetically, some seemingly related to the ALK signaling pathways. However, their role in resistance still need to be confirmed.

Conclusions. Induced crizotinib resistance in ALK-fusion lung PDX can be useful to investigate crizotinib resistant mechanism and future drugs overcoming the resistance.

References

1. Koivunen, J.P., et al. EML4-ALK fusion gene and efficacy of an ALK kinase inhibitor in lung cancer. Clinical cancer research : an official journal of the American Association for Cancer Research 14, 4275-4283 (2008).

2. Kwak, E.L., et al. Anaplastic lymphoma kinase inhibition in non-small-cell lung cancer. N Engl J Med 363, 1693-1703 (2010).

3. Takeuchi, K., et al. RET, ROS1 and ALK fusions in lung cancer. Nature medicine 18, 378-381 (2012).

4. Katayama, R., et al. Mechanisms of acquired crizotinib resistance in ALK-rearranged lung Cancers. Science translational medicine 4, 120ra117 (2012).

5. Katayama, R., et al. Two novel ALK mutations mediate acquired resistance to the next-generation ALK inhibitor alectinib. Clinical cancer research : an official journal of the American Association for Cancer Research 20, 5686-5696 (2014).

6. Friboulet, L., et al. The ALK inhibitor ceritinib overcomes crizotinib resistance in non-small cell lung cancer. Cancer discovery 4, 662-673 (2014).

7. Yang, M., et al. Overcoming erlotinib resistance with tailored treatment regimen in patient-derived xenografts from naive Asian NSCLC patients. Int J Cancer 132, E74-84 (2013).

Citation Format: Jianyun Deng, Zhun Wang, Jie Cai, Sheng Guo, Jean-Pierre Wery, Henry Li. Induction of resistances to crizotinib in lung patient derived xenograft. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C82.