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MTE01 - Preclinical Models of Lung Cancer (Ticketed Session) (ID 811)
- Event: WCLC 2018
- Type: Meet the Expert Session
- Track: Biology
- Presentations: 1
- Now Available
- Coordinates: 9/24/2018, 07:00 - 08:00, Room 206 F
MTE01.02 - Lung Patient Derived Xenograft and Organoid (Now Available) (ID 11547)
07:30 - 08:00 | Author(s): Quan Li
Establishment of preclinical lung cancer models that closely match patient tumor biology is imperative for developing therapeutic strategies with the most translational relevance. Non small cell lung cancer (NSCLC) cell lines grown under 2D conditions or as cell line-derived xenografts (CDXs) are the most widely used models. They have been complemented with murine models engineered to develop lung cancer after introduction of specific genetic alterations (GEMMs). Lung cancer cell lines are readily amenable to mechanistic studies and economical high-throughput drug screening. However, for many NSCLC cell lines, the spectrum of mutations and copy number alterations have drifted considerably relative to patient tumors 1. This finding, in conjunction with long-term adaption to heterologous in vitro growth conditions, raise concerns about the extent to which cell line biology and potential drug responses may have deviated from clinical tumors. GEMMs are powerful tools for studying specific oncogenic mechanisms in isolation in vivo, but these models lack the intratumoral heterogeneity of patient tumors, which is thought to play a major role in the development of drug resistance. Furthermore, ideally, GEMMs should be constructed using the appropriate cell of origin context, which is challenging, as there are differences in the compositions of human and murine airways, and the cellular origins for most forms of lung cancer have not been established.
NSCLC patient-derived xenografts (PDXs) overcome some of the limitations of these other models. They show much less genetic drift than cell lines, and their mRNA expression and the phospho-tyrosyl proteome more closely match patient tumors 1, 2. We have established a large collection of NSCLC PDXs from surgically resected tumors and endobronchial ultrasound-guided (EBUS) and CT-guided biopsies. Tumor specimens were initially implanted in the subcutaneous flanks of NSG mice (NOD SCID gamma, non-obese diabetic severe combined immunodeficiency, gamma). The PDX tumors have been viably cryopreserved and can be serially passaged in NOD SCID mice. Most of our collection comprises the major histologic subtypes of NSCLC [52 adenocarcinomas (LUAD) and 62 squamous cell carcinomas (LUSC)]. They, along with the primary patient tumors, are being molecularly profiled at multiple levels so that they can be optimally used for personalized medicine studies and novel integrated approaches to understand NSCLC pathogenesis, prognosis, and treatment. These levels include copy number variations, exome mutations, DNA methylation, mRNA and miRNA expression, and proteomics. In general, the PDX models recapitulate the mutation spectrum, copy number variations, and gene expression of matched patient histologies. They also recapitulate sensitivity and resistance to known targeted therapeutics (e.g. EGFR inhibitors), and thus, can be used to dissect mechanisms underlying differential drug responses. Such studies are ongoing, including investigation of potentially new biomarker-targeted therapeutic combinations. We have also found that not all patient tumor fragments engraft successfully, and that successful engraftment correlates with poor prognosis of the patient 3. We are using this relationship to discover a new molecular fingerprint to predict clinical outcome, as well as understand the bases that distinguish less and more aggressive tumor behavior.
In parallel, we have developed methods to grow organoids from primary patient tumors and PDX models in 3D culture using Matrigel (PDO and XDO, respectively). For LUAD, both the PDO and XDO success rate of establishing bona fide organoid models is ~20%. Our stringent criteria include a minimum capacity of 10 passages and a split ratio of at least 1:3. LUSC has been more difficult to establish as organoid models, with a success rate of 17%, and only from PDXs, so far. Using these methods, we have established 4 models of each histology, which we have confirmed form tumors when transplanted into mice. Molecular profiling indicates that the organoids maintain the same mutation spectrum and copy number variations of their parental tumor tissue. These models offer distinct advantages over PDXs and cell lines. As compared to standard 2D cultures, they recapitulate the appropriate tissue histology, and thus, possibly clinically relevant growth control mechanisms, even while growing ex vivo. This notion is further supported by the ex vivo conditions supporting gene expression patterns, which allows the organoids to be segregated into their respective tumor histologies when using signatures derived from patient or PDX material. Given the low cost, rapid growth rates, and ease of in vitro manipulation, these models are ideally suited for rapid discovery and testing of new therapeutic strategies that can be matched to specific patient molecular profiles.
In summary, generation of molecularly profiled PDX and organoid models offer great opportunity for translational and personalized medicine in NSCLC.
1. Gao, H. et al. High-throughput screening using patient-derived tumor xenografts to predict clinical trial drug response. Nat. Med. 21, 1318-1325 (2015).
2. Wang, D. et al. Molecular heterogeneity of non-small cell lung carcinoma patient-derived xenografts closely reflect their primary tumors. Int. J. Cancer 140, 662-673 (2017).
3. John, T. et al. The ability to form primary tumor xenografts is predictive of increased risk of disease recurrence in early-stage non-small cell lung cancer. Clin. Cancer Res. 17, 134-141 (2011).
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