Dipartimento di Oncologia - test

Descrizione del progetto

Title:
Deciphering intratumor heterogeneity in epithelial ovarian cancer using patient derived xenografts

Topic:
To study intratumor heterogeneity (ITH) exploiting patient derived xenografts of ovarian cancer . The in-depth functional and genomic analyses of other PDX platforms showed that clonal selection occurred at engraftment and propagations. Interestingly, similar clonal expansion patterns emerged in independent grafts of the same starting tumor population indicating that specific genomic aberrations could reproducibly determine evolutionary trajectories. This project is
mostly based on PDX lines of HGS-EOC that we have established. These PDX lines showed functional intra-line heterogeneity, i.e. different growth rate and response to drugs of individual PDXs, suggesting that they might be suitable models to study ITH of EOCs.

Background:
The extensive intratumor heterogeneity (ITH) revealed by sequencing cancer genomes is an essential determinant of tumor progression, diagnosis and treatment. It is the result of the action of the evolutionary forces of mutation and selection. A high level of ITH affects high-grade serous epithelial ovarian cancer (HGS-EOC) and may contribute to the failure of cure, by initiating phenotypic diversity and enabling more aggressive and drug resistant clones. The studies of breast and non-small cell lung carcinomas and leukemia showed that ITH evolves also during the growth of these tumors as patient derived xenografts (PDXs). The question of whether the clonal dynamics seen in PDXs reproduce the clonal evolution of the patient's source tumor still remains. Nevertheless, the study of the clonal evolution of PDXs of HGS-EOC might provide useful information for functional studies aimed at using this model.

Goal:
The in-depth functional and genomic analyses of other PDX platforms showed that clonal selection occurred at engraftment and propagations. Interestingly, similar clonal expansion patterns emerged in independent grafts of the same starting tumor population indicating that specific genomic aberrations could reproducibly determine evolutionary trajectories. This project is
mostly based on PDX lines of HGS-EOC that we have established. These PDX lines showed functional intra-line heterogeneity, i.e. different growth rate and response to drugs of individual PDXs, suggesting that they might be suitable models to study ITH of EOCs.
Aims
-To evaluate the ITH of PDXs of HGS-EOC.
-To measure the clonal dynamics of HGS-EOC PDXs.
-To assess if clonal dynamics in these PDXs is not stochastic, but deterministic.
-To understand how well these PDXs reflect the clonal composition and dynamics of patient tumors.
-To attempt the identification of driver genetic aberrations that enable clonal fitness in these PDXs.

Achievements:
We have established and propagated 32 PDX lines of HGS-EOCs up to 6 generations. Others are under scrutiny and propagation. We are carrying out: (i) an unbiased functional classification of PDXs in each line as far as growth rate and response to platinum drugs; (ii) exome sequencing of PDXs; (iii) data analysis to assess clonal composition and dynamics. Future work entails (iv) replicas of PDXs to assess consistency of genomic clone selection; (v) lineage tracing of PDX propagating cells; (vi) exome sequencing and data analyses of source tumors to detect pre-existing genomic clones; (vii) comparison of the clonal dynamics of source tumors and the relevant PDX lines by studying spatially separated samples of HGS-EOC; (viii) comparison of the clonal dynamics of source tumors and PDX lines prior and after drug treatment; (ix) in silico exploratory identification of genetic aberrations that give rise to clonal fitness.