Development and Characterization of Bladder Cancer Patient-Derived Xenografts for Molecularly Guided Targeted Therapy

Abstract

BackgroundThe overarching goal of this project is to establish a patient-derived bladder cancer xenograft (PDX) platform, annotated with deep sequencing and patient clinical information, to accelerate the development of new treatment options for bladder cancer patients. Herein, we describe the creation, initial characterization and use of the platform for this purpose.Methods and FindingsTwenty-two PDXs with annotated clinical information were established from uncultured unselected clinical bladder cancer specimens in immunodeficient NSG mice. The morphological fidelity was maintained in PDXs. Whole exome sequencing revealed that PDXs and parental patient cancers shared 92–97% of genetic aberrations, including multiple druggable targets. For drug repurposing, an EGFR/HER2 dual inhibitor lapatinib was effective in PDX BL0440 (progression-free survival or PFS of 25.4 days versus 18.4 days in the control, p = 0.007), but not in PDX BL0269 (12 days versus 13 days in the control, p = 0.16) although both expressed HER2. To screen for the most effective MTT, we evaluated three drugs (lapatinib, ponatinib, and BEZ235) matched with aberrations in PDX BL0269; but only a PIK3CA inhibitor BEZ235 was effective (p<0.0001). To study the mechanisms of secondary resistance, a fibroblast growth factor receptor 3 inhibitor BGJ398 prolonged PFS of PDX BL0293 from 9.5 days of the control to 18.5 days (p<0.0001), and serial biopsies revealed that the MAPK/ERK and PIK3CA-AKT pathways were activated upon resistance. Inhibition of these pathways significantly prolonged PFS from 12 day of the control to 22 days (p = 0.001). To screen for effective chemotherapeutic drugs, four of the first six PDXs were sensitive to the cisplatin/gemcitabine combination, and chemoresistance to one drug could be overcome by the other drug.ConclusionThe PDX models described here show good correlation with the patient at the genomic level and known patient response to treatment. This supports further evaluation of the PDXs for their ability to accurately predict a patient’s response to new targeted and combination strategies for bladder cancer.

Microdose-Induced Drug–DNA Adducts as Biomarkers of Chemotherapy Resistance in Humans and Mice

“…We developed a diagnostic microdosing protocol to identify resistance to gemcitabine for use in a mouse model of human bladder cancer. We established four patient-derived tumor xenograft (PDX) mouse models from randomly selected myoinvasive bladder cancer patient volunteers using previously described protocols for nod scid gamma severe combined immune deficient (NSG) mice (26). These models were named BL0269 (TM00015), BL0293 (TM00016), BL0440 (TM00024) and BL0645 (TM01339), where the BL number is the UC Davis Comprehensive Cancer Center Biorepository number (http://www.ucdmc.ucdavis.edu/cancer/research/sharedresources/specimen.html) and the TM number is the Jackson Laboratory PDX database identifier (http://tumor.informatics.jax.org/mtbwi/pdxSearch.do).…”

“…Targeted sequencing data (whole-exome or JAX Cancer Treatment Profile) for each of the PDX (26) were filtered for 184 known DNA repair genes, including those found to correlate with response to neoadjuvant chemotherapy (NAC), such as ATM , FANCC , RB1 , BRCA1 , BRCA2 , ERCC1 , ERCC2 , and RAD51C (SI Table 5 and SI Table 6) (3, 36-39). A total of 112 somatic variants were identified in the four PDX models (SI Table 7).…”

“…Whole-exome sequencing (WES) on the Illumina platform was previously performed for each bladder cancer PDX model (26), but with new data analysis specific to DNA repair genes. Details are in Supplemental Information and the the raw sequence data files are publicly available through the NCBI BioProject database (https://www.ncbi.nlm.nih.gov/bioproject/) with Accession Number PRJNA352282.…”

WOMEN IN CANCER PROFILE: From physics to cancer biology and everywhere in between

“…Since then, she had moved to her first independent position in the California Northstate School of Pharmacy, but we still continued to collaborate, recently publishing a paper together on the effects of microRNAs in bladder cancer (Vinall et al 2016). Collaboration with Dr Pan, the medical oncologist who had conducted a clinical trial based on my 2008 study also yielded a publication on the utility of patient-derived xenografts (PDX) on individualized therapy in bladder cancer patients (Pan et al 2015). These collaborations all taught me something new, something important, and something I would not have otherwise learned.…”

Genomic profiling is predictive of response to cisplatin treatment but not to PI3K inhibition in bladder cancer patient-derived xenografts

“…To date, there is a limited number of established bladder cancer PDX models [4] that are molecularly characterized and available for testing drug resistance and sensitivity. Recent high throughput genomic studies have revealed several gene and pathway alterations associated with MIBC [5, 6], including PI3K/AKT/mTOR and ERK/MEK/RAS pathways as drivers of bladder cancer progression and potential targets for therapeutic interventions [3].…”